1054 lines
33 KiB
Go
1054 lines
33 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package container creates and manipulates containers.
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package container
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import (
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"context"
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"encoding/json"
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"fmt"
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"io/ioutil"
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"os"
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"os/exec"
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"os/signal"
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"path/filepath"
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"regexp"
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"strconv"
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"strings"
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"syscall"
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"time"
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"github.com/cenkalti/backoff"
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"github.com/gofrs/flock"
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specs "github.com/opencontainers/runtime-spec/specs-go"
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"gvisor.googlesource.com/gvisor/pkg/log"
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"gvisor.googlesource.com/gvisor/pkg/sentry/control"
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"gvisor.googlesource.com/gvisor/runsc/boot"
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"gvisor.googlesource.com/gvisor/runsc/cgroup"
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"gvisor.googlesource.com/gvisor/runsc/sandbox"
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"gvisor.googlesource.com/gvisor/runsc/specutils"
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)
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const (
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// metadataFilename is the name of the metadata file relative to the
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// container root directory that holds sandbox metadata.
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metadataFilename = "meta.json"
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// metadataLockFilename is the name of a lock file in the container
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// root directory that is used to prevent concurrent modifications to
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// the container state and metadata.
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metadataLockFilename = "meta.lock"
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)
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// validateID validates the container id.
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func validateID(id string) error {
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// See libcontainer/factory_linux.go.
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idRegex := regexp.MustCompile(`^[\w+-\.]+$`)
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if !idRegex.MatchString(id) {
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return fmt.Errorf("invalid container id: %v", id)
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}
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return nil
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}
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// Container represents a containerized application. When running, the
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// container is associated with a single Sandbox.
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//
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// Container metadata can be saved and loaded to disk. Within a root directory,
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// we maintain subdirectories for each container named with the container id.
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// The container metadata is stored as a json within the container directory
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// in a file named "meta.json". This metadata format is defined by us and is
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// not part of the OCI spec.
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//
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// Containers must write their metadata files after any change to their internal
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// states. The entire container directory is deleted when the container is
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// destroyed.
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//
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// When the container is stopped, all processes that belong to the container
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// must be stopped before Destroy() returns. containerd makes roughly the
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// following calls to stop a container:
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// - First it attempts to kill the container process with
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// 'runsc kill SIGTERM'. After some time, it escalates to SIGKILL. In a
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// separate thread, it's waiting on the container. As soon as the wait
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// returns, it moves on to the next step:
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// - It calls 'runsc kill --all SIGKILL' to stop every process that belongs to
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// the container. 'kill --all SIGKILL' waits for all processes before
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// returning.
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// - Containerd waits for stdin, stdout and stderr to drain and be closed.
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// - It calls 'runsc delete'. runc implementation kills --all SIGKILL once
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// again just to be sure, waits, and then proceeds with remaining teardown.
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//
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type Container struct {
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// ID is the container ID.
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ID string `json:"id"`
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// Spec is the OCI runtime spec that configures this container.
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Spec *specs.Spec `json:"spec"`
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// BundleDir is the directory containing the container bundle.
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BundleDir string `json:"bundleDir"`
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// Root is the directory containing the container metadata file. If this
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// container is the root container, Root and RootContainerDir will be the
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// same.
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Root string `json:"root"`
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// CreatedAt is the time the container was created.
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CreatedAt time.Time `json:"createdAt"`
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// Owner is the container owner.
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Owner string `json:"owner"`
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// ConsoleSocket is the path to a unix domain socket that will receive
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// the console FD.
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ConsoleSocket string `json:"consoleSocket"`
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// Status is the current container Status.
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Status Status `json:"status"`
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// GoferPid is the PID of the gofer running along side the sandbox. May
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// be 0 if the gofer has been killed.
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GoferPid int `json:"goferPid"`
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// goferIsChild is set if a gofer process is a child of the current process.
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//
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// This field isn't saved to json, because only a creator of a gofer
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// process will have it as a child process.
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goferIsChild bool
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// Sandbox is the sandbox this container is running in. It's set when the
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// container is created and reset when the sandbox is destroyed.
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Sandbox *sandbox.Sandbox `json:"sandbox"`
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// RootContainerDir is the root directory containing the metadata file of the
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// sandbox root container. It's used to lock in order to serialize creating
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// and deleting this Container's metadata directory. If this container is the
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// root container, this is the same as Root.
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RootContainerDir string
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}
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// Load loads a container with the given id from a metadata file. id may be an
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// abbreviation of the full container id, in which case Load loads the
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// container to which id unambiguously refers to.
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// Returns ErrNotExist if container doesn't exist.
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func Load(rootDir, id string) (*Container, error) {
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log.Debugf("Load container %q %q", rootDir, id)
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if err := validateID(id); err != nil {
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return nil, fmt.Errorf("validating id: %v", err)
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}
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cRoot, err := findContainerRoot(rootDir, id)
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if err != nil {
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// Preserve error so that callers can distinguish 'not found' errors.
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return nil, err
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}
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// Lock the container metadata to prevent other runsc instances from
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// writing to it while we are reading it.
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unlock, err := lockContainerMetadata(cRoot)
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if err != nil {
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return nil, err
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}
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defer unlock()
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// Read the container metadata file and create a new Container from it.
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metaFile := filepath.Join(cRoot, metadataFilename)
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metaBytes, err := ioutil.ReadFile(metaFile)
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if err != nil {
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if os.IsNotExist(err) {
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// Preserve error so that callers can distinguish 'not found' errors.
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return nil, err
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}
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return nil, fmt.Errorf("reading container metadata file %q: %v", metaFile, err)
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}
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var c Container
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if err := json.Unmarshal(metaBytes, &c); err != nil {
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return nil, fmt.Errorf("unmarshaling container metadata from %q: %v", metaFile, err)
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}
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// If the status is "Running" or "Created", check that the sandbox
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// process still exists, and set it to Stopped if it does not.
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//
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// This is inherently racey.
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if c.Status == Running || c.Status == Created {
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// Check if the sandbox process is still running.
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if !c.isSandboxRunning() {
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// Sandbox no longer exists, so this container definitely does not exist.
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c.changeStatus(Stopped)
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} else if c.Status == Running {
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// Container state should reflect the actual state of the application, so
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// we don't consider gofer process here.
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if err := c.SignalContainer(syscall.Signal(0), false); err != nil {
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c.changeStatus(Stopped)
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}
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}
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}
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return &c, nil
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}
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func findContainerRoot(rootDir, partialID string) (string, error) {
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// Check whether the id fully specifies an existing container.
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cRoot := filepath.Join(rootDir, partialID)
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if _, err := os.Stat(cRoot); err == nil {
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return cRoot, nil
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}
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// Now see whether id could be an abbreviation of exactly 1 of the
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// container ids. If id is ambigious (it could match more than 1
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// container), it is an error.
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cRoot = ""
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ids, err := List(rootDir)
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if err != nil {
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return "", err
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}
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for _, id := range ids {
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if strings.HasPrefix(id, partialID) {
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if cRoot != "" {
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return "", fmt.Errorf("id %q is ambiguous and could refer to multiple containers: %q, %q", partialID, cRoot, id)
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}
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cRoot = id
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}
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}
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if cRoot == "" {
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return "", os.ErrNotExist
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}
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log.Debugf("abbreviated id %q resolves to full id %q", partialID, cRoot)
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return filepath.Join(rootDir, cRoot), nil
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}
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// List returns all container ids in the given root directory.
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func List(rootDir string) ([]string, error) {
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log.Debugf("List containers %q", rootDir)
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fs, err := ioutil.ReadDir(rootDir)
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if err != nil {
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return nil, fmt.Errorf("reading dir %q: %v", rootDir, err)
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}
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var out []string
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for _, f := range fs {
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out = append(out, f.Name())
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}
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return out, nil
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}
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// Create creates the container in a new Sandbox process, unless the metadata
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// indicates that an existing Sandbox should be used. The caller must call
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// Destroy() on the container.
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func Create(id string, spec *specs.Spec, conf *boot.Config, bundleDir, consoleSocket, pidFile, userLog string) (*Container, error) {
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log.Debugf("Create container %q in root dir: %s", id, conf.RootDir)
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if err := validateID(id); err != nil {
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return nil, err
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}
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unlockRoot, err := maybeLockRootContainer(spec, conf.RootDir)
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if err != nil {
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return nil, err
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}
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defer unlockRoot()
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// Lock the container metadata file to prevent concurrent creations of
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// containers with the same id.
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containerRoot := filepath.Join(conf.RootDir, id)
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unlock, err := lockContainerMetadata(containerRoot)
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if err != nil {
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return nil, err
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}
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defer unlock()
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// Check if the container already exists by looking for the metadata
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// file.
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if _, err := os.Stat(filepath.Join(containerRoot, metadataFilename)); err == nil {
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return nil, fmt.Errorf("container with id %q already exists", id)
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} else if !os.IsNotExist(err) {
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return nil, fmt.Errorf("looking for existing container in %q: %v", containerRoot, err)
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}
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c := &Container{
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ID: id,
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Spec: spec,
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ConsoleSocket: consoleSocket,
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BundleDir: bundleDir,
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Root: containerRoot,
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Status: Creating,
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CreatedAt: time.Now(),
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Owner: os.Getenv("USER"),
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RootContainerDir: conf.RootDir,
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}
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// The Cleanup object cleans up partially created containers when an error occurs.
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// Any errors occuring during cleanup itself are ignored.
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cu := specutils.MakeCleanup(func() { _ = c.Destroy() })
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defer cu.Clean()
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// If the metadata annotations indicate that this container should be
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// started in an existing sandbox, we must do so. The metadata will
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// indicate the ID of the sandbox, which is the same as the ID of the
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// init container in the sandbox.
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if isRoot(spec) {
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log.Debugf("Creating new sandbox for container %q", id)
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// Create and join cgroup before processes are created to ensure they are
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// part of the cgroup from the start (and all tneir children processes).
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cg, err := cgroup.New(spec)
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if err != nil {
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return nil, err
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}
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if cg != nil {
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// If there is cgroup config, install it before creating sandbox process.
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if err := cg.Install(spec.Linux.Resources); err != nil {
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return nil, fmt.Errorf("configuring cgroup: %v", err)
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}
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}
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if err := runInCgroup(cg, func() error {
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ioFiles, specFile, err := c.createGoferProcess(spec, conf, bundleDir)
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if err != nil {
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return err
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}
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// Start a new sandbox for this container. Any errors after this point
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// must destroy the container.
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c.Sandbox, err = sandbox.New(id, spec, conf, bundleDir, consoleSocket, userLog, ioFiles, specFile, cg)
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return err
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}); err != nil {
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return nil, err
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}
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} else {
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// This is sort of confusing. For a sandbox with a root
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// container and a child container in it, runsc sees:
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// * A container struct whose sandbox ID is equal to the
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// container ID. This is the root container that is tied to
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// the creation of the sandbox.
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// * A container struct whose sandbox ID is equal to the above
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// container/sandbox ID, but that has a different container
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// ID. This is the child container.
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sbid, ok := specutils.SandboxID(spec)
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if !ok {
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return nil, fmt.Errorf("no sandbox ID found when creating container")
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}
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log.Debugf("Creating new container %q in sandbox %q", c.ID, sbid)
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// Find the sandbox associated with this ID.
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sb, err := Load(conf.RootDir, sbid)
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if err != nil {
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return nil, err
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}
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c.Sandbox = sb.Sandbox
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if err := c.Sandbox.CreateContainer(c.ID); err != nil {
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return nil, err
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}
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}
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c.changeStatus(Created)
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// Save the metadata file.
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if err := c.save(); err != nil {
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return nil, err
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}
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// Write the PID file. Containerd considers the create complete after
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// this file is created, so it must be the last thing we do.
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if pidFile != "" {
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if err := ioutil.WriteFile(pidFile, []byte(strconv.Itoa(c.SandboxPid())), 0644); err != nil {
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return nil, fmt.Errorf("error writing PID file: %v", err)
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}
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}
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cu.Release()
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return c, nil
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}
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// Start starts running the containerized process inside the sandbox.
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func (c *Container) Start(conf *boot.Config) error {
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log.Debugf("Start container %q", c.ID)
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unlockRoot, err := maybeLockRootContainer(c.Spec, c.RootContainerDir)
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if err != nil {
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return err
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}
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defer unlockRoot()
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unlock, err := c.lock()
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if err != nil {
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return err
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}
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defer unlock()
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if err := c.requireStatus("start", Created); err != nil {
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return err
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}
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// "If any prestart hook fails, the runtime MUST generate an error,
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// stop and destroy the container" -OCI spec.
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if c.Spec.Hooks != nil {
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if err := executeHooks(c.Spec.Hooks.Prestart, c.State()); err != nil {
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return err
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}
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}
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if isRoot(c.Spec) {
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if err := c.Sandbox.StartRoot(c.Spec, conf); err != nil {
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return err
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}
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} else {
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// Join cgroup to strt gofer process to ensure it's part of the cgroup from
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// the start (and all tneir children processes).
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if err := runInCgroup(c.Sandbox.Cgroup, func() error {
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// Create the gofer process.
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ioFiles, mountsFile, err := c.createGoferProcess(c.Spec, conf, c.BundleDir)
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if err != nil {
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return err
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}
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defer mountsFile.Close()
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cleanMounts, err := specutils.ReadMounts(mountsFile)
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if err != nil {
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return fmt.Errorf("reading mounts file: %v", err)
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}
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c.Spec.Mounts = cleanMounts
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return c.Sandbox.StartContainer(c.Spec, conf, c.ID, ioFiles)
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}); err != nil {
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return err
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}
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}
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// "If any poststart hook fails, the runtime MUST log a warning, but
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// the remaining hooks and lifecycle continue as if the hook had
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// succeeded" -OCI spec.
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if c.Spec.Hooks != nil {
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executeHooksBestEffort(c.Spec.Hooks.Poststart, c.State())
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}
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c.changeStatus(Running)
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return c.save()
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}
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// Restore takes a container and replaces its kernel and file system
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// to restore a container from its state file.
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func (c *Container) Restore(spec *specs.Spec, conf *boot.Config, restoreFile string) error {
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log.Debugf("Restore container %q", c.ID)
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unlock, err := c.lock()
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if err != nil {
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return err
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}
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defer unlock()
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if err := c.requireStatus("restore", Created); err != nil {
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return err
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}
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// "If any prestart hook fails, the runtime MUST generate an error,
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// stop and destroy the container" -OCI spec.
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if c.Spec.Hooks != nil {
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if err := executeHooks(c.Spec.Hooks.Prestart, c.State()); err != nil {
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return err
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}
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}
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if err := c.Sandbox.Restore(c.ID, spec, conf, restoreFile); err != nil {
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return err
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}
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c.changeStatus(Running)
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return c.save()
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}
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// Run is a helper that calls Create + Start + Wait.
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func Run(id string, spec *specs.Spec, conf *boot.Config, bundleDir, consoleSocket, pidFile, userLog string, detach bool) (syscall.WaitStatus, error) {
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log.Debugf("Run container %q in root dir: %s", id, conf.RootDir)
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c, err := Create(id, spec, conf, bundleDir, consoleSocket, pidFile, userLog)
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if err != nil {
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return 0, fmt.Errorf("creating container: %v", err)
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}
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// Clean up partially created container if an error ocurrs.
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// Any errors returned by Destroy() itself are ignored.
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cu := specutils.MakeCleanup(func() {
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c.Destroy()
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})
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defer cu.Clean()
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if conf.RestoreFile != "" {
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log.Debugf("Restore: %v", conf.RestoreFile)
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if err := c.Restore(spec, conf, conf.RestoreFile); err != nil {
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return 0, fmt.Errorf("starting container: %v", err)
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}
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} else {
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if err := c.Start(conf); err != nil {
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return 0, fmt.Errorf("starting container: %v", err)
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}
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}
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if detach {
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cu.Release()
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return 0, nil
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}
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return c.Wait()
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}
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// Execute runs the specified command in the container. It returns the PID of
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// the newly created process.
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func (c *Container) Execute(args *control.ExecArgs) (int32, error) {
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log.Debugf("Execute in container %q, args: %+v", c.ID, args)
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if err := c.requireStatus("execute in", Created, Running); err != nil {
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return 0, err
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}
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args.ContainerID = c.ID
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return c.Sandbox.Execute(args)
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}
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|
|
// Event returns events for the container.
|
|
func (c *Container) Event() (*boot.Event, error) {
|
|
log.Debugf("Getting events for container %q", c.ID)
|
|
if err := c.requireStatus("get events for", Created, Running, Paused); err != nil {
|
|
return nil, err
|
|
}
|
|
return c.Sandbox.Event(c.ID)
|
|
}
|
|
|
|
// SandboxPid returns the Pid of the sandbox the container is running in, or -1 if the
|
|
// container is not running.
|
|
func (c *Container) SandboxPid() int {
|
|
if err := c.requireStatus("get PID", Created, Running, Paused); err != nil {
|
|
return -1
|
|
}
|
|
return c.Sandbox.Pid
|
|
}
|
|
|
|
// Wait waits for the container to exit, and returns its WaitStatus.
|
|
// Call to wait on a stopped container is needed to retrieve the exit status
|
|
// and wait returns immediately.
|
|
func (c *Container) Wait() (syscall.WaitStatus, error) {
|
|
log.Debugf("Wait on container %q", c.ID)
|
|
return c.Sandbox.Wait(c.ID)
|
|
}
|
|
|
|
// WaitRootPID waits for process 'pid' in the sandbox's PID namespace and
|
|
// returns its WaitStatus.
|
|
func (c *Container) WaitRootPID(pid int32) (syscall.WaitStatus, error) {
|
|
log.Debugf("Wait on PID %d in sandbox %q", pid, c.Sandbox.ID)
|
|
if !c.isSandboxRunning() {
|
|
return 0, fmt.Errorf("sandbox is not running")
|
|
}
|
|
return c.Sandbox.WaitPID(c.Sandbox.ID, pid)
|
|
}
|
|
|
|
// WaitPID waits for process 'pid' in the container's PID namespace and returns
|
|
// its WaitStatus.
|
|
func (c *Container) WaitPID(pid int32) (syscall.WaitStatus, error) {
|
|
log.Debugf("Wait on PID %d in container %q", pid, c.ID)
|
|
if !c.isSandboxRunning() {
|
|
return 0, fmt.Errorf("sandbox is not running")
|
|
}
|
|
return c.Sandbox.WaitPID(c.ID, pid)
|
|
}
|
|
|
|
// SignalContainer sends the signal to the container. If all is true and signal
|
|
// is SIGKILL, then waits for all processes to exit before returning.
|
|
// SignalContainer returns an error if the container is already stopped.
|
|
// TODO(b/113680494): Distinguish different error types.
|
|
func (c *Container) SignalContainer(sig syscall.Signal, all bool) error {
|
|
log.Debugf("Signal container %q: %v", c.ID, sig)
|
|
// Signaling container in Stopped state is allowed. When all=false,
|
|
// an error will be returned anyway; when all=true, this allows
|
|
// sending signal to other processes inside the container even
|
|
// after the init process exits. This is especially useful for
|
|
// container cleanup.
|
|
if err := c.requireStatus("signal", Running, Stopped); err != nil {
|
|
return err
|
|
}
|
|
if !c.isSandboxRunning() {
|
|
return fmt.Errorf("sandbox is not running")
|
|
}
|
|
return c.Sandbox.SignalContainer(c.ID, sig, all)
|
|
}
|
|
|
|
// SignalProcess sends sig to a specific process in the container.
|
|
func (c *Container) SignalProcess(sig syscall.Signal, pid int32) error {
|
|
log.Debugf("Signal process %d in container %q: %v", pid, c.ID, sig)
|
|
if err := c.requireStatus("signal a process inside", Running); err != nil {
|
|
return err
|
|
}
|
|
if !c.isSandboxRunning() {
|
|
return fmt.Errorf("sandbox is not running")
|
|
}
|
|
return c.Sandbox.SignalProcess(c.ID, int32(pid), sig, false)
|
|
}
|
|
|
|
// ForwardSignals forwards all signals received by the current process to the
|
|
// container process inside the sandbox. It returns a function that will stop
|
|
// forwarding signals.
|
|
func (c *Container) ForwardSignals(pid int32, fgProcess bool) func() {
|
|
log.Debugf("Forwarding all signals to container %q PID %d fgProcess=%t", c.ID, pid, fgProcess)
|
|
sigCh := make(chan os.Signal, 1)
|
|
signal.Notify(sigCh)
|
|
go func() {
|
|
for s := range sigCh {
|
|
log.Debugf("Forwarding signal %d to container %q PID %d fgProcess=%t", s, c.ID, pid, fgProcess)
|
|
if err := c.Sandbox.SignalProcess(c.ID, pid, s.(syscall.Signal), fgProcess); err != nil {
|
|
log.Warningf("error forwarding signal %d to container %q: %v", s, c.ID, err)
|
|
}
|
|
}
|
|
log.Debugf("Done forwarding signals to container %q PID %d fgProcess=%t", c.ID, pid, fgProcess)
|
|
}()
|
|
|
|
return func() {
|
|
signal.Stop(sigCh)
|
|
close(sigCh)
|
|
}
|
|
}
|
|
|
|
// Checkpoint sends the checkpoint call to the container.
|
|
// The statefile will be written to f, the file at the specified image-path.
|
|
func (c *Container) Checkpoint(f *os.File) error {
|
|
log.Debugf("Checkpoint container %q", c.ID)
|
|
if err := c.requireStatus("checkpoint", Created, Running, Paused); err != nil {
|
|
return err
|
|
}
|
|
return c.Sandbox.Checkpoint(c.ID, f)
|
|
}
|
|
|
|
// Pause suspends the container and its kernel.
|
|
// The call only succeeds if the container's status is created or running.
|
|
func (c *Container) Pause() error {
|
|
log.Debugf("Pausing container %q", c.ID)
|
|
unlock, err := c.lock()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer unlock()
|
|
|
|
if c.Status != Created && c.Status != Running {
|
|
return fmt.Errorf("cannot pause container %q in state %v", c.ID, c.Status)
|
|
}
|
|
|
|
if err := c.Sandbox.Pause(c.ID); err != nil {
|
|
return fmt.Errorf("pausing container: %v", err)
|
|
}
|
|
c.changeStatus(Paused)
|
|
return c.save()
|
|
}
|
|
|
|
// Resume unpauses the container and its kernel.
|
|
// The call only succeeds if the container's status is paused.
|
|
func (c *Container) Resume() error {
|
|
log.Debugf("Resuming container %q", c.ID)
|
|
unlock, err := c.lock()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer unlock()
|
|
|
|
if c.Status != Paused {
|
|
return fmt.Errorf("cannot resume container %q in state %v", c.ID, c.Status)
|
|
}
|
|
if err := c.Sandbox.Resume(c.ID); err != nil {
|
|
return fmt.Errorf("resuming container: %v", err)
|
|
}
|
|
c.changeStatus(Running)
|
|
return c.save()
|
|
}
|
|
|
|
// State returns the metadata of the container.
|
|
func (c *Container) State() specs.State {
|
|
return specs.State{
|
|
Version: specs.Version,
|
|
ID: c.ID,
|
|
Status: c.Status.String(),
|
|
Pid: c.SandboxPid(),
|
|
Bundle: c.BundleDir,
|
|
}
|
|
}
|
|
|
|
// Processes retrieves the list of processes and associated metadata inside a
|
|
// container.
|
|
func (c *Container) Processes() ([]*control.Process, error) {
|
|
if err := c.requireStatus("get processes of", Running, Paused); err != nil {
|
|
return nil, err
|
|
}
|
|
return c.Sandbox.Processes(c.ID)
|
|
}
|
|
|
|
// Destroy stops all processes and frees all resources associated with the
|
|
// container.
|
|
func (c *Container) Destroy() error {
|
|
log.Debugf("Destroy container %q", c.ID)
|
|
|
|
// We must perform the following cleanup steps:
|
|
// * stop the container and gofer processes,
|
|
// * remove the container filesystem on the host, and
|
|
// * delete the container metadata directory.
|
|
//
|
|
// It's possible for one or more of these steps to fail, but we should
|
|
// do our best to perform all of the cleanups. Hence, we keep a slice
|
|
// of errors return their concatenation.
|
|
var errs []string
|
|
|
|
unlock, err := maybeLockRootContainer(c.Spec, c.RootContainerDir)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer unlock()
|
|
|
|
if err := c.stop(); err != nil {
|
|
err = fmt.Errorf("stopping container: %v", err)
|
|
log.Warningf("%v", err)
|
|
errs = append(errs, err.Error())
|
|
}
|
|
|
|
if err := os.RemoveAll(c.Root); err != nil && !os.IsNotExist(err) {
|
|
err = fmt.Errorf("deleting container root directory %q: %v", c.Root, err)
|
|
log.Warningf("%v", err)
|
|
errs = append(errs, err.Error())
|
|
}
|
|
|
|
c.changeStatus(Stopped)
|
|
|
|
// "If any poststop hook fails, the runtime MUST log a warning, but the
|
|
// remaining hooks and lifecycle continue as if the hook had succeeded" -OCI spec.
|
|
// Based on the OCI, "The post-stop hooks MUST be called after the container is
|
|
// deleted but before the delete operation returns"
|
|
// Run it here to:
|
|
// 1) Conform to the OCI.
|
|
// 2) Make sure it only runs once, because the root has been deleted, the container
|
|
// can't be loaded again.
|
|
if c.Spec.Hooks != nil {
|
|
executeHooksBestEffort(c.Spec.Hooks.Poststop, c.State())
|
|
}
|
|
|
|
if len(errs) == 0 {
|
|
return nil
|
|
}
|
|
return fmt.Errorf(strings.Join(errs, "\n"))
|
|
}
|
|
|
|
// save saves the container metadata to a file.
|
|
//
|
|
// Precondition: container must be locked with container.lock().
|
|
func (c *Container) save() error {
|
|
log.Debugf("Save container %q", c.ID)
|
|
metaFile := filepath.Join(c.Root, metadataFilename)
|
|
meta, err := json.Marshal(c)
|
|
if err != nil {
|
|
return fmt.Errorf("invalid container metadata: %v", err)
|
|
}
|
|
if err := ioutil.WriteFile(metaFile, meta, 0640); err != nil {
|
|
return fmt.Errorf("writing container metadata: %v", err)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// stop stops the container (for regular containers) or the sandbox (for
|
|
// root containers), and waits for the container or sandbox and the gofer
|
|
// to stop. If any of them doesn't stop before timeout, an error is returned.
|
|
func (c *Container) stop() error {
|
|
var cgroup *cgroup.Cgroup
|
|
|
|
if c.Sandbox != nil {
|
|
log.Debugf("Destroying container %q", c.ID)
|
|
if err := c.Sandbox.DestroyContainer(c.ID); err != nil {
|
|
return fmt.Errorf("destroying container %q: %v", c.ID, err)
|
|
}
|
|
// Only uninstall cgroup for sandbox stop.
|
|
if c.Sandbox.IsRootContainer(c.ID) {
|
|
cgroup = c.Sandbox.Cgroup
|
|
}
|
|
// Only set sandbox to nil after it has been told to destroy the container.
|
|
c.Sandbox = nil
|
|
}
|
|
|
|
// Try killing gofer if it does not exit with container.
|
|
if c.GoferPid != 0 {
|
|
log.Debugf("Killing gofer for container %q, PID: %d", c.ID, c.GoferPid)
|
|
if err := syscall.Kill(c.GoferPid, syscall.SIGKILL); err != nil {
|
|
// The gofer may already be stopped, log the error.
|
|
log.Warningf("Error sending signal %d to gofer %d: %v", syscall.SIGKILL, c.GoferPid, err)
|
|
}
|
|
}
|
|
|
|
if err := c.waitForStopped(); err != nil {
|
|
return err
|
|
}
|
|
|
|
// Gofer is running in cgroups, so Cgroup.Uninstall has to be called after it.
|
|
if cgroup != nil {
|
|
if err := cgroup.Uninstall(); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (c *Container) waitForStopped() error {
|
|
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
|
|
defer cancel()
|
|
b := backoff.WithContext(backoff.NewConstantBackOff(100*time.Millisecond), ctx)
|
|
op := func() error {
|
|
if c.isSandboxRunning() {
|
|
if err := c.SignalContainer(syscall.Signal(0), false); err == nil {
|
|
return fmt.Errorf("container is still running")
|
|
}
|
|
}
|
|
if c.GoferPid == 0 {
|
|
return nil
|
|
}
|
|
if c.goferIsChild {
|
|
// The gofer process is a child of the current process,
|
|
// so we can wait it and collect its zombie.
|
|
wpid, err := syscall.Wait4(int(c.GoferPid), nil, syscall.WNOHANG, nil)
|
|
if err != nil {
|
|
return fmt.Errorf("error waiting the gofer process: %v", err)
|
|
}
|
|
if wpid == 0 {
|
|
return fmt.Errorf("gofer is still running")
|
|
}
|
|
|
|
} else if err := syscall.Kill(c.GoferPid, 0); err == nil {
|
|
return fmt.Errorf("gofer is still running")
|
|
}
|
|
c.GoferPid = 0
|
|
return nil
|
|
}
|
|
return backoff.Retry(op, b)
|
|
}
|
|
|
|
func (c *Container) createGoferProcess(spec *specs.Spec, conf *boot.Config, bundleDir string) ([]*os.File, *os.File, error) {
|
|
// Start with the general config flags.
|
|
args := conf.ToFlags()
|
|
|
|
var goferEnds []*os.File
|
|
|
|
// nextFD is the next available file descriptor for the gofer process.
|
|
// It starts at 3 because 0-2 are used by stdin/stdout/stderr.
|
|
nextFD := 3
|
|
|
|
if conf.LogFilename != "" {
|
|
logFile, err := os.OpenFile(conf.LogFilename, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
|
|
if err != nil {
|
|
return nil, nil, fmt.Errorf("opening log file %q: %v", conf.LogFilename, err)
|
|
}
|
|
defer logFile.Close()
|
|
goferEnds = append(goferEnds, logFile)
|
|
args = append(args, "--log-fd="+strconv.Itoa(nextFD))
|
|
nextFD++
|
|
}
|
|
|
|
if conf.DebugLog != "" {
|
|
debugLogFile, err := specutils.DebugLogFile(conf.DebugLog, "gofer")
|
|
if err != nil {
|
|
return nil, nil, fmt.Errorf("opening debug log file in %q: %v", conf.DebugLog, err)
|
|
}
|
|
defer debugLogFile.Close()
|
|
goferEnds = append(goferEnds, debugLogFile)
|
|
args = append(args, "--debug-log-fd="+strconv.Itoa(nextFD))
|
|
nextFD++
|
|
}
|
|
|
|
args = append(args, "gofer", "--bundle", bundleDir)
|
|
if conf.Overlay {
|
|
args = append(args, "--panic-on-write=true")
|
|
}
|
|
|
|
// Open the spec file to donate to the sandbox.
|
|
specFile, err := specutils.OpenSpec(bundleDir)
|
|
if err != nil {
|
|
return nil, nil, fmt.Errorf("opening spec file: %v", err)
|
|
}
|
|
defer specFile.Close()
|
|
goferEnds = append(goferEnds, specFile)
|
|
args = append(args, "--spec-fd="+strconv.Itoa(nextFD))
|
|
nextFD++
|
|
|
|
// Create pipe that allows gofer to send mount list to sandbox after all paths
|
|
// have been resolved.
|
|
mountsSand, mountsGofer, err := os.Pipe()
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
defer mountsGofer.Close()
|
|
goferEnds = append(goferEnds, mountsGofer)
|
|
args = append(args, fmt.Sprintf("--mounts-fd=%d", nextFD))
|
|
nextFD++
|
|
|
|
// Add root mount and then add any other additional mounts.
|
|
mountCount := 1
|
|
for _, m := range spec.Mounts {
|
|
if specutils.Is9PMount(m) {
|
|
mountCount++
|
|
}
|
|
}
|
|
|
|
sandEnds := make([]*os.File, 0, mountCount)
|
|
for i := 0; i < mountCount; i++ {
|
|
fds, err := syscall.Socketpair(syscall.AF_UNIX, syscall.SOCK_STREAM|syscall.SOCK_CLOEXEC, 0)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
sandEnds = append(sandEnds, os.NewFile(uintptr(fds[0]), "sandbox IO FD"))
|
|
|
|
goferEnd := os.NewFile(uintptr(fds[1]), "gofer IO FD")
|
|
defer goferEnd.Close()
|
|
goferEnds = append(goferEnds, goferEnd)
|
|
|
|
args = append(args, fmt.Sprintf("--io-fds=%d", nextFD))
|
|
nextFD++
|
|
}
|
|
|
|
binPath := specutils.ExePath
|
|
cmd := exec.Command(binPath, args...)
|
|
cmd.ExtraFiles = goferEnds
|
|
cmd.Args[0] = "runsc-gofer"
|
|
|
|
// Enter new namespaces to isolate from the rest of the system. Don't unshare
|
|
// cgroup because gofer is added to a cgroup in the caller's namespace.
|
|
nss := []specs.LinuxNamespace{
|
|
{Type: specs.IPCNamespace},
|
|
{Type: specs.MountNamespace},
|
|
{Type: specs.NetworkNamespace},
|
|
{Type: specs.PIDNamespace},
|
|
{Type: specs.UTSNamespace},
|
|
}
|
|
|
|
// Setup any uid/gid mappings, and create or join the configured user
|
|
// namespace so the gofer's view of the filesystem aligns with the
|
|
// users in the sandbox.
|
|
userNS := specutils.FilterNS([]specs.LinuxNamespaceType{specs.UserNamespace}, spec)
|
|
nss = append(nss, userNS...)
|
|
specutils.SetUIDGIDMappings(cmd, spec)
|
|
if len(userNS) != 0 {
|
|
// We need to set UID and GID to have capabilities in a new user namespace.
|
|
cmd.SysProcAttr.Credential = &syscall.Credential{Uid: 0, Gid: 0}
|
|
}
|
|
|
|
// Start the gofer in the given namespace.
|
|
log.Debugf("Starting gofer: %s %v", binPath, args)
|
|
if err := specutils.StartInNS(cmd, nss); err != nil {
|
|
return nil, nil, fmt.Errorf("Gofer: %v", err)
|
|
}
|
|
log.Infof("Gofer started, PID: %d", cmd.Process.Pid)
|
|
c.GoferPid = cmd.Process.Pid
|
|
c.goferIsChild = true
|
|
return sandEnds, mountsSand, nil
|
|
}
|
|
|
|
// changeStatus transitions from one status to another ensuring that the
|
|
// transition is valid.
|
|
func (c *Container) changeStatus(s Status) {
|
|
switch s {
|
|
case Creating:
|
|
// Initial state, never transitions to it.
|
|
panic(fmt.Sprintf("invalid state transition: %v => %v", c.Status, s))
|
|
|
|
case Created:
|
|
if c.Status != Creating {
|
|
panic(fmt.Sprintf("invalid state transition: %v => %v", c.Status, s))
|
|
}
|
|
if c.Sandbox == nil {
|
|
panic("sandbox cannot be nil")
|
|
}
|
|
|
|
case Paused:
|
|
if c.Status != Running {
|
|
panic(fmt.Sprintf("invalid state transition: %v => %v", c.Status, s))
|
|
}
|
|
if c.Sandbox == nil {
|
|
panic("sandbox cannot be nil")
|
|
}
|
|
|
|
case Running:
|
|
if c.Status != Created && c.Status != Paused {
|
|
panic(fmt.Sprintf("invalid state transition: %v => %v", c.Status, s))
|
|
}
|
|
if c.Sandbox == nil {
|
|
panic("sandbox cannot be nil")
|
|
}
|
|
|
|
case Stopped:
|
|
if c.Status != Creating && c.Status != Created && c.Status != Running && c.Status != Stopped {
|
|
panic(fmt.Sprintf("invalid state transition: %v => %v", c.Status, s))
|
|
}
|
|
|
|
default:
|
|
panic(fmt.Sprintf("invalid new state: %v", s))
|
|
}
|
|
c.Status = s
|
|
}
|
|
|
|
func (c *Container) isSandboxRunning() bool {
|
|
return c.Sandbox != nil && c.Sandbox.IsRunning()
|
|
}
|
|
|
|
func (c *Container) requireStatus(action string, statuses ...Status) error {
|
|
for _, s := range statuses {
|
|
if c.Status == s {
|
|
return nil
|
|
}
|
|
}
|
|
return fmt.Errorf("cannot %s container %q in state %s", action, c.ID, c.Status)
|
|
}
|
|
|
|
// lock takes a file lock on the container metadata lock file.
|
|
func (c *Container) lock() (func() error, error) {
|
|
return lockContainerMetadata(filepath.Join(c.Root, c.ID))
|
|
}
|
|
|
|
// lockContainerMetadata takes a file lock on the metadata lock file in the
|
|
// given container root directory.
|
|
func lockContainerMetadata(containerRootDir string) (func() error, error) {
|
|
if err := os.MkdirAll(containerRootDir, 0711); err != nil {
|
|
return nil, fmt.Errorf("creating container root directory %q: %v", containerRootDir, err)
|
|
}
|
|
f := filepath.Join(containerRootDir, metadataLockFilename)
|
|
l := flock.NewFlock(f)
|
|
if err := l.Lock(); err != nil {
|
|
return nil, fmt.Errorf("acquiring lock on container lock file %q: %v", f, err)
|
|
}
|
|
return l.Unlock, nil
|
|
}
|
|
|
|
// maybeLockRootContainer locks the sandbox root container. It is used to
|
|
// prevent races to create and delete child container sandboxes.
|
|
func maybeLockRootContainer(spec *specs.Spec, rootDir string) (func() error, error) {
|
|
if isRoot(spec) {
|
|
return func() error { return nil }, nil
|
|
}
|
|
|
|
sbid, ok := specutils.SandboxID(spec)
|
|
if !ok {
|
|
return nil, fmt.Errorf("no sandbox ID found when locking root container")
|
|
}
|
|
sb, err := Load(rootDir, sbid)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
unlock, err := sb.lock()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return unlock, nil
|
|
}
|
|
|
|
func isRoot(spec *specs.Spec) bool {
|
|
return specutils.ShouldCreateSandbox(spec)
|
|
}
|
|
|
|
// runInCgroup executes fn inside the specified cgroup. If cg is nil, execute
|
|
// it in the current context.
|
|
func runInCgroup(cg *cgroup.Cgroup, fn func() error) error {
|
|
if cg == nil {
|
|
return fn()
|
|
}
|
|
restore, err := cg.Join()
|
|
defer restore()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return fn()
|
|
}
|