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The new agent requires a container runtime to execute workflow actions. This commit introduces a Docker runtime. Signed-off-by: Chris Doherty <chris.doherty4@gmail.com>
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,9 @@ | ||
| package runtime | ||
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| const ( | ||
| // ReasonMountPath is the path used by Actions to write their failure reasons. | ||
| ReasonMountPath = "/tinkerbell/failure-reason" | ||
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| // MessageMountPath is the path used by Actions to write their failure message. | ||
| MessageMountPath = "/tinkerbell/failure-message" | ||
| ) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,202 @@ | ||
| package runtime | ||
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| import ( | ||
| "context" | ||
| "fmt" | ||
| "io" | ||
| "regexp" | ||
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| retry "github.com/avast/retry-go" | ||
| "github.com/docker/docker/api/types" | ||
| "github.com/docker/docker/api/types/container" | ||
| "github.com/docker/docker/api/types/mount" | ||
| "github.com/docker/docker/client" | ||
| "github.com/go-logr/logr" | ||
| "github.com/tinkerbell/tink/internal/agent" | ||
| "github.com/tinkerbell/tink/internal/agent/runtime/internal" | ||
| "github.com/tinkerbell/tink/internal/agent/workflow" | ||
| "github.com/tinkerbell/tink/internal/ptr" | ||
| ) | ||
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| var _ agent.ContainerRuntime = &Docker{} | ||
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| // Docker is a docker runtime that satisfies agent.ContainerRuntime. | ||
| type Docker struct { | ||
| log logr.Logger | ||
| client *client.Client | ||
| } | ||
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| // Run satisfies agent.ContainerRuntime. | ||
| func (d *Docker) Run(ctx context.Context, a workflow.Action) error { | ||
| pullImage := func() error { | ||
| // We need the image to be available before we can create a container. | ||
| image, err := d.client.ImagePull(ctx, a.Image, types.ImagePullOptions{}) | ||
| if err != nil { | ||
| return fmt.Errorf("docker: %w", err) | ||
| } | ||
| defer image.Close() | ||
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| // Docker requires everything to be read from the images ReadCloser for the image to actually | ||
| // be pulled. We may want to log image pulls in a circular buffer somewhere for debugability. | ||
| if _, err = io.Copy(io.Discard, image); err != nil { | ||
| return fmt.Errorf("docker: %w", err) | ||
| } | ||
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| return nil | ||
| } | ||
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| err := retry.Do(pullImage, retry.Attempts(5), retry.DelayType(retry.BackOffDelay)) | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| // TODO: Support all the other things on the action such as volumes. | ||
| cfg := container.Config{ | ||
| Image: a.Image, | ||
| Env: toDockerEnv(a.Env), | ||
| } | ||
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| failureFiles, err := internal.NewFailureFiles() | ||
| if err != nil { | ||
| return fmt.Errorf("create action failure files: %w", err) | ||
| } | ||
| defer failureFiles.Close() | ||
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| hostCfg := container.HostConfig{ | ||
| Mounts: []mount.Mount{ | ||
| { | ||
| Type: mount.TypeBind, | ||
| Source: failureFiles.ReasonPath(), | ||
| Target: ReasonMountPath, | ||
| }, | ||
| { | ||
| Type: mount.TypeBind, | ||
| Source: failureFiles.MessagePath(), | ||
| Target: MessageMountPath, | ||
| }, | ||
| }, | ||
| } | ||
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| containerName := toContainerName(a.ID) | ||
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| // Docker uses the entrypoint as the default command. The Tink Action Cmd property is modeled | ||
| // as being the command launched in the container hence it is used as the entrypoint. Args | ||
| // on the action are therefore the command portion in Docker. | ||
| if a.Cmd != "" { | ||
| cfg.Entrypoint = append(cfg.Entrypoint, a.Cmd) | ||
| } | ||
| if len(a.Args) > 0 { | ||
| cfg.Cmd = append(cfg.Cmd, a.Args...) | ||
| } | ||
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| // TODO: Figure out container logging. We probably want to save it somewhere for debugability. | ||
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| create, err := d.client.ContainerCreate(ctx, &cfg, &hostCfg, nil, nil, containerName) | ||
| if err != nil { | ||
| return fmt.Errorf("docker: %w", err) | ||
| } | ||
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| // Always try to remove the container on exit. | ||
| defer func() { | ||
| // Force remove containers in an attempt to preserve space in memory constraints environments. | ||
| // In rare cases this may create orphaned volumes that the Docker CLI won't clean up. | ||
| opts := types.ContainerRemoveOptions{ | ||
| Force: true, | ||
| RemoveLinks: true, | ||
| } | ||
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| // We can't use the context passed to Run() as it may have been cancelled so we use Background() | ||
| // instead. | ||
| err := d.client.ContainerRemove(context.Background(), create.ID, opts) | ||
| if err != nil { | ||
| d.log.Info("Couldn't remove container", "container_name", containerName, "error", err) | ||
| } | ||
| }() | ||
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| // Issue the wait with a 'next-exit' condition so we can await a response originating from | ||
| // ContainerStart(). | ||
| waitBody, waitErr := d.client.ContainerWait(ctx, create.ID, container.WaitConditionNextExit) | ||
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| if err := d.client.ContainerStart(ctx, create.ID, types.ContainerStartOptions{}); err != nil { | ||
| return fmt.Errorf("docker: %w", err) | ||
| } | ||
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| select { | ||
| case result := <-waitBody: | ||
| if result.StatusCode == 0 { | ||
| return nil | ||
| } | ||
| return failureFiles.ToError() | ||
|
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| case err := <-waitErr: | ||
| return fmt.Errorf("docker: %w", err) | ||
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| case <-ctx.Done(): | ||
| // We can't use the context passed to Run() as its been cancelled. | ||
| err := d.client.ContainerStop(context.Background(), create.ID, container.StopOptions{ | ||
| Timeout: ptr.Int(5), | ||
| }) | ||
| if err != nil { | ||
| d.log.Info("Failed to gracefully stop container", "error", err) | ||
| } | ||
| return fmt.Errorf("docker: %w", ctx.Err()) | ||
| } | ||
| } | ||
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| var validContainerName = regexp.MustCompile(`[^a-zA-Z0-9_.-]`) | ||
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| // toContainerName converts an action ID into a usable container name. | ||
| func toContainerName(actionID string) string { | ||
| // Prepend 'tinkerbell_' so we guarantee the additional constraints on the first character. | ||
| return "tinkerbell_" + validContainerName.ReplaceAllString(actionID, "_") | ||
| } | ||
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| func toDockerEnv(env map[string]string) []string { | ||
| var de []string | ||
| for k, v := range env { | ||
| de = append(de, fmt.Sprintf("%v=%v", k, v)) | ||
| } | ||
| return de | ||
| } | ||
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| // NewDocker creates a new Docker instance. | ||
| func NewDocker(opts ...DockerOption) (*Docker, error) { | ||
| o := &Docker{ | ||
| log: logr.Discard(), | ||
| } | ||
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| var err error | ||
| o.client, err = client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation()) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
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| for _, fn := range opts { | ||
| fn(o) | ||
| } | ||
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| return o, nil | ||
| } | ||
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| // DockerOption defines optional configuration for a Docker instance. | ||
| type DockerOption func(*Docker) | ||
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| // WithLogger returns an option to configure the logger on a Docker instance. | ||
| func WithLogger(log logr.Logger) DockerOption { | ||
| return func(o *Docker) { | ||
| if log.GetSink() == nil { | ||
| return | ||
| } | ||
| o.log = log | ||
| } | ||
| } | ||
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| // WithClient returns an option to configure a Docker client on a Docker instance. | ||
| func WithClient(clnt *client.Client) DockerOption { | ||
| return func(o *Docker) { | ||
| if clnt == nil { | ||
| return | ||
| } | ||
| o.client = clnt | ||
| } | ||
| } |
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