以编程方式检查Docker容器进程是否以非零状态结束

Question

I'm working on a Go application which starts some Docker containers using Go Docker SDK. I need to check if containers' processes exit with zero (success) status code.

Here's the minimal working example:

package main

import (
    "context"
    "io"
    "log"
    "os"

    "github.com/docker/docker/api/types"
    "github.com/docker/docker/api/types/container"
    "github.com/docker/docker/client"
)

func main() {
    ctx := context.Background()

    cli, err := client.NewEnvClient()
    if err != nil {
        log.Fatal(err)
    }

    reader, err := cli.ImagePull(
        ctx,
        "docker.io/library/alpine",
        types.ImagePullOptions{},
    )
    if err != nil {
        log.Fatal(err)
    }
    io.Copy(os.Stdout, reader)

    resp, err := cli.ContainerCreate(ctx, &container.Config{
        Image: "alpine",
        Cmd:   []string{"sh", "-c", "echo hello world; return 1"},
        Tty:   true,
    }, nil, nil, "")
    if err != nil {
        log.Fatal(err)
    }

    err = cli.ContainerStart(
        ctx,
        resp.ID,
        types.ContainerStartOptions{},
    )
    if err != nil {
        log.Fatal(err)
    }

    statusCh, errCh := cli.ContainerWait(
        ctx,
        resp.ID,
        container.WaitConditionNotRunning,
    )
    select {
    case err := <-errCh:
        if err != nil {
            log.Fatal(err)
        }
    case <-statusCh:
    }

    out, err := cli.ContainerLogs(
        ctx,
        resp.ID,
        types.ContainerLogsOptions{ShowStdout: true},
    )
    if err != nil {
        log.Fatal(err)
    }

    io.Copy(os.Stdout, out)
}

As you can see, the process in the container ends with non-zero status (sh -c "echo hello world; return 1"). However, it doesn't log any fatal errors and simply displays hello world when built and executed:

{"status":"Pulling from library/alpine","id":"latest"}
{"status":"Digest: sha256:7043076348bf5040220df6ad703798fd8593a0918d06d3ce30c6c93be117e430"}
{"status":"Status: Image is up to date for alpine:latest"}
hello world

How can I check that container process exited with non-zero status using Docker Go SDK?

Answer 1

I think you should use the status channel to get the exit code. The error channel seems to be used to signal if there was an error while talking to the docker daemon, see https://godoc.org/github.com/docker/docker/client#Client.ContainerWait.

This works for me:

select {
case err := <-errCh:
    if err != nil {
        log.Fatal(err)
    }
case status := <-statusCh:
    log.Printf("status.StatusCode: %#+v
", status.StatusCode)
}