trying to use $(command) inside docker sdk entrypoint

Question

so as the title says, I'm trying to execute a simple command inside entrypoint using golang docker sdk (docker api).

func RunBatch(imageName, containerName string, entrypoint []string, volumes []string) string {
    ctx := context.Background()
    c := getClient()

    cfg := &container.Config{Entrypoint: entrypoint, Tty: true, Image: imageName}
    hostCfg := &container.HostConfig{Mounts: make([]mount.Mount, len(volumes))}
    netCfg := &network.NetworkingConfig{}
    startCfg := types.ContainerStartOptions{}

    for i := range volumes {
        vols := strings.Split(volumes[i], ":")

        hostCfg.Mounts[i] = mount.Mount{
            Type:   mount.TypeBind,
            Source: config.Config.BaseDir + vols[0],
            Target: vols[1],
        }
    }

    resp, err := c.ContainerCreate(ctx, cfg, hostCfg, netCfg, containerName)
    if err != nil {
        log.Fatal().Err(err)
    }

    err = c.ContainerStart(ctx, resp.ID, startCfg)
    if err != nil {
        log.Fatal().Err(err)
    }

    _, err = c.ContainerWait(ctx, resp.ID)
    if err != nil {
        log.Fatal().Err(err)
    }

    err = c.ContainerRemove(ctx, resp.ID, types.ContainerRemoveOptions{})
    if err != nil {
        log.Fatal().Err(err)
    }

    return resp.ID
}

and the entrypoint I'm passing here is ["touch", "/app/$(date +'%T')"] but the created file looks like $(date +'%T'), I've also tried and failed with ${date +'%T'} and with backqoute as well. how can I execute those ?!

score 3 · Accepted Answer · answered Jul 03 '20 at 17:57

Unlike the shell form, the exec form does not invoke a command shell. This means that normal shell processing does not happen. For example, ENTRYPOINT [ "echo", "$HOME" ] will not do variable substitution on $HOME. If you want shell processing then either use the shell form or execute a shell directly, for example: ENTRYPOINT [ "sh", "-c", "echo $HOME" ].

trying to use $(command) inside docker sdk entrypoint

1 Answers1