从Go代码构建Docker映像

Question

I'm trying to build a Docker image using the Docker API and Docker Go libraries (https://github.com/docker/engine-api/). Code example:

package main
import (
    "fmt"
    "github.com/docker/engine-api/client"
    "github.com/docker/engine-api/types"
    "golang.org/x/net/context"
)
func main() {
    defaultHeaders := map[string]string{"User-Agent": "engine-api-cli-1.0"}
    cli, err := client.NewClient("unix:///var/run/docker.sock", "v1.22", nil, defaultHeaders)
    if err != nil {
        panic(err)
    }
    fmt.Print(cli.ClientVersion())
    opt := types.ImageBuildOptions{
        CPUSetCPUs:   "2",
        CPUSetMems:   "12",
        CPUShares:    20,
        CPUQuota:     10,
        CPUPeriod:    30,
        Memory:       256,
        MemorySwap:   512,
        ShmSize:      10,
        CgroupParent: "cgroup_parent",
        Dockerfile:   "dockerSrc/docker-debug-container/Dockerfile",
    }
    _, err = cli.ImageBuild(context.Background(), nil, opt)
    if err == nil || err.Error() != "Error response from daemon: Server error" {
        fmt.Printf("expected a Server Error, got %v", err)
    }
}

The error is always same:

Error response from daemon: Cannot locate specified Dockerfile: dockerSrc/docker-debug-container/Dockerfile

or

Error response from daemon: Cannot locate specified Dockerfile: Dockerfile

Things I've checked:

1. The folder exists in build path
2. I tried both relative and absolute path
3. There are no softlinks in the path
4. I tried the same folder for binary and Dockerfile
5. docker build <path> works
6. and bunch of other stuff

My other option was to use RemoteContext which looks like it works, but only for fully self contained dockerfiles, and not the ones with "local file presence".

---

Update: Tried passing tar as buffer, but got the same result with the following:

  dockerBuildContext, err := os.Open("<path to>/docker-debug-    container/docker-debug-container.tar")
  defer dockerBuildContext.Close()

    opt := types.ImageBuildOptions{
        Context:      dockerBuildContext,
        CPUSetCPUs:   "2",
        CPUSetMems:   "12",
        CPUShares:    20,
        CPUQuota:     10,
        CPUPeriod:    30,
        Memory:       256,
        MemorySwap:   512,
        ShmSize:      10,
        CgroupParent: "cgroup_parent",
        //  Dockerfile:   "Dockerfile",
    }

    _, err = cli.ImageBuild(context.Background(), nil, opt)

Answer 1

@Mangirdas: staring at a screen long enough DOES help - at least in my case. I have been stuck with the same issue for some time now. You were right to use the tar file (your second example). If you look at the API doc here https://docs.docker.com/engine/reference/api/docker_remote_api_v1.24/#/build-image-from-a-dockerfile you can see that it expects a tar. What really helped me was looking at other implementations of the client, perl and ruby in my case. Both create a tar on the fly when being asked to build an image from a directory. Anyway, you only need to put your dockerBuildContext somewhere else (see the cli.ImageBuild())

dockerBuildContext, err := os.Open("/Path/to/your/docker/tarfile.tar")
defer dockerBuildContext.Close()

buildOptions := types.ImageBuildOptions{
    Dockerfile:   "Dockerfile", // optional, is the default
}

buildResponse, err := cli.ImageBuild(context.Background(), dockerBuildContext, buildOptions)
if err != nil {
    log.Fatal(err)
}
defer buildResponse.Body.Close()

I am not there with naming the images properly yet, but at least I can create them... Hope this helps. Cheers