Can't find Dockerfile as client on Windows

[taraspos]

Hello,
using client connecting to remote docker daemon.
When connecting from Linux to Docker daemon installed on CoreOS everything is ok.
When connecting from Windows to Docker daemon installed on CoreOS and trying to build docker image(on remote system) I get API error (500): {\"message\":\"Cannot locate specified Dockerfile: Dockerfile\"}. Pull images works ok.

err := client.BuildImage(docker.BuildImageOptions{
    Name: item.Name,
    // Dockerfile:     "Dockerfile",
    SuppressOutput: true,
    OutputStream:   &buf,
    RmTmpContainer: true,
    ContextDir:     filepath.Join(app.cnf.DockerfilesPath, item.Name),
})

where is: app.cnf.DockerfilesPath = "images" and item.Name = app1
Dockerfile is located in the: images/app1/Dockerfile

Building on remote docker daemon from client on Linux passes, and failing on Windows...

Any ideas why?

[fsouza]

@trane9991 try with path.Join instead of filepath.Join. This information is probably compared to the contents of the tarball sent to the remote server and tar always uses /, even on Windows.

[taraspos]

@fsouza
Hello, I have found a problem. I created simple test application which creates Tar archives with use createTarStream method(https://github.com/fsouza/go-dockerclient/blob/master/tar.go#L20) and I found that problem is in the resolving relative path on Windows.
Example:
Creating 2 tar packages from the same directory, only one time with relative path and next time with absolute path:

func main() {
    path1 := `images`
    path2 := `bash`
    tarStr1, err := createTarStream(filepath.Join(path1, path2), "Dockerfile")
    fmt.Println(err)
    outFile1, err := os.Create(`test.tar`)
    // handle err
    defer outFile1.Close()
    _, err = io.Copy(outFile1, tarStr1)

    // ---------------------------

    path3 := `d:\Workspace\Git\go\src\test\images`
    path4 := `bash`
    tarStr2, err := createTarStream(filepath.Join(path3, path4), "Dockerfile")
    fmt.Println(err)
    outFile2, err := os.Create(`test2.tar`)
    // handle err
    defer outFile2.Close()
    _, err = io.Copy(outFile2, tarStr2)
}

checking results:

Conclusion:
Tar package created from directory with relative path is empty.

[taraspos]

@fsouza
As a workaround adding absContextDir, err := filepath.Abs(filepath.Join(app.cnf.DockerfilesPath, item.Name)) works fine, but the issue need to be fixed in the library.

P.S. I tried to replace validateContextDirectory(https://github.com/fsouza/go-dockerclient/blob/master/tar.go#L67) with the builder.ValidateContextDirectory( https://github.com/fsouza/go-dockerclient/blob/master/tar.go#L67), but looks like issue persist. Need more testing.

[willseward]

@fsouza Does this bug still exist in the library? If so, you would be willing to implement the work-around that @trane9991 mentioned?

It would be nice to get https://github.com/dnephin/dobi working on Windows.

[ghost]

This is also causing a problem in Harbur Captain on Windows. I have opened a bug there (harbur/captain#77) but it seems a fix here would be the correct solution.

[fsouza]

I apologize for leaving this bug hanging for so long. I just pushed a tentative fix. Unfortunately I don't have a Windows host where I can reproduce the bug nor test the fix, but the CI build did succeed: https://ci.appveyor.com/project/fsouza/go-dockerclient/build/355.

@jward-2ndwatch can you give it a shot?

[ghost]

I will try to make some time and give it a shot soon. Thanks for getting to this.

[ghost]

@fsouza I rebuilt Harbur Captain with this update and it looks like it solved the issue I was having. 👍

[fsouza]

@jward-2ndwatch thank you very much for confirming!