Can we retrieve logs from a Dockerfile build ?

[minor skiff]

I tried implementing log retrieval the same way that with an exec, is there anyway to get stdout/stderr/exitcode of a docker build ?

Kind regards

    build, err := dag.Container().
        Build(source, dagger.ContainerBuildOpts{
            Dockerfile: "Dockerfile",
        }).Sync(ctx)
    ...
    stdout, err := build.Stdout(ctx)
    if err != nil {
        return "", "", 0, fmt.Errorf("failed to fetch stdout: %w", err)
    }

   stdout: input: container.build.stdout resolve: no command has been set: stdout requires an exec

[quiet flare]

Hi, this is not currently implemented. Could you open an issue for this please?

[short dagger]

@quiet flare Did this ever get picked up? Hitting this error now

[quiet flare]

hey! I don't think I've seen that issue. @jovial nebula do you remember seeing this in the dagger/dagger repo by any chance?

[jovial nebula]

there's no way i know of getting the logs of a docker build

getting build.Stdout will just get the result of the last exec in the build

actually, no it won't

it's expected, it gets the last withExec - there isn't a withExec

i can't find the issue either: but we'll probably bundle similar work into https://github.com/dagger/dagger/issues/10413

we need to do huge refactoring of how we support docker builds, supporting them as a native feature doesn't seem sustainable long term (since it's really tricky to implement features like this)

[short dagger]

What about logs of a withExec after a dockerBuild?

That's what I'm trying to do, and it still errors with stdout requires an exec, even though there is an exec

[jovial nebula]

can you share a code snippet?

[quiet flare]

MB this seems to work:

type Dockerfile struct{}

func (m *Dockerfile) Test(ctx context.Context) (string, error) {
    return dag.Directory().WithNewFile("Dockerfile", "FROM alpine").DockerBuild().WithExec([]string{"cat", "/etc/os-release"}).Stdout(ctx)
}

[short dagger]

I was hoping to return a container and append stdout on the command, but I'll try that

[quiet flare]

you can also do that:

i.e:

type Dockerfile struct{}

func (m *Dockerfile) Test(ctx context.Context) *dagger.Container {
    return dag.Directory().WithNewFile("Dockerfile", "FROM alpine").DockerBuild().WithExec([]string{"cat", "/etc/os-release"})
}

and then dagger -c 'test | stdout'. That also works

[jovial nebula]

if you want it fully defined in the docker file, you could set the entry point?

then you can just WithExec with useEntrypoint=true

[short dagger]

Hmmm, that didn't work for me. Wrapping something else up then I'll retry

Function ends with:

    ctr.WithExec([]string{binary, "validate", fmt.Sprintf("--config=%s", configfile)})

    return ctr, nil

Command results in:

✘ .stdout: String! 0.0s
! no command has been set: stdout requires an exec

dagger -c 'validate ../otel-collector-sidecar --vars CLOUDWATCH_LOG_GROUP=testloggroup,CLOUDWATCH_LOG_STREAM=testlogstream | stdout' results in no command has been set: stdout requires an exec

[quiet flare]

@short dagger don't forget to re-assign the return of ctr.WithExec

I'm missing the complete context but from the snippet you shared, it seems like you're not re-assigning the return of WithExec to ctr

so basically:

    ctr = ctr.WithExec([]string{binary, "validate", fmt.Sprintf("--config=%s", configfile)})

    return ctr, nil

[short dagger]

Ahhh 🤦‍♂️

Rookie errors huh