Multiple contexts

[mikepurvis]

Description

Hello! I’m new to bake and quite enjoying it. However, as far as I can tell, the bake action doesn’t support multiple contexts.

What I’m trying to do in my Actions workflow is:

1. Have an initial job that checks out the main repo and prepares a lockfile referencing several other repos.
2. Pass that lockfile to the next job as an artifact.
3. In the next job (a multiplatform matrix), run a bake that consumes the lockfile and hopefully avoids creating a new local clone of the main repo.

I can definitely mount a secret into the bake build, but I don’t think I can mount a regular file unless it’s part of the context. Is there a way I can reference the local workspace while still having buildx make its own clone of the main repo?

[polarathene]

Disregard this (pretty sure you weren't requesting this)

Could you illustrate this better?

• You're referring to source input (for v6, may be renamed to context input in a future release) with Path and Git contexts?
• Your description suggests declaring the action twice (step 1, then in the step 3 matrix), but I assume you're referring to "multiple contexts" (Path + Git) here within a single one of those actions? (step 3)

---

Or are you referring to a targets context field? (Unrelated to this action)

In that case you have context target field defaulting to the path it's given . and that will either be relative to the Git context (separate implicit git clone) or Path context (local workspace directory). If you then want to add an additional build context (relevant for a Dockerfile only) for a target (regardless of docker bake or docker build) you would add additional build contexts. For Docker Bake targets this is the contexts field.

In Docker Bake if you're already using the Git context, then to reference files from the local workspace you would add a build context with a value cwd:// and append the relative path to that (from the current working directory of the docker bake command to run, aka the local workspace).

---

Here's an example:

target "default" {
  # Implicit default, unless you've changed it:
  #context = "."

  contexts = {
    cwd = "cwd://"
  }

  # Other fields you set in your target (unrelated):
  dockerfile-inline = <<-HEREDOC
    FROM scratch
    COPY --link ./hello.txt /
    COPY --link --from=cwd README.md /
  HEREDOC

  output = ["./artifacts/"]
}

In the dockerfile-inline field, you can see the Dockerfile is using that additional build context by referencing the name it was assigned.

• The named build contexts have precedence over both a stage target name or a registry image name of the same value (should they conflict, useful if you want to override a stage target with another Bake target image).
• cwd:// is specific to Docker Bake, but you can reference additional remote contexts too (like with Git or HTTPS URIs) as the inverse.

So with the actions default to use Git context, you will want to use cwd:// like shown above, you can however give the context name associated to it anything you like, that part doesn't have to be cwd.