feat: support custom BuildKit frontends - #83
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Signed-off-by: Zachary Spar <zachspar@gmail.com>
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cc @katiewasnothere -- apologies for the ping, but I'd greatly appreciate some eyes on this. I'm trying to consolidate my tooling, and blocked on being able to build my images with Apple |
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Background
This PR implements my feature request in #82 to enable building images using custom BuildKit frontends (ie.
# syntax=ghcr.io/builderhub/yamlfile:latest,BUILDKIT_SYNTAX, and explicitgateway.v0metadata), while keeping the existing nativedockerfile.v1path for plain Dockerfiles.Previously the shim always parsed the build file as a Dockerfile before the build started and always ran a hard-coded
dockerfile.v1frontend. That broke external frontends like Yamlfile with errors such asunknown instruction: apiVersion:.New Approach
Native Dockerfiles keep existing shim-specific behavior. External frontends delegate to the declared frontend image via BuildKit’s gateway mechanism.
Eventually it would be nice if we wire
frontend/frontend-optmetadata fromcontainer, but that is not a requirement to achieve the desired behavior.flowchart TD Input[Build file bytes] --> Resolve[resolveFrontend] Resolve -->|native| Native[Skip external path] Native --> Parse[parseDockerfileMetadata + dockerfile.v1] Resolve -->|external| Skip[Skip Dockerfile parse] Skip --> Stage[stageBuildDefinition + fssync staging] Stage --> Gateway[forwardGateway to gateway.v0]