fix: add docker-container buildx builder to resolve push-by-digest failures#495
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Both amd64 and arm64 prebuild jobs failed with: ERROR: failed to build: push-by-digest is currently not implemented for docker driver, please create a new builder instance Root cause: devcontainer CLI uses --output push-by-digest=true which requires the docker-container buildx driver. GitHub-hosted runners now default to the docker driver which does not support push-by-digest. Fix: add a 'Set up Docker Buildx' step that creates a docker-container driver builder via `docker buildx create --use --driver docker-container --name devcontainer-builder --bootstrap` (placed between 'Install Dev Container CLI' and 'Decide whether to push'). The builder is created manually (not via docker/setup-buildx-action) to avoid the separate Docker Hub authentication round-trip that action introduces. Update validate-devcontainer.bats: rename the test to reflect that we now DO create a builder but not via setup-buildx-action, and add an assertion that docker-container driver is specified.
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[WIP] Fix failing GitHub Actions job 'Build (arm64)'
fix: add docker-container buildx builder to resolve push-by-digest failures
Jun 21, 2026
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Both
Build (amd64)andBuild (arm64)prebuild jobs fail becausepush-by-digest=true(used bydevcontainer build --output) requires thedocker-containerbuildx driver, but GitHub-hosted runners now default to thedockerdriver which doesn't support it.Changes
.github/workflows/devcontainer-prebuild.yaml— adds a "Set up Docker Buildx" step (after CLI install, before build) that creates adocker-containerdriver builder:--bootstrapstarts the BuildKit container eagerly.docker/setup-buildx-actionis intentionally avoided to skip its Docker Hub authentication round-trip.tests/bash/validate-devcontainer.bats— updates the buildx test to reflect the new approach: still assertsdocker/setup-buildx-actionis absent, and now also assertsdocker buildx createwithdocker-containerdriver is present.