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fix: copy the docker buildx plugin so nixpacks builds actually work
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nixpacks shells out to `docker build`, which defaults to BuildKit;
without the buildx CLI plugin every build failed outright.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
This commit is contained in:
Darío Sevilla
2026-10-08 04:31:55 +02:00
parent 223b1ab8eb
commit 698173c79d
2 changed files with 11 additions and 0 deletions
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3
Dockerfile
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@@ -27,6 +27,9 @@ RUN apt-get update && apt-get install -y --no-install-recommends git openssh-cli
&& rm -rf /var/lib/apt/lists/*
COPY --from=nixpacks /usr/bin/nixpacks /usr/local/bin/nixpacks
COPY --from=dockercli /usr/local/bin/docker /usr/local/bin/docker
# nixpacks shells out to `docker build`, which defaults to BuildKit — needs the buildx
# plugin present or it fails with "BuildKit is enabled but the buildx component is missing".
COPY --from=dockercli /usr/local/libexec/docker/cli-plugins/docker-buildx /usr/local/libexec/docker/cli-plugins/docker-buildx
WORKDIR /repo
COPY package.json package-lock.json ./

8
LESSONS.md
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@@ -22,6 +22,14 @@ specific `vX.Y.Z` tag + exact filename) over extracting it from someone else's D
repo needs a key with access mounted into the container (`SSH_DIR` in `docker-compose.yml`,
reusing the host's own deploy key) — confirmed both failures back to back while deploying.
## `docker build` needs the buildx plugin present to use BuildKit
Nixpacks shells out to `docker build`, which defaults to BuildKit. The manager's image only
copied the bare `docker` CLI binary from `docker:27-cli`, not its buildx plugin, so every
build failed with "BuildKit is enabled but the buildx component is missing or broken" —
confirmed on the first real build attempt. Fixed by also copying
`/usr/local/libexec/docker/cli-plugins/docker-buildx` from the same `docker:27-cli` image.
## Nixpacks silently picks its own default runtime version
Nixpacks does not fail when a repo's `engines`/version requirement isn't met — it silently falls back to its own default (e.g. picked Node 18 for a repo requiring Node >=20 in `Social-MCP`). The build goes green, then the container crashes at runtime (`crypto is not defined`, missing globals, etc.).