Two bugs made the first CI run fail with 'waiting for connection:
context deadline exceeded':
1. Container started without --network landed on default bridge,
while job containers run on git_default -> name unresolvable,
bridge IP unreachable cross-network.
2. moby/buildkit default entrypoint only listens on a unix socket.
driver: remote needs TCP. Added --addr tcp://0.0.0.0:8375 and
changed endpoint from docker-container://name (only valid for
the docker-container driver) to tcp://name:8375.
Both verified on the oracle host: buildx remote driver connects,
Status running, platforms linux/arm64,v7,v6.
The default docker-container driver of docker/setup-buildx-action ignores
driver-opts labels (container created with labels={}) and the Docker API
cannot PATCH labels on existing containers. Start a privileged, labeled
buildkitd ourselves (idempotent, restart unless-stopped) and connect via
driver: remote endpoint docker-container://<name>.
meda