feat(driver): add simple entrypoint script

Signed-off-by: Chris Goller <[email protected]>

Dockerfile

@@ -13,7 +13,9 @@ RUN \
 FROM --platform=$TARGETPLATFORM ubuntu:20.04
 
 RUN apt-get update && apt-get install -y ca-certificates && rm -rf /var/lib/apt/lists/*
+COPY entrypoint.sh /usr/bin/entrypoint.sh
 COPY --from=build /out/depot /usr/bin/depot
 COPY --from=build /out/buildkitd /usr/bin/buildkitd
 COPY --from=build /out/buildctl /usr/bin/buildctl
-ENTRYPOINT ["/usr/bin/depot"]
+
+ENTRYPOINT ["/usr/bin/entrypoint.sh"]

entrypoint.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+run_program() {
+  program_name=$1
+  shift
+  exec "/usr/bin/$program_name" "$@"
+}
+
+if [ $# -eq 0 ]; then
+    run_program "depot" "$@"
+else
+  # buildkitd and buildctl are used to support buildx drivers.
+  if [ "$1" = "buildkitd" ]; then
+    run_program "$@"
+  elif [ "$1" = "buildctl" ]; then
+    run_program "$@"
+  else
+    run_program "depot" "$@"
+  fi
+fi