Use buildx functions for faster build

.github/workflows/build-image.yml

@@ -40,7 +40,8 @@ jobs:
         with:
           context: .
           platforms: linux/amd64,linux/arm64
+          builder: ${{ steps.buildx.outputs.name }}
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
-          cache-from: type=registry,ref=tootsuite/mastodon:edge
-          cache-to: type=inline
+          cache-from: type=gha
+          cache-to: type=gha,mode=max

Dockerfile

@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1.4
 FROM ubuntu:20.04 as build-dep
 
 # Use bash for the shell
@@ -65,8 +66,8 @@ RUN cd /opt/mastodon && \
 FROM ubuntu:20.04
 
 # Copy over all the langs needed for runtime
-COPY --from=build-dep /opt/node /opt/node
-COPY --from=build-dep /opt/ruby /opt/ruby
+COPY --from=build-dep --link /opt/node /opt/node
+COPY --from=build-dep --link /opt/ruby /opt/ruby
 
 # Add more PATHs to the PATH
 ENV PATH="${PATH}:/opt/ruby/bin:/opt/node/bin:/opt/mastodon/bin"
@@ -97,7 +98,7 @@ RUN apt-get update && \
 
 # Copy over mastodon source, and dependencies from building, and set permissions
 COPY --chown=mastodon:mastodon . /opt/mastodon
-COPY --from=build-dep --chown=mastodon:mastodon /opt/mastodon /opt/mastodon
+COPY --from=build-dep --link --chown=mastodon:mastodon /opt/mastodon /opt/mastodon
 
 # Run mastodon services in prod mode
 ENV RAILS_ENV="production"