switch docker build to use backend:bundle

packages/backend/Dockerfile

@@ -1,16 +1,25 @@
-FROM node:14-buster
+# This dockerfile builds an image for the backend package.
+# It should be executed with the root of the repo as docker context.
+#
+# Before building this image, be sure to have run the following commands in the repo root:
+#
+# yarn install
+# yarn tsc
+# yarn build
 
-WORKDIR /usr/src/app
+FROM node:14-buster-slim
+
+WORKDIR /app
 
 # Copy repo skeleton first, to avoid unnecessary docker cache invalidation.
 # The skeleton contains the package.json of each package in the monorepo,
 # and along with yarn.lock and the root package.json, that's enough to run yarn install.
-ADD yarn.lock package.json skeleton.tar ./
+ADD yarn.lock package.json packages/backend/dist/skeleton.tar.gz ./
 
 RUN yarn install --frozen-lockfile --production --network-timeout 300000 && rm -rf "$(yarn cache dir)"
 
 # This will copy the contents of the dist-workspace when running the build-image command.
 # Do not use this Dockerfile outside of that command, as it will copy in the source code instead.
-COPY . .
+ADD packages/backend/dist/bundle.tar.gz app-config.yaml ./
 
 CMD ["node", "packages/backend"]