chore(container): add the branch name to the container

.github/workflows/ci.yml

@@ -87,6 +87,7 @@ jobs:
 
           VER="$(git describe --tags 2>/dev/null)"
           echo "version=${VER}" >> "$GITHUB_OUTPUT"
+          echo "branch=${REF}" >> "$GITHUB_OUTPUT"
 
           echo 'tags<<EOF' >> "$GITHUB_OUTPUT"
           if [[ "$REF" == "main" ]]; then
@@ -105,6 +106,7 @@ jobs:
           platforms: linux/amd64
           build-args: |
             VERSION=${{ steps.info.outputs.version }}
+            BRANCH=${{ steps.info.outputs.branch }}
 
   publish-image:
     name: Publish Image

.gitignore

@@ -29,6 +29,7 @@ vendor/bundle
 
 Procfile.local
 VERSION
+BRANCH
 
 .rubocop-https*
 .env*

Dockerfile

@@ -43,8 +43,10 @@ COPY ./docker/wait-for.sh /docker-entrypoint.sh
 COPY --chown=postal . .
 
 # Export the version
-ARG VERSION=unspecified
+ARG VERSION=null
-RUN echo $VERSION > VERSION
+ARG BRANCH=null
+RUN echo $VERSION > VERSION \
+  && echo $BRANCH > BRANCH
 
 # Set paths for when running in a container
 ENV POSTAL_CONFIG_FILE_PATH=/config/postal.yml