fix: Optimize layer order and docker ignores

.dockerignore

@@ -0,0 +1,5 @@
+_build
+cover
+.elixir_ls
+*.dump
+.journal-*

.gitlab-ci.yml

@@ -33,9 +33,9 @@ deploy_to_tags:
     - npm install
     - npx semantic-release
 
-deploy_to_registry:
-  stage: deploy
-  needs: ['test']
+build_image_for_commit:
+  stage: test
+  needs: []
   image: "docker:19.03.12"
   services:
     - name: docker:19.03.12-dind
@@ -45,6 +45,19 @@ deploy_to_registry:
     - docker login "https://${CI_REGISTRY}" -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD
     - docker pull $CI_REGISTRY_IMAGE:latest || true
     - docker build --cache-from $CI_REGISTRY_IMAGE:latest -t $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA .
+    - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
+
+deploy_commit_image_to_tag:
+  stage: deploy
+  needs: ['test']
+  image: "docker:19.03.12"
+  services:
+    - name: docker:19.03.12-dind
+  only:
+    - tags
+  script:
+    - docker login "https://${CI_REGISTRY}" -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD
+    - docker pull $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
     - docker tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA $CI_REGISTRY_IMAGE:$CI_COMMIT_TAG
     - docker tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA $CI_REGISTRY_IMAGE:latest
     - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_TAG

Dockerfile

@@ -8,10 +8,6 @@ ENV MIX_HOME=/opt/mix
 RUN mix local.hex --force \
   && mix local.rebar --force
 
-WORKDIR /root/app
-
-ADD ./ /root/app/
-
 EXPOSE 4000
 
 ARG MIX_ENV=prod
@@ -19,8 +15,15 @@ RUN echo ${MIX_ENV}
 ENV MIX_ENV=$MIX_ENV
 ENV PORT=4000
 
+WORKDIR /root/app
+
+ADD ./mix.exs /root/app/mix.exs
+ADD ./mix.lock /root/app/mix.lock
 RUN mix deps.get
 RUN mix deps.compile
+
+ADD ./ /root/app/
+
 RUN MAKE=cmake mix compile
 RUN mix phx.digest