Reduce Docker image size

* Remove the apt cache after installing
* Don't create pip caches
* Sync .dockerignore with .gitignore files, except for frontend/out,
  which is needed for build

.dockerignore

@@ -1,10 +1,8 @@
-**/.DS_store
-.coverage
+# .gitignore
 .env
 .envrc
-.git
-extension
 *.sqlite3
+node_modules
 env/
 __pycache__
 web-ext-artifacts/
@@ -13,3 +11,38 @@ static/downloads
 static/css
 static/scss/libs
 staticfiles
+coverage/
+junit.xml
+
+# frontend/.gitignore
+frontend/public/mockServiceWorker.js
+frontend/node_modules
+frontend/.pnp
+frontend/.pnp.js
+frontend/coverage
+frontend/.next/
+# Needed by Docker
+# frontend/out/
+frontend/build
+frontend/.DS_Store
+frontend/*.pem
+frontend/npm-debug.log*
+frontend/yarn-debug.log*
+frontend/yarn-error.log*
+frontend/.env.local
+frontend/.env.development.local
+frontend/.env.test.local
+frontend/.env.production.local
+frontend/.vercel
+
+# frontend/.husky/_/.gitignore
+frontend/.husky
+
+# Other
+**/.DS_store
+**/__pycache__
+.buildpacks
+.coverage
+.git
+.pytest_cache
+extension

Dockerfile

@@ -20,8 +20,11 @@ ENV CIRCLE_BRANCH=${CIRCLE_BRANCH:-unknown} \
     CIRCLE_TAG=${CIRCLE_TAG:-unknown} \
     CIRCLE_SHA1=${CIRCLE_SHA1:-unknown}
 
-RUN apt-get update && apt-get install -y libpq-dev
-RUN pip install --upgrade pip
+RUN set -eux; \
+        apt-get update; \
+        apt-get install -y --no-install-recommends libpq-dev; \
+        rm -rf /var/lib/apt/lists/*
+RUN pip install --no-cache --upgrade pip
 
 RUN groupadd --gid 10001 app && \
     useradd -g app --uid 10001 --shell /usr/sbin/nologin --create-home --home-dir /app app
@@ -34,7 +37,7 @@ USER app
 COPY --from=gulp-builder --chown=app /app/static ./static
 
 COPY --chown=app ./requirements.txt /app/requirements.txt
-RUN pip install -r requirements.txt
+RUN pip install --no-cache -r requirements.txt
 COPY --chown=app . /app
 COPY --chown=app .env-dist /app/.env