Optimize Dockerfile

Optimize Dockerfile, reduce build time.

.dockerignore

@@ -5,3 +5,4 @@ public/assets
 node_modules
 storybook
 neo4j
+vendor/bundle

Dockerfile

@@ -5,7 +5,7 @@ ENV RAILS_ENV=production \
 
 WORKDIR /mastodon
 
-COPY . /mastodon
+COPY Gemfile Gemfile.lock package.json yarn.lock /mastodon/
 
 RUN BUILD_DEPS=" \
     postgresql-dev \
@@ -28,4 +28,6 @@ RUN BUILD_DEPS=" \
  && apk del $BUILD_DEPS \
  && rm -rf /tmp/* /var/cache/apk/*
 
+COPY . /mastodon
+
 VOLUME /mastodon/public/system /mastodon/public/assets