Add unrequired files to dockerignore to save images space

Author: entantoencuanto

.dockerignore

@@ -1,11 +1,11 @@
 # Ignore bundler config.
 /.bundle
 
-# Ignore all logfiles and tempfiles.
+# Ignore all logfiles and tempfiles, including those nested inside the engines.
 /log/*
 /tmp/*
-!/log/.keep
-!/tmp/.keep
+**/log/*
+**/tmp/*
 
 # Ignore Byebug command history file.
 .byebug_history
@@ -24,3 +24,21 @@ public/uploads
 **/*.rspec-failures
 vendor/bundle
 .git
+
+# Node dependencies: reinstalled inside the image by `npm install`.
+node_modules
+**/node_modules
+
+# Dummy apps generated by the engines' specs. Git-ignored, ~3.8 GB, and pulled
+# into the image by the `ADD decidim-* decidim-*` lines in Dockerfile.production.
+decidim-*/spec/decidim_dummy_app
+
+# Asset builds: regenerated by `bin/rake assets:precompile` (see
+# config/shakapacker.yml). packs-test is test-only and never needed in the image.
+/public/packs-test
+/public/decidim-packs
+/storage
+
+# Keep the placeholder files the broader rules above would otherwise drop.
+!/log/.keep
+!/tmp/.keep