Finally think I fixed the docker dev on rebuild/restart when gem vers…

…ions change.

See: https://nickjanetakis.com/blog/dealing-with-lock-files-when-using-ruby-node-and-elixir-with-docker
for an EXACT description of the problem. Now with this change and the checked in Gemfile.lock,
it should be easy to see when a change happens on a rebuild and check that into src
ctrl (plus, it should just work).

TESTING:
- rebuilt the container and verified I can login.

Dockerfile

@@ -26,7 +26,12 @@ WORKDIR /app
 COPY Gemfile /app/Gemfile
 COPY Gemfile.lock /app/Gemfile.lock
 COPY rubycas-server.gemspec /app/rubycas-server.gemspec
-RUN bundle install
+
+# See this article for why we copy to /tmp
+# We have a runtime script to check this so we can deal
+# with changes properly when gem versions get updated.
+# https://nickjanetakis.com/blog/dealing-with-lock-files-when-using-ruby-node-and-elixir-with-docker
+RUN bundle install && cp Gemfile.lock /tmp
 
 # Do this after bundle install b/c if we do it before then changing any files
 # causes bundle install to be invalidated and run again on the next build 

docker-compose/scripts/docker_compose_run.sh

@@ -4,4 +4,26 @@
 # into the actual application config.yml file. Note: envsubst needs gettext to be installed.
 envsubst < /app/docker-compose/config/config.yml > /app/config/config.yml
 
+# Take from here: https://nickjanetakis.com/blog/dealing-with-lock-files-when-using-ruby-node-and-elixir-with-docker
+# To deal with problems when the Gemfile.lock changes in between runs of
+# bundle install
+set -e
+
+built_lock_file="/tmp/Gemfile.lock"
+current_lock_file="Gemfile.lock"
+
+function cp_built_lock_file() {
+    cp "${built_lock_file}" "${current_lock_file}"
+}
+
+if [ -f "${current_lock_file}" ]; then
+    diff="$(diff "${built_lock_file}" "${current_lock_file}")"
+    if [ "${diff}" != "" 2>/dev/null ]; then
+        cp_built_lock_file
+    fi
+else
+    cp_built_lock_file
+fi
+
+
 bundle exec rubycas-server -p 3002 -c /app/config/config.yml