Make forum container available even when services are missing

This is especially useful on Kubernetes. With this change, the forum
container no longer crashes whenever mongodb or elasticsearch are
unavailable. Instead, it just waits for thoses services to be up.

Previously, we could not run forum migrations in Kubernetes because they
relied on exec-ing the migration command in the running container -- and
there was no such container, because the services where not already up.

tutor/templates/build/forum/Dockerfile

@@ -7,8 +7,14 @@ RUN apt update && \
   apt upgrade -y && \
   apt install -y git wget autoconf bison build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev libgdbm-dev
 
+# Install dockerize to wait for mongodb/elasticsearch availability
+ARG DOCKERIZE_VERSION=v0.6.1
+RUN wget -O /tmp/dockerize.tar.gz https://github.com/jwilder/dockerize/releases/download/$DOCKERIZE_VERSION/dockerize-linux-amd64-$DOCKERIZE_VERSION.tar.gz \
+    && tar -C /usr/local/bin -xzvf /tmp/dockerize.tar.gz \
+    && rm /tmp/dockerize.tar.gz
+
 # Install ruby-build for building specific version of ruby
-RUN git clone https://github.com/sstephenson/ruby-build.git /openedx/ruby-build
+RUN git clone https://github.com/rbenv/ruby-build.git /openedx/ruby-build
 WORKDIR /openedx/ruby-build
 RUN PREFIX=/usr/local ./install.sh
 
@@ -28,10 +34,17 @@ RUN git clone https://github.com/edx/cs_comments_service.git --branch open-relea
 WORKDIR /openedx/cs_comments_service
 RUN bundle install --deployment
 
+COPY ./bin /openedx/bin
+ENV PATH /openedx/bin:${PATH}
+ENTRYPOINT ["docker-entrypoint.sh"]
+
 ENV RACK_ENV staging
 ENV NEW_RELIC_ENABLE false
 ENV API_KEY forumapikey
 ENV SEARCH_SERVER "http://elasticsearch:9200"
-ENV MONGOHQ_URL "mongodb://mongodb/cs_comments_service"
+ENV MONGODB_AUTH ""
+ENV MONGODB_HOST "mongodb"
+ENV MONGODB_PORT "27017"
+ENV MONGOHQ_URL "mongodb://$MONGODB_AUTH$MONGODB_HOST:$MONGODB_PORT/cs_comments_service"
 EXPOSE 4567
 CMD ./bin/unicorn -c config/unicorn_tcp.rb -I '.'

tutor/templates/build/forum/bin/docker-entrypoint.sh

@@ -0,0 +1,6 @@
+#!/bin/sh -e
+
+echo "Waiting for mongodb/elasticsearch..."
+dockerize -wait tcp://$MONGODB_HOST:$MONGODB_PORT -wait $SEARCH_SERVER/content -wait-retry-interval 5s -timeout 600s
+
+exec "$@"

tutor/templates/k8s/deployments.yml

@@ -69,8 +69,12 @@ spec:
           env:
             - name: SEARCH_SERVER
               value: "http://{{ ELASTICSEARCH_HOST }}:{{ ELASTICSEARCH_PORT }}"
-            - name: MONGOHQ_URL
-              value: "mongodb://{% if MONGODB_USERNAME and MONGODB_PASSWORD %}{{ MONGODB_USERNAME}}:{{ MONGODB_PASSWORD }}@{% endif %}{{ MONGODB_HOST }}:{{ MONGODB_PORT }}/cs_comments_service"
+            - name: MONGODB_AUTH
+              value: "{% if MONGODB_USERNAME and MONGODB_PASSWORD %}{{ MONGODB_USERNAME}}:{{ MONGODB_PASSWORD }}@{% endif %}"
+            - name: MONGODB_HOST
+              value: "{{ MONGODB_HOST }}"
+            - name: MONGODB_PORT
+              value: "{{ MONGODB_PORT }}"
 {% endif %}
 ---
 apiVersion: apps/v1

tutor/templates/local/docker-compose.yml

@@ -95,7 +95,9 @@ services:
     image: {{ DOCKER_REGISTRY }}{{ DOCKER_IMAGE_FORUM }}
     environment:
       SEARCH_SERVER: "http://{{ ELASTICSEARCH_HOST }}:{{ ELASTICSEARCH_PORT }}"
-      MONGOHQ_URL: "mongodb://{% if MONGODB_USERNAME and MONGODB_PASSWORD %}{{ MONGODB_USERNAME}}:{{ MONGODB_PASSWORD }}@{% endif %}{{ MONGODB_HOST }}:{{ MONGODB_PORT }}/cs_comments_service"
+      MONGODB_AUTH: "{% if MONGODB_USERNAME and MONGODB_PASSWORD %}{{ MONGODB_USERNAME}}:{{ MONGODB_PASSWORD }}@{% endif %}"
+      MONGODB_HOST: "{{ MONGODB_HOST }}"
+      MONGODB_PORT: "{{ MONGODB_PORT }}"
     restart: unless-stopped
     depends_on:
       {% if ACTIVATE_ELASTICSEARCH %}- elasticsearch{% endif %}