Make it easier to install extra XBlocks

As per issues #35 and #84

.gitignore

@@ -2,3 +2,4 @@
 config/
 data-*/
 TODO
+openedx/requirements/private.*

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Changelog
 
+- 2018-1113 [Improvement] Facilitate install of extra XBlocks. Thanks @frob!
 - 2018-10-30 [Bugfix] Fix rabbitmq restart policy
 - 2018-10-03 [Improvement/Bugfix] Fix and accelerate Android application build
 - 2018-10-02 [Improvement] Bump Open edX version to hawthorn.2

README.md

@@ -252,7 +252,15 @@ The images are built, tagged and uploaded to Docker Hub in one command:
 
     make dockerhub
   
-## Troubleshooting
+## Help/Troubleshooting
+
+### How to add extra XBlocks to the LMS/CMS?
+
+Additional requirements can be added to the `openedx/requirements/private.txt` file. Then, the `openedx` docker image must be rebuilt to include the new requirements. For instance:
+
+    echo "git+https://github.com/open-craft/xblock-poll.git" >> openedx/requirements/private.txt
+    make build-openedx
+    make run
 
 ### Help! Your containers are eating all my RAM/CPU/CHEESE
 

openedx/Dockerfile

@@ -47,19 +47,23 @@ RUN ln -s /openedx/config/lms.env.json /openedx/ \
   && ln -s /openedx/config/lms.auth.json /openedx/ \
   && ln -s /openedx/config/cms.auth.json /openedx/
 
-VOLUME /openedx/config
-VOLUME /openedx/data
-VOLUME /openedx/edx-platform
-
 # Dockerize will be useful to wait for mysql DB availability
 ENV DOCKERIZE_VERSION v0.6.1
 RUN curl -L -o 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 dockerize.tar.gz \
     && rm dockerize.tar.gz
 
+# Install private requirements as late as possible, so they can be modified frequently
+COPY ./requirements/private.txt /tmp/
+RUN pip install --src ../venv/src -r /tmp/private.txt
+
 # Copy convenient scripts
 COPY ./bin/docker-entrypoint.sh /usr/local/bin/
 
+VOLUME /openedx/config
+VOLUME /openedx/data
+VOLUME /openedx/edx-platform
+
 # service variant is "lms" or "cms"
 ENV SERVICE_VARIANT lms
 ENV SETTINGS universal.production

openedx/requirements/private.txt

@@ -0,0 +1,3 @@
+# Add your additional requirements here, such as xblocks. This file is not
+# under version control, which means that your changes will not be committed to
+# the upstream repository.