AWS: CodeDeploy for a Docker Compose project? - django

Question

My current objective is to have Travis deploy our Django+Docker-Compose project upon successful merge of a pull request to our Git master branch. I have done some work setting up our AWS CodeDeploy since Travis has builtin support for it. When I got to the AppSpec and actual deployment part, at first I tried to have an AfterInstall script do docker-compose build and then have an ApplicationStart script do docker-compose up. The containers that have images pulled from the web are our PostgreSQL container (named db, image aidanlister/postgres-hstore which is the usual postgres image plus the hstore extension), the Redis container (uses the redis image), and the Selenium container (image selenium/standalone-firefox). The other two containers, web and worker, which are the Django server and Celery worker respectively, use the same Dockerfile to build an image. The main command is:
CMD paver docker_run
which uses a pavement.py file:
from paver.easy import task
from paver.easy import sh
#task
def docker_run():
migrate()
collectStatic()
updateRequirements()
startServer()
#task
def migrate():
sh('./manage.py makemigrations --noinput')
sh('./manage.py migrate --noinput')
#task
def collectStatic():
sh('./manage.py collectstatic --noinput')
# find any updates to existing packages, install any new packages
#task
def updateRequirements():
sh('pip install --upgrade -r requirements.txt')
#task
def startServer():
sh('./manage.py runserver 0.0.0.0:8000')
Here is what I (think I) need to make happen each time a pull request is merged:
Have Travis deploy changes using CodeDeploy, based on deploy section in .travis.yml tailored to our CodeDeploy setup
Start our Docker containers on AWS after successful deployment using our docker-compose.yml
How do I get this second step to happen? I'm pretty sure ECS is actually not what is needed here. My current status right now is that I can get Docker started with sudo service docker start but I cannot get docker-compose up to be successful. Though deployments are reported as "successful", this is only because the docker-compose up command is run in the background in the Validate Service section script. In fact, when I try to do docker-compose up manually when ssh'd into the EC2 instance, I get stuck building one of the containers, right before the CMD paver docker_run part of the Dockerfile.

Answer 1

This took a long time to work out, but I finally figured out a way to deploy a Django+Docker-Compose project with CodeDeploy without Docker-Machine or ECS.
One thing that was important was to make an alternate docker-compose.yml that excluded the selenium container--all it did was cause problems and was only useful for local testing. In addition, it was important to choose an instance type that could handle building containers. The reason why containers couldn't be built from our Dockerfile was that the instance simply did not have the memory to complete the build. Instead of a t1.micro instance, an m3.medium is what worked. It is also important to have sufficient disk space--8GB is far too small. To be safe, 256GB would be ideal.
It is important to have an After Install script run service docker start when doing the necessary Docker installation and setup (including installing Docker-Compose). This is to explicitly start running the Docker daemon--without this command, you will get the error Could not connect to Docker daemon. When installing Docker-Compose, it is important to place it in /opt/bin/ so that the binary is used via /opt/bin/docker-compose. There are problems with placing it in /usr/local/bin (I don't exactly remember what problems, but it's related to the particular Linux distribution for the Amazon Linux AMI). The After Install script needs to be run as root (runas: root in the appspec.yml AfterInstall section).
Additionally, the final phase of deployment, which is starting up the containers with docker-compose up (more specifically /opt/bin/docker-compose -f docker-compose-aws.yml up), needs to be run in the background with stdin and stdout redirected to /dev/null:
/opt/bin/docker-compose -f docker-compose-aws.yml up -d > /dev/null 2> /dev/null < /dev/null &
Otherwise, once the server is started, the deployment will hang because the final script command (in the ApplicationStart section of my appspec.yml in my case) doesn't exit. This will probably result in a deployment failure after the default deployment timeout of 1 hour.
If all goes well, then the site can finally be accessed at the instance's public DNS and port in your browser.