Docker Compose Continuous Deployment setup - docker

Question

I am looking for a way to deploy docker-compose images and / or builds to a remote sever, specifically but not limited to a DigitalOcean VPS.
docker-compose is currently working on the CircleCI Continuous Integration service, where it automatically verifies that tests pass. But, it should deploy automatically on success.
My docker-compose.yml is looking like this:
version: '2'
services:
web:
image: name/repo:latest
ports:
- "3000:3000"
volumes:
- /app/node_modules
- .:/app
depends_on:
- mongo
- redis
mongo:
image: mongo
command: --smallfiles
volumes:
- ./data/mongodb:/data/db
redis:
image: redis
volumes:
- ./data/redis:/data
docker-compose.override.yml:
version: '2'
services:
web:
build: .
circle.yml relevant part:
deployment:
latest:
branch: master
commands:
- docker login -e $DOCKER_EMAIL -u $DOCKER_USER -p $DOCKER_PASS
- docker push name/repo:$CIRCLE_SHA1
- docker push name/repo:latest

Answer 1

Your docker-compose and circle configurations are already looking pretty good.
Your docker-compose.yml is already setup to gather the image from the Docker Hub, which is being uploaded after tests have passed. We will use this image on the remote server, which instead of building the image up every time (which takes a long time), we'll use this already prepared one.
You did well into separating the build: . into a docker-compose.override.yml file, as priority issues can arise if we use a docker-compose.prod.yml file.
Let's get started with the deployment:
There are various ways of getting your deployment done. The most popular ones are probably SSH and Webhooks.
We'll use SSH.
Edit your circle.yml config to take an additional step, which to load our .scripts/deploy.sh bash file:
deployment:
latest:
branch: master
commands:
- docker login -e $DOCKER_EMAIL -u $DOCKER_USER -p $DOCKER_PASS
- docker push name/repo:$CIRCLE_SHA1
- docker push name/repo:latest
- .scripts/deploy.sh
deploy.sh will contain a few instructions to connect into our remote server through SSH and update both the repository and Docker images and reload Docker Compose services.
Prior executing it, you should have a remote server that contains your project folder (i.e. git clone https://github.com/zurfyx/my-project), and both Docker and Docker Compose installed.
deploy.sh
#!/bin/bash
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
(
cd "$DIR/.." # Go to project dir.
ssh $SSH_USERNAME#$SSH_HOSTNAME -o StrictHostKeyChecking=no <<-EOF
cd $SSH_PROJECT_FOLDER
git pull
docker-compose pull
docker-compose stop
docker-compose rm -f
docker-compose -f docker-compose.yml -f docker-compose.prod.yml up -d
EOF
)
Notice: last EOF is not indented. That's how bash HEREDOC works.
deploy.sh steps explained:
ssh $SSH_USERNAME#$SSH_HOSTNAME: connects to the remote host through SSH. -o StrictHostChecking=no avoids the SSH asking whether we trust the server.
cd $SSH_PROJECT_FOLDER: browses to the project folder (the one you did gather through git clone ...)
git pull: updates project folder. That's important to keep docker-compose / Dockerfile updated, as well as any shared volume that depends on some source code file.
docker-compose stop: Our remote dependencies have just been downloaded. Stop the docker-compose services which are current running.
docker-compose rm -f: Remove docker-compose services. This step is really important, otherwise we'll reuse old volumes.
docker-compose -f docker-compose.yml -f docker-compose.prod.yml up -d. Execute your docker-compose.prod.yml which extends docker-compose.yml in detached mode.
On your CI you will need to fill in the following environment variables (that the deployment script uses):
$SSH_USERNAME: your SSH username (i.e. root)
$SSH_HOSTNAME: your SSH hostname (i.e. stackoverflow.com)
$SSH_PROJECT_FOLDER: the folder where the project is stored (either relative or absolute to where the $SSH_USERNAME is on login. (i.e. my-project/)
What about the SSH password? CircleCI in this case offers a way to store SSH keys, so password is no longer needed when logging in through SSH.
Otherwise simply edit the deploy.sh SSH connection to something like this:
sshpass -p your_password ssh user#hostname
More about SSH password here.
In conclusion, all we had to do was to create a script that connected with our remote server to let it know that the source code had been updated. Well, and to perform the appropriate upgrading steps.
FYI, that's similar to how the alternative Webhooks method work.

Answer 2

WatchTower solves this for you.
https://github.com/v2tec/watchtower
Your CI just needs to build the images and push to the registry. Then WatchTower polls the registry every N seconds and automagically restarts your services using the latest and greatest images. It's as simple as adding this code to your compose yaml:
watchtower:
image: v2tec/watchtower
volumes:
- /var/run/docker.sock:/var/run/docker.sock
- /root/.docker/config.json:/config.json
command: --interval 30