How do I automate deployment to Docker with CircleCI?

My circle.yml file and my CircleCI account are set up to use Docker for testing already, but I'd like to move to continuous deployment upon a successful build.

Here's what I have so far in circle.yml:

machine:
  services:
    - docker

dependencies:
  override:
    - docker info
    - docker build -t pgeiss/appname .

test:
  override:
    - docker run -d -p 8080:8080 pgeiss/appname; sleep 10
    - curl --retry 10 --retry-delay 5 -v http://localhost:8080/res.json

A few things need to happen for this to work properly. First, add a deployment section to circle.yml:

deployment:
  main: # or whatever your deployment is called
    branch: master # or whatever branch you want to deploy
    commands:
      - docker login -e (your email here) -u (your username here) -p (your password here)
      - docker push pgeiss/appname
      - ./start.sh

Thanks to this blog post for the following script. Then, make a file called start.sh in the top level of your repository (if you use a different name, change the circle.yml's last line) that contains the following:

#!/usr/bin/env bash

echo "stopping running application"
ssh $DEPLOY_USER@$DEPLOY_HOST 'docker stop dodsv'
ssh $DEPLOY_USER@$DEPLOY_HOST 'docker rm dodsv'

echo "pulling latest version of the code"
ssh $DEPLOY_USER@$DEPLOY_HOST 'docker pull pgeiss/appname-webapp:latest'

echo "starting the new version"
ssh $DEPLOY_USER@$DEPLOY_HOST 'docker run -d --restart=always --name dodsv -p 80:5432 pgeiss/appname:latest'

echo "success!"

exit 0

Finally, to allow the script to work you'll need to set the script to be executable with chmod and add the environment variables and your DEPLOY_USER's ssh key (preferably) or credentials (if no ssh key) to CircleCI. After doing that CircleCI should deploy your app after a successful build.

StackExchange DevOps Q#251, answer score: 7