A sample git post-receive hook to deploy with docker. Use the latest commit hash as image tags to make sure the latest gets pulled always, assumes services were deployed using docker stack deploy.

docker-git-post-receive.sh

#!/bin/bash

PREFIX="MY CLIENT -"
REPO_PATH='/home/ubuntu/server/client'

ACCEPTABLE_BRANCH="DEV"

COMPOSE_FILE="docker-compose.production.yml"
CLIENT_IMAGE="127.0.0.1:5000/mpc_nginx_client"


deploy () {
  cd $REPO_PATH
  # FRONTEND_TAG is being used in the compose file as the tag variable
  # image: 127.0.0.1:5000/mpc_nginx_client:${FRONTEND_TAG}
  export FRONTEND_TAG=$(env -i git log -1 --pretty=%h)
  
  # fetch and reset the latest branch
  env -i git fetch origin $ACCEPTABLE_BRANCH
  env -i git checkout -B $ACCEPTABLE_BRANCH --track origin/$ACCEPTABLE_BRANCH
  
  # build and tag the image using the latest commit hash (short)
  docker-compose -f $COMPOSE_FILE build nginx_client
  docker tag $CLIENT_IMAGE:$FRONTEND_TAG $CLIENT_IMAGE:latest
  # push to local registry defined in the compose file
  docker-compose -f $COMPOSE_FILE push nginx_client
  # apply rolling updates to services assuming they were deployed using docker stack deploy
  docker service update \
    --image $CLIENT_IMAGE:$FRONTEND_TAG \
  # rollback to previous version on failue
    --update-failure-action rollback \
  # monitor the service for upto 1 minute before confirming the update
    --update-monitor 1m \
    mpc_nginx_client
}

# read the incoming branch and if matched with the acceptable branch
# run deploy method else exit with message
while read oldrev newrev refname
do
    INCOMING_BRANCH=$(git rev-parse --symbolic --abbrev-ref $refname)
    echo "$PREFIX Received branch $INCOMING_BRANCH"

    if [ "$INCOMING_BRANCH" == "$ACCEPTABLE_BRANCH" ]; then
        echo "$PREFIX received branch is same as branch on client repo"
        deploy
    else
        echo "$PREFIX received branch is not $ACCEPTABLE_BRANCH"
    fi
done