GitLab CI: zero downtime docker deployment

volumes_from:
    - applications
    - applications1

volumes_from:
    - php-fpm

links:
    - php-fpm

container_name: php-fpm

version: '2'
services:
### Applications Code Container #############################
    applications:
        container_name: application
        image: registry.gitlab.lc:5000/develop/ed:develop.sources.last
### Applications1 Code Container ############################
    applications1:
        container_name: application1
        image: registry.gitlab.lc:5000/develop/ed:docker.sources.last
### PHP-FPM Container #######################################
    php-fpm:
        image: registry.gitlab.lc:5000/develop/ed:php-fpm-ed-sq
        volumes_from:
            - applications
            - applications1
        expose:
            - "9000"
### Nginx Server Container ##################################
    nginx:
        container_name: nginx
        image: registry.gitlab.lc:5000/develop/ed:nginx-ed-sq
        volumes_from:
            - php-fpm
        depends_on:
            - "websocket"
        ports:
            - "${HTTP_PORT}:80"
            - "443:443"
### Redis Container #########################################
    redis:
        container_name: redis
        image: registry.gitlab.lc:5000/develop/ed:redis-ed-sq
        volumes:
            - redis:/data
        ports:
            - "6379:6379"
### Memcached Container #####################################
    memcached:
        container_name: memcached
        image: registry.gitlab.lc:5000/develop/ed:memcached-ed-sq
        volumes:
            - memcached:/var/lib/memcached
        ports:
            - "11211:11211"
### Websocket Container ######################################
    websocket:
        container_name: websocket
        restart: always
        image: registry.gitlab.lc:5000/develop/ed:websocket-ed-sq
        depends_on:
            - "redis"
        environment:
            - WS_PORT=${WS_PORT}
            - REDIS_HOST=${REDIS_HOST}
            - REDIS_PORT=${REDIS_PORT}
            - REDIS_PASS=${REDIS_PASS}
        volumes_from:
            - php-fpm
        ports:
            - "${WS_PORT}:${WS_PORT}"
### SDCV Container ##########################################
    sdcv:
        container_name: sdcv
        image: registry.gitlab.lc:5000/develop/ed:sdcv-ed-sq
        ports:
            - "9095:9095"
### Volumes Setup ###########################################
volumes:
    memcached:
        driver: "local"
    redis:
        driver: "local"

#!/bin/bash
NGINX_INCLUDE_PATH=/opt/nginx/include
 
echo "Updating nginx upsteam directive..."
# change string of ip addresses separated by / into an array
IFS="/" read -r -a addresses <<< $CONTAINERS
 
# update the upsteam directive contained within the upstream.include file
echo "upstream backend {" > $NGINX_INCLUDE_PATH/upstream.include
for container in $addresses; do
  echo "  server $container:9000;" >> $NGINX_INCLUDE_PATH/upstream.include
done
echo "}" >> $NGINX_INCLUDE_PATH/upstream.include

...
COPY ./nginx.conf /opt/nginx/nginx.conf
COPY ./conf.d/site.conf /opt/nginx/conf.d/site.conf
COPY ./include/upstream.include /opt/nginx/include/upstream.include
COPY ./update_upstream_directive.sh /usr/local/bin/
RUN chmod +x /usr/local/bin/*.sh
...

#!/bin/bash
DIRECTORY=~/docker
DC_FILE=docker-compose-staging.yml
ENV_FILE=.env.staging.lc
PROJECT_NETWORK=docker_default
SERVICES="applications applications1 php-fpm"
 
cd $DIRECTORY;
set -o allexport; . $ENV_FILE;
docker-compose -f $DC_FILE pull;
 
for service in $SERVICES; do
  # split needed container names that are already running into an array
  old_cont=($(docker-compose -f $DC_FILE ps $service | awk '{ print $1 }' | tail -n +3))
 
  # create the new containers with latest code changes
  docker-compose -f $DC_FILE up --scale $service=2 -d --no-deps $service
 
  if [ "$service" == "php-fpm" ]; then
    # create array with new containers only
    all_cont=($(docker-compose -f $DC_FILE ps $service | awk '{ print $1 }' | tail -n +3))
    new_cont=($(echo ${old_cont[*]} ${all_cont[*]} | tr ' ' '\n' | sort | uniq -u))
 
    # loop through containers and get IP addresses separated by / so they can be exported below
    IP_ADDRESSES=""
    for element in ${new_cont[*]}; do
      IP_ADDRESSES+="$(docker inspect -f {{.NetworkSettings.Networks.$PROJECT_NETWORK.IPAddress}} $element)/"
    done
 
    # run script to update the upstream.include file in nginx container
    docker-compose -f $DC_FILE exec -T nginx bash -c "export CONTAINERS=$IP_ADDRESSES && /usr/local/bin/update_upstream_directive.sh"
    sleep 5
    # Reload nginx service to update the upstream.include file in nginx container
    docker-compose -f $DC_FILE exec -T nginx bash -c "nginx -s reload"
  fi
  # stops the old containers
  for container in $old_cont; do
    docker kill $container
  done
 
  # deletes the old containers
  docker rm $(docker ps -aqf status=exited)
 
  # rename new containers to start at 1 and go up sequentially
  newly_started_cont=($(docker-compose -f $DC_FILE ps $service | awk '{ print $1 }' | tail -n +3))
  counter=0
  while [ $counter -lt ${#newly_started_cont[*]} ]; do
    for container in $newly_started_cont; do
      new_name=$(echo "${container%?}$(($counter+1))")
      docker rename $container $new_name
    done
    let counter=counter+1
  done
done
docker-compose -f $DC_FILE up -d --force-recreate --no-deps nginx