Docker stack deploy without downtime

deploymentdockerstack

I am following the Docker tutorial and do it in my own version

version: "3.1"
services:
    web:
        image: registry.gitlab.com/xxxx/xxxx:latest
        deploy:
             replicas: 2
        ports:
             - "8888:80"
    mysql:
        image: mysql:latest
        environment:
           MYSQL_ROOT_PASSWORD: password
           MYSQL_USER: user
           MYSQL_PASS: password
        ports:
             - "8889:3306"
        volumes: 
           - mysql-data:/var/lib/mysql
volumes:
   mysql-data:

Whenever I change some code, I rebuild new docker image and run update. 

docker stack deploy --compose-file docker-compose.yml xxxx-learn

Then I noticed some downtime. They will start new container one at the time and stop old container one at the time. Then problem is that it takes a few minutes to download new image and it takes time for web server to run.

One solution that I was thinking of is to run Nginx load balancing in front of those two web server replicas. But is there any better solution?

Best Answer

You should put restart policy and stop_grace_period on your compose file:

version: "3.1"
services:
    web:
        stop_grace_period: 10s
        deploy:
             replicas: 2
             restart_policy:
               condition: on-failure
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