Zero-Downtime-Deployment

Zero downtime deployment with Swarm, HEALTHCHECK and Dnsrr:


https://www.youtube.com/watch?v=dLBGoaMz7dQ

https://github.com/BretFisher/browncoat

https://www.youtube.com/watch?v=oWrwi1NiViw


https://medium.com/better-programming/zero-downtime-deployment-with-docker-swarm-d84d8d9d9a14
https://medium.com/better-programming/zero-downtime-deployment-with-docker-swarm-d84d8d9d9a14

<if you update the nginx:1.18/latest image, you'll see that ninx run 6 replicas until the new image is stable!!
Don't forget to install visualizer to see the process in live.
/>  docker service create --name=viz --publish=8080:8080/tcp --constraint=node.role==manager --mount=type=bind,src=/var/run/docker.sock,dst=/var/run/docker.sock bretfisher/visualizer


version: '3.7'
services:
  nginx:
    image: "nginx:latest"

    ports:
      - '80:80'
    deploy:
      replicas: 4
      update_config:
        parallelism: 2
        order: start-first
        failure_action: rollback
        delay: 10s
      rollback_config:
        parallelism: 0
        order: stop-first
      restart_policy:
        condition: any
        delay: 5s
        max_attempts: 3
        window: 120s
    healthcheck:
      test: ["CMD", "curl", "--fail", "http://18.218.210.112"]
      interval: 20s
      timeout: 10s
      retries: 3


/> docker stack deploy --compose-file=docker-compose.yml nginx


================================================================================
<Important project>


vim dockerfile:

FROM php:7.2.2-apache
COPY ./index.php  /var/www/html
RUN docker-php-ext-install mysqli

<First, build the image,  docker build -t apach:latest . >
--------------------------------------------------------------------------------

vim index.php:


<?php
define('HOST', "18.218.210.112");
define('DBUSER', "root");
define('PASS', "1234");
define('DB', "myexample");
define('PORT', 3306);

$link=mysqli_connect(HOST,DBUSER,PASS,DB,PORT);

// Check connection
if (mysqli_connect_errno($link)){
    echo "Failure to connect: " . mysqli_connect_error();
}

$sql = "SELECT * FROM mytable";
$result = $link->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        echo  $row["myfield"]. "<br>";
    }
} else {
    echo "0 results";
}
$link->close();
?>
--------------------------------------------------------------------------------
 vim init.sql:


CREATE DATABASE myexample;
USE myexample;
CREATE TABLE mytable (myfield VARCHAR(20));
INSERT INTO mytable VALUES ('Hello'), ('Dolly');

--------------------------------------------------------------------------------

vim docker-compose.yml:

version: '3.7'
services:
  db:
    environment:
      MYSQL_ROOT_PASSWORD: 1234
    image: "mysql:5.7"
    volumes:
      - ./init.sql:/docker-entrypoint-initdb.d/init.sql
      - data-mysql:/var/lib/mysql
    ports:
      - '3306:3306'
    deploy:
      replicas: 2
    healthcheck:
      test: ["CMD-SHELL", 'mysqladmin ping']
      interval: 10s
      timeout: 5s
      retries: 10

  nginx:
    image: apach:latest
    depends_on:
      - db
    ports:
      - '80:80'
    deploy:
      replicas: 2
      update_config:
        parallelism: 2
        order: start-first
        failure_action: rollback
        delay: 10s
      rollback_config:
        parallelism: 0
        order: stop-first
      restart_policy:
        condition: any
        delay: 5s
        max_attempts: 3
        window: 120s
    healthcheck:
      test: ["CMD", "curl", "--fail", "http://18.218.210.112"]
      interval: 20s
      timeout: 10s
      retries: 3

volumes:
  data-mysql:
    driver: local





/>  docker stack deploy --compose-file=docker-compose.yml nginx