Docker Compose

 

Docker Compose
it is a microservice approach to create containers and manage containers for orchestration.

docker-compose is a tool for defining and running multi-container Docker applications. With docker-compose, you use a YAML file to configure your application’s services. Then, with a single command, you create and start all the services from your configuration.

Using Compose is basically a three-step process:
1. Define your app’s environment with a Dockerfile so it can be reproduced anywhere.
2. Define the services that make up your app in docker-compose.yml so they can be run together in an isolated environment.
3. Run docker-compose up and Compose starts and runs your entire app.

Docker Compose commands:

docker-compose up -d	This will create a network, and create the containers as per defined in the docker-compose.yml file
docker-compose down	This will stop and remove the containers then it will remove the network. The containers stopped and removed are as of defined in the docker-compose.yml file.
docker-compose scale db=2	If for exam[le in the docker-compose.yml file, you specified a db container, using the scale command, it will create for you 2 db containers.

Install Docker compose file
sudo curl -L "https://github.com/docker/compose/releases/download/1.23.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

chmod +x /usr/local/bin/docker-compose

docker-compose --version

Example 1:

version: '3.3' 

services: 

         db: 

                 image: mysql:5.7 

                 volumes: 

                   - db_data:/var/lib/mysql 

                 restart: always 

                 environment: 

                     MYSQL_ROOT_PASSWORD: somewordpress 

                     MYSQL_DATABASE: wordpress 

                     MYSQL_USER: wordpress 

                     MYSQL_PASSWORD: wordpress 

         wordpress: 

             depends_on: 

                     - db 

                         image: wordpress:latest 

                         ports:

                          - "80:80" 

                         restart: always 

                         environment: 

                             WORDPRESS_DB_HOST: db:3306 

                             WORDPRESS_DB_USER: wordpress 

                             WORDPRESS_DB_PASSWORD: wordpress 

                             WORDPRESS_DB_NAME: wordpress 

                        volumes: 

                          db_data: {}

docker-compose up -d
docker-compose down

Example 2

version: '3.3' 

services: 

     db: 

         image: ramansharma95/mysql 

     webapp: 

         image: ramansharma95/webapp 

         ports: 

             - "80:80"

Run the following command in mysql container:

docker exec -it <<containerid>> bash 

mysql -uroot -pwhizlabs
create database company;
use company;
create table employee ( name varchar(30), mobile varchar(30));
select * from employee;