1. Create a docker-compose.yml File

You can create a Docker Compose file with the default name docker-compose.yml or choose a custom name. If you use a different file name, specify it with the -f option in Docker Compose commands. For example, if you name your file my-compose-file.yml, you would run:

docker-compose -f my-compose-file.yml up

Custom Name: Use the -f option to specify a different file name.

This file defines your application’s services, their configurations, volumes, and networks.

The docker-compose.yml file contains :

Example:

##### version: '3.8'  Specify the version of Docker Compose syntax to use

services:  
  web:  
##### image: ubuntu  Use the official Ubuntu image
##### command: sleep infinity  Keep the container running by using a command
    networks:  
##### - my_network  Connect the web service to the custom network

  db:  
##### image: mysql:5.7  Use the official MySQL image version 5.7
    environment:  
##### MYSQL_ROOT_PASSWORD: example  Set the root password for MySQL
    volumes:  
##### - db_data:/var/lib/mysql  Persist database data using a named volume
    networks:  
##### - my_network  Connect the db service to the custom network

networks:  
  my_network:  
##### driver: bridge  Use the default bridge network driver

volumes:  
##### db_data:  Declare the named volume used by the db service

This example defines two services: web (an Ubuntu ) and db (a MySQL database). It also defines a volume db_data to persist the database data.

2. Run the Application

 docker-compose up .

This command builds (if necessary) and starts all containers, creating the necessary networks and volumes.

3. Scale Services

To start all the services defined in the docker-compose.yml file and scale a specific service, use the following command:

docker-compose up --scale web=3

This command will run three instances of the web service. The --scale option allows you to specify the number of instances (or replicas) you want to run for a particular service.

4. Stop and Remove Containers

To stop and remove the containers, networks, and volumes defined in the docker-compose.yml file, use: docker-compose down This command stops all running containers and removes the resources created by docker-compose up.

5. Viewing Logs

You can view the combined logs from all services with: docker-compose logs [service_name]