What is docker compose?

Docker compose is a tool for defining & running multi-container docker applications

• use yaml files to configure application services (docker-compose.yml)
• can start all services with a single command (docker compose up)
• can stop all services with a single command (docker compose down)
• can scale up selected services when required

Step 1: Install docker compose

Docker Desktop for Mac and Windows, Docker Toolbox already include Compose along with other Docker apps, so Mac & Windows users do not need to install Compose separately.

For Linux

$ sudo curl -L "https://github.com/docker/compose/releases/download/1.26.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

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

Check if installed successfully

$ docker-compose -v

Still unable to install docker-compose?

Follow the tutorial: https://docs.docker.com/compose/install/

Step 2: Create docker compose file at any location

$ touch docker-compose.yml

Enter the following instructions in docker-compose.yml file. This will be used to create services(web and database in this case)

version: "3"
services:
    web:
        image: nginx
    
    database:
        image: redis

Step 3: Check the validity of the compose file

# move into the compose file directory and run the command
$ docker-compose config

If any error occurs, please refer: https://docs.docker.com/compose/compose-file/

Step 4: Run docker-compose.yml file

$ docker-compose up

It will start all the services in one command.

To start in detached mode

$ docker-compose up -d

Step 5: Check current containers

List all containers using this command

$ docker ps

Step 6: Stop all services

$ docker-compose down

It will stop all the running services in one command

Step 7: Scaling services

You can scale up any service using this command

$ docker-compose up -d --scale <service-key>=<number-of-instance>

# Example
$ docker-compose up -d --scale database=4