Docker Compose is a tool that allows developers to define and run Docker applications that span multiple containers. The applications are defined in a YAML file called docker-compose.yml, which specifies the containers, their configuration, as well as the networks and volumes that will be used. In this post, we'll go over the Docker Compose YAML syntax and show you how to create a docker-compose.yml file.A Docker Compose YAML file is a text file that contains the definition of one or more services. A service is a containerized application, and the compose file specifies the configuration, environment variables, and networking information for each service. The compose file also defines any shared volumes or networks that the containers will use.
A basic Docker Compose YAML file consists of four main parts: version, services, volumes, and networks. Here's an example of a basic docker-compose.yml file:
Following example file .
Version
The version key specifies the version of the Docker Compose file format that the file adheres to. The current version as of this writing is version 3.
Services
The services section specifies the different containers that make up the application. Each service has a name, which is used to identify the container, and a configuration, which specifies the Docker image, the ports to expose, the environment variables, and other options.
Volumes
The volumes section specifies the shared volumes that the containers will use. Volumes allow data to persist across container restarts and can be used to share data between containers.
In the example above, we have one volume named db-data.
Networks
The networks section specifies the network settings for the containers. Networks allow containers to communicate with each other, and they can be used to isolate containers from each other.
version: "3"
services:
web:
build: .
ports:
- "8000:8000"
db:
image: postgres
environment:
POSTGRES_USER: myuser
POSTGRES_PASSWORD: mypassword
volumes:
db-data:
networks:
backend: