docker-compose

Published May 5, 2023 Last updated May 5, 2023 Edit Source

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docker-compose is a tool that allows for management of multiple docker containers. It is basically a docker container container other subcontainers that makes it easy for the subcontainers to communicate with each other. It is written in a docker-compose.yml.

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# docker-compose.yml
version: "3.9"
services: #images to run
  web: #arbitrary name for a service
    build: . #will build the image defined in Dockerfile at the defined path
    ports:
      - "8000:5000"
  redis:
    image: "redis:alpine" #use local image if found, else pulls from dockerhub

subcontainers are defined as services in docker-compose.yml. Unless the codebase is a monorepo, there needs to be a way to update services individually.

a. It could be done in a monorepo, but these could be large. If a developer only has to work on one of the services, it doesn’t make sense to have them download the rest of the codebase to be able to work.

b. The solution: make all the services into their own image and use the image property for services. This way, the project file for the services doesn’t have to be on the same repository as the docker-compose.yml file. If the image is on dockerhub, you don’t even need to have the source code.