mongodbHow to set up a MongoDB replica with Docker Compose?

Setting up a MongoDB replica with Docker Compose is a straightforward process.

1. Create a docker-compose.yml file with the following content:

version: '3'
services:
  mongo-primary:
    image: mongo
    ports:
      - 27017:27017
    volumes:
      - ./data/primary:/data/db
    command: mongod --replSet rs0
  mongo-secondary:
    image: mongo
    ports:
      - 27018:27017
    volumes:
      - ./data/secondary:/data/db
    command: mongod --replSet rs0

2. Start the containers with docker-compose up -d

3. Connect to the primary container with docker exec -it mongo-primary mongo

4. Initialize the replica set with the following command:

rs.initiate(
  {
    _id: "rs0",
    members: [
      { _id: 0, host: "mongo-primary:27017" },
      { _id: 1, host: "mongo-secondary:27017" }
    ]
  }
)

5. Verify the replica set is working with rs.status()

Helpful links

• Docker Compose Documentation
• MongoDB Replica Set Documentation

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