docker-compose.yml

name: my-mongo-cluster

services:
  # Uncomment and modify the following section to include your application.
  # Ensure that the application is configured to connect to the MongoDB replica set.

  # app:
  #   image: my-app:latest
  #   depends_on:
  #     mongo-init-replica:
  #       condition: service_completed_successfully
  #     mongo1:
  #       condition: service_healthy
  #   command:
  #     ["--hostname", "0.0.0.0", "--mongo-db", "mongodb://mongo1:27017/my db"]

  mongo1:
    image: mongo:7-jammy
    stop_grace_period: 30s
    ports:
      - 27017:27017
    volumes:
      - mongo1-data:/data/db
    command: ["--replSet", "rs0", "--quiet"]
    healthcheck:
      test: ["CMD", "mongosh", "--eval", "db.runCommand('ping').ok"]
      interval: 2s
      timeout: 10s
      retries: 5

  mongo2:
    image: mongo:7-jammy
    stop_grace_period: 30s
    ports:
      - 27018:27017
    volumes:
      - mongo2-data:/data/db
    command: ["--replSet", "rs0", "--quiet"]
    healthcheck:
      test: ["CMD", "mongosh", "--eval", "db.runCommand('ping').ok"]
      interval: 2s
      timeout: 10s
      retries: 5

  mongo3:
    image: mongo:7-jammy
    stop_grace_period: 30s
    ports:
      - 27019:27017
    volumes:
      - mongo3-data:/data/db
    command: ["--replSet", "rs0", "--quiet"]
    healthcheck:
      test: ["CMD", "mongosh", "--eval", "db.runCommand('ping').ok"]
      interval: 2s
      timeout: 10s
      retries: 5

  mongo-init-replica:
    image: mongo:7-jammy
    depends_on:
      mongo1:
        condition: service_healthy
      mongo2:
        condition: service_healthy
      mongo3:
        condition: service_healthy
    command: >
      bash -c '
        mongosh --host mongo1:27017 --eval "
          let status = 0;
          try {
            status = rs.status().myState;
          } catch (e) {
            status = -1;
          }

          if (status > 0) {
            print(\"Replica set already initiated.\");
          } else {
            rs.initiate({
              _id: \"rs0\",
              members: [
                { _id: 0, host: \"mongo1:27017\" },
                { _id: 1, host: \"mongo2:27017\" },
                { _id: 2, host: \"mongo3:27017\" }
              ]
            });
          }
          let attempts = 0;
          const maxAttempts = 120 / 0.5; // Timeout after 2 minutes
          while (true) {
            const rsStatus = rs.status();
            const primaryExists = rsStatus.members.some(member => member.state === 1);
            if (primaryExists) {
              print(\"Replica set is fully operational.\");
              break;
            } else if (attempts >= maxAttempts) {
              print(\"Failed to initialize replica set within the timeout period.\");
              break;
            } else {
              print(\"Waiting for replica set to initialize...\");
              sleep(500);
              attempts++;
            }
          }
        "
      '

volumes:
  mongo1-data:
  mongo2-data:
  mongo3-data: