MongoDB Replica Set

# SSH into your server
ssh root@your-server-ip

# Using a custom SSH key
ssh -i ~/.ssh/id_rsa root@your-server-ip

# Create and navigate to project directory
mkdir -p ~/apps/mongodb-replicaset
cd ~/apps/mongodb-replicaset

services:
  mongodb-primary:
    image: mongo:7
    ports:
      - "27017:27017"
    entrypoint:
      - bash
      - -c
      - |
          set -e
          KEYFILE_PATH=/etc/mongo-keyfile/keyfile
          if [ ! -s $$KEYFILE_PATH ]; then
            umask 077
            openssl rand -base64 756 > $$KEYFILE_PATH
            chown mongodb:mongodb $$KEYFILE_PATH
            chmod 0400 $$KEYFILE_PATH
          fi
          exec docker-entrypoint.sh "$$@"
      - --
    command: ["--replSet", "rs0", "--bind_ip_all", "--keyFile", "/etc/mongo-keyfile/keyfile"]
    environment:
      - MONGO_INITDB_ROOT_USERNAME=admin
      - MONGO_INITDB_ROOT_PASSWORD=<your-mongo-password>
    volumes:
      - mongodb_primary_data:/data/db
      - mongodb_keyfile:/etc/mongo-keyfile
    restart: unless-stopped
    healthcheck:
      test: ["CMD", "mongosh", "--quiet", "--username", "admin", "--password", "<your-mongo-password>", "--authenticationDatabase", "admin", "--eval", "db.adminCommand('ping').ok"]
      interval: 30s
      timeout: 10s
      retries: 5

  mongodb-secondary1:
    image: mongo:7
    entrypoint:
      - bash
      - -c
      - |
          set -e
          KEYFILE_PATH=/etc/mongo-keyfile/keyfile
          until [ -s $$KEYFILE_PATH ]; do
            echo "Waiting for MongoDB keyfile..."
            sleep 1
          done
          exec docker-entrypoint.sh "$$@"
      - --
    command: ["--replSet", "rs0", "--bind_ip_all", "--keyFile", "/etc/mongo-keyfile/keyfile", "--auth"]
    volumes:
      - mongodb_secondary1_data:/data/db
      - mongodb_keyfile:/etc/mongo-keyfile:ro
    depends_on:
      - mongodb-primary
    restart: unless-stopped

  mongodb-secondary2:
    image: mongo:7
    entrypoint:
      - bash
      - -c
      - |
          set -e
          KEYFILE_PATH=/etc/mongo-keyfile/keyfile
          until [ -s $$KEYFILE_PATH ]; do
            echo "Waiting for MongoDB keyfile..."
            sleep 1
          done
          exec docker-entrypoint.sh "$$@"
      - --
    command: ["--replSet", "rs0", "--bind_ip_all", "--keyFile", "/etc/mongo-keyfile/keyfile", "--auth"]
    volumes:
      - mongodb_secondary2_data:/data/db
      - mongodb_keyfile:/etc/mongo-keyfile:ro
    depends_on:
      - mongodb-primary
    restart: unless-stopped

  mongodb-init:
    image: mongo:7
    depends_on:
      - mongodb-primary
      - mongodb-secondary1
      - mongodb-secondary2
    restart: "no"
    environment:
      - MONGO_USER=admin
      - MONGO_PASSWORD=<your-mongo-password>
    entrypoint:
      - bash
      - -lc
      - |
          set -e

          echo "Waiting for MongoDB primary (auth)..."
          until mongosh --quiet mongodb-primary:27017/admin --authenticationDatabase admin --username $$MONGO_USER --password $$MONGO_PASSWORD --eval "db.adminCommand({ ping: 1 }).ok" 2>/dev/null | grep -q 1; do
            sleep 1
          done

          echo "Waiting for MongoDB secondaries..."
          until mongosh --quiet mongodb-secondary1:27017/admin --eval "db.hello().ok" 2>/dev/null | grep -q 1; do
            sleep 1
          done
          until mongosh --quiet mongodb-secondary2:27017/admin --eval "db.hello().ok" 2>/dev/null | grep -q 1; do
            sleep 1
          done

          # Idempotency: if already configured, do nothing.
          if mongosh --quiet mongodb-primary:27017/admin --authenticationDatabase admin --username $$MONGO_USER --password $$MONGO_PASSWORD --eval "db.hello().setName" 2>/dev/null | grep -q rs0; then
            echo "Replica set already initialized."
            exit 0
          fi

          echo "Initializing replica set..."
          mongosh --quiet mongodb-primary:27017/admin --authenticationDatabase admin --username $$MONGO_USER --password $$MONGO_PASSWORD --eval "rs.initiate({_id: 'rs0', members: [{_id: 0, host: 'mongodb-primary:27017'}, {_id: 1, host: 'mongodb-secondary1:27017'}, {_id: 2, host: 'mongodb-secondary2:27017'}]})"

          echo "Waiting for PRIMARY..."
          until mongosh --quiet mongodb-primary:27017/admin --authenticationDatabase admin --username $$MONGO_USER --password $$MONGO_PASSWORD --eval "db.hello().isWritablePrimary ? 1 : 0" 2>/dev/null | grep -q 1; do
            sleep 1
          done

          echo "Replica set initialized."

volumes:
  mongodb_primary_data:
  mongodb_secondary1_data:
  mongodb_secondary2_data:
  mongodb_keyfile:

# Start the containers in detached mode
docker compose up -d

# Check if containers are running
docker compose ps

# View logs
docker compose logs -f

# Allow the application port through firewall
sudo ufw allow 27017/tcp
sudo ufw reload

# Access your app at:
# http://your-server-ip:27017