MongoDB

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Creating a MongoDB Database

1. Navigate to your project
2. Select the environment
3. Click “Add Service” and select “MongoDB”
4. Configure the database settings

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Basic Configuration

• Name - A friendly name for your database
• App Name - The Docker service name (used for internal DNS)
• Description - Optional description
• Docker Image - Default: mongo:latest (recommended: mongo:7 or mongo:6)

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Database Credentials

• Database User - Username for database access (typically root-level access)
• Database Password - Password for the user

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Advanced Settings

• External Port - Optional port to expose MongoDB externally (default internal port: 27017)
• Command - Override the default container command
• Args - Additional arguments to pass to MongoDB
• Replica Sets - Enable replica set configuration for high availability
• Environment Variables - Additional custom environment variables

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Replica Sets

• Creates a replica set named rs0
• Initializes with a single member
• Automatically creates the root user after replica set initialization
• Required for features like transactions and change streams

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Connection Strings

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Internal Connection (from other services)

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Without Replica Sets

mongodb://[user]:[password]@[appName]:27017

mongodb://myuser:mypassword@my-mongo:27017

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With Replica Sets

mongodb://[user]:[password]@[appName]:27017/?replicaSet=rs0

mongodb://myuser:mypassword@my-mongo:27017/?replicaSet=rs0

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External Connection

mongodb://[user]:[password]@[host]:[externalPort]

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Connection String Formats

mongodb://username:password@hostname:27017/database?authSource=admin

mongosh "mongodb://username:password@hostname:27017/?authSource=admin"

const { MongoClient } = require('mongodb');

const client = new MongoClient(
  'mongodb://myuser:mypassword@my-mongo:27017/?authSource=admin'
);

await client.connect();
const db = client.db('myapp');

from pymongo import MongoClient

client = MongoClient(
    host="my-mongo",
    port=27017,
    username="myuser",
    password="mypassword",
    authSource="admin"
)

db = client.myapp

mongodb://username:password@hostname:27017/database?authSource=admin&replicaSet=rs0

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Environment Variables

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Data Persistence

• Mount Path: /data/db
• Volume Name: {appName}-data

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Resource Configuration

Memory Limit: 2GB        # Maximum memory
Memory Reservation: 1GB   # Guaranteed memory
CPU Limit: 2.0           # Maximum CPU cores
CPU Reservation: 0.5     # Guaranteed CPU cores

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Operations

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Starting the Database

POST /api/mongo/start
{
  "mongoId": "your-mongo-id"
}

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Stopping the Database

POST /api/mongo/stop
{
  "mongoId": "your-mongo-id"
}

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Reloading the Database

POST /api/mongo/reload
{
  "mongoId": "your-mongo-id"
}

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Rebuilding the Database

POST /api/mongo/rebuild
{
  "mongoId": "your-mongo-id"
}

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Accessing MongoDB Shell

docker exec -it $(docker ps -qf "name=my-mongo") mongosh -u myuser -p mypassword --authenticationDatabase admin

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Common MongoDB Commands

// Show all databases
show dbs

// Switch to database (creates if doesn't exist)
use myapp

// Show collections
show collections

// Insert document
db.users.insertOne({ name: "John", email: "[email protected]" })

// Find documents
db.users.find({})
db.users.findOne({ name: "John" })

// Update document
db.users.updateOne(
  { name: "John" },
  { $set: { email: "[email protected]" } }
)

// Delete document
db.users.deleteOne({ name: "John" })

// Create index
db.users.createIndex({ email: 1 }, { unique: true })

// Show indexes
db.users.getIndexes()

// Count documents
db.users.countDocuments()

// Show current user
db.runCommand({ connectionStatus: 1 })

// Show replica set status (if enabled)
rs.status()

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Database Administration

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Creating Additional Users

use admin
db.createUser({
  user: "appuser",
  pwd: "password",
  roles: [
    { role: "readWrite", db: "myapp" }
  ]
})

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User Roles

• read - Read data from all non-system collections
• readWrite - Read and modify data
• dbAdmin - Database administration tasks
• userAdmin - Create and modify users
• root - Superuser role (all privileges)

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Backup and Restore

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Manual Backup with mongodump

mongodump --uri="mongodb://user:pass@my-mongo:27017/?authSource=admin" --out=/backup

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Manual Restore with mongorestore

mongorestore --uri="mongodb://user:pass@my-mongo:27017/?authSource=admin" /backup

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Backups

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Troubleshooting

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Connection Refused

• Verify the service is running in Dokploy UI
• Check the service name matches your appName
• Ensure your application is in the same Docker network

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Authentication Failed

• Verify credentials in the database settings
• Ensure authSource=admin is in connection string
• Check if using the correct username and password
• For replica sets, ensure authentication is configured correctly

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Replica Set Issues

• Check replica set status: rs.status()
• Verify the service name is resolvable in Docker network
• Ensure MongoDB had time to initialize (check logs)

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Out of Memory

• Increase memory limits in resource configuration
• Check MongoDB logs for memory-related errors
• Consider using WiredTiger storage engine settings
• Optimize queries and indexes

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Best Practices

1. Use Specific Versions - Pin to specific MongoDB versions (e.g., mongo:7.0.5) instead of latest
2. Enable Replica Sets - Use replica sets for production to enable transactions
3. Strong Passwords - Use strong, randomly generated passwords
4. Regular Backups - Configure automated backups and test restoration
5. Indexes - Create indexes for frequently queried fields
6. Connection Pooling - Use connection pooling in your applications
7. Monitor Resources - Watch memory and CPU usage, especially disk I/O
8. Security - Don’t expose MongoDB externally; use VPN or SSH tunnels

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Performance Tuning

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WiredTiger Cache

--wiredTigerCacheSizeGB=1

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Connection Pool Settings

const client = new MongoClient(uri, {
  maxPoolSize: 50,
  minPoolSize: 10,
  maxIdleTimeMS: 30000
});

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Indexes

// Single field index
db.users.createIndex({ email: 1 })

// Compound index
db.users.createIndex({ lastName: 1, firstName: 1 })

// Text index for search
db.articles.createIndex({ content: "text" })

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Query Optimization

db.users.find({ email: "[email protected]" }).explain("executionStats")

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Transactions (Replica Sets Required)

const session = client.startSession();

try {
  session.startTransaction();
  
  await db.collection('accounts').updateOne(
    { _id: 'account1' },
    { $inc: { balance: -100 } },
    { session }
  );
  
  await db.collection('accounts').updateOne(
    { _id: 'account2' },
    { $inc: { balance: 100 } },
    { session }
  );
  
  await session.commitTransaction();
} catch (error) {
  await session.abortTransaction();
  throw error;
} finally {
  await session.endSession();
}

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Change Streams (Replica Sets Required)

const changeStream = db.collection('users').watch();

changeStream.on('change', (change) => {
  console.log('Change detected:', change);
});

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Next Steps