Creating users and roles in MongoDB - Try It Yourself

Creating users and roles

📖 Scenario: You are setting up a MongoDB database for a small company. You need to create users with specific roles to control access to the database.

🎯 Goal: Learn how to create users and assign roles in MongoDB to manage database access securely.

📋 What You'll Learn

Create a user with read-only access to a database

Create a user with readWrite access to a database

Create a custom role with specific privileges

Assign the custom role to a new user

💡 Why This Matters

🌍 Real World

In real companies, controlling who can read or write data is important for security and data integrity.

💼 Career

Database administrators and backend developers often create users and roles to manage access in production databases.

1

Create a read-only user

Use the db.createUser() method to create a user called readonlyUser with password readonlyPass123 who has the read role on the companyDB database.

MongoDB

# Use db.createUser() to create readonlyUser with read role on companyDB
# Your code here

Hint

Remember to specify the user name, password, and roles array with the correct role and database.

2

Create a readWrite user

Create a user called writerUser with password writePass456 who has the readWrite role on the companyDB database using db.createUser().

MongoDB

db.createUser({
  user: "readonlyUser",
  pwd: "readonlyPass123",
  roles: [ { role: "read", db: "companyDB" } ]
})

# Create writerUser with readWrite role on companyDB
# Your code here

Hint

Use the same method as before but change the user name, password, and role to readWrite.

3

Create a custom role

Use db.createRole() to create a role called customReporter on the companyDB database. This role should have the privilege to find documents on the reports collection.

MongoDB

db.createUser({
  user: "readonlyUser",
  pwd: "readonlyPass123",
  roles: [ { role: "read", db: "companyDB" } ]
})

db.createUser({
  user: "writerUser",
  pwd: "writePass456",
  roles: [ { role: "readWrite", db: "companyDB" } ]
})

# Create customReporter role with find privilege on reports collection
# Your code here

Hint

Define the role name, privileges with resource and actions, and an empty roles array.

4

Assign the custom role to a new user

Create a user called reportUser with password reportPass789 who has the customReporter role on the companyDB database using db.createUser().

MongoDB

db.createUser({
  user: "readonlyUser",
  pwd: "readonlyPass123",
  roles: [ { role: "read", db: "companyDB" } ]
})

db.createUser({
  user: "writerUser",
  pwd: "writePass456",
  roles: [ { role: "readWrite", db: "companyDB" } ]
})

db.createRole({
  role: "customReporter",
  privileges: [
    {
      resource: { db: "companyDB", collection: "reports" },
      actions: [ "find" ]
    }
  ],
  roles: []
})

# Create reportUser with customReporter role on companyDB
# Your code here

Hint

Use db.createUser with the new user name, password, and assign the customReporter role.

Practice

1. What is the primary purpose of creating users in MongoDB?

easy

A. To control who can access the database

B. To store data in collections

C. To optimize query performance

D. To backup the database automatically

Solution

1. Step 1: Understand user creation in MongoDB

   Users in MongoDB are created to manage access to the database system.

2. Step 2: Identify the purpose of users

   Users control who can connect and perform actions on the database.

3. Final Answer:

   To control who can access the database -> Option A

4. Quick Check:

   Users = Access control [OK]

Hint: Users manage access, not data or backups [OK]

Common Mistakes:

• Confusing users with data storage
• Thinking users optimize queries
• Assuming users handle backups

2. Which of the following is the correct syntax to create a user with read-only access on the sales database in MongoDB?

easy

A. db.createUser({user: 'reader', pwd: 'pass', roles: [{role: 'read', db: 'sales'}]})

B. db.createUser({user: 'reader', pwd: 'pass', roles: ['read']})

C. db.addUser('reader', 'pass', 'read')

D. db.users.insert({user: 'reader', pwd: 'pass', role: 'read'})

Solution

1. Step 1: Recall MongoDB user creation syntax

   The correct syntax uses db.createUser() with roles as an array of objects specifying role and database.

2. Step 2: Check each option

   db.createUser({user: 'reader', pwd: 'pass', roles: [{role: 'read', db: 'sales'}]}) correctly specifies the role 'read' on the 'sales' database. db.createUser({user: 'reader', pwd: 'pass', roles: ['read']}) misses the database name, C uses deprecated syntax, D tries to insert directly into users collection which is invalid.

3. Final Answer:

   db.createUser({user: 'reader', pwd: 'pass', roles: [{role: 'read', db: 'sales'}]}) -> Option A

4. Quick Check:

   Roles need role and db fields [OK]

Hint: Roles need role and db fields in array [OK]

Common Mistakes:

• Omitting the database in roles
• Using deprecated addUser method
• Trying to insert user directly into collection

3. Given the following command in MongoDB shell:

db.createUser({user: 'adminUser', pwd: 'secure123', roles: [{role: 'userAdminAnyDatabase', db: 'admin'}]})

What permission does the user adminUser have?

medium

A. Can read data from any database

B. Can manage users on any database

C. Can only read the admin database

D. Can write data to any database

Solution

1. Step 1: Understand the role userAdminAnyDatabase

   This role allows managing users and roles across all databases.

2. Step 2: Analyze the permissions given

   The user can create, modify, and delete users on any database but does not have read or write data permissions by default.

3. Final Answer:

   Can manage users on any database -> Option B

4. Quick Check:

   userAdminAnyDatabase = user management [OK]

Hint: userAdminAnyDatabase manages users, not data [OK]

Common Mistakes:

• Assuming it grants read or write data access
• Confusing admin database with all databases
• Thinking it only applies to admin database

4. You try to create a user with this command:

db.createUser({user: 'testUser', pwd: 'test123', roles: ['readWrite']})

But it fails. What is the most likely reason?

medium

A. Password is too short

B. User already exists

C. Roles must be objects specifying role and database

D. Missing database name in createUser command

Solution

1. Step 1: Check roles format in createUser

   Roles must be an array of objects with role and db fields, not just strings.

2. Step 2: Identify the error cause

   The command uses roles as strings, which is invalid syntax causing failure.

3. Final Answer:

   Roles must be objects specifying role and database -> Option C

4. Quick Check:

   Roles = [{role: '', db: ''}] [OK]

Hint: Roles need role and db objects, not strings [OK]

Common Mistakes:

• Using role names as plain strings
• Ignoring role database specification
• Assuming password length causes failure

5. You want to create a custom role named reportViewer that allows users to only read data from the reports collection in the analytics database. Which command correctly creates this role?

hard

A. db.createRole({role: 'reportViewer', privileges: [{resource: {db: 'analytics', collection: 'reports'}, actions: ['read']}], roles: []})

B. db.createRole({role: 'reportViewer', privileges: [{resource: {db: 'analytics'}, actions: ['read']}], roles: []})

C. db.createRole({role: 'reportViewer', privileges: [{resource: {collection: 'reports'}, actions: ['find']}], roles: []})

D. db.createRole({role: 'reportViewer', privileges: [{resource: {db: 'analytics', collection: 'reports'}, actions: ['find']}], roles: []})

Solution

1. Step 1: Understand custom role creation syntax

   Custom roles require specifying privileges with resource (db and collection) and actions allowed.

2. Step 2: Analyze each option's privileges

   db.createRole({role: 'reportViewer', privileges: [{resource: {db: 'analytics', collection: 'reports'}, actions: ['find']}], roles: []}) correctly specifies the database 'analytics', collection 'reports', and action 'find' which allows reading documents. db.createRole({role: 'reportViewer', privileges: [{resource: {db: 'analytics'}, actions: ['read']}], roles: []}) uses 'read' action on the whole database, not just the collection. db.createRole({role: 'reportViewer', privileges: [{resource: {collection: 'reports'}, actions: ['find']}], roles: []}) misses the database name. db.createRole({role: 'reportViewer', privileges: [{resource: {db: 'analytics', collection: 'reports'}, actions: ['read']}], roles: []}) uses 'read' action which is not a valid action for privileges; 'find' is correct for reading documents.

3. Final Answer:

   db.createRole({role: 'reportViewer', privileges: [{resource: {db: 'analytics', collection: 'reports'}, actions: ['find']}], roles: []}) -> Option D

4. Quick Check:

   Custom role needs db, collection, and 'find' action [OK]

Hint: Use 'find' action for read on specific collection [OK]

Common Mistakes:

• Using 'read' action instead of 'find'
• Omitting database name in resource
• Specifying collection without database