Creating first admin user in Jenkins - Step-by-Step CLI Walkthrough

Introduction

When you install Jenkins for the first time, you need to create an admin user to securely manage your Jenkins server. This user has full control to configure and run jobs.

Right after installing Jenkins to secure access.

When setting up Jenkins on a new server for your team.

When you want to restrict who can change Jenkins settings.

Before creating any build jobs to keep your server safe.

When you want to manage users and permissions centrally.

Commands

This command shows the initial admin password Jenkins generates during installation. You need this password to unlock Jenkins the first time you open it in your browser.

Terminal

sudo cat /var/lib/jenkins/secrets/initialAdminPassword

Expected Output

3f4e5d6c7b8a9e0f1d2c3b4a5e6f7d8c

This command creates the first admin user by sending the required user details to Jenkins setup wizard API. It automates the web form submission.

Terminal

curl -X POST http://localhost:8080/setupWizard/createAdminUser \
  --data-urlencode 'username=admin' \
  --data-urlencode 'password1=AdminPass123' \
  --data-urlencode 'password2=AdminPass123' \
  --data-urlencode 'fullname=Administrator' \
  --data-urlencode 'email=[e-mail]'

Expected Output

{"status":"success","message":"Admin user created"}

→

-X POST - Specifies the HTTP POST method to send data.

→

--data-urlencode - Encodes and sends form data fields.

This command verifies that the admin user was created by accessing Jenkins API with the new admin credentials.

Terminal

curl -u admin:AdminPass123 http://localhost:8080/api/json

Expected Output

{"assignedLabels":[{}],"mode":"NORMAL","nodeDescription":"the master Jenkins node","numExecutors":2,"description":null,"jobs":[],"overallLoad":{},"primaryView":{"name":"All"},"quietingDown":false,"slaveAgentPort":50000,"unlabeledLoad":{},"useCrumbs":true,"useSecurity":true,"views":[{"name":"All"}]}

→

-u admin:AdminPass123 - Uses basic authentication with admin username and password.

Key Concept

If you remember nothing else from this pattern, remember: Jenkins creates a temporary initial admin password that you must use to unlock and create your first admin user.

Common Mistakes

Trying to access Jenkins before reading the initial admin password.

Jenkins will not let you proceed without unlocking it first using the initial password.

Always read the initial admin password from the secrets file before accessing Jenkins the first time.

Skipping the admin user creation and leaving Jenkins unsecured.

Without an admin user, Jenkins is open and vulnerable to unauthorized access.

Complete the admin user creation step immediately after unlocking Jenkins.

Using weak or default passwords for the admin user.

Weak passwords make your Jenkins server easy to hack.

Choose a strong, unique password for the admin user.

Summary

Read the initial admin password from Jenkins secrets to unlock the server.

Create the first admin user by submitting user details to Jenkins setup API.

Verify admin user creation by accessing Jenkins API with new credentials.

Practice

1. Why is it important to create the first admin user in Jenkins?

easy

A. To speed up the build process

B. To secure the Jenkins server by controlling access

C. To reduce the server's memory usage

D. To automatically install plugins

Solution

1. Step 1: Understand Jenkins security basics

   Jenkins requires an admin user to control who can access and manage the server.

2. Step 2: Recognize the role of the first admin user

   This user sets permissions and protects the server from unauthorized access.

3. Final Answer:

   To secure the Jenkins server by controlling access -> Option B

4. Quick Check:

   Security = Control access [OK]

Hint: First admin user controls access and security [OK]

Common Mistakes:

• Thinking admin user speeds up builds
• Confusing admin user with plugin installer
• Believing admin user reduces memory use

2. Which of the following is the correct syntax to create a new admin user using Jenkins Groovy script console?

easy

A. jenkins.createUser('admin', 'password')

B. Jenkins.instance.createUser('admin', 'password')

C. Jenkins.security.createAccount('admin', 'password')

D. jenkins.model.Jenkins.instance.securityRealm.createAccount('admin', 'password')

Solution

1. Step 1: Recall Jenkins Groovy script for user creation

   The correct method to create a user is via the securityRealm's createAccount method.

2. Step 2: Match the exact syntax

   jenkins.model.Jenkins.instance.securityRealm.createAccount('admin', 'password') is the valid syntax.

3. Final Answer:

   jenkins.model.Jenkins.instance.securityRealm.createAccount('admin', 'password') -> Option D

4. Quick Check:

   securityRealm.createAccount = correct syntax [OK]

Hint: Use securityRealm.createAccount to add users [OK]

Common Mistakes:

• Using Jenkins.instance.createUser which does not exist
• Calling jenkins.createUser directly
• Using Jenkins.security.createAccount which is invalid

3. What will be the result of running this Groovy script in Jenkins script console?

def instance = jenkins.model.Jenkins.instance
instance.securityRealm.createAccount('admin', 'admin123')

medium

A. Creates a new admin user named 'admin' with password 'admin123'

B. Throws an error because createAccount is undefined

C. Deletes the existing admin user

D. Changes the Jenkins system password

Solution

1. Step 1: Analyze the script commands

   The script gets the Jenkins instance and calls createAccount on securityRealm with username and password.

2. Step 2: Understand createAccount effect

   This method creates a new user with the given credentials in Jenkins.

3. Final Answer:

   Creates a new admin user named 'admin' with password 'admin123' -> Option A

4. Quick Check:

   createAccount adds user = Creates a new admin user named 'admin' with password 'admin123' [OK]

Hint: createAccount adds user with given name and password [OK]

Common Mistakes:

• Assuming it deletes users
• Expecting a system password change
• Thinking createAccount is undefined

4. You tried to create the first admin user with this script:

jenkins.model.Jenkins.instance.securityRealm.createAccount('admin')

Why does it fail?

medium

A. Missing password argument in createAccount method

B. Incorrect method name, should be createUser

C. Jenkins instance is not accessible in script console

D. Username 'admin' is reserved and cannot be used

Solution

1. Step 1: Check method parameters

   createAccount requires two parameters: username and password.

2. Step 2: Identify missing argument

   The script only provides username, missing the password argument, causing failure.

3. Final Answer:

   Missing password argument in createAccount method -> Option A

4. Quick Check:

   Two arguments needed = Missing password argument in createAccount method [OK]

Hint: createAccount needs username and password [OK]

Common Mistakes:

• Using wrong method name
• Assuming Jenkins instance is inaccessible
• Thinking 'admin' username is reserved

5. You want to automate creating the first admin user during Jenkins startup using an initialization Groovy script. Which approach is correct?

hard

A. Add the user credentials in config.xml directly

B. Run the createAccount command manually after Jenkins starts

C. Place a Groovy script with createAccount call in init.groovy.d directory

D. Modify Jenkins WAR file to include the user

Solution

1. Step 1: Understand Jenkins initialization scripts

   Jenkins runs Groovy scripts placed in init.groovy.d folder during startup.

2. Step 2: Automate user creation

   Placing a script with createAccount call there creates the admin user automatically on startup.

3. Final Answer:

   Place a Groovy script with createAccount call in init.groovy.d directory -> Option C

4. Quick Check:

   init.groovy.d scripts run at startup [OK]

Hint: Use init.groovy.d scripts for startup automation [OK]

Common Mistakes:

• Trying manual commands only
• Editing config.xml directly (not recommended)
• Modifying Jenkins WAR file (complex and unsafe)