Script approval and sandbox in Jenkins - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of script approval in Jenkins?

Script approval in Jenkins ensures that only safe and trusted scripts run in the system, protecting it from harmful or untrusted code.

beginner

What is the Jenkins sandbox for scripts?

The Jenkins sandbox is a safe environment where scripts run with limited permissions to prevent harmful actions on the system.

intermediate

How does Jenkins handle a script that is not approved?

Jenkins blocks the execution of unapproved scripts and requires an administrator to review and approve them before they can run.

beginner

Where can you find the list of scripts waiting for approval in Jenkins?

In Jenkins, the list of scripts waiting for approval is found under 'Manage Jenkins' > 'In-process Script Approval'.

intermediate

Why is it important to use script approval and sandbox in Jenkins pipelines?

Using script approval and sandbox protects the Jenkins server from running unsafe scripts that could damage the system or leak sensitive data.

What happens if a Jenkins pipeline script uses a method not yet approved?

A The script runs without restrictions.

B The script execution is blocked until approval.

C Jenkins automatically approves the method.

D The script is deleted.

Jenkins blocks scripts using unapproved methods until an administrator approves them.

Where do you approve scripts in Jenkins?

A Dashboard > New Item

B Manage Plugins

C Manage Jenkins > In-process Script Approval

D Build History

Script approvals are managed under 'Manage Jenkins' > 'In-process Script Approval'.

What is the Jenkins sandbox designed to do?

A Allow all scripts to run without checks.

B Speed up script execution.

C Store backup scripts.

D Run scripts with limited permissions for safety.

The sandbox restricts script permissions to protect the system.

Who can approve scripts in Jenkins?

A Jenkins administrator

B Any user

C Only the script author

D External users

Only Jenkins administrators have permission to approve scripts.

Why should you avoid disabling the Jenkins sandbox?

A It protects the system from unsafe scripts.

B It makes scripts run faster.

C It is required for all plugins.

D It automatically approves scripts.

Disabling the sandbox removes safety checks and risks system security.

Explain how Jenkins script approval and sandbox work together to keep your system safe.

Think about how Jenkins controls what scripts can do and who decides.

Describe the steps to approve a new script method in Jenkins.

Consider what happens from running the script to approval.

Practice

1. What is the main purpose of script approval in Jenkins?

easy

A. To automatically run all scripts without restrictions

B. To protect Jenkins by allowing admins to approve unsafe scripts before execution

C. To speed up the build process by skipping script checks

D. To disable all scripts in Jenkins

Solution

1. Step 1: Understand script approval role

   Script approval is designed to protect Jenkins by controlling which scripts can run.

2. Step 2: Identify admin involvement

   Admins review and approve scripts to prevent unsafe code from running.

3. Final Answer:

   To protect Jenkins by allowing admins to approve unsafe scripts before execution -> Option B

4. Quick Check:

   Script approval = Admin review for safety [OK]

Hint: Script approval means admin checks scripts before running [OK]

Common Mistakes:

• Thinking scripts run automatically without checks
• Confusing script approval with disabling scripts
• Assuming script approval speeds up builds

2. Which of the following is the correct way to enable sandbox mode in a Jenkins Pipeline script?

easy

A. Check the 'Use Groovy Sandbox' option in the Pipeline script configuration

B. Use @Sandbox annotation at the top of the script

C. Add sandbox=true inside the Jenkinsfile

D. Enable sandbox mode in Jenkins global settings only

Solution

1. Step 1: Identify sandbox enabling method

   Sandbox mode is enabled by checking the 'Use Groovy Sandbox' box in the Pipeline script configuration.

2. Step 2: Verify other options

   Annotations or code inside Jenkinsfile do not enable sandbox; global settings do not control this per script.

3. Final Answer:

   Check the 'Use Groovy Sandbox' option in the Pipeline script configuration -> Option A

4. Quick Check:

   Sandbox enabled via checkbox in script config [OK]

Hint: Sandbox mode is a checkbox in Pipeline script config [OK]

Common Mistakes:

• Trying to enable sandbox with code annotations
• Assuming sandbox is a global-only setting
• Adding sandbox flags inside Jenkinsfile

3. Given this Jenkins Pipeline snippet running with sandbox enabled:

node {
  def result = sh(script: 'echo Hello', returnStdout: true).trim()
  echo result
}

What will be the output?

medium

A. No output because sandbox blocks shell commands

B. Syntax error due to sandbox

C. result

D. Hello

Solution

1. Step 1: Analyze the sh step

   sh(script: 'echo Hello', returnStdout: true).trim() executes 'echo Hello', captures stdout, trims to 'Hello', assigns to result.

2. Step 2: Analyze echo step

   echo result prints the value of result ('Hello'). In Jenkins Pipeline, the echo step prints variable values directly. Sandbox allows whitelisted steps like sh and echo.

3. Final Answer:

   Hello -> Option D

4. Quick Check:

   sh captures stdout, echo prints var value [OK]

Hint: In Pipeline, echo result prints result's value [OK]

Common Mistakes:

• Thinking echo prints literal 'result' like shell
• Believing sandbox blocks whitelisted sh commands
• Expecting syntax error from sandbox

4. You wrote a Jenkins Pipeline script that uses a method not whitelisted in the sandbox. The build fails with a script approval error. What should you do to fix this?

medium

A. Restart Jenkins to clear the error

B. Remove sandbox mode and run the script without restrictions

C. Ask the Jenkins admin to approve the method in the script approval page

D. Rewrite the script to avoid using any methods

Solution

1. Step 1: Understand script approval error cause

   The error occurs because the method is not approved in Jenkins script approval.

2. Step 2: Fix by admin approval

   The correct fix is to have the Jenkins admin approve the method via the script approval UI.

3. Final Answer:

   Ask the Jenkins admin to approve the method in the script approval page -> Option C

4. Quick Check:

   Approval needed for unapproved methods [OK]

Hint: Unapproved methods need admin approval, not disabling sandbox [OK]

Common Mistakes:

• Disabling sandbox instead of approving scripts
• Trying to remove methods instead of approval
• Restarting Jenkins does not fix approval errors

5. You want to run a custom Groovy script in Jenkins Pipeline that uses a non-whitelisted method and also requires sandbox protection. Which approach correctly balances safety and functionality?

hard

A. Run the script with sandbox enabled and request admin approval for the method

B. Disable sandbox and run the script directly to avoid approval delays

C. Rewrite the script to avoid all non-whitelisted methods, ignoring sandbox

D. Run the script outside Jenkins and import results to avoid sandbox issues

Solution

1. Step 1: Understand sandbox and approval roles

   Sandbox protects Jenkins by restricting unsafe code; approval allows safe exceptions.

2. Step 2: Balance safety and functionality

   Enabling sandbox with admin approval keeps Jenkins safe while allowing needed methods.

3. Final Answer:

   Run the script with sandbox enabled and request admin approval for the method -> Option A

4. Quick Check:

   Sandbox + approval = safe and functional scripts [OK]

Hint: Use sandbox plus admin approval for safe custom scripts [OK]

Common Mistakes:

• Disabling sandbox risking Jenkins security
• Avoiding needed methods by rewriting scripts unnecessarily
• Running scripts outside Jenkins complicates workflow