Custom notification logic in Jenkins - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of custom notification logic in Jenkins?

Custom notification logic allows Jenkins to send tailored messages based on build results or specific conditions, improving communication and response.

beginner

Which Jenkins plugin is commonly used to implement custom notification logic?

The 'Email Extension Plugin' is commonly used to create custom email notifications with flexible triggers and content.

intermediate

How can you trigger notifications only on build failures in Jenkins pipeline scripts?

Use conditional statements in the pipeline script to check if the build status is 'FAILURE' and then call the notification step.

intermediate

What is the advantage of using scripted pipeline for custom notification logic?

Scripted pipelines offer more control and flexibility to define complex notification rules and customize message content dynamically.

beginner

Name two common notification channels Jenkins can use besides email.

Jenkins can send notifications via Slack and Microsoft Teams using their respective plugins or webhooks.

Which Jenkins plugin helps send customized email notifications?

A Pipeline Utility Steps

B Email Extension Plugin

C Docker Plugin

D Git Plugin

The Email Extension Plugin allows sending customized email notifications based on build status and conditions.

In a Jenkins pipeline, how do you send a notification only if the build fails?

A Check if currentBuild.result == 'SUCCESS'

B Send notification unconditionally

C Check if currentBuild.result == 'FAILURE'

D Use a post-build action without conditions

You check the build result and send notifications only when it equals 'FAILURE' to avoid unnecessary alerts.

Which notification channel is NOT commonly integrated with Jenkins?

A Twitter

B Microsoft Teams

C Slack

D Email

Twitter is not a common notification channel for Jenkins; Slack, Teams, and Email are standard.

What is a benefit of using scripted pipelines for notifications?

A Less flexibility

B Automatic notifications without code

C No need for plugins

D More control over notification logic

Scripted pipelines allow detailed control and customization of notification logic.

Which Jenkins feature helps you define when to send notifications?

A Triggers and conditions

B Build history

C Workspace cleanup

D Source code management

Triggers and conditions let you specify when notifications should be sent, such as on failure or success.

Explain how you would implement custom notification logic in a Jenkins pipeline to notify only on failures.

Think about conditional checks and notification steps.

List common notification channels Jenkins supports and why customizing notifications is useful.

Consider integration options and benefits.

Practice

1. What is the main purpose of using custom notification logic in Jenkins pipelines?

easy

A. To send notifications for every build regardless of status

B. To restart the Jenkins server automatically after each build

C. To disable all notifications permanently

D. To send notifications only when specific build conditions are met

Solution

1. Step 1: Understand notification goals

   Custom notification logic aims to reduce noise by sending alerts only when necessary.

2. Step 2: Identify correct behavior

   Sending notifications only on specific build results (like failure) keeps the team focused.

3. Final Answer:

   To send notifications only when specific build conditions are met -> Option D

4. Quick Check:

   Custom notifications = selective alerts [OK]

Hint: Think about reducing alert noise to stay focused [OK]

Common Mistakes:

• Assuming notifications should always be sent
• Confusing disabling notifications with custom logic
• Believing Jenkins restarts after every build

2. Which Jenkins pipeline syntax correctly checks if the build failed before sending a notification?

easy

A. if (currentBuild.result = 'FAILURE') { notify() }

B. if (build.status == 'SUCCESS') { notify() }

C. if (currentBuild.currentResult == 'FAILURE') { notify() }

D. if (currentBuild.currentResult === FAILURE) { notify() }

Solution

1. Step 1: Identify correct property and comparison

   Use currentBuild.currentResult to get build status and compare with string 'FAILURE'.

2. Step 2: Check syntax correctness

   if (currentBuild.currentResult == 'FAILURE') { notify() } uses correct equality operator (==) and string comparison.

3. Final Answer:

   if (currentBuild.currentResult == 'FAILURE') { notify() } -> Option C

4. Quick Check:

   Correct property and comparison = if (currentBuild.currentResult == 'FAILURE') { notify() } [OK]

Hint: Use currentBuild.currentResult with 'FAILURE' string and == [OK]

Common Mistakes:

• Using single equals (=) instead of double (==)
• Comparing to SUCCESS instead of FAILURE
• Missing quotes around 'FAILURE'
• Using undefined variable FAILURE without quotes

3. Given this Jenkins pipeline snippet:

post {
  failure {
    script {
      if (currentBuild.previousBuild?.result == 'SUCCESS') {
        notify('Build failed after success')
      }
    }
  }
}

What happens if the previous build was successful and the current build failed?

medium

A. Notification 'Build failed after success' is sent

B. No notification is sent

C. Notification is sent only if current build succeeded

D. Pipeline throws a syntax error

Solution

1. Step 1: Analyze condition in failure block

   The post.failure block runs only if current build failed. Inside, it checks if previous build result was 'SUCCESS'.

2. Step 2: Evaluate condition outcome

   If previous build was successful and current failed, condition is true, so notify is called with the message.

3. Final Answer:

   Notification 'Build failed after success' is sent -> Option A

4. Quick Check:

   Previous success + current failure triggers notification [OK]

Hint: Check previousBuild?.result and current failure block [OK]

Common Mistakes:

• Thinking notification sends on success builds
• Ignoring the safe navigation operator '?'
• Assuming syntax error due to optional chaining

4. You wrote this Jenkins pipeline snippet to notify only on failure after success:

post {
  failure {
    script {
      if (currentBuild.previousBuild.result == 'SUCCESS') {
        notify('Failed after success')
      }
    }
  }
}

But it sometimes throws a NullPointerException. What is the likely cause?

medium

A. notify function is undefined

B. previousBuild can be null, so accessing result causes error

C. failure block cannot contain if statements

D. currentBuild.previousBuild.result is always 'FAILURE'

Solution

1. Step 1: Identify potential null values

   currentBuild.previousBuild can be null if no previous build exists.

2. Step 2: Understand error cause

   Accessing result on null causes NullPointerException. Safe navigation operator ?. avoids this.

3. Final Answer:

   previousBuild can be null, so accessing result causes error -> Option B

4. Quick Check:

   Null previousBuild causes error without safe navigation [OK]

Hint: Use ?. to safely access previousBuild properties [OK]

Common Mistakes:

• Ignoring possibility of null previousBuild
• Assuming notify is always defined
• Thinking failure block disallows if statements

5. You want to send a notification only when the build status changes from SUCCESS to FAILURE or from FAILURE to SUCCESS. Which Jenkins pipeline snippet correctly implements this logic?

hard

A. post {
failure {
script {
if (currentBuild.previousBuild?.result == 'SUCCESS') {
notify('Failed after success')
}
}
}
success {
script {
if (currentBuild.previousBuild?.result == 'FAILURE') {
notify('Succeeded after failure')
}
}
}
}

B. post {
success {
notify('Build succeeded')
}
failure {
notify('Build failed')
}
}

C. post {
always {
script {
if (currentBuild.previousBuild?.result != currentBuild.currentResult) {
notify('Build status changed')
}
}
}
}

D. post {
always {
notify('Build finished')
}
}

Solution

1. Step 1: Understand the requirement

   Notify only when build status flips between SUCCESS and FAILURE, not on every build.

2. Step 2: Analyze each option

   post { failure { script { if (currentBuild.previousBuild?.result == 'SUCCESS') { notify('Failed after success') } } } success { script { if (currentBuild.previousBuild?.result == 'FAILURE') { notify('Succeeded after failure') } } } } checks previous build result and current build result in success and failure blocks separately, sending notifications only on status change.

3. Final Answer:

   post { failure { script { if (currentBuild.previousBuild?.result == 'SUCCESS') { notify('Failed after success') } } } success { script { if (currentBuild.previousBuild?.result == 'FAILURE') { notify('Succeeded after failure') } } } } -> Option A

4. Quick Check:

   Status change detection needs previousBuild checks in success and failure blocks [OK]

Hint: Check previousBuild result differs from current in success and failure blocks [OK]

Common Mistakes:

• Sending notifications on every build regardless of status change
• Not checking previous build result
• Using always block without condition