Branch indexing and scanning in Jenkins - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to trigger branch indexing in a Jenkins Pipeline.

Jenkins

properties([pipelineTriggers([[1]('H/5 * * * *')])])

Drag options to blanks, or click blank then click option'

Acron

BgithubPush

CpollSCM

DtimerTrigger

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'cron' instead of 'pollSCM' triggers a scheduled job but does not specifically trigger branch indexing.

Using 'githubPush' only triggers on GitHub push events, not branch indexing.

Using 'timerTrigger' is not a valid Jenkins trigger.

The pollSCM trigger tells Jenkins to check the source control for new branches or changes, which triggers branch indexing.

2fill in blank

medium

Complete the code to scan all branches in a Multibranch Pipeline job.

Jenkins

multibranchPipelineJob('example') {
  branchSources {
    git {
      id('1234')
      remote('https://github.com/example/repo.git')
    }
  }
  [1] {
    cron('H * * * *')
  }
}

Drag options to blanks, or click blank then click option'

AscanTriggers

Bscanners

Ctriggers

DbranchSources

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'triggers' configures build triggers, not branch scanning.

Using 'branchSources' defines the source repositories, not scanning triggers.

Using 'scanners' is not a valid block name.

The scanTriggers block configures how Jenkins scans branches in a Multibranch Pipeline job.

3fill in blank

hard

Fix the error in the Jenkinsfile to correctly scan branches every 15 minutes.

Jenkins

multibranchPipelineJob('example') {
  scanTriggers {
    cron('[1]')
  }
}

Drag options to blanks, or click blank then click option'

AH/15 * * * *

B*/15 * * * *

C15 * * * *

DH/5 * * * *

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*/15 * * * *' works in standard cron but Jenkins recommends 'H/15' for better load distribution.

Using '15 * * * *' runs only once per hour at minute 15.

Using 'H/5 * * * *' runs every 5 minutes, not 15.

The H/15 * * * * syntax tells Jenkins to run the scan every 15 minutes with a hashed start time to spread load.

4fill in blank

hard

Fill both blanks to configure branch indexing to exclude branches matching a pattern and to set the scan interval.

Jenkins

multibranchPipelineJob('example') {
  branchSources {
    git {
      remote('https://github.com/example/repo.git')
      [1]('feature/*')
    }
  }
  scanTriggers {
    cron('[2]')
  }
}

Drag options to blanks, or click blank then click option'

AexcludeBranches

BincludeBranches

CH/10 * * * *

DH/30 * * * *

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'includeBranches' instead of 'excludeBranches' changes which branches are scanned.

Using 'H/30 * * * *' scans every 30 minutes, not 10.

Omitting branch exclusion causes all branches to be scanned.

excludeBranches('feature/*') tells Jenkins to skip branches starting with 'feature/'. The cron H/10 * * * * sets scanning every 10 minutes.

5fill in blank

hard

Fill all three blanks to create a Jenkinsfile snippet that scans branches, includes only 'main' and 'release/*' branches, and triggers scanning every 20 minutes.

Jenkins

multibranchPipelineJob('example') {
  branchSources {
    git {
      remote('https://github.com/example/repo.git')
      [1]('main')
      [2]('release/*')
    }
  }
  scanTriggers {
    cron('[3]')
  }
}

Drag options to blanks, or click blank then click option'

AincludeBranches

BexcludeBranches

CH/20 * * * *

DbranchFilter

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'excludeBranches' instead of 'includeBranches' changes the scanning behavior.

Using 'branchFilter' is not a valid method here.

Using incorrect cron syntax causes scanning to fail or run at wrong intervals.

Using includeBranches twice specifies which branches to scan. The cron H/20 * * * * triggers scanning every 20 minutes.

Practice

1. What is the main purpose of branch indexing in Jenkins Multibranch Pipeline jobs?

easy

A. To manually trigger builds for a single branch

B. To delete old builds from the Jenkins server

C. To automatically discover and build all branches in a repository

D. To configure user permissions for branches

Solution

1. Step 1: Understand branch indexing concept

   Branch indexing automatically finds all branches in a source code repository for Jenkins to build.

2. Step 2: Identify its main benefit

   This avoids manual job creation for each branch, saving time and effort.

3. Final Answer:

   To automatically discover and build all branches in a repository -> Option C

4. Quick Check:

   Branch indexing = automatic branch discovery [OK]

Hint: Branch indexing means Jenkins finds branches itself [OK]

Common Mistakes:

• Thinking branch indexing triggers manual builds only
• Confusing branch indexing with build cleanup
• Assuming it manages user permissions

2. Which Jenkins job type should you use to enable branch indexing and scanning?

easy

A. Multibranch Pipeline

B. Freestyle project

C. Matrix project

D. External job

Solution

1. Step 1: Identify job types in Jenkins

   Freestyle and Matrix projects do not support automatic branch discovery.

2. Step 2: Recognize Multibranch Pipeline features

   Multibranch Pipeline jobs are designed to scan repositories and index branches automatically.

3. Final Answer:

   Multibranch Pipeline -> Option A

4. Quick Check:

   Branch indexing requires Multibranch Pipeline job [OK]

Hint: Use Multibranch Pipeline for branch scanning [OK]

Common Mistakes:

• Choosing Freestyle project which lacks branch scanning
• Confusing Matrix project with Multibranch Pipeline
• Selecting External job which is unrelated

3. Given a Multibranch Pipeline job configured to scan every 1 hour, what happens when a new branch is pushed to the repository?

medium

A. Jenkins immediately builds the new branch

B. Jenkins ignores the new branch until manual scan

C. Jenkins deletes the new branch from the repository

D. Jenkins detects and indexes the new branch during the next scheduled scan

Solution

1. Step 1: Understand scan trigger timing

   The job is set to scan branches every 1 hour, not instantly.

2. Step 2: Predict behavior on new branch push

   Jenkins will detect and index the new branch during the next scheduled scan, not immediately.

3. Final Answer:

   Jenkins detects and indexes the new branch during the next scheduled scan -> Option D

4. Quick Check:

   Scheduled scan finds new branches [OK]

Hint: Scheduled scans find new branches, not instant builds [OK]

Common Mistakes:

• Assuming immediate build on branch push
• Thinking Jenkins ignores new branches without manual scan
• Believing Jenkins deletes new branches automatically

4. You configured a Multibranch Pipeline job but Jenkins does not detect new branches after pushing them. What is the most likely cause?

medium

A. The Jenkins server is offline

B. Branch indexing is disabled or scan trigger is not set

C. The repository URL is incorrect

D. The branches are deleted automatically after scan

Solution

1. Step 1: Check branch indexing settings

   If branch indexing or scan triggers are disabled, Jenkins won't detect new branches automatically.

2. Step 2: Consider other causes

   Incorrect repo URL or offline server would cause broader failures, not just missing branches.

3. Final Answer:

   Branch indexing is disabled or scan trigger is not set -> Option B

4. Quick Check:

   Branch indexing must be enabled for detection [OK]

Hint: Enable branch indexing and scan triggers to detect branches [OK]

Common Mistakes:

• Ignoring branch indexing settings
• Assuming Jenkins deletes branches automatically
• Blaming repository URL without checking indexing

5. How can you configure a Jenkins Multibranch Pipeline job to automatically build only branches matching the pattern feature/* during branch indexing?

hard

A. Set the Branch Sources filter with feature/* under 'Include branches matching' pattern

B. Manually create jobs for each feature branch

C. Use a post-build script to delete other branches

D. Configure the job to scan all branches without filters

Solution

1. Step 1: Use branch source filtering

   Jenkins Multibranch Pipeline allows filtering branches by patterns in the Branch Sources settings.

2. Step 2: Apply the pattern filter

   Setting 'Include branches matching' to feature/* ensures only those branches are indexed and built.

3. Final Answer:

   Set the Branch Sources filter with feature/* under 'Include branches matching' pattern -> Option A

4. Quick Check:

   Branch filters limit builds to matching branches [OK]

Hint: Use branch source filters to build specific branch patterns [OK]

Common Mistakes:

• Creating manual jobs instead of using filters
• Not applying branch filters and building all branches
• Using post-build scripts to filter branches incorrectly