Branch discovery configuration in Jenkins - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Branch Discovery in Jenkins Multibranch Pipeline

What is the primary purpose of the Branch Discovery trait in Jenkins Multibranch Pipeline jobs?

A To automatically find and create jobs for branches in the source repository

B To delete branches from the source repository after build completion

C To merge all branches into the main branch before building

D To restrict builds only to the default branch

💡 Hint

Think about how Jenkins finds branches to build automatically.

The Branch Discovery trait tells Jenkins to scan the source repository and create jobs for each branch it finds. This enables automatic building of new branches without manual job creation.

💻 Command Output

intermediate

Effect of Branch Discovery Setting on Job Creation

Given a Jenkins Multibranch Pipeline configured with Branch Discovery trait set to Discover branches that are also filed as PRs, what will Jenkins do when scanning the repository?

A Create jobs only for the default branch

B Create jobs for all branches regardless of pull requests

C Create jobs only for branches that have open pull requests

D Create jobs for branches without any pull requests

💡 Hint

Focus on the meaning of 'also filed as PRs'.

This setting tells Jenkins to create jobs only for branches that have an associated open pull request, ignoring other branches.

❓ Configuration

advanced

Configuring Branch Discovery to Exclude Certain Branches

Which configuration snippet correctly excludes branches named feature/temp-* from being discovered in Jenkins Multibranch Pipeline?

A Add a <code>Filter by name (with wildcards)</code> trait with pattern <code>feature/temp-*</code> and set to exclude

B Add a <code>Filter by name (with wildcards)</code> trait with pattern <code>feature/temp-*</code> and set to include

C Add a <code>Branch Discovery</code> trait with pattern <code>feature/temp-*</code> to include only those branches

D Add a <code>Pull Request Discovery</code> trait with pattern <code>feature/temp-*</code> to exclude those branches

💡 Hint

Think about how to exclude branches by name using traits.

The Filter by name (with wildcards) trait allows excluding branches matching a pattern by setting the exclude option. This prevents Jenkins from discovering those branches.

❓ Troubleshoot

advanced

Troubleshooting Missing Branches in Jenkins Multibranch Pipeline

You notice that some branches are not appearing as jobs in your Jenkins Multibranch Pipeline scan. Which of the following is the most likely cause?

A The Jenkinsfile is missing in the root of the repository

B Branch Discovery trait is configured to discover only branches with open pull requests

C The repository URL is incorrect

D Jenkins server is offline

💡 Hint

Consider how Branch Discovery settings affect which branches are found.

If Branch Discovery is set to discover only branches with open pull requests, branches without PRs will not be created as jobs, causing them to be missing.

🔀 Workflow

expert

Optimizing Branch Discovery for Large Repositories

You manage a Jenkins Multibranch Pipeline for a large repository with hundreds of branches. To reduce load, you want Jenkins to discover only branches that have been updated in the last 7 days. Which approach best achieves this?

A Use the <code>Filter by name (with wildcards)</code> trait to exclude old branches

B Use the <code>Suppress automatic SCM triggering</code> option and trigger builds manually

C Configure Branch Discovery to include only branches matching a date-based pattern

D Use a custom script in the Jenkinsfile to skip builds for branches not updated in 7 days

💡 Hint

Think about how to control build execution based on branch update time.

Jenkins Branch Discovery does not support filtering branches by last update date. Using a script in the Jenkinsfile to skip builds for old branches is the best way to reduce load while still discovering all branches.