Multiple SCM repositories in Jenkins - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Jenkins Pipeline: Multiple SCM Checkout Output

Consider this Jenkins pipeline snippet that checks out two Git repositories sequentially. What will be the output of the sh 'ls -1' command inside the dir('repo2') block?

Jenkins

pipeline {
  agent any
  stages {
    stage('Checkout Multiple Repos') {
      steps {
        dir('repo1') {
          checkout([$class: 'GitSCM', branches: [[name: '*/main']], userRemoteConfigs: [[url: 'https://github.com/example/repo1.git']]])
        }
        dir('repo2') {
          checkout([$class: 'GitSCM', branches: [[name: '*/main']], userRemoteConfigs: [[url: 'https://github.com/example/repo2.git']]])
          sh 'ls -1'
        }
      }
    }
  }
}

A A list of files and folders from the root of repo1 repository.

B An empty output because the directory is empty.

C A Jenkins error indicating the directory 'repo2' does not exist.

D A list of files and folders from the root of repo2 repository.

💡 Hint

Think about where the checkout command places the files and what the 'dir' step does.

The 'dir' step changes the working directory. The checkout inside 'dir('repo2')' clones repo2 into that folder. So 'ls -1' lists repo2's root contents.

❓ Configuration

intermediate

Declarative Pipeline: Correct Multiple SCM Checkout Syntax

Which Jenkins declarative pipeline snippet correctly checks out two different Git repositories into separate folders?

A

steps {
  dir('repo1') {
    checkout([$class: 'GitSCM', branches: [[name: '*/main']], userRemoteConfigs: [[url: 'https://github.com/example/repo1.git']]])
  }
  dir('repo2') {
    checkout([$class: 'GitSCM', branches: [[name: '*/main']], userRemoteConfigs: [[url: 'https://github.com/example/repo2.git']]])
  }
}

B

steps {
  checkout([$class: 'GitSCM', branches: [[name: '*/main']], userRemoteConfigs: [[url: 'https://github.com/example/repo1.git']]])
  checkout([$class: 'GitSCM', branches: [[name: '*/main']], userRemoteConfigs: [[url: 'https://github.com/example/repo2.git']]])
}

C

steps {
  checkout([$class: 'MultipleSCM', scms: [
    [$class: 'GitSCM', userRemoteConfigs: [[url: 'https://github.com/example/repo1.git']]],
    [$class: 'GitSCM', userRemoteConfigs: [[url: 'https://github.com/example/repo2.git']]]
  ]])
}

D

steps {
  dir('repo1') {
    git url: 'https://github.com/example/repo1.git'
  }
  git url: 'https://github.com/example/repo2.git'
}

💡 Hint

Remember that each checkout inside a 'dir' block clones into that folder.

Option A uses 'dir' to change folders and performs separate checkouts, which is the correct way to clone multiple repos into separate directories in declarative pipelines.

❓ Troubleshoot

advanced

Troubleshooting: Jenkins Pipeline Fails on Multiple SCM Checkout

A Jenkins pipeline with multiple SCM checkouts fails with the error: hudson.plugins.git.GitException: Command "git checkout -f refs/remotes/origin/main" returned status code 128. What is the most likely cause?

A The Git repository URL is incorrect or unreachable.

B The workspace folder is not clean and has conflicting files from previous checkouts.

C The Jenkins agent does not have Git installed.

D The pipeline syntax for multiple SCM checkout is invalid.

💡 Hint

Think about what happens if files from previous checkouts remain in the workspace.

Git checkout errors with status 128 often happen when the workspace has leftover files causing conflicts. Cleaning the workspace before checkout usually fixes this.

🔀 Workflow

advanced

Jenkins Pipeline: Correct Order of Steps for Multiple SCM Checkout and Build

What is the correct order of steps in a Jenkins pipeline stage that checks out two repositories and then builds the project?

A 1,3,2,4

B 1,2,3,4

C 2,1,4,3

D 2,4,1,3

💡 Hint

You must checkout a repo before building it.

You first checkout repo1, then build it, then checkout repo2, then build it. This ensures each build runs on the correct code.

✅ Best Practice

expert

Best Practice: Managing Credentials for Multiple SCM Repositories in Jenkins

Which approach is the best practice for securely managing credentials when checking out multiple private Git repositories in a Jenkins pipeline?

A Ask users to enter credentials manually each time the pipeline runs.

B Hardcode usernames and passwords directly in the pipeline script for each repository checkout.

C Store all credentials in Jenkins Credentials Manager and reference each by ID in the respective checkout step.

D Use the same credential ID for all repositories regardless of different access requirements.

💡 Hint

Think about security and automation in Jenkins pipelines.

Storing credentials securely in Jenkins Credentials Manager and referencing them by ID in checkout steps is the recommended secure and automated approach.