@Library annotation in Jenkins - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to load a shared library named 'utils' in a Jenkins pipeline.

Jenkins

@Library('[1]') _
pipeline {
    agent any
    stages {
        stage('Example') {
            steps {
                echo 'Using shared library'
            }
        }
    }
}

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

Autils

Bcommon

CsharedLib

Dlibrary

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong library name that is not configured in Jenkins.

Forgetting to add the underscore (_) after the annotation.

The @Library annotation requires the exact name of the shared library to load, here 'utils'.

2fill in blank

medium

Complete the code to load multiple shared libraries 'utils' and 'helpers' in a Jenkins pipeline.

Jenkins

@Library(['[1]', 'helpers']) _
pipeline {
    agent any
    stages {
        stage('Test') {
            steps {
                echo 'Multiple libraries loaded'
            }
        }
    }
}

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

Atools

Bcommon

Cutils

Dlibs

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets for multiple libraries.

Missing quotes around library names.

To load multiple libraries, list their names in an array. Here, 'utils' and 'helpers' are loaded.

3fill in blank

hard

Fix the error in the code to properly load the 'tools' shared library with a version '1.0'.

Jenkins

@Library('[1]@1.0') _
pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                echo 'Library version loaded'
            }
        }
    }
}

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

Atools:1.0

Btools@1.0

Ctools-1.0

Dtools

Attempts:

3 left

💡 Hint

Common Mistakes

Including the version in the blank causing '@1.0' to appear twice.

Using wrong separators like '-' or ':'.

The version is specified after '@' in the string. The blank should only contain the library name 'tools'.

4fill in blank

hard

Fill both blanks to load the 'common' library with version '2.1' and alias it as 'cmn'.

Jenkins

@Library('[1]@[2]') cmn
pipeline {
    agent any
    stages {
        stage('Deploy') {
            steps {
                script {
                    cmn.deployApp()
                }
            }
        }
    }
}

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

Acommon

B2.1

C1.0

Dutils

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping version and name in blanks.

Using wrong version numbers.

The library name is 'common' and the version is '2.1' to match the alias usage.

5fill in blank

hard

Fill all three blanks to load libraries 'alpha', 'beta' version '3.0', and 'gammaLib'.

Jenkins

@Library(['[1]', 'beta@[2]', '[3]@1.5']) _
pipeline {
    agent any
    stages {
        stage('Integration') {
            steps {
                script {
                    alpha.run()
                    beta.test()
                    gammaLib.deploy()
                }
            }
        }
    }
}

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

Aalpha

B3.0

CgammaLib

Ddelta

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing library names and versions in wrong blanks.

Using wrong library names not matching the code.

The libraries are 'alpha', 'beta' with version '3.0', and 'gammaLib' with version '1.5'.

Practice

1. What is the main purpose of the @Library annotation in Jenkins pipelines?

easy

A. To specify the pipeline agent type

B. To load shared code libraries for reuse in pipelines

C. To define environment variables for the pipeline

D. To trigger downstream jobs automatically

Solution

1. Step 1: Understand the role of @Library

   The @Library annotation is used to load shared libraries in Jenkins pipelines.

2. Step 2: Identify its main purpose

   Loading shared libraries allows reuse of code and better organization of pipeline scripts.

3. Final Answer:

   To load shared code libraries for reuse in pipelines -> Option B

4. Quick Check:

   @Library loads shared libraries = C [OK]

Hint: Remember: @Library loads reusable code libraries [OK]

Common Mistakes:

• Confusing @Library with environment variable setup
• Thinking it triggers jobs instead of loading code
• Using it to specify pipeline agents

2. Which of the following is the correct syntax to load a shared library named 'utils' in a Jenkinsfile?

easy

A. @Library('utils') _

B. @Library utils _

C. library('utils') _

D. @LoadLibrary('utils') _

Solution

1. Step 1: Recall the correct syntax for @Library

   The correct syntax uses parentheses and quotes around the library name, followed by an underscore.

2. Step 2: Match the syntax to options

   @Library('utils') _ matches @Library('utils') _, which is correct.

3. Final Answer:

   @Library('utils') _ -> Option A

4. Quick Check:

   Correct syntax uses parentheses and underscore = A [OK]

Hint: Use parentheses and underscore after @Library [OK]

Common Mistakes:

• Omitting parentheses or quotes
• Using wrong annotation like @LoadLibrary
• Placing underscore before the annotation

3. Given this Jenkinsfile snippet:

@Library('mathLib') _
pipeline {
  agent any
  stages {
    stage('Calculate') {
      steps {
        script {
          echo mathLib.add(2, 3).toString()
        }
      }
    }
  }
}

What will be the output if the shared library 'mathLib' has a method add(a, b) that returns the sum of two numbers?

medium

A. 5

B. mathLib.add(2, 3)

C. Error: method not found

D. 23

Solution

1. Step 1: Understand the method call in the script block

   The code calls mathLib.add(2, 3) which returns the sum of 2 and 3.

2. Step 2: Convert the result to string and echo

   The result 5 is converted to string and printed by echo.

3. Final Answer:

   5 -> Option A

4. Quick Check:

   Sum of 2 and 3 = 5 [OK]

Hint: Method returns sum; echo prints '5' as string [OK]

Common Mistakes:

• Expecting the method name printed instead of result
• Confusing concatenation with addition
• Assuming method is missing causing error

4. You wrote this at the top of your Jenkinsfile:

@Library('commonLib')
pipeline {
  agent any
  stages {
    stage('Test') {
      steps {
        script {
          commonLib.doSomething()
        }
      }
    }
  }
}

But Jenkins throws an error saying Missing required underscore after @Library annotation. How do you fix it?

medium

A. Change @Library to @LoadLibrary

B. Remove the parentheses from @Library

C. Place the underscore before the annotation like _ @Library('commonLib')

D. Add an underscore _ immediately after the annotation like @Library('commonLib') _

Solution

1. Step 1: Identify the syntax error from the message

   The error says the underscore is missing after @Library, which is required syntax.

2. Step 2: Correct the syntax by adding underscore

   Add an underscore immediately after the annotation: @Library('commonLib') _.

3. Final Answer:

   Add an underscore _ immediately after the annotation like @Library('commonLib') _ -> Option D

4. Quick Check:

   Underscore after @Library fixes syntax [OK]

Hint: Always put underscore right after @Library(...) [OK]

Common Mistakes:

• Omitting the underscore
• Placing underscore before annotation
• Changing annotation name incorrectly

5. You want to load two shared libraries named 'utils' and 'helpers' in your Jenkinsfile. Which is the correct way to do this using the @Library annotation?

hard

A. @Library('utils_helpers') _

B. @Library('utils') _ @Library('helpers') _

C. @Library(['utils', 'helpers']) _

D. @Library('utils,helpers') _

Solution

1. Step 1: Recall how to load multiple libraries

   Multiple libraries can be loaded by passing a list of names inside @Library annotation.

2. Step 2: Identify correct syntax for multiple libraries

   The correct syntax is @Library(['utils', 'helpers']) _ which loads both libraries at once.

3. Final Answer:

   @Library(['utils', 'helpers']) _ -> Option C

4. Quick Check:

   Use list inside @Library for multiple libs [OK]

Hint: Use list syntax inside @Library to load many libs [OK]

Common Mistakes:

• Trying to use multiple @Library annotations
• Passing comma-separated string instead of list
• Combining names into one string without list