Implicit vs explicit loading in Jenkins - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to load a shared library explicitly in Jenkins Pipeline.

Jenkins

def lib = library('[1]').myLib

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

AsharedLib

BloadLibrary

Cmy-shared-library

DlibraryLoad

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name instead of the library name string.

Explicit loading uses the library() step with the library name as a string.

2fill in blank

medium

Complete the code to use implicit loading of a shared library in Jenkins Pipeline.

Jenkins

@Library('[1]') _

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

AlibraryLoad

BloadLibrary

CsharedLib

Dmy-shared-library

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong annotation or misspelling the library name.

Implicit loading uses the @Library annotation with the library name.

3fill in blank

hard

Fix the error in the explicit loading code to correctly call a function from the shared library.

Jenkins

def lib = library('[1]')
lib.[2]()

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

Amy-shared-library

BcallFunction

CmySharedLibrary

DrunFunction

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable instead of a string for the library name.

The library name must be a string matching the shared library name. Then call lib.callFunction() from the library object.

4fill in blank

hard

Fill both blanks to explicitly load a shared library and call its function named 'buildApp'.

Jenkins

def lib = library('[1]')
lib.[2]()

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

Amy-shared-library

BbuildApp

CdeployApp

DrunBuild

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up function names or using incorrect library names.

Explicit loading requires the library name string and then calling the function by its exact name.

5fill in blank

hard

Fill all three blanks to implicitly load a shared library named 'utils' and call its 'testConnection' function.

Jenkins

@Library('[1]') _
def result = [2].[3]()

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

Autils

CtestConnection

DrunTest

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the library in annotation and variable.

Implicit loading uses the @Library annotation with the library name, then calls the function on the library object.

Practice

1. What is the main difference between implicit and explicit loading of shared libraries in Jenkins pipelines?

easy

A. Implicit loading loads libraries from GitHub, explicit loads from local files.

B. Implicit loading requires manual script calls, explicit loading is automatic.

C. Implicit loading is only for scripted pipelines, explicit is for declarative pipelines.

D. Implicit loading uses the @Library annotation, explicit uses the library() step.

Solution

1. Step 1: Understand implicit loading

   Implicit loading uses the @Library annotation at the top of the Jenkinsfile to automatically load shared libraries.

2. Step 2: Understand explicit loading

   Explicit loading uses the library() step inside the pipeline script to load libraries manually when needed.

3. Final Answer:

   Implicit loading uses the @Library annotation, explicit uses the library() step. -> Option D

4. Quick Check:

   Implicit = @Library, Explicit = library() [OK]

Hint: Remember: @Library is automatic, library() is manual [OK]

Common Mistakes:

• Confusing which method is automatic
• Thinking explicit loading is automatic
• Mixing up syntax of @Library and library()
• Assuming implicit loading requires code inside pipeline

2. Which of the following is the correct syntax for implicit loading of a shared library named 'utils' in a Jenkinsfile?

easy

A. library('utils')

B. @Library('utils') _

C. loadLibrary('utils')

D. import 'utils'

Solution

1. Step 1: Recall implicit loading syntax

   Implicit loading uses the @Library('libraryName') _ annotation at the top of the Jenkinsfile.

2. Step 2: Check options for correct syntax

   @Library('utils') _ matches the correct syntax: @Library('utils') _. Others are incorrect or invalid in Jenkins.

3. Final Answer:

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

4. Quick Check:

   Implicit loading = @Library('name') _ [OK]

Hint: Implicit loading always starts with @Library and ends with underscore [OK]

Common Mistakes:

• Using library() instead of @Library for implicit loading
• Missing the underscore after @Library annotation
• Using import or loadLibrary which are invalid
• Placing @Library inside pipeline steps

3. Given the Jenkinsfile snippet below, what will be the output if the shared library 'mathLib' has a function add(a, b) that returns the sum?

@Library('mathLib') _
pipeline {
  agent any
  stages {
    stage('Add') {
      steps {
        script {
          def result = add(3, 4)
          echo "Sum is ${result}"
        }
      }
    }
  }
}

medium

A. Sum is 7

B. Error: add() function not found

C. Sum is 34

D. Pipeline fails to load

Solution

1. Step 1: Identify loading method

   The Jenkinsfile uses implicit loading with @Library('mathLib') _, so the library functions are available automatically.

2. Step 2: Understand function call and output

   The add(3, 4) function returns 7, so the echo prints "Sum is 7".

3. Final Answer:

   Sum is 7 -> Option A

4. Quick Check:

   Implicit loading allows direct function use = Sum is 7 [OK]

Hint: Implicit loading lets you call library functions directly [OK]

Common Mistakes:

• Assuming add() is undefined without explicit library() call
• Confusing string concatenation with addition
• Thinking pipeline fails due to missing library
• Ignoring the underscore after @Library

4. You have this Jenkins pipeline snippet:

pipeline {
  agent any
  stages {
    stage('Load Lib') {
      steps {
        script {
          @Library('toolsLib') _
          def result = toolFunc()
          echo "Result: ${result}"
        }
      }
    }
  }
}

What is the problem with this code?

medium

A. The @Library annotation cannot be used inside the script block.

B. The library name 'toolsLib' is invalid syntax.

C. The function toolFunc() must be called with library() step.

D. The echo statement is missing parentheses.

Solution

1. Step 1: Check usage of @Library annotation

   The @Library annotation must be placed at the top of the Jenkinsfile, not inside script blocks or stages.

2. Step 2: Identify error cause

   Using @Library inside the script block causes a syntax error; explicit loading with library() should be used inside scripts.

3. Final Answer:

   The @Library annotation cannot be used inside the script block. -> Option A

4. Quick Check:

   @Library only at top, not inside script [OK]

Hint: Put @Library only at the top of Jenkinsfile [OK]

Common Mistakes:

• Placing @Library inside pipeline steps
• Confusing explicit and implicit loading syntax
• Assuming library() is optional inside script
• Ignoring syntax error from misplaced annotation

5. You want to load two shared libraries in a Jenkins pipeline: 'libA' implicitly and 'libB' explicitly. Which Jenkinsfile snippet correctly achieves this?

hard

A. @Library('libB') _
pipeline {
agent any
stages {
stage('Use LibA') {
steps {
script {
library('libA')
libAFunc()
libBFunc()
}
}
}
}
}

B. pipeline {
agent any
stages {
stage('Use LibA and LibB') {
steps {
script {
library('libA')
library('libB')
libAFunc()
libBFunc()
}
}
}
}
}

C. @Library('libA') _
pipeline {
agent any
stages {
stage('Use LibB') {
steps {
script {
library('libB')
libBFunc()
}
}
}
}
}

D. @Library('libA') _
@Library('libB') _
pipeline {
agent any
stages {
stage('Use Both') {
steps {
script {
libAFunc()
libBFunc()
}
}
}
}
}

Solution

1. Step 1: Understand implicit and explicit loading together

   Implicit loading uses @Library('libA') _ at the top. Explicit loading uses library('libB') inside the script block.

2. Step 2: Check each option for correct usage

   @Library('libA') _ pipeline { agent any stages { stage('Use LibB') { steps { script { library('libB') libBFunc() } } } } } correctly uses implicit loading for 'libA' and explicit loading for 'libB' inside the script block. Others misuse annotations or load both explicitly or implicitly incorrectly.

3. Final Answer:

   @Library('libA') _ at top (implicit for libA), library('libB') inside script (explicit for libB) -> Option C

4. Quick Check:

   Implicit @Library top, explicit library() inside script [OK]

Hint: Implicit @Library top, explicit library() inside script block [OK]

Common Mistakes:

• Using multiple @Library annotations for explicit loading
• Calling library() outside script block
• Loading both libraries only explicitly or only implicitly
• Misplacing annotations inside pipeline stages