Environment variables in builds in Jenkins - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to access the environment variable named 'BUILD_NUMBER' in a Jenkins pipeline.

Jenkins

echo "Build number is: $[1]"

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

ABUILD_NUMBER

BJOB_NAME

CBUILD_ID

DWORKSPACE

Attempts:

3 left

💡 Hint

Common Mistakes

Using JOB_NAME instead of BUILD_NUMBER

Using WORKSPACE which is the build directory path

The environment variable BUILD_NUMBER holds the current build number in Jenkins pipelines.

2fill in blank

medium

Complete the code to set a custom environment variable named 'MY_VAR' with value 'hello' in a Jenkins pipeline.

Jenkins

environment {
  MY_VAR = '[1]'
}

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

Ahello

Bworld

Cgreetings

Dhi

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect value like 'world' or 'hi'

Not using quotes around the value

To set a custom environment variable, assign the desired string value. Here, MY_VAR is set to hello.

3fill in blank

hard

Fix the error in the code to correctly print the environment variable 'MY_VAR' in a Jenkins pipeline script.

Jenkins

echo "Value is: $[1]"

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

Aenvironment.MY_VAR

BMY_VAR

Cenv['MY_VAR']

Denv.MY_VAR

Attempts:

3 left

💡 Hint

Common Mistakes

Using just MY_VAR without env prefix

Using environment.MY_VAR which is invalid

In Jenkins scripted pipelines, environment variables are accessed via env.VAR_NAME. So env.MY_VAR is correct.

4fill in blank

hard

Fill both blanks to create a map of environment variables with keys as variable names and values uppercased, filtering only variables starting with 'BUILD'.

Jenkins

def buildVars = env.getEnvironment().findAll { k, v -> k.[1]('BUILD') }
return buildVars.collectEntries { k, v -> [k, v[2]] }

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

AstartsWith

B.toUpperCase()

C.toLowerCase()

Dcontains

Attempts:

3 left

💡 Hint

Common Mistakes

Using contains instead of startsWith

Using toLowerCase instead of toUpperCase

The startsWith method filters keys starting with 'BUILD'. The toUpperCase() ensures values are uppercase.

5fill in blank

hard

Fill all three blanks to define a Jenkins pipeline stage that prints the value of an environment variable 'DEPLOY_ENV' and fails the build if it is not set.

Jenkins

stage('Check Env') {
  steps {
    script {
      def envVar = env.[1]
      if (envVar == [2]) {
        error('[3]')
      }
      echo "Deploying to: ${envVar}"
    }
  }
}

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

ADEPLOY_ENV

Bnull

CDEPLOY_ENV is not set!

DBUILD_ENV

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable name like BUILD_ENV

Comparing to empty string instead of null

Not providing an error message

The environment variable DEPLOY_ENV is accessed via env.DEPLOY_ENV. If it is null, the build fails with the error message.

Practice

1. What is the main purpose of environment variables in Jenkins builds?

easy

A. To write the build script itself

B. To display the build logs on the screen

C. To store data like secrets or settings without changing the build code

D. To install Jenkins plugins automatically

Solution

1. Step 1: Understand environment variables role

   Environment variables hold data such as secrets, settings, or dynamic values needed during the build without modifying the build code.

2. Step 2: Identify the correct purpose in Jenkins context

   Jenkins uses environment variables to pass information to builds safely and flexibly.

3. Final Answer:

   To store data like secrets or settings without changing the build code -> Option C

4. Quick Check:

   Environment variables = store build data [OK]

Hint: Environment variables hold build data, not code or logs [OK]

Common Mistakes:

• Confusing environment variables with build scripts
• Thinking environment variables show logs
• Assuming environment variables install plugins

2. Which syntax correctly defines an environment variable named VERSION with value 1.0 in a Jenkins pipeline?

easy

A. environment { VERSION = '1.0' }

B. environment { 'VERSION' = '1.0' }

C. environment { VERSION: '1.0'; }

D. environment { VERSION == '1.0' }

Solution

1. Step 1: Recall Jenkins pipeline environment syntax

   In Jenkins declarative pipelines, environment variables are defined using environment { VAR_NAME = 'value' } syntax.

2. Step 2: Identify correct syntax

   environment { VERSION = '1.0' } uses = which is the correct syntax inside the environment block.

3. Final Answer:

   environment { VERSION = '1.0' } -> Option A

4. Quick Check:

   Use equals sign for key-value in environment block [OK]

Hint: Use = not colon or double equals in environment block [OK]

Common Mistakes:

• Using colon instead of equals sign
• Using double equals which is invalid
• Putting quotes around variable name incorrectly

3. Given this Jenkins pipeline snippet:

pipeline {
  environment {
    BUILD_TYPE = 'release'
  }
  stages {
    stage('Print') {
      steps {
        echo "Build type is: ${BUILD_TYPE}"
      }
    }
  }
}

What will be printed during the build?

medium

A. Error: BUILD_TYPE not defined

B. Build type is: ${BUILD_TYPE}

C. Build type is:

D. Build type is: release

Solution

1. Step 1: Understand environment variable usage in pipeline

   The environment block sets BUILD_TYPE to 'release'. The echo step uses ${BUILD_TYPE} to access this variable.

2. Step 2: Predict output of echo command

   The variable is replaced by its value, so the output will be 'Build type is: release'.

3. Final Answer:

   Build type is: release -> Option D

4. Quick Check:

   Variable expands to value in echo [OK]

Hint: Variables in ${} expand to their values in echo [OK]

Common Mistakes:

• Expecting literal ${BUILD_TYPE} printed
• Thinking variable is empty if not exported
• Assuming error if variable is defined in environment block

4. You wrote this Jenkins pipeline snippet:

pipeline {
  environment {
    API_KEY = SECRET_KEY
  }
  stages {
    stage('Test') {
      steps {
        echo "API key is ${API_KEY}"
      }
    }
  }
}

But the build fails with an error about SECRET_KEY. What is the problem?

medium

A. You must quote the value: API_KEY = "$SECRET_KEY"

B. SECRET_KEY is not defined in Jenkins environment

C. You cannot use environment variables inside environment block directly

D. You should use single quotes instead of double quotes

Solution

1. Step 1: Analyze variable usage in environment block

   The environment block tries to assign API_KEY the value of SECRET_KEY. This requires SECRET_KEY to be defined in Jenkins environment or injected.

2. Step 2: Identify cause of error

   If SECRET_KEY is not defined anywhere, Jenkins cannot resolve it, causing the build to fail.

3. Final Answer:

   SECRET_KEY is not defined in Jenkins environment -> Option B

4. Quick Check:

   Undefined variables cause build errors [OK]

Hint: Ensure referenced env vars exist before using them [OK]

Common Mistakes:

• Assuming quoting fixes undefined variable errors
• Thinking environment block cannot use variables at all
• Using single quotes which prevent variable expansion

5. You want to pass a dynamic build number as an environment variable BUILD_NUM to your Jenkins pipeline and print it. Which snippet correctly achieves this?

hard

A. environment { BUILD_NUM = "${env.BUILD_NUMBER}" }

B. environment { BUILD_NUM == "${env.BUILD_NUMBER}" }

C. environment { BUILD_NUM = env.BUILD_NUMBER; }

D. environment { BUILD_NUM: env.BUILD_NUMBER; }

Solution

1. Step 1: Recall correct syntax for environment variables with dynamic values

   In Jenkins declarative pipelines, environment variables are defined with equals sign syntax and string values. To use a dynamic value like env.BUILD_NUMBER, it must be inside quotes and referenced with ${}.

2. Step 2: Identify correct option

   environment { BUILD_NUM = "${env.BUILD_NUMBER}" } uses BUILD_NUM = "${env.BUILD_NUMBER}" which correctly sets the environment variable to the current build number.

3. Final Answer:

   environment { BUILD_NUM = "${env.BUILD_NUMBER}" } -> Option A

4. Quick Check:

   Use equals sign and ${} for dynamic env vars [OK]

Hint: Use equals sign and ${env.VAR} inside quotes for dynamic vars [OK]

Common Mistakes:

• Using double equals instead of equals sign
• Not quoting the dynamic variable
• Omitting ${} around env variable