Dynamic parameter values in Jenkins - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a dynamic choice parameter in Jenkins pipeline.

Jenkins

properties([parameters([choice(name: 'ENV', choices: [1], description: 'Select environment')])])

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

A"dev, staging, prod"

B['dev', 'staging', 'prod']

C["dev", "staging", "prod"]

D"dev\nstaging\nprod"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a list instead of a newline-separated string.

Using commas inside the string instead of newlines.

The choice parameter expects a string with newline-separated options.

2fill in blank

medium

Complete the code to set a dynamic string parameter with a default value.

Jenkins

properties([parameters([string(name: 'VERSION', defaultValue: [1], description: 'Enter version')])])

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

A"1.0.0"

B1.0.0

C'1.0.0'

Dversion

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting the version string.

Using single quotes which may cause syntax issues.

The defaultValue must be a string, so it needs to be quoted with double quotes.

3fill in blank

hard

Fix the error in the code to dynamically generate choices from a Groovy list.

Jenkins

def envs = ['dev', 'qa', 'prod']
properties([parameters([choice(name: 'ENV', choices: [1], description: 'Choose environment')])])

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

Aenvs

Benvs.join('\n')

Cenvs.toString()

Denvs.join(',')

Attempts:

3 left

💡 Hint

Common Mistakes

Joining with commas instead of newlines.

Passing the list directly without conversion.

The choices parameter requires a newline-separated string, so joining the list with '\n' is correct.

4fill in blank

hard

Fill both blanks to create a dynamic boolean parameter with a default value.

Jenkins

properties([parameters([booleanParam(name: [1], defaultValue: [2], description: 'Enable feature')])])

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

A"ENABLE_FEATURE"

Btrue

Cfalse

DENABLE_FEATURE

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting the parameter name.

Using string 'true' instead of boolean true.

The name must be a string, so it needs quotes. The defaultValue is a boolean true.

5fill in blank

hard

Fill all three blanks to define a dynamic choice parameter with options generated from a list and a description.

Jenkins

def branches = ['main', 'develop', 'feature']
properties([parameters([choice(name: [1], choices: [2], description: [3])])])

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

A"BRANCH"

Bbranches.join('\n')

C"Select the git branch to build"

Dbranches.toString()

Attempts:

3 left

💡 Hint

Common Mistakes

Using toString() for choices instead of joining with newlines.

Not quoting name or description.

The name and description must be strings, so they need quotes. The choices must be a newline-separated string from the list.

Practice

1. What is the main purpose of using dynamic parameter values in Jenkins jobs?

easy

A. To update input options based on other inputs or external data

B. To make Jenkins jobs run faster

C. To disable user inputs during job execution

D. To automatically restart failed jobs

Solution

1. Step 1: Understand dynamic parameters

   Dynamic parameters change their available options based on other inputs or external data sources.

2. Step 2: Identify the purpose

   This makes Jenkins jobs flexible and user-friendly by showing relevant choices dynamically.

3. Final Answer:

   To update input options based on other inputs or external data -> Option A

4. Quick Check:

   Dynamic parameters update options dynamically [OK]

Hint: Dynamic parameters change options based on other inputs [OK]

Common Mistakes:

• Thinking dynamic parameters speed up job execution
• Confusing dynamic parameters with job restart features
• Assuming dynamic parameters disable inputs

2. Which Jenkins plugin is commonly used to create dynamic parameter values based on a script?

easy

A. Pipeline Plugin

B. Git Plugin

C. Active Choices Plugin

D. Mailer Plugin

Solution

1. Step 1: Identify plugins for dynamic parameters

   The Active Choices Plugin allows parameters to be dynamically generated using Groovy scripts.

2. Step 2: Exclude unrelated plugins

   Git Plugin manages source control, Pipeline Plugin manages job pipelines, and Mailer Plugin sends emails, none create dynamic parameters.

3. Final Answer:

   Active Choices Plugin -> Option C

4. Quick Check:

   Active Choices Plugin enables dynamic parameters [OK]

Hint: Active Choices Plugin supports scripted dynamic parameters [OK]

Common Mistakes:

• Choosing Git Plugin for dynamic parameters
• Confusing Pipeline Plugin with parameter plugins
• Selecting Mailer Plugin unrelated to parameters

3. Given this Groovy script for an Active Choices parameter:

return ['dev', 'test', 'prod'].findAll { it.startsWith(params.ENV_PREFIX ?: '') }

What will be the parameter options if ENV_PREFIX is set to t?

medium

A. ['dev', 'test', 'prod']

B. ['test']

C. ['prod']

D. []

Solution

1. Step 1: Understand the script filtering

   The script returns list items starting with the value of ENV_PREFIX. Here, ENV_PREFIX is 't'.

2. Step 2: Filter the list

   From ['dev', 'test', 'prod'], only 'test' starts with 't'.

3. Final Answer:

   ['test'] -> Option B

4. Quick Check:

   Filter by prefix 't' gives ['test'] [OK]

Hint: Filter list by prefix to find matching options [OK]

Common Mistakes:

• Ignoring the prefix filter and returning full list
• Choosing empty list when prefix matches an item
• Selecting wrong matching item

4. You wrote this Active Choices script:

return ['one', 'two', 'three'].filter { it.contains(params.SEARCH) }

But Jenkins shows a syntax error. What is the problem?

medium

A. The parameter SEARCH must be declared as a string

B. The list should be a map, not a list

C. The script must use double quotes for strings

D. The method should be findAll instead of filter

Solution

1. Step 1: Check Groovy list filtering methods

   Groovy uses findAll to filter lists, not filter which causes syntax error.

2. Step 2: Confirm other parts are correct

   The list syntax and parameter usage are valid; string quotes can be single or double.

3. Final Answer:

   The method should be findAll instead of filter -> Option D

4. Quick Check:

   Use findAll for filtering lists in Groovy [OK]

Hint: Use findAll, not filter, to filter lists in Groovy [OK]

Common Mistakes:

• Using filter instead of findAll causes syntax errors
• Thinking list must be a map for filtering
• Believing quotes type causes syntax error

5. You want a Jenkins job parameter that lists all Git branches dynamically from a repository URL. Which approach correctly implements this dynamic parameter?

hard

A. Use Active Choices Plugin with a Groovy script that runs git ls-remote --heads <repo_url> and parses branch names

B. Use a String parameter and ask users to type branch names manually

C. Use a Boolean parameter to select if branches should be listed

D. Use a fixed Choice parameter with hardcoded branch names

Solution

1. Step 1: Identify dynamic branch listing method

   Active Choices Plugin with Groovy script can run shell commands to fetch live branch names from Git.

2. Step 2: Exclude static or unrelated options

   String parameter requires manual input, Boolean parameter is not for listing, fixed Choice is static and not dynamic.

3. Final Answer:

   Use Active Choices Plugin with a Groovy script that runs git ls-remote --heads <repo_url> and parses branch names -> Option A

4. Quick Check:

   Active Choices + git command fetches dynamic branches [OK]

Hint: Use Active Choices with git command to list branches dynamically [OK]

Common Mistakes:

• Using static parameters instead of dynamic scripts
• Choosing Boolean parameter for listing options
• Forgetting to parse git command output