Dynamic parameter values in Jenkins - Step-by-Step Execution

Process Flow - Dynamic parameter values

Start Job

↓

Display Parameters

↓

User selects parameter

↓

Parameter triggers dynamic update?

No→Use default/static value

Yes↓

Fetch new parameter values dynamically

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Update parameter options

↓

User confirms selections

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Run Job with selected parameters

The job starts by showing parameters. If a parameter triggers dynamic updates, new values are fetched and options updated before running the job.

Execution Sample

Jenkins

properties([
  parameters([
    choice(name: 'ENV', choices: ['dev', 'qa', 'prod'], description: 'Select environment'),
    choice(name: 'VERSION', choices: getVersions(params.ENV), description: 'Select version')
  ])
])

This Jenkins pipeline snippet shows how the 'VERSION' parameter choices depend dynamically on the selected 'ENV' parameter.

Process Table

Step	Action	Parameter	Value/Choices	Result
1	Start job	-	-	Parameters displayed with ENV choices ['dev', 'qa', 'prod'] and VERSION empty
2	User selects ENV	ENV	dev	Trigger dynamic update for VERSION
3	Fetch versions for ENV=dev	VERSION	['1.0', '1.1', '1.2']	VERSION choices updated
4	User selects VERSION	VERSION	1.1	Parameter selection complete
5	Run job with parameters	ENV, VERSION	dev, 1.1	Job executes with selected parameters
6	User changes ENV	ENV	prod	Trigger dynamic update for VERSION
7	Fetch versions for ENV=prod	VERSION	['2.0', '2.1']	VERSION choices updated
8	User selects VERSION	VERSION	2.0	Parameter selection complete
9	Run job with parameters	ENV, VERSION	prod, 2.0	Job executes with updated parameters

💡 Job runs after user selects parameters and dynamic values are updated accordingly.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 6	After Step 7	Final
ENV	null	dev	dev	prod	prod	prod
VERSION choices	[]	[]	['1.0', '1.1', '1.2']	['1.0', '1.1', '1.2']	['2.0', '2.1']	['2.0', '2.1']
VERSION selected	null	null	1.1	1.1	1.1	2.0

Key Moments - 2 Insights

Why does the VERSION parameter choices change after selecting ENV?

Because VERSION depends on ENV, selecting ENV triggers fetching new VERSION choices dynamically as shown in steps 2 and 3 of the execution table.

What happens if the user changes ENV after selecting VERSION?

Changing ENV again triggers a dynamic update of VERSION choices (steps 6 and 7), so the previously selected VERSION may no longer be valid and must be reselected.

Visual Quiz - 3 Questions

Look at the execution table, what are the VERSION choices after the user selects ENV as 'dev'?

A ['1.0', '1.1', '1.2']

B ['2.0', '2.1']

C ['dev', 'qa', 'prod']

D []

💡 Hint

Check step 3 in the execution table where ENV is 'dev' and VERSION choices are updated.

At which step does the job run with ENV='prod' and VERSION='2.0'?

A Step 5

B Step 7

C Step 9

D Step 3

💡 Hint

Look for the step where parameters ENV='prod' and VERSION='2.0' are used to run the job.

If the user never changes ENV, what happens to VERSION choices after step 1?

A They default to ['2.0', '2.1']

B They remain empty

C They update dynamically

D They default to ['1.0', '1.1', '1.2']

💡 Hint

Refer to the variable_tracker and execution_table steps before ENV selection triggers updates.

Concept Snapshot

Dynamic Parameter Values in Jenkins:
- Parameters can depend on others.
- Selecting one parameter triggers update of dependent parameter choices.
- Use functions to fetch dynamic choices based on current selections.
- Job runs only after user confirms all parameters.
- Helps customize builds based on user input dynamically.

Full Transcript

This visual execution shows how Jenkins handles dynamic parameter values. The job starts by displaying parameters. When the user selects the ENV parameter, it triggers fetching new choices for the VERSION parameter dynamically. The user then selects a VERSION from updated options. The job runs with these selected parameters. If the user changes ENV again, VERSION choices update accordingly, requiring reselection. This process ensures parameters adapt dynamically based on user input before the job runs.