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Runtime parameters

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Azure DevOps Services | Azure DevOps Server 2022 | Azure DevOps Server 2020

Runtime parameters let you have more control over what values can be passed to a pipeline. With runtime parameters you can:

  • Supply different values to scripts and tasks at runtime
  • Control parameter types, ranges allowed, and defaults
  • Dynamically select jobs and stages with template expressions

You can specify parameters in templates and in the pipeline. Parameters have data types such as number and string, and they can be restricted to a subset of values. The parameters section in a YAML defines what parameters are available.

Parameters are only available at template parsing time. Parameters are expanded just before the pipeline runs so that values surrounded by ${{ }} are replaced with parameter values. Use variables if you need your values to be more widely available during your pipeline run.

Note

This guidance does not apply to classic pipelines. For parameters in classic pipelines, see Process parameters (classic).

Parameters must contain a name and data type. Parameters cannot be optional. A default value needs to be assigned in your YAML file or when you run your pipeline. If you do not assign a default value or set default to false, the first available value will be used.

Use parameters in pipelines

Set runtime parameters at the beginning of a YAML. This example pipeline accepts the value of image and then outputs the value in the job. The trigger is set to none so that you can select the value of image when you manually trigger your pipeline to run.

parameters:
- name: image
  displayName: Pool Image
  type: string
  default: ubuntu-latest
  values:
  - windows-latest
  - ubuntu-latest
  - macOS-latest

trigger: none

jobs:
- job: build
  displayName: build
  pool: 
    vmImage: ${{ parameters.image }}
  steps:
  - script: echo building $(Build.BuildNumber) with ${{ parameters.image }}

When the pipeline runs, you select the Pool Image. If you do not make a selection, the default option, ubuntu-latest gets used.

runtime parameters

Use conditionals with parameters

You can also use parameters as part of conditional logic. With conditionals, part of a YAML will only run if it meets the if criteria.

Use parameters to determine what steps run

This pipeline only runs a step when the boolean parameter test is true.

parameters:
- name: image
  displayName: Pool Image
  values:
  - windows-latest
  - ubuntu-latest
  - macOS-latest
- name: test
  displayName: Run Tests?
  type: boolean
  default: false

trigger: none

jobs:
- job: build
  displayName: Build and Test
  pool: 
    vmImage: ${{ parameters.image }}
  steps:
  - script: echo building $(Build.BuildNumber)
  - ${{ if eq(parameters.test, true) }}:
    - script: echo "Running all the tests"

Use parameters to set what configuration is used

You can also use parameters to set which job runs. In this example, a different job runs depending on the value of config.

parameters:
- name: configs
  type: string
  default: 'x86,x64'

trigger: none

jobs:
- ${{ if contains(parameters.configs, 'x86') }}:
  - job: x86
    steps:
    - script: echo Building x86...
- ${{ if contains(parameters.configs, 'x64') }}:
  - job: x64
    steps:
    - script: echo Building x64...
- ${{ if contains(parameters.configs, 'arm') }}:
  - job: arm
    steps:
    - script: echo Building arm...

Selectively exclude a stage

You can also use parameters to set whether a stage runs. In this example, the Performance Test stage runs if the parameter runPerfTests is true.

parameters:
- name: runPerfTests
  type: boolean
  default: false

trigger: none

stages:
- stage: Build
  displayName: Build
  jobs:
  - job: Build
    steps:
    - script: echo running Build


- stage: UnitTest
  displayName: Unit Test
  dependsOn: Build
  jobs:
  - job: UnitTest
    steps:
    - script: echo running UnitTest


- ${{ if eq(parameters.runPerfTests, true) }}:
  - stage: PerfTest
    displayName: Performance Test
    dependsOn: Build
    jobs:
    - job: PerfTest
      steps:
      - script: echo running PerfTest


- stage: Deploy
  displayName: Deploy
  dependsOn: UnitTest
  jobs:
  - job: Deploy
    steps:
    - script: echo running UnitTest

Loop through parameters

You can also loop through your string, number, and boolean parameters.

In this example, you loop through parameters and print out each parameter name and value.

# start.yaml
parameters:
- name: myStringName
  type: string
  default: a string value
- name: myMultiString
  type: string
  default: default
  values:
  - default
  - ubuntu
- name: myNumber
  type: number
  default: 2
  values:
  - 1
  - 2
  - 4
  - 8
  - 16
- name: myBoolean
  type: boolean
  default: true

steps: 
- ${{ each parameter in parameters }}:
  - script: echo ${{ parameter.Key }} 
  - script: echo ${{ parameter.Value }}

# azure-pipeline.yaml
trigger: none

extends:
  template: start.yaml

Check for an empty parameter object

You can use the length() expression to check whether an object parameter has no value.

parameters:
- name: foo
  type: object
  default: []

steps:
- checkout: none
- ${{ if eq(length(parameters.foo), 0) }}:
  - script: echo Foo is empty
    displayName: Foo is empty

Parameter data types

Data type Notes
string string
number may be restricted to values:, otherwise any number-like string is accepted
boolean true or false
object any YAML structure
step a single step
stepList sequence of steps
job a single job
jobList sequence of jobs
deployment a single deployment job
deploymentList sequence of deployment jobs
stage a single stage
stageList sequence of stages

The step, stepList, job, jobList, deployment, deploymentList, stage, and stageList data types all use standard YAML schema format. This example includes string, number, boolean, object, step, and stepList.

parameters:
- name: myString
  type: string
  default: a string
- name: myMultiString
  type: string
  default: default
  values:
  - default
  - ubuntu
- name: myNumber
  type: number
  default: 2
  values:
  - 1
  - 2
  - 4
  - 8
  - 16
- name: myBoolean
  type: boolean
  default: true
- name: myObject
  type: object
  default:
    foo: FOO
    bar: BAR
    things:
    - one
    - two
    - three
    nested:
      one: apple
      two: pear
      count: 3
- name: myStep
  type: step
  default:
    script: echo my step
- name: mySteplist
  type: stepList
  default:
    - script: echo step one
    - script: echo step two

trigger: none

jobs: 
- job: stepList
  steps: ${{ parameters.mySteplist }}
- job: myStep
  steps:
    - ${{ parameters.myStep }}

FAQ

How can I use variables inside of templates?

There are times when it may be useful to set parameters to values based on variables. Parameters are expanded early in processing a pipeline run so not all variables will be available. To see what predefined variables are available in templates, see Use predefined variables.

In this example, the predefined variables Build.SourceBranch and Build.Reason are used in conditions in template.yml.

# File: azure-pipelines.yml
trigger:
- main

extends:
  template: template.yml

# File: template.yml
steps:
- script: echo Build.SourceBranch = $(Build.SourceBranch) # outputs refs/heads/main
- script: echo Build.Reason = $(Build.Reason) # outputs IndividualCI
- ${{ if eq(variables['Build.SourceBranch'], 'refs/heads/main') }}: 
  - script: echo I run only if Build.SourceBranch = refs/heads/main 
- ${{ if eq(variables['Build.Reason'], 'IndividualCI') }}: 
  - script: echo I run only if Build.Reason = IndividualCI 
- script: echo I run after the conditions