PowerShell-master/.github/instructions/onebranch-condition-syntax.instructions.md

metadata

applyTo: .pipelines/**/*.{yml,yaml}

OneBranch Pipeline Condition Syntax

Overview

Azure Pipelines (OneBranch) uses specific syntax for referencing variables and parameters in condition expressions. Using the wrong syntax will cause conditions to fail silently or behave unexpectedly.

Variable Reference Patterns

In Condition Expressions

✅ Correct Pattern:

condition: eq(variables['VariableName'], 'value')
condition: or(eq(variables['VAR1'], 'true'), eq(variables['VAR2'], 'true'))
condition: and(succeeded(), eq(variables['Architecture'], 'fxdependent'))

❌ Incorrect Patterns:

# Don't use $(VAR) string expansion in conditions
condition: eq('$(VariableName)', 'value')

# Don't use direct variable references
condition: eq($VariableName, 'value')

In Script Content (pwsh, bash, etc.)

✅ Correct Pattern:

- pwsh: |
    $value = '$(VariableName)'
    Write-Host "Value: $(VariableName)"

In Input Fields

✅ Correct Pattern:

inputs:
  serviceEndpoint: '$(ServiceEndpoint)'
  sbConfigPath: '$(SBConfigPath)'

Parameter References

Template Parameters (Compile-Time)

✅ Correct Pattern:

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

steps:
  - task: SomeTask@1
    condition: eq('${{ parameters.OfficialBuild }}', 'true')

Note: Parameters use ${{ parameters.Name }} because they're evaluated at template compile-time.

Runtime Variables (Execution-Time)

✅ Correct Pattern:

steps:
  - pwsh: |
      Write-Host "##vso[task.setvariable variable=MyVar]somevalue"
    displayName: Set Variable

  - task: SomeTask@1
    condition: eq(variables['MyVar'], 'somevalue')

Common Scenarios

Scenario 1: Check if Variable Equals Value

- task: DoSomething@1
  condition: eq(variables['PREVIEW'], 'true')

Scenario 2: Multiple Variable Conditions (OR)

- task: DoSomething@1
  condition: or(eq(variables['STABLE'], 'true'), eq(variables['LTS'], 'true'))

Scenario 3: Multiple Variable Conditions (AND)

- task: DoSomething@1
  condition: and(succeeded(), eq(variables['Architecture'], 'fxdependent'))

Scenario 4: Complex Conditions

- task: DoSomething@1
  condition: and(
    succeededOrFailed(),
    ne(variables['UseAzDevOpsFeed'], ''),
    eq(variables['Build.SourceBranch'], 'refs/heads/master')
  )

Scenario 5: Built-in Variables

- task: CodeQL3000Init@0
  condition: eq(variables['Build.SourceBranch'], 'refs/heads/master')

- step: finalize
  condition: eq(variables['Agent.JobStatus'], 'SucceededWithIssues')

Scenario 6: Parameter vs Variable

parameters:
  - name: OfficialBuild
    type: boolean

steps:
  # Parameter condition (compile-time)
  - task: SignFiles@1
    condition: eq('${{ parameters.OfficialBuild }}', 'true')

  # Variable condition (runtime)
  - task: PublishArtifact@1
    condition: eq(variables['PUBLISH_ENABLED'], 'true')

Why This Matters

String Expansion $(VAR) in Conditions:

• When you use '$(VAR)' in a condition, Azure Pipelines attempts to expand it as a string
• If the variable is undefined or empty, it becomes an empty string ''
• The condition eq('', 'true') will always be false
• This makes debugging difficult because there's no error message

Variables Array Syntax variables['VAR']:

• This is the proper way to reference runtime variables in conditions
• Azure Pipelines correctly evaluates the variable's value
• Undefined variables are handled properly by the condition evaluator
• This is the standard pattern used throughout Azure Pipelines

Reference Examples

Working examples can be found in:

• .pipelines/templates/linux.yml - Build.SourceBranch conditions
• .pipelines/templates/windows-hosted-build.yml - Architecture conditions
• .pipelines/templates/compliance/apiscan.yml - CODEQL_ENABLED conditions
• .pipelines/templates/insert-nuget-config-azfeed.yml - Complex AND/OR conditions

Quick Reference Table

Context	Syntax	Example
Condition expression	variables['Name']	condition: eq(variables['PREVIEW'], 'true')
Script content	$(Name)	pwsh: Write-Host "$(PREVIEW)"
Task input	$(Name)	inputs: path: '$(Build.SourcesDirectory)'
Template parameter	${{ parameters.Name }}	condition: eq('${{ parameters.Official }}', 'true')

Troubleshooting

Condition Always False

If your condition is always evaluating to false:

1. Check if you're using '$(VAR)' instead of variables['VAR']
2. Verify the variable is actually set (add a debug step to print the variable)
3. Check the variable value is exactly what you expect (case-sensitive)

Variable Not Found

If you get errors about variables not being found:

1. Ensure the variable is set before the condition is evaluated
2. Check that the variable name is spelled correctly
3. Verify the variable is in scope (job vs. stage vs. pipeline level)

Best Practices

1. Always use variables['Name'] in conditions - This is the correct Azure Pipelines pattern
2. Use $(Name) for string expansion in scripts and inputs
3. Use ${{ parameters.Name }} for template parameters (compile-time)
4. Add debug steps to verify variable values when troubleshooting conditions
5. Follow existing patterns in the repository - grep for condition: to see examples

Common Mistakes

❌ Mistake 1: String expansion in condition

condition: eq('$(PREVIEW)', 'true')  # WRONG

✅ Fix:

condition: eq(variables['PREVIEW'], 'true')  # CORRECT

❌ Mistake 2: Missing quotes around parameter

condition: eq(${{ parameters.Official }}, true)  # WRONG

✅ Fix:

condition: eq('${{ parameters.Official }}', 'true')  # CORRECT

❌ Mistake 3: Mixing syntax

condition: or(eq('$(STABLE)', 'true'), eq(variables['LTS'], 'true'))  # INCONSISTENT

✅ Fix:

condition: or(eq(variables['STABLE'], 'true'), eq(variables['LTS'], 'true'))  # CORRECT