PowerShell-master/.github/instructions/log-grouping-guidelines.instructions.md

metadata

applyTo:
  - build.psm1
  - tools/ci.psm1
  - .github/**/*.yml
  - .github/**/*.yaml

Log Grouping Guidelines for GitHub Actions

Purpose

Guidelines for using Write-LogGroupStart and Write-LogGroupEnd to create collapsible log sections in GitHub Actions CI/CD runs.

Key Principles

1. Groups Cannot Be Nested

GitHub Actions does not support nested groups. Only use one level of grouping.

❌ Don't:

Write-LogGroupStart -Title "Outer Group"
Write-LogGroupStart -Title "Inner Group"
# ... operations ...
Write-LogGroupEnd -Title "Inner Group"
Write-LogGroupEnd -Title "Outer Group"

✅ Do:

Write-LogGroupStart -Title "Operation A"
# ... operations ...
Write-LogGroupEnd -Title "Operation A"

Write-LogGroupStart -Title "Operation B"
# ... operations ...
Write-LogGroupEnd -Title "Operation B"

2. Groups Should Be Substantial

Only create groups for operations that generate substantial output (5+ lines). Small groups add clutter without benefit.

❌ Don't:

Write-LogGroupStart -Title "Generate Resource Files"
Write-Log -message "Run ResGen"
Start-ResGen
Write-LogGroupEnd -Title "Generate Resource Files"

✅ Do:

Write-Log -message "Run ResGen (generating C# bindings for resx files)"
Start-ResGen

3. Groups Should Represent Independent Operations

Each group should be a logically independent operation that users might want to expand/collapse separately.

✅ Good examples:

• Install Native Dependencies
• Install .NET SDK
• Build PowerShell
• Restore NuGet Packages

❌ Bad examples:

• Individual project restores (too granular)
• Small code generation steps (too small)
• Sub-steps of a larger operation (would require nesting)

4. One Group Per Iteration Is Excessive

Avoid putting log groups inside loops where each iteration creates a separate group. This would probably cause nesting.

❌ Don't:

$projects | ForEach-Object {
    Write-LogGroupStart -Title "Restore Project: $_"
    dotnet restore $_
    Write-LogGroupEnd -Title "Restore Project: $_"
}

✅ Do:

Write-LogGroupStart -Title "Restore All Projects"
$projects | ForEach-Object {
    Write-Log -message "Restoring $_"
    dotnet restore $_
}
Write-LogGroupEnd -Title "Restore All Projects"

Usage Pattern

Write-LogGroupStart -Title "Descriptive Operation Name"
try {
    # ... operation code ...
    Write-Log -message "Status updates"
}
finally {
    # Ensure group is always closed
}
Write-LogGroupEnd -Title "Descriptive Operation Name"

When to Use Log Groups

Use log groups for:

• Major build phases (bootstrap, restore, build, test, package)
• Installation operations (dependencies, SDKs, tools)
• Operations that produce 5+ lines of output
• Operations where users might want to collapse verbose output

Don't use log groups for:

• Single-line operations
• Code that's already inside another group
• Loop iterations with minimal output per iteration
• Diagnostic or debug output that should always be visible

Examples from build.psm1

Good Usage

function Start-PSBootstrap {
    # Multiple independent operations, each with substantial output
    Write-LogGroupStart -Title "Install Native Dependencies"
    # ... apt-get/yum/brew install commands ...
    Write-LogGroupEnd -Title "Install Native Dependencies"

    Write-LogGroupStart -Title "Install .NET SDK"
    # ... dotnet installation ...
    Write-LogGroupEnd -Title "Install .NET SDK"
}

Avoid

# Too small - just 2-3 lines
Write-LogGroupStart -Title "Generate Resource Files (ResGen)"
Write-Log -message "Run ResGen"
Start-ResGen
Write-LogGroupEnd -Title "Generate Resource Files (ResGen)"

GitHub Actions Syntax

These functions emit GitHub Actions workflow commands:

• Write-LogGroupStart → ::group::Title
• Write-LogGroupEnd → ::endgroup::

In the GitHub Actions UI, this renders as collapsible sections with the specified title.

Testing

Test log grouping locally:

$env:GITHUB_ACTIONS = 'true'
Import-Module ./build.psm1
Write-LogGroupStart -Title "Test"
Write-Log -Message "Content"
Write-LogGroupEnd -Title "Test"

Output should show:

::group::Test
Content
::endgroup::

References

• GitHub Actions: Grouping log lines
• build.psm1: Write-LogGroupStart and Write-LogGroupEnd function definitions