Cross-platform GitHub status reporting powershell script for VSTS

report.ps1

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
$statusUrl = '$(GitHub.StatusUrl)'
$token = '$(GitHub.Token)'

if ($env:FIXEDSOURCEVERSION -eq $true) { return; }

# When the commit that triggered the build/release is a PR merge commit, 
# this task will adjust the Build.SourceVersion to the original commit, not the 
# merge commit

$message = "$env:BUILD_SOURCEVERSIONMESSAGE"
$commit = "$env:BUILD_SOURCEVERSION"
$sourceBranch = "$env:BUILD_SOURCEBRANCH"
$isPR = $sourceBranch.StartsWith('refs/pull/')

if ([string]::IsNullOrWhitespace($message)) {
  Write-Host "No commit message was found. Determining current commit message for commit $commit..."
  if ([string]::IsNullOrWhitespace($env:RELEASE_RELEASEID)) {
    $message = (git log -1 --pretty=%s).trim()
    Write-Host "Got commit message for build definition from git: $message"
  } else {
      # We can't invoke git from a RD since there isn't a repo clone in place
      $uri = "https://api.github.com/repos/$(GitHub.Repository)/commits/$commit" + '?access_token=' + '$(GitHub.Token)'
      Write-Host "Retrieving commit info from $uri"
      # Get the commit message from GitHub via API
      $message = Invoke-WebRequest -UseBasicParsing -Uri $uri | %{ (ConvertFrom-Json $_.Content).commit.message }
      $message = ($message -split '\r?\n')[0]
      Write-Host "Got commit message for release definition from GitHub: $message"
  }
}

if (($message -match '^Merge ([^\s]+) into [^\s]+$') -and $isPR -eq $true) {
  $commit = $matches[1]

  if ($env:BUILD_SOURCEVERSION -match $commit) {
    Write-Host "Current SourceVersion already matches $commit, no need to update it"
  } else {
    Write-Host "Adjusting PR commit from $env:BUILD_SOURCEVERSION to $commit"
    Write-Host "##vso[task.setvariable variable=Build.SourceVersion;]$commit"
    Write-Host "##vso[task.setvariable variable=FixedSourceVersion;]true"
  }
} else {
  Write-Host "Current commit message '$message' did not match the pattern for a merge commit. Leaving source version as $commit"
}

if (!$env:BUILD_SOURCEVERSION) {
  # when manually triggering a build from a PR merge branch, the 
  # source version isn't set at all
  # we need to report the status on the actual commit just before it
  # Note this only applies to build definitions, since releases always 
  # have a source version they are being created for.
  
  $merge = (git show | select-string Merge)[-1].ToString().Trim()
  Write-Host ("merge {0}" -f  $merge)
  $commit = git rev-parse $merge.Split(' ')[1]
  Write-Host ("##{0}[task.setvariable variable=Build.SourceVersion;]{1}" -f "vso", $commit)
} else {
  $commit = $env:BUILD_SOURCEVERSION
}

$repo = '$(GitHub.Repository)'
$api = 'https://api.github.com'
$uri = "$api/repos/$repo/statuses/$commit"
$state = '$(GitHub.State)'

switch ($state)
{
  'SucceededWithIssues' { $state = 'error' }
  'Canceled' { $state = 'pending' }
  'Failed' { $state = 'failure' }
  'pending' { $state = 'pending' }
  default { $state = 'success' }
}   

$body = ConvertTo-Json @{ state = $state; context = '$(GitHub.Context)'; description = '$(GitHub.Description)'; target_url = $statusUrl }

Write-Host "Reporting status update to GitHub at $uri with state $state"
Write-Host $body

$uri = $uri + '?access_token=' + $token

Invoke-WebRequest -Method Post -UseBasicParsing -Uri $uri -Body $body