Get ms alias from github identity

eng/common/scripts/Get-MsAlias-FromGithub.ps1

@@ -0,0 +1,64 @@
+<#
+.DESCRIPTION
+Get the corresponding ms alias from github identity
+.PARAMETER AadToken
+The aad access token.
+.PARAMETER GithubName
+Github identity. E.g sima-zhu
+.PARAMETER ContentType
+Content type of http requests.
+.PARAMETER AdditionalHeaders
+Additional parameters for http request headers in key-value pair format, e.g. @{ key1 = val1; key2 = val2; key3 = val3}
+#>
+[CmdletBinding(SupportsShouldProcess = $true)]
+param(
+  [Parameter(Mandatory = $true)]
+  [string]$AadToken,
+
+  [Parameter(Mandatory = $true)]
+  [string]$GithubName,
+
+  [Parameter(Mandatory = $false)]
+  [string]$ApiVersion = "2019-10-01",
+
+  [Parameter(Mandatory = $false)]
+  [string]$ContentType = "application/json",
+
+  [Parameter(Mandatory = $false)]
+  [hashtable]$AdditionalHeaders
+)
+. "${PSScriptRoot}\logging.ps1"
+
+$OpensourceAPIBaseURI = "https://repos.opensource.microsoft.com/api/people/links/github/$GithubName"
+
+$Headers = @{
+    "Authorization" = "Bearer $AadToken"
+    "Content-Type" = $ContentType
+    "api-version" = $ApiVersion
+}
+
+function Load-RequestHeaders() {
+    if ($AdditionalHeaders) {
+        return $Headers + $AdditionalHeaders
+    }
+    return $Headers
+}
+
+
+try {
+    $headers = Load-RequestHeaders
+    Write-Host "Fetching ms alias for github identity: $GithubName."
+    $resp = Invoke-RestMethod $OpensourceAPIBaseURI -Method 'GET' -Headers $Headers
+}
+catch { 
+    LogError $_
+    exit 1
+}
+
+$resp | Write-Verbose
+
+if ($resp.aad) {
+    return $resp.aad.alias
+}
+
+LogError "Failed to retrieve the ms alias from given github identity: $GithubName."