Add SQL Server readiness checks to Windows pipeline setup (#4172)

Author: paulmedynski

eng/pipelines/common/templates/steps/configure-sql-server-win-step.yml

@@ -162,10 +162,28 @@ steps:
         #Change the access level for FileStream for SQLServer
         Set-ExecutionPolicy Unrestricted
         Import-Module "sqlps"
-        Invoke-Sqlcmd -ServerInstance "$machineName" @"
-            EXEC sp_configure filestream_access_level, 2;
-            RECONFIGURE;
+
+        # Retry loop: SQL Server may be temporarily unavailable after enabling FileStream via WMI.
+        # Worst-case budget: 10 attempts x (5s connection timeout + 5s sleep) = ~100s
+        $tries = 0
+        while ($true) {
+            $tries++
+            try {
+                Invoke-Sqlcmd -ServerInstance "$machineName" -ConnectionTimeout 5 @"
+                    EXEC sp_configure filestream_access_level, 2;
+                    RECONFIGURE;
         "@
+                Write-Host "FileStream access level configured successfully."
+                break
+            } catch {
+                if ($tries -ge 10) {
+                    Write-Host "##[error]Failed to configure FileStream access level after $tries tries."
+                    throw
+                }
+                Write-Host "Failed to connect to SQL Server (attempt $tries/10). Retrying in 5 seconds..."
+                Start-Sleep -Seconds 5
+            }
+        }
       displayName: 'Enable FileStream [Win]'
       env:
         SQL_USER: ${{parameters.user }}
@@ -250,6 +268,31 @@ steps:
       Restart-Service -Name "$serviceName" -Force
       Restart-Service -Name MSSQLSERVER* -Force
 
+      # Wait for SQL Server to be ready to accept connections after restart.
+      # Worst-case budget: 20 attempts x (5s connection timeout + 3s sleep) = ~160s
+      $machineName = $env:COMPUTERNAME
+      if ("${{parameters.instanceName }}" -ne "MSSQLSERVER") {
+          $machineName += "\${{parameters.instanceName }}"
+      }
+
+      Import-Module "sqlps"
+      $tries = 0
+      while ($true) {
+          $tries++
+          try {
+              Invoke-Sqlcmd -ServerInstance "$machineName" -Query "SELECT @@VERSION" -ConnectionTimeout 5
+              Write-Host "SQL Server is ready after restart (attempt $tries)."
+              break
+          } catch {
+              if ($tries -ge 20) {
+                  Write-Host "##[error]SQL Server did not become ready after $tries attempts."
+                  throw
+              }
+              Write-Host "Waiting for SQL Server to start (attempt $tries/20)..."
+              Start-Sleep -Seconds 3
+          }
+      }
+
     displayName: 'Restart SQL Server [Win]'
 
   - powershell: |