Add drain script for docker-windows job

jobs/docker-windows/spec

@@ -3,6 +3,7 @@ name: docker-windows
 
 templates:
   pre-start.ps1: bin/pre-start.ps1
+  drain.ps1: bin/drain.ps1
 
 packages:
 - docker-windows

jobs/docker-windows/templates/drain.ps1

@@ -0,0 +1,19 @@
+$ErrorActionPreference = "Stop";
+
+echo "Querying docker service" | Out-File -Encoding ASCII -Append "c:\var\vcap\sys\log\docker-windows\drain.log"
+$docker=(Get-Service | where { $_.Name -eq 'docker' })
+if ($docker -eq $null) {
+    echo "Docker service not found; Exiting 0" | Out-File -Encoding ASCII -Append "c:\var\vcap\sys\log\docker-windows\drain.log"
+    "0"
+    Exit 0
+}
+
+echo "Docker service found" | Out-File -Encoding ASCII -Append "c:\var\vcap\sys\log\docker-windows\drain.log"
+If ($docker.Status -Eq "Running") {
+    echo "Docker service running; Stopping" | Out-File -Encoding ASCII -Append "c:\var\vcap\sys\log\docker-windows\drain.log"
+    Stop-Service $docker |  Out-File -Encoding ASCII -Append "c:\var\vcap\sys\log\docker-windows\drain.log"
+}
+echo "Docker service drained; Exit 0" | Out-File -Encoding ASCII -Append "c:\var\vcap\sys\log\docker-windows\drain.log"
+
+"0"
+Exit 0