osutil,deploy: on GCE, deploy with enough scope to log on GCL

Otherwise, if scope is missing, warn about it.

Change-Id: If840c4f5783708dd5693993ca39b10fd2ad5442e

pkg/deploy/gce/deploy.go

@@ -48,6 +48,7 @@ import (
 	compute "google.golang.org/api/compute/v1"
 	storage "google.golang.org/api/storage/v1"
 	"google.golang.org/cloud"
+	"google.golang.org/cloud/logging"
 	cloudstorage "google.golang.org/cloud/storage"
 )
 
@@ -87,6 +88,7 @@ var (
 func NewOAuthConfig(clientID, clientSecret string) *oauth2.Config {
 	return &oauth2.Config{
 		Scopes: []string{
+			logging.Scope,
 			compute.DevstorageFull_controlScope,
 			compute.ComputeScope,
 			"https://www.googleapis.com/auth/sqlservice",
@@ -377,6 +379,7 @@ func (d *Deployer) createInstance(computeService *compute.Service, ctx *context.
 			{
 				Email: "default",
 				Scopes: []string{
+					logging.Scope,
 					compute.DevstorageFull_controlScope,
 					compute.ComputeScope,
 					"https://www.googleapis.com/auth/sqlservice",

pkg/deploy/gce/handler.go

@@ -1048,6 +1048,7 @@ This tool helps you create your own private Camlistore instance running on Googl
 				<li>APIs and auth &gt APIs &gt Google Cloud Storage</li>
 				<li>APIs and auth &gt APIs &gt Google Cloud Storage JSON API</li>
 				<li>APIs and auth &gt APIs &gt Google Compute Engine</li>
+				<li>APIs and auth &gt APIs &gt Google Cloud Logging API</li>
 			</ul>
 		</ul>
 		</td></tr>

pkg/osutil/gce/gce.go

@@ -77,6 +77,20 @@ func LogWriter() (w io.Writer) {
 		log.Printf("Error getting project ID: %v", err)
 		return
 	}
+	scopes, _ := metadata.Scopes("default")
+	haveScope := func(scope string) bool {
+		for _, x := range scopes {
+			if x == scope {
+				return true
+			}
+		}
+		return false
+	}
+	if !haveScope(logging.Scope) {
+		log.Printf("when this Google Compute Engine VM instance was created, it wasn't granted enough access to use Google Cloud Logging (Scope URL: %v).", logging.Scope)
+		return
+	}
+
 	hc, err := google.DefaultClient(oauth2.NoContext)
 	if err != nil {
 		log.Printf("Error creating default GCE OAuth2 client: %v", err)