cloudinfo: bugfix openstack identified as aws

Because openstack and aws uses the exact same api,
the previous method to check for if running on aws
would have returned true on openstack as well.

utils/cloudinfo/aws.go

@@ -15,24 +15,26 @@
 package cloudinfo
 
 import (
-	"time"
-
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/ec2metadata"
 	"github.com/aws/aws-sdk-go/aws/session"
+	"io/ioutil"
+	"strings"
 
 	info "github.com/google/cadvisor/info/v1"
 )
 
+const (
+	ProductVerFileName = "/sys/class/dmi/id/product_version"
+	Amazon             = "amazon"
+)
+
 func onAWS() bool {
-	// the default client behavior retried the operation multiple times with a 5s timeout per attempt.
-	// if you were not on aws, you would block for 20s when invoking this operation.
-	// we reduce retries to 0 and set the timeout to 2s to reduce the time this blocks when not on aws.
-	client := ec2metadata.New(session.New(&aws.Config{MaxRetries: aws.Int(0)}))
-	if client.Config.HTTPClient != nil {
-		client.Config.HTTPClient.Timeout = time.Duration(2 * time.Second)
+	data, err := ioutil.ReadFile(ProductVerFileName)
+	if err != nil {
+		return false
 	}
-	return client.Available()
+	return strings.Contains(string(data), Amazon)
 }
 
 func getAwsMetadata(name string) string {