Short-circuit ec2 function defaults when not in AWS

Signed-off-by: Dave Henderson <[email protected]>

aws/ec2info.go

@@ -38,7 +38,15 @@ func ec2Client(region string) (client InstanceDescriber) {
 
 // Tag -
 func (e *Ec2Info) Tag(tag string, def ...string) string {
+	if e.metaClient.nonAWS {
+		returnDefault(def)
+	}
+
 	instanceID := e.metaClient.Meta("instance-id")
+	if instanceID == "" {
+		return returnDefault(def)
+	}
+
 	input := &ec2.DescribeInstancesInput{
 		InstanceIds: aws.StringSlice([]string{instanceID}),
 	}

aws/ec2info_test.go

@@ -60,6 +60,21 @@ func TestTag_ValidKey(t *testing.T) {
 	assert.Equal(t, "bar", e.Tag("foo", "default"))
 }
 
+func TestTag_NonEC2(t *testing.T) {
+	server, ec2meta := MockServer(404, "")
+	defer server.Close()
+	client := DummyInstanceDescriber{}
+	e := &Ec2Info{
+		describer: func() InstanceDescriber {
+			return client
+		},
+		metaClient: ec2meta,
+	}
+
+	assert.Equal(t, "", e.Tag("foo"))
+	assert.Equal(t, "default", e.Tag("foo", "default"))
+}
+
 // test doubles
 type DummyInstanceDescriber struct {
 	tags []*ec2.Tag

aws/ec2meta.go

@@ -16,6 +16,7 @@ const DefaultEndpoint = "http://169.254.169.254"
 type Ec2Meta struct {
 	Endpoint string
 	Client   *http.Client
+	nonAWS   bool
 }
 
 // returnDefault -
@@ -26,16 +27,32 @@ func returnDefault(def []string) string {
 	return ""
 }
 
+func unreachable(err error) bool {
+	if strings.Contains(err.Error(), "request canceled") ||
+		strings.Contains(err.Error(), "no route to host") ||
+		strings.Contains(err.Error(), "host is down") {
+		return true
+	}
+
+	return false
+}
+
 func (e *Ec2Meta) retrieveMetadata(url string, key string, def ...string) string {
+	if e.nonAWS {
+		return returnDefault(def)
+	}
+
 	if e.Client == nil {
-		e.Client = &http.Client{
-			Timeout: 5 * time.Second,
-		}
+		e.Client = &http.Client{Timeout: 500 * time.Millisecond}
 	}
 	resp, err := e.Client.Get(url)
 	if err != nil {
+		if unreachable(err) {
+			e.nonAWS = true
+		}
 		return returnDefault(def)
 	}
+
 	defer resp.Body.Close()
 	if resp.StatusCode > 399 {
 		return returnDefault(def)

aws/testutils.go

@@ -21,6 +21,6 @@ func MockServer(code int, body string) (*httptest.Server, *Ec2Meta) {
 	}
 	httpClient := &http.Client{Transport: tr}
 
-	client := &Ec2Meta{server.URL + "/", httpClient}
+	client := &Ec2Meta{server.URL + "/", httpClient, false}
 	return server, client
 }