Handle queries where the EC2 subPath is "/"

We were reporting 404 errors when hitting the address

https://metadata.equinixmetal.net/2009-04-04/meta-data/

The trailing slash was routing us to a method that assumed subPath had
an endpoint in it. So account for an empty subPath by returning
metadata.ItemNames() as we would if the trailing slash was not included
in the request.

Signed-off-by: Scott Garman <[email protected]>

pkg/api/v1/router_instance_ec2_metadata.go

@@ -91,9 +91,10 @@ func (r *Router) instanceEc2MetadataItemGet(c *gin.Context) {
 	}
 
 	if subPath, ok := c.Params.Get("subpath"); ok {
-		// If subPath is empty, we're just hitting the EC2 endpoint with a trailing
-		// slash, so perform the same operation as in instanceEc2MetadataGet()
-		if subPath == "" {
+		// If subPath is only a fwd slash, we're just hitting the EC2 endpoint
+		// with a trailing slash, so return the ItemNames as we would in
+		// instanceEc2MetadataGet()
+		if subPath == "/" {
 			c.String(http.StatusOK, strings.Join(metadata.ItemNames(), "\n"))
 			return
 		}

pkg/api/v1/router_instance_ec2_metadata_test.go

@@ -14,6 +14,20 @@ import (
 	v1api "go.hollow.sh/metadataservice/pkg/api/v1"
 )
 
+// GetEc2MetadataItemPathWithoutTrim is used to test routing edge cases where
+// the trailing '/' is kept
+func getEc2MetadataItemPathWithoutTrim(itemPath string) string {
+	fullpath := v1api.GetEc2MetadataItemPath(itemPath)
+
+	// GetEc2MetadataItemPath() calls path.Join(), which strips trailing slashes.
+	// So restore a trailing slash if itemPath came with one
+	if itemPath != "" && itemPath[len(itemPath)-1:] == "/" {
+		fullpath += "/"
+	}
+
+	return fullpath
+}
+
 func TestGetEc2MetadataByIP(t *testing.T) {
 	router := *testHTTPServer(t)
 
@@ -405,4 +419,25 @@ func TestGetEc2MetadataItemByIP(t *testing.T) {
 			}
 		})
 	}
+
+	t.Run("check routing works with trailing slash in the url", func(t *testing.T) {
+		w := httptest.NewRecorder()
+
+		standardFields := "instance-id\nhostname\niqn\nplan\nfacility\ntags\noperating-system\npublic-keys"
+
+		itemName := "/"
+		instanceIP := "139.178.82.3"
+		expectedStatus := http.StatusOK
+		expectedBody := fmt.Sprintf("%s\npublic-ipv4\npublic-ipv6\nlocal-ipv4", standardFields)
+
+		req, _ := http.NewRequestWithContext(context.TODO(), http.MethodGet, getEc2MetadataItemPathWithoutTrim(itemName), nil)
+		req.RemoteAddr = net.JoinHostPort(instanceIP, "0")
+		router.ServeHTTP(w, req)
+
+		assert.Equal(t, expectedStatus, w.Code)
+
+		if expectedStatus == http.StatusOK {
+			assert.Equal(t, expectedBody, w.Body.String())
+		}
+	})
 }