Add period at end of metadata.google.internal to prevent unnecessary DNS lookups.

src/core/lib/security/credentials/alts/alts_credentials.cc

@@ -31,7 +31,7 @@
 #include "src/core/lib/security/security_connector/alts/alts_security_connector.h"
 
 #define GRPC_CREDENTIALS_TYPE_ALTS "Alts"
-#define GRPC_ALTS_HANDSHAKER_SERVICE_URL "metadata.google.internal:8080"
+#define GRPC_ALTS_HANDSHAKER_SERVICE_URL "metadata.google.internal.:8080"
 
 grpc_alts_credentials::grpc_alts_credentials(
     const grpc_alts_credentials_options* options,

src/core/lib/security/credentials/credentials.h

@@ -60,7 +60,7 @@ typedef enum {
 
 #define GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS 60
 
-#define GRPC_COMPUTE_ENGINE_METADATA_HOST "metadata.google.internal"
+#define GRPC_COMPUTE_ENGINE_METADATA_HOST "metadata.google.internal."
 #define GRPC_COMPUTE_ENGINE_METADATA_TOKEN_PATH \
   "/computeMetadata/v1/instance/service-accounts/default/token"
 

src/core/lib/security/credentials/google_default/google_default_credentials.cc

@@ -46,7 +46,7 @@
 
 /* -- Constants. -- */
 
-#define GRPC_COMPUTE_ENGINE_DETECTION_HOST "metadata.google.internal"
+#define GRPC_COMPUTE_ENGINE_DETECTION_HOST "metadata.google.internal."
 
 /* -- Default credentials. -- */
 

test/core/security/credentials_test.cc

@@ -534,7 +534,7 @@ static void test_channel_oauth2_google_iam_composite_creds(void) {
 static void validate_compute_engine_http_request(
     const grpc_httpcli_request* request) {
   GPR_ASSERT(request->handshaker != &grpc_httpcli_ssl);
-  GPR_ASSERT(strcmp(request->host, "metadata.google.internal") == 0);
+  GPR_ASSERT(strcmp(request->host, "metadata.google.internal.") == 0);
   GPR_ASSERT(
       strcmp(request->http.path,
              "/computeMetadata/v1/instance/service-accounts/default/token") ==
@@ -930,7 +930,7 @@ static int default_creds_metadata_server_detection_httpcli_get_success_override(
   response->hdr_count = 1;
   response->hdrs = headers;
   GPR_ASSERT(strcmp(request->http.path, "/") == 0);
-  GPR_ASSERT(strcmp(request->host, "metadata.google.internal") == 0);
+  GPR_ASSERT(strcmp(request->host, "metadata.google.internal.") == 0);
   GRPC_CLOSURE_SCHED(on_done, GRPC_ERROR_NONE);
   return 1;
 }
@@ -1020,7 +1020,7 @@ static int default_creds_gce_detection_httpcli_get_failure_override(
     grpc_closure* on_done, grpc_httpcli_response* response) {
   /* No magic header. */
   GPR_ASSERT(strcmp(request->http.path, "/") == 0);
-  GPR_ASSERT(strcmp(request->host, "metadata.google.internal") == 0);
+  GPR_ASSERT(strcmp(request->host, "metadata.google.internal.") == 0);
   *response = http_response(200, "");
   GRPC_CLOSURE_SCHED(on_done, GRPC_ERROR_NONE);
   return 1;