Add UDS resolver

packages/grpc-js/src/resolver-uds.ts

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  Resolver,
+  ResolverListener,
+  registerResolver,
+  registerDefaultResolver,
+} from './resolver';
+
+function getUdsName(target: string): string {
+  /* Due to how this resolver is registered, it should only be constructed
+   * with strings that start with 'unix:'. Other strings may result in
+   * nonsensical output. If the string starts with 'unix://' that entire
+   * prefix needs to be ignored */
+  if (target.startsWith('unix://')) {
+    return target.substring(7);
+  } else {
+    return target.substring(5);
+  }
+}
+
+class UdsResolver implements Resolver {
+  private addresses: string[] = [];
+  constructor(target: string, private listener: ResolverListener) {
+    this.addresses = [getUdsName(target)];
+  }
+  updateResolution(): void {
+    process.nextTick(
+      this.listener.onSuccessfulResolution,
+      this.addresses,
+      null,
+      null
+    );
+  }
+
+  static getDefaultAuthority(target: string): string {
+    return 'localhost';
+  }
+}
+
+export function setup() {
+  registerResolver('unix:', UdsResolver);
+}

packages/grpc-js/src/resolver.ts

@@ -18,6 +18,7 @@
 import { ServiceError } from './call';
 import { ServiceConfig } from './service-config';
 import * as resolver_dns from './resolver-dns';
+import * as resolver_uds from './resolver-uds';
 import { StatusObject } from './call-stream';
 
 /**
@@ -137,4 +138,5 @@ export function getDefaultAuthority(target: string): string {
 
 export function registerAll() {
   resolver_dns.setup();
+  resolver_uds.setup();
 }

packages/grpc-js/test/test-resolver.ts

@@ -121,5 +121,41 @@ describe('Name Resolver', () => {
       const resolver = resolverManager.createResolver(target, listener);
       resolver.updateResolution();
     });
+    it('Should handle a relative Unix Domain Socket name', done => {
+      const target = 'unix:socket';
+      const listener: resolverManager.ResolverListener = {
+        onSuccessfulResolution: (
+          addressList: string[],
+          serviceConfig: ServiceConfig | null,
+          serviceConfigError: StatusObject | null
+        ) => {
+          assert(addressList.includes('socket'));
+          done();
+        },
+        onError: (error: StatusObject) => {
+          done(new Error(`Failed with status ${error.details}`));
+        },
+      };
+      const resolver = resolverManager.createResolver(target, listener);
+      resolver.updateResolution();
+    });
+    it('Should handle an absolute Unix Domain Socket name', done => {
+      const target = 'unix:///tmp/socket';
+      const listener: resolverManager.ResolverListener = {
+        onSuccessfulResolution: (
+          addressList: string[],
+          serviceConfig: ServiceConfig | null,
+          serviceConfigError: StatusObject | null
+        ) => {
+          assert(addressList.includes('/tmp/socket'));
+          done();
+        },
+        onError: (error: StatusObject) => {
+          done(new Error(`Failed with status ${error.details}`));
+        },
+      };
+      const resolver = resolverManager.createResolver(target, listener);
+      resolver.updateResolution();
+    });
   });
 });