fix(auth): new IAM auth grpc service per token update

Update credentials.ts and utils.ts to create
instance of GrpcSerivce per token update instead
of using one instance per application. This must
help with unhandled disconnections ydb-platform#175 ydb-platform#150

.gitignore

@@ -9,6 +9,7 @@ build/
 
 #personal
 .idea/
+.vscode/
 .DS_Store
 
 # git merge leftovers

src/credentials.ts

@@ -47,22 +47,38 @@ export class TokenAuthService implements IAuthService {
     }
 }
 
-export class IamAuthService extends GrpcService<IamTokenService> implements IAuthService {
+class TempIamAuthService extends GrpcService<IamTokenService> {
+    constructor(iamCredentials: IIamCredentials, sslCredentials: ISslCredentials) {
+        super(
+            iamCredentials.iamEndpoint,
+            'yandex.cloud.iam.v1.IamTokenService',
+            IamTokenService,
+            sslCredentials,
+        );
+    }
+
+    create(request: yandex.cloud.iam.v1.ICreateIamTokenRequest) {
+        return this.api.create(request)
+    }
+
+    destroy() {
+        this.api.end()
+    }
+}
+
+export class IamAuthService implements IAuthService {
     private jwtExpirationTimeout = 3600 * 1000;
     private tokenExpirationTimeout = 120 * 1000;
     private tokenRequestTimeout = 10 * 1000;
     private token: string = '';
     private tokenTimestamp: DateTime|null;
+    private tokenUpdateInProgress: Boolean = false;
     private readonly iamCredentials: IIamCredentials;
+    private readonly sslCredentials: ISslCredentials
 
     constructor(iamCredentials: IIamCredentials, sslCredentials?: ISslCredentials) {
-        super(
-            iamCredentials.iamEndpoint,
-            'yandex.cloud.iam.v1.IamTokenService',
-            IamTokenService,
-            sslCredentials || makeDefaultSslCredentials(),
-        );
         this.iamCredentials = iamCredentials;
+        this.sslCredentials = sslCredentials || makeDefaultSslCredentials()
         this.tokenTimestamp = null;
     }
 
@@ -88,24 +104,37 @@ export class IamAuthService extends GrpcService<IamTokenService> implements IAut
         );
     }
 
-    private sendTokenRequest(): Promise<ICreateIamTokenResponse> {
-        const tokenPromise = this.api.create({jwt: this.getJwtRequest()});
-        return withTimeout<ICreateIamTokenResponse>(tokenPromise, this.tokenRequestTimeout);
+    private async sendTokenRequest(): Promise<ICreateIamTokenResponse> {
+        let tempIamAuthService = new TempIamAuthService(this.iamCredentials, this.sslCredentials)
+        const tokenPromise = tempIamAuthService.create({jwt: this.getJwtRequest()});
+        const result = await withTimeout<ICreateIamTokenResponse>(tokenPromise, this.tokenRequestTimeout);
+        tempIamAuthService.destroy()
+        return result
     }
 
     private async updateToken() {
+        this.tokenUpdateInProgress=true
         const {iamToken} = await this.sendTokenRequest();
         if (iamToken) {
             this.token = iamToken;
             this.tokenTimestamp = DateTime.utc();
+            this.tokenUpdateInProgress=false
         } else {
+            this.tokenUpdateInProgress=false
             throw new Error('Received empty token from IAM!');
         }
     }
 
+    private async waitUntilTokenUpdated() {
+        while(this.tokenUpdateInProgress) await sleep(1)
+        return
+    }
+
     public async getAuthMetadata(): Promise<grpc.Metadata> {
         if (this.expired) {
-            await this.updateToken();
+            // block updateToken calls while token updating
+            if(this.tokenUpdateInProgress) await this.waitUntilTokenUpdated()
+            else await this.updateToken();
         }
         return makeCredentialsMetadata(this.token);
     }

src/utils.ts

@@ -55,6 +55,11 @@ export abstract class GrpcService<Api extends $protobuf.rpc.Service> {
             new grpc.Client(host, grpc.credentials.createSsl(sslCredentials.rootCertificates, sslCredentials.clientPrivateKey, sslCredentials.clientCertChain)) :
             new grpc.Client(host, grpc.credentials.createInsecure());
         const rpcImpl: $protobuf.RPCImpl = (method, requestData, callback) => {
+            if(null===method && requestData === null && callback === null) {
+                // signal `end` from protobuf service
+                client.close()
+                return
+            }
             const path = `/${this.name}/${method.name}`;
             client.makeUnaryRequest(path, _.identity, _.identity, requestData, callback);
         };

tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "extends": "./tsconfig-base.json",
+  "compilerOptions": {
+    "target": "es2017",
+    "module": "commonjs",
+    "outDir": "build/cjs"
+  }
+}