feat(refresh): add forceRefreshOnFailure flag for refreshing token on…

… error (#790)

src/auth/jwtclient.ts

@@ -83,7 +83,10 @@ export class JWT extends OAuth2Client {
       optionsOrEmail && typeof optionsOrEmail === 'object'
         ? optionsOrEmail
         : {email: optionsOrEmail, keyFile, key, keyId, scopes, subject};
-    super({eagerRefreshThresholdMillis: opts.eagerRefreshThresholdMillis});
+    super({
+      eagerRefreshThresholdMillis: opts.eagerRefreshThresholdMillis,
+      forceRefreshOnFailure: opts.forceRefreshOnFailure,
+    });
     this.email = opts.email;
     this.keyFile = opts.keyFile;
     this.key = opts.key;

src/auth/oauth2client.ts

@@ -354,6 +354,12 @@ export interface RefreshOptions {
   // milliseconds from expiring".
   // Defaults to a value of 300000 (5 minutes).
   eagerRefreshThresholdMillis?: number;
+
+  // Whether to attempt to lazily refresh tokens on 401/403 responses
+  // even if an attempt is made to refresh the token preemptively based
+  // on the expiry_date.
+  // Defaults to false.
+  forceRefreshOnFailure?: boolean;
 }
 
 export class OAuth2Client extends AuthClient {
@@ -375,6 +381,8 @@ export class OAuth2Client extends AuthClient {
 
   eagerRefreshThresholdMillis: number;
 
+  forceRefreshOnFailure: boolean;
+
   /**
    * Handles OAuth2 flow for Google APIs.
    *
@@ -402,6 +410,7 @@ export class OAuth2Client extends AuthClient {
     this.redirectUri = opts.redirectUri;
     this.eagerRefreshThresholdMillis =
       opts.eagerRefreshThresholdMillis || 5 * 60 * 1000;
+    this.forceRefreshOnFailure = !!opts.forceRefreshOnFailure;
   }
 
   protected static readonly GOOGLE_TOKEN_INFO_URL =
@@ -896,15 +905,18 @@ export class OAuth2Client extends AuthClient {
         // - We haven't already retried.  It only makes sense to retry once.
         // - The response was a 401 or a 403
         // - The request didn't send a readableStream
-        // - An access_token and refresh_token were available, but no
-        //   expiry_date was availabe. This can happen when developers stash
-        //   the access_token and refresh_token for later use, but the
-        //   access_token fails on the first try because it's expired.
+        // - An access_token and refresh_token were available, but either no
+        //   expiry_date was available or the forceRefreshOnFailure flag is set.
+        //   The absent expiry_date case can happen when developers stash the
+        //   access_token and refresh_token for later use, but the access_token
+        //   fails on the first try because it's expired. Some developers may
+        //   choose to enable forceRefreshOnFailure to mitigate time-related
+        //   errors.
         const mayRequireRefresh =
           this.credentials &&
           this.credentials.access_token &&
           this.credentials.refresh_token &&
-          !this.credentials.expiry_date;
+          (!this.credentials.expiry_date || this.forceRefreshOnFailure);
         const isReadableStream = res.config.data instanceof stream.Readable;
         const isAuthErr = statusCode === 401 || statusCode === 403;
         if (!retry && isAuthErr && !isReadableStream && mayRequireRefresh) {

src/auth/refreshclient.ts

@@ -44,7 +44,8 @@ export class UserRefreshClient extends OAuth2Client {
     optionsOrClientId?: string | UserRefreshClientOptions,
     clientSecret?: string,
     refreshToken?: string,
-    eagerRefreshThresholdMillis?: number
+    eagerRefreshThresholdMillis?: number,
+    forceRefreshOnFailure?: boolean
   ) {
     const opts =
       optionsOrClientId && typeof optionsOrClientId === 'object'
@@ -54,11 +55,13 @@ export class UserRefreshClient extends OAuth2Client {
             clientSecret,
             refreshToken,
             eagerRefreshThresholdMillis,
+            forceRefreshOnFailure,
           };
     super({
       clientId: opts.clientId,
       clientSecret: opts.clientSecret,
       eagerRefreshThresholdMillis: opts.eagerRefreshThresholdMillis,
+      forceRefreshOnFailure: opts.forceRefreshOnFailure,
     });
     this._refreshToken = opts.refreshToken;
   }

test/test.oauth2.ts

@@ -1094,6 +1094,32 @@ describe(__filename, () => {
         done();
       });
     });
+
+    it(`should refresh token if the server returns ${code} with forceRefreshOnFailure`, done => {
+      const client = new OAuth2Client({
+        clientId: CLIENT_ID,
+        clientSecret: CLIENT_SECRET,
+        redirectUri: REDIRECT_URI,
+        forceRefreshOnFailure: true,
+      });
+      const scope = nock('http://example.com')
+        .get('/access')
+        .reply(code, {
+          error: {code, message: 'Invalid Credentials'},
+        });
+      const scopes = mockExample();
+      client.credentials = {
+        access_token: 'initial-access-token',
+        refresh_token: 'refresh-token-placeholder',
+        expiry_date: new Date().getTime() + 500000,
+      };
+      client.request({url: 'http://example.com/access'}, err => {
+        scope.done();
+        scopes[0].done();
+        assert.strictEqual('abc123', client.credentials.access_token);
+        done();
+      });
+    });
   });
 
   it('should not retry requests with streaming data', done => {