Error 500 backendError with Gmail API and Google APIs Node Client

Question

I'm trying to use the new Gmail API with the Google API Node client. I created a new project from the developer console, set up a new "Service Account" Client ID, and enabled access to the API.

As a proof of concept, I am simply trying to list the threads in my inbox. When I enable the OAuth 2.0 toggle for the API explorer and enter my email address, the request succeeds and I see a JSON response with data.

Now I try to do the same in Node:

var googleapis = require('googleapis');

var SERVICE_ACCOUNT_EMAIL = '...SNIP...';

// generated by: openssl pkcs12 -in ...SNIP...p12 -out key.pem -nocerts -nodes
var SERVICE_ACCOUNT_KEY_FILE = 'key.pem';
var jwt = new googleapis.auth.JWT(
        SERVICE_ACCOUNT_EMAIL,
        SERVICE_ACCOUNT_KEY_FILE,
        null,
        ['https://www.googleapis.com/auth/gmail.readonly']);

googleapis
    .discover('gmail', 'v1')
    .execute(function(err, client) {

        jwt.authorize(function(err, result) {
            if(err) console.error(err);
            else console.log(result);

            client.gmail.users.threads.list()
                .withAuthClient(jwt)
                .execute(function(err, result) {
                    if(err) console.error(err);
                    else console.log(result);
            });
        });
    });

First I print the results of the authorize() call, which looks like it returns a token, so I think I have all the OAuth stuff setup properly:

{ access_token: '...SNIP...',
  token_type: 'Bearer',
  expires_in: 1404277946,
  refresh_token: 'jwt-placeholder' }

Then I try to actually use the API, but I get an error:

{ errors: 
   [ { domain: 'global',
       reason: 'backendError',
       message: 'Backend Error' } ],
  code: 500,
  message: 'Backend Error' }

At this point, I don't know what else to try. I think the OAuth stuff is working properly, because I haven't gotten any authentication errors. I also think the API itself is working and my account is fine, because I can use it through the API Explorer. I don't see any indication that the Node library is at fault either. In short, I have no idea what the problem is. Any ideas?

score 0 · Answer 1 · answered Jul 09 '14 at 05:19

0

You are using the Service Account to authenticate your requests to GMail. Your Service Account will not have a Gmail as far as I know, only users have GMail. For this reason you will need to do the OAuth2 flow with the user (see here for example).

answered Jul 09 '14 at 05:19

Ryan Seys

264
1
9

1

Hmm, that is pretty interesting. I'm trying to do the same thing - namely use a OAuth 2.0 Service Account with the Gmail API and also hitting a 500 Backend Error. Do you have a source for where it says that you can't use a Service Account with the GMail API? I thought that because this was created through a user's Google Developer Console, it would be associated with that user? – victorhooi Jan 07 '15 at 02:49
Yeah, it says [here](https://developers.google.com/gmail/api/auth/about-auth) that auth is done by authenticating a user with OAuth 2.0 flow and describes the general auth flow with authenticating the end user: 1. During development, register the application in the Google Developers Console. 2. When the app launches, request that the user grant access to data in their Google account. 3. If the user consents, your application requests and receives credentials to access the Gmail API. 4. Refresh the credentials (if necessary). – Ryan Seys Oct 08 '15 at 00:50

Error 500 backendError with Gmail API and Google APIs Node Client

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