google cloud authentication with bearer token via nodejs

Question

My client has a GraphQL API running on Google cloud run.

I have recieved a service account for authentication as well as access to the gcloud command line tool.

When using gcloud command line like so:

gcloud auth print-identity-token

I can generate a token that can be used to make post requests to the api. This works and I can make successful post requests to the api from postman, insomnia and from my nodejs app.

However, when I use JWT authentication with "googleapis" or "google-auth" npm libraries like so :

var { google } = require('googleapis')

let privatekey = require('./auth/google/service-account.json')

let jwtClient = new google.auth.JWT(
  privatekey.client_email,
  null,
  privatekey.private_key,
  ['https://www.googleapis.com/auth/cloud-platform']
)

jwtClient.authorize(function(err, _token) {
  if (err) {
    console.log(err)
    return err
  } else {
    console.log('token obj:', _token)
  }
})

This outputs a "bearer" token:

token obj: {
  access_token: 'ya29.c.Ko8BvQcMD5zU-0raojM_u2FZooWMyhB9Ni0Yv2_dsGdjuIDeL1tftPg0O17uFrdtkCuJrupBBBK2IGfUW0HGtgkYk-DZiS1aKyeY9wpXTwvbinGe9sud0k1POA2vEKiGONRqFBSh9-xms3JhZVdCmpBi5EO5aGjkkJeFI_EBry0E12m2DTm0T_7izJTuGQ9hmyw',
  token_type: 'Bearer',
  expiry_date: 1581954138000,
  id_token: undefined,
  refresh_token: 'jwt-placeholder'
}

however this bearer token does not work as the one above and always gives an "unauthorised error 401" when making the same requests as with the gcloud command "gcloud auth print-identity-token".

Please help, I am not sure why the first bearer token works but the one generated with JWT does not.

EDIT

I have also tried to get an identity token instead of an access token like so :

let privatekey = require('./auth/google/service-account.json')

let jwtClient = new google.auth.JWT(
  privatekey.client_email,
  null,
  privatekey.private_key,
  []
)

jwtClient
  .fetchIdToken('https://my.audience.url')
  .then((res) => console.log('res:', res))
  .catch((err) => console.log('err', err))

This prints an identity token, however, using this also just gives a "401 unauthorised" message.

Edit to show how I am calling the endpoint

Just a side note, any of these methods below work with the command line identity token, however when generated via JWT, it returns a 401

Method 1:

 const client = new GraphQLClient(baseUrl, {
        headers: {
          Authorization: 'Bearer ' + _token.id_token
        }
      })
      const query = `{
        ... my graphql query goes here ...
    }`
      client
        .request(query)
        .then((data) => {
          console.log('result from query:', data)
          res.send({ data })
          return 0
        })
        .catch((err) => {
          res.send({ message: 'error ' + err })
          return 0
        })
    }

Method 2 (using the "authorized" client I have created with google-auth):

  const res = await client.request({
    url: url,
    method: 'post',
    data: `{
        My graphQL query goes here ...
    }`
  })
  console.log(res.data)
}

Answer 1

Here is an example in node.js that correctly creates an Identity Token with the correct audience for calling a Cloud Run or Cloud Functions service.

Modify this example to fit the GraphQLClient. Don't forget to include the Authorization header in each call.

    // This program creates an OIDC Identity Token from a service account
    // and calls an HTTP endpoint with the Identity Token as the authorization
    
    var { google } = require('googleapis')
    const request = require('request')
    
    // The service account JSON key file to use to create the Identity Token
    let privatekey = require('/config/service-account.json')
    
    // The HTTP endpoint to call with an Identity Token for authorization
    // Note: This url is using a custom domain. Do not use the same domain for the audience
    let url = 'https://example.jhanley.dev'
    
    // The audience that this ID token is intended for (example Google Cloud Run service URL)
    // Do not use a custom domain name, use the Assigned by Cloud Run url
    let audience = 'https://example-ylabperdfq-uc.a.run.app'
    
    let jwtClient = new google.auth.JWT(
        privatekey.client_email,
        null,
        privatekey.private_key,
        audience
    )
    
    jwtClient.authorize(function(err, _token) {
        if (err) {
            console.log(err)
            return err
        } else {
            // console.log('token obj:', _token)
    
            request(
                {
                    url: url,
                    headers: {
                        "Authorization": "Bearer " + _token.id_token
                    }
                },
                function(err, response, body) {
                    if (err) {
                        console.log(err)
                        return err
                    } else {
                        // console.log('Response:', response)
                        console.log(body)
                    }
                }
            );
        }
    })