Pub/Sub Publisher requires additional auth dependency on App Engine Standard J8

[jabubake]

Publisher times out on App Engine Standard Java 8, work around is to include

<dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>com.google.auth</groupId>
        <artifactId>google-auth-library-credentials</artifactId>
        <version>0.7.0</version>
      </dependency>
    </dependencies>
  </dependencyManagement>

[ludoch]

Do we fully understand now (i.e we are not going via the appIdentify GAE API path anymore but a new path using the missing google-auth-library-credentials classes?)
Why don't we have a user friendly error message for this case? Are we swallowing exceptions?

[lesv]

The customer wrote me and said:

Did an experiment bypassing the App Default Credentials on AppEngine:

See https://github.com/hienle-hps/getting-started-java/blob/pubsub_manual_token/appengine-standard-java8/helloworld/src/main/java/com/example/gaejava8standard/HelloAppEngine.java#L70

Steps:

1. Use gcloud auth application-default login on local box and run Main.java (see above project) to dump your local bearer token.
2. Replace TOKEN in the code above with this token and then gradle appengineDeploy.

Results:
The google-cloud PubSub client works.

[jabubake]

Fixed via #2284