Authentication failures using Spanner with `appengine:run` for App Engine Standard J8

[jabubake]

Auth errors using both plugins in
mvn appengine:run : http://mvnrepository.com/artifact/com.google.cloud.tools/appengine-maven-plugin/1.3.1
mvn appengine:devserver : https://mvnrepository.com/artifact/com.google.appengine/appengine-maven-plugin/1.9.53

IAM Errors on creating, querying :
- com.google.cloud.spanner.SpannerException: PERMISSION_DENIED: io.grpc.StatusRuntimeException: PERMISSION_DENIED: Access denied. Missing IAM permission: spanner.databases.create.

• com.google.cloud.spanner.SpannerException: PERMISSION_DENIED: io.grpc.StatusRuntimeException: PERMISSION_DENIED: Access denied. Missing IAM permission: spanner.sessions.create.

I've verified within the servlet that GOOGLE_APPLICATION_CREDENTIALS exists and is valid.
Same code works fine when using the Jetty Plugin mvn jetty:run

[jabubake]

@ludoch @lesv FYI

[garrettjonesgoogle]

@jabubake is there any chance this is related to #2209 ?

[lesv]

I've done this, but I may have added the IAM permission to the app engine service account. Could you retest this and we may need to document on Doug's new page.

[neozwu]

I tested some spanner sample code on GAE 8 today and with right IAM it should work now.