How to use the loopback?

[Benjamin Tan]

I'm trying to use the loopback via the environment_type option:

options = PipelineOptions(["--runner=PortableRunner",
                                           
"--environment_config=-apachebeam/python3.7_sdk ",
                                           "--environment_type=LOOPBACK",
                                           "--job_endpoint=dnnserver2:8099"])

Previouly, I've done:

./gradlew -p sdks/python/container buildAll

And ran the Spark job server:

./gradlew :runners:spark:job-server:runShadow 
-PsparkMasterUrl=spark://dnnserver2:7077

However, I get a pretty cryptic error message:

org.apache.beam.vendor.guava.v26_0_jre.com.google.common.util.concurrent.UncheckedExecutionException:
 org.apache.beam.vendor.grpc.v1p21p0.io.grpc.StatusRuntimeException: 
UNIMPLEMENTED: Method not found!

Any ideas?