This guide is for troubleshooting gRPC implementations based on C core library (sources for most of them are living in the grpc/grpc repository).
Extra logging can be very useful for diagnosing problems. All gRPC implementations based on C core library support the GRPC_VERBOSITY and GRPC_TRACE environment variables that can be used to increase the amount of information that gets printed to stderr.
GRPC_VERBOSITY is used to set the minimum level of log messages printed by gRPC (supported values are DEBUG, INFO and ERROR). If this environment variable is unset, only ERROR logs will be printed.
GRPC_TRACE can be used to enable extra logging for some internal gRPC components. Enabling the right traces can be invaluable for diagnosing for what is going wrong when things aren't working as intended. Possible values for GRPC_TRACE are listed in Environment Variables Overview. Multiple traces can be enabled at once (use comma as separator).
# Enable debug logs for an application GRPC_VERBOSITY=debug ./helloworld_application_using_grpc
# Print information about invocations of low-level C core API. # Note that trace logs of log level DEBUG won't be displayed. # Also note that most tracers user log level INFO, so without setting # GPRC_VERBOSITY accordingly, no traces will be printed. GRPC_VERBOSITY=info GRPC_TRACE=api ./helloworld_application_using_grpc
# Print info from 3 different tracers, including tracing logs with log level DEBUG GRPC_VERBOSITY=debug GRPC_TRACE=tcp,http,api ./helloworld_application_using_grpc
Known limitations: GPRC_TRACE=tcp is currently not implemented for Windows (you won't see any tcp traces).
Please note that the GRPC_TRACE environment variable has nothing to do with gRPC's “tracing” feature (= tracing RPCs in microservice environment to gain insight about how requests are processed by deployment), it is merely used to enable printing of extra logs.