Server: Instrumentation and Logging

gruf comes out of the box with a couple of instrumentation interceptors packed in: output metadata timings and StatsD support.

Output Metadata Timing

Enabled by default, this will push timings for successful responses through the response output metadata back to the client.

StatsD

The StatsD support is not enabled by default. To enable it, you'll want to do:

Gruf.configure do |c|
  c.interceptors.use(
    Gruf::Interceptors::Instrumentation::Statsd,
    client: ::Statsd.new('my.statsd.host', 8125),
    prefix: 'my_application_prefix.rpc'
  )
end

This will measure counts and timings for each endpoint.

Request Logging

Gruf 1.2+ comes built with request logging out of the box; you'll get Rails-style logs with your gRPC calls:

# plain
I, [2017-07-14T09:50:54.200506 #70571]  INFO -- : [GRPC::Ok] (thing_service.get_thing) [0.348ms]
# logstash
I, [2017-07-14T09:51:03.299050 #70595]  INFO -- : {"message":"[GRPC::Ok] (thing_service.get_thing) [0.372ms]","service":"thing_service","method":"thing_service.get_thing","grpc_status":"GRPC::Ok"}

It supports formatters (including custom ones) that you can use to specify the formatting of the logging:

Gruf.configure do |c|
  c.interceptors.use(
    Gruf::Interceptors::Instrumentation::RequestLogging::Interceptor,
    formatter: :logstash
  )
end

It comes with a few more options as well:

Option	Description	Default
formatter	The formatter to use. By default :plain and :logstash are supported.	:logstash
log_parameters	If set to true, will log parameters in the response	false
blocklist	An array of parameter key names to redact from logging, in path.to.key format	[]
redacted_string	The string to use for redacted parameters.	REDACTED
ignore_methods	An array of method names to ignore from logging. E.g. ['namespace.health.check']	[]

It's important to maintain a safe blocklist should you decide to log parameters; gruf does no parameter sanitization on its own. We also recommend blocklisting parameters that may contain very large values (such as binary or json data).

Other Options

There are other options for observability packaged as gems:

• gruf-lightstep provides drop-in support for LightStep tracing
• gruf-prometheus adds full support for Prometheus metrics in your Gruf applications
• gruf-zipkin adds ZipKin support for gruf controllers
• gruf-stackdriver-trace adds Google Stackdriver tracing

---

Next: Server: Testing