Jaeger itself is a distributed, microservices based system. If you run it in production, you will likely want to setup adequate monitoring for different components, e.g. to ensure that the backend is not saturated by too much tracing data.

Metrics

By default Jaeger microservices expose metrics in Prometheus format. It is controlled by the following command line options:

• --admin.http.host-port the port number where the HTTP admin server is running
• --metrics-backend controls how the measurements are exposed. The default value is prometheus, another option is expvar, the Go standard mechanism for exposing process level statistics.
• --metrics-http-route specifies the name of the HTTP endpoint used to scrape the metrics (/metrics by default).

Each Jaeger component exposes the metrics scraping endpoint on the admin port:

Prometheus monitoring mixin for Jaeger

The Prometheus monitoring mixin for Jaeger provides a starting point for people wanting to monitor Jaeger using Prometheus, Alertmanager, and Grafana. This includes a prebuilt dashboard  . For more information, see the documentation  .

Logging

Jaeger components only log to standard out, using structured logging library go.uber.org/zap  configured to write log lines as JSON encoded strings, for example:

{"level":"info","ts":1615914981.7914007,"caller":"flags/admin.go:111","msg":"Starting admin HTTP server","http-addr":":14269"}
{"level":"info","ts":1615914981.7914548,"caller":"flags/admin.go:97","msg":"Admin server started","http.host-port":"[::]:14269","health-status":"unavailable"}

The log level can be adjusted via --log-level command line switch; default level is info.

Traces

Jaeger has the ability to trace some of its own components, namely the requests to the Query service. For example, if you start all-in-one as described in Getting Started , and refresh the UI screen a few times, you will see jaeger-all-in-one populated in the Services dropdown. If you prefer not to see these traces in the Jaeger UI, you can disable them by running Jaeger backend components with OTEL_TRACES_SAMPLER=always_off environment variable, for example:

docker run -e OTEL_TRACES_SAMPLER=always_off -p 16686:16686 jaegertracing/all-in-one:1.61