b3k / frettchen

Pure Elixir Jaeger Client

Frettchen

Frettchen (German for Ferret) is a pure elixir client library for tracing in distributed microservices using the Jaeger backend. It is still in development and not recommended for production for two reasons:

1. It has a dependency on elixir-thrift 2.0 (https://github.com/pinterest/elixir-thrift) which is not yet available on hex.

2. It currently samples 100% of your traces. This is not a desirable feature for production systems.

Architecture

Assuming familiarity with Jaeger, every Trace is a process. A Span is a struct that is part of a map inside a Trace process. Interacting with a Span is done throught the Frettchen.Span module. A complete example looks like this.

def simple_trace() do
    span = Trace.start("foo")
    |> Span.open("bar")

    (.. do some stuff)

    span
    |> Span.close()
  end

Each Trace has it's own configuration about where to report spans. They can either be sent via UDP to the Jaeger Agent or TCP to the Jaeger Collector. They can also be reported to a Null Reporter or a Logging Reporter. Please review Frettchen.Configuration for configuration options. A Trace also has a time out that will close any open Span's which ensures that there are no dangling Spans.

Once a Span is closed it gets sent to a Collector Producer that then dispatches it to a reporter. If the reporter is the Remote reporter it invokes a ConsumerSupervisor that then creates a new process to send the data to Jaeger. This way traffic can be shaped before it gets sent to Jaeger.

Installation

def deps do
  [{:frettchen, github: "maxneuvians/frettchen"}]
end

License

MIT