pbyrne84.github.io

ZIO 2/Scala/tracing/layering/logging/testing/Opentracing

zio2playground

Full readme and code can be found at https://github.com/pbyrne84/zio2playground

The project has been done with tests so parts are runnable in an observable fashion.

(exert from the projects README that has all the instructions)

1. Service layering in tests including shared layering. As mentioned there are some gotchas.
2. How to set up an external tool in intellij, this enables run a test without a plugin without having to focus off a coding tab.
3. Tracing through the application using OpenTelemetry, this enables Zipkin etc. This includes setting current context from incoming headers. We want to keep the trace across system boundaries. Not having this sort of stuff can make a fun day a much less than fun day.

4. How we log the trace in the logging, so we can get some kibana or similar goodness. This implementation uses logback as not everything is likely to be pure ZIO.log in an application. There is an example of monkeying around with the MDC in LoggingSL4JExample. This handles java util and direct SL4J logging which probably simulates a lot of production environments. For example, I don’t think a functionally pure version of PAC4J is on anyone’s todo list. Anything security based should be implemented as few times as possible, unless you like crackers.

   
   MDC stuff does have its limitations due to issues with copying between threads, ideally async is being done by the effect system and the java stuff is not async by nature.

   It is a bit hacky but an idea of how to do it, I had to hijack the zio package to read the fiber ref to get the zio.logging.logContext where this is held.

   B3TracingOps.serverSpan creates a span and add it to the logging context.

5. ZIO.log does add to the MDC but only for that call. The logback.xml config adds all MDC to the log hence number LoggingSL4JExample is doing something similar for the java logging calls.

This knowledge also applies to Smithy4sZioOpentracing.md