Telemetry Reactor for GoLang

TReactor is a microservice designed to test and experiment with observability of microservices. You can play with it on your own machine in local more, but it gets interesting when you deploy it on a Kubernetes cluster or an Istio mesh.

In cluster mode you can have a bit over 120 microservices (atoms in the mendeleev table). You control treactor by giving it some interesting molecules.

Motivation

I created this microservice to let me inspect what happens inside the kubernetes cluster or a mesh. I've noticed that not all the scenario's and products worked that well together, certainly when you go a bit beyond the happy path. This microservice will enable me to make reproducibles. I hope it's also helpful for other people to learn technologies like tracing, kubernetes networking, logging, istio, etc...

I will start using (and extending) treactor for bug reports, articles and talks. Let's see if this will get as popular as httpbin is ;).

Features

• Create cascading microservice calls from one origin call
• Configure tracing and logging
• Inspect headers, every level in the call hierarchy

Example

To see what treactor does lets take a very simple example. TReactor works by splitting molecules:

[[H]]^2[O]

Everything between the brackets [] will be a call to the next microservice. The brackets can be prefixed with a number and an optional parameter (s or p), this tells treactor how many times the service needs to be called and how ( sequential or parallel). Multiple calls can be make by appending them using ^ (sequential) or * (parallel).

Depending the content of the bracket the call will be different. If treactor detects an atom a call to the corresponding atom service will be made. But if treactor detects another sub-molecule it calls the next bond and apply the same logic till only atoms are left. So the example above will result in:

http://treactor-api/treact/split?molecule=[[H]]^2[O]

calling

• http://bond-1/treact/split?molecule=[h]
• http://atom-o/treact/atom/o?atom=o
• http://atom-o/treact/atom/o?atom=o

bond will split the molecule [H] (ok, this looks strange, but each bracket is a layer) into it's atoms, in this case only 1 H:

• http://atom-h/treact/atom?atom=H

Try the local installation, to see how it looks in the trace (this will make it more clear).

Installation

Pre-Requirement

Create a directory tmp and work in this repo. Don't worry, they are in the .gitignore so you do not accidentally check them in.

Local

Build the treactor from source

go install ./cmd/treactor/

Set the environmental variables. Replace project-name project with your own

export PORT=3330
export TREACTOR_NAME=reactor-api
export TREACTOR_VERSION=1
export TREACTOR_DEBUG=1
export TREACTOR_PROFILE=0
export TREACTOR_MODE=local

Fire up the treactor

treactor

And test it by calling:

http://localhost:3330/treact/split?molecule=[[H]]^2[O]

Go to the Cloud Console, select Trace.

Kubernetes

Not yet fully tested/supported

go install ./cmd/trprep/

kubectl label namespace default istio-injection=disabled --overwrite

Istio

Not yet fully tested/supported

kubectl label namespace default istio-injection=enabled --overwrite

Specification

Reactor Prepare (trprep)

Prepares the Kubernetes files, from the templates

Environment Variables

NAME	Description	Default
PORT	Port
SERVICE_NAME	Application name	treactor
SERVICE_VERSION	Application version	0.0.0
TREACTOR_MODE	Reactor mode (local, k8s)	local
TREACTOR_TRACE_PROPAGATION	OpenTelemetry propagator (w3c)	w3c

Molecule spec

S    [H,x=1,y=2,z=3]*2[O,x=1,y=2,z=3],x=1,y=2,z=3
A     H,x=1,y=2,z=3
A                      O,x=1,y=2,z=3

S    2[5[Ur,log:1,xyz:4]^5[C,log:1,xyz:4]],x:1,y:2
O1     5[Ur,log:1,xyz:4]^5[C,log:1,xyz:4]
A        Ur,log:1,xyz:4
A                          C,log:1,xyz:4