r/golang

1d ago

u/BigMek_

gosim - library for simulation of file system, multi-host network and other things for reproducible tests of apps

Hey r/golang, I maintain a library which simulates a virtual filesystem, network with several hosts, timers, restarts of a computer and so on. It works inside a Go process, without cgroups, eBPF, QEMU, etc. Pure Go simulation and almost full programmatical control of the runtime.

The problem

We develop and maintain several clustered data-processing applications and libraries that are difficult to test against real-world scenarios, some of them:

latency spikes on a single host in a cluster

temporary read-only file system

run out of free space on a disk and adding free space in some time

one-way network connectivity

The library simplified dramatically and sped up some groups of test cases, no need to run tests with Docker or Kubernetes, no maintenance of proxies or virtual routers, no heavy dependencies for virtual file systems.

Additionally I added metrics for…