hobble

A fault-injection reverse proxy: sits between a client and a real target service, and lets you deliberately inject latency, error status codes, or dropped connections, so you can test how your client handles a flaky backend. Successor to gaze, same spirit: small, focused, single static binary.

hobble -t https://api.example.com -l :8080 \
  --latency 200ms-800ms \
  --status 500=0.1 \
  --drop 0.05

Point your client at hobble instead of the real target, and observe how it handles latency, errors, and dropped connections.

Install

Homebrew (macOS / Linux)

brew install mangrisano/hobble/hobble

Go

go install github.com/mangrisano/hobble/cmd/hobble@latest

Or from a local clone:

go install ./cmd/hobble

The binary lands in $(go env GOPATH)/bin, which must be on your PATH.

Pre-built binaries

No Go toolchain? Grab a ready-made binary for your platform (Linux, macOS and Windows, amd64/arm64) from the latest release. For example, on macOS (arm64):

VERSION=0.1.0
curl -sL "https://github.com/mangrisano/hobble/releases/download/v${VERSION}/hobble_${VERSION}_darwin_arm64.tar.gz" | tar xz
./hobble --help

Usage

hobble [flags]

Flag	Repeatable	Default	Description
-t, --target	no	—	Target URL to proxy requests to (required).
-l, --listen	no	:8080	Address to listen on.
--latency	no	0	Latency to inject: fixed (200ms) or range (200ms-800ms).
--status	yes	—	Status code to inject with a probability, e.g. 500=0.1.
--drop	no	0	Probability of dropping the connection (no response at all).

Examples

Inject a fixed 500ms latency on every request:

hobble -t https://api.example.com --latency 500ms

Return a 500 on 10% of requests, and a 503 on 5%:

hobble -t https://api.example.com --status 500=0.1 --status 503=0.05

Simulate a flaky network: random latency, occasional 5xx, occasional dropped connection:

hobble -t https://api.example.com \
  --latency 200ms-800ms \
  --status 500=0.1 \
  --drop 0.05

How it works

Each request first rolls against --drop, then against the configured --status rules, then (if neither fires) gets delayed by --latency before being forwarded to the real target via a standard httputil.ReverseProxy. Drop, status injection, and latency are mutually exclusive per request — they don't stack on top of each other.

Project layout

cmd/hobble/       package main — cobra flag parsing and wiring
internal/proxy/   package proxy — rule parsing, reverse proxy, fault middleware

Development

go build ./...
go test ./...
go vet ./...

Requires Go 1.27+.

License

MIT — see LICENSE.