README
¶
RWND
A local HTTP reverse proxy that logs request/response pairs and supports deterministic replay for debugging.
Description
RWND is a lightweight CLI tool that sits in front of an HTTP service, records & logs incoming requests and outgoing responses, and let's you replay them later in a determinstic, step-by-step way so as to allow for easy debugging of your services.
It acts as a reverse proxy during recording, writing traffic to structured log files, then replays that traffic back into a target service to help debug behavior, test changes, or reproduce tricky issues.
Motivation
I often have run into bugs that showed up only specific request sequences or timing conditions. Logging helped but they didn't let you re-run the problem. Because of this manual reproduction was slow, unreliable and sometimes impossible.
Relying on normal test scripts and curl commands usually would fail to capture the shape of the traffic resulting in hard to reproduce bugs
So using RWND I can now:
- Capture real HTTP traffic with zero app changes
- Rewind and replay requests deterministically
- Step through interactions and observe behavior under identical conditions
By doing this I was able to turn this from guesswork or just harder generalized scripting to a cleaner quicker repeatable debugging process
Quick Start
- Install
rwnd
go install github.com/BarrettBr/RWND/cmd/rwnd@latest
- Record traffic
rwnd proxy --listen :8080 --target http://localhost:3000
- Replay traffic
rwnd replay
Usage
Proxy Mode
Proxy mode is used for setting up the reverse proxy and recording the data
rwnd proxy [options]
Available Flags:
--listen: Address to listen on (Default:8080)--target: Upstream service to forward traffic to--log: Path to write recorded traffic (Defaults to.rwnd/logs/)--help / -h: Shows help
Replay Mode
Replay mode is used for replaying the recorded data and being able to step through it
rwnd replay [options]
By default, replay uses the most recent log file in .rwnd/logs/.
Available Flags:
--log: Path to a recorded traffic log or log directory--help / -h: Shows help
Docker
RWND can be built and run as a minimal container image using the provided Dockerfile.
Build the image: docker build -t rwnd .
Run RWND Example:
docker run --rm -it \
-p 8080:8080 \
-v $(pwd)/.rwnd:/app/.rwnd \
rwnd --listen :8080 --target http://example.com
RWND runs as a non-root user inside the container and writes logs to
/app/.rwnd/logs so the command above would mount that to your working directories ./.rwnd/ folder.
Contributing
Contributions are welcome.
Feel free to open an issue or submit a pull request if interested in:
- Improving replay controls
- Supporting additional protocols or formats
- Adding filtering or request selection
- Tightening performance or determinism
Directories
¶
| Path | Synopsis |
|---|---|
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cmd
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rwnd
command
Command rwnd is the RWND CLI entry point.
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Command rwnd is the RWND CLI entry point. |
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internal
|
|
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app
Package app holds shared application workflows used by CLI and TUI.
|
Package app holds shared application workflows used by CLI and TUI. |
|
cli
Package cli implements the command-line interface for RWND.
|
Package cli implements the command-line interface for RWND. |
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config
Package config defines application configuration and CLI argument parsing.
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Package config defines application configuration and CLI argument parsing. |
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datastore
Package datastore provides persistence for recorded traffic logs.
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Package datastore provides persistence for recorded traffic logs. |
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logger
Package logger asynchronously pushes records to a datastore.
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Package logger asynchronously pushes records to a datastore. |
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logpath
Package logpath provides helpers for resolving log file paths.
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Package logpath provides helpers for resolving log file paths. |
|
model
Package model defines shared structures for captured traffic.
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Package model defines shared structures for captured traffic. |
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proxy
Package proxy implements a reverse proxy that records traffic.
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Package proxy implements a reverse proxy that records traffic. |
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replay
Package replay provides interactive replay of recorded traffic.
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Package replay provides interactive replay of recorded traffic. |
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tui
Package tui provides the RWND terminal UI.
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Package tui provides the RWND terminal UI. |