Traffic Shadowing

Using Goreplay to shadow http service traffic. (with Docker container example)

Gor is an open-source tool for capturing and replaying live HTTP traffic into a test environment in order to continuously test your system with real data.

It can be used to increase confidence in code deployments, configuration changes and infrastructure changes.

• Documentation for Gor
• Official Website

In this project we are going to build two http services with golang echo library and then shadow our http requests between these services with help of Gor.

Requirements

Make sure to have Golang version 19+ installed on your system.

After that you need to have Gor installed on your system. You can install it on MacOS with brew:

brew install gor

Or you can clone the original repository and build it:

# installing gor on your local system
curl https://github.com/buger/goreplay/archive/refs/tags/v2.0.0-rc2.tar.gz -O -J -L

# unzip the downloaded file
tar -xf goreplay-2.0.0-rc2.tar.gz

Use the following script:

chmod +x setup/raw/install.sh
./setup/raw/install.sh

Now test the installation:

gor

2022/10/09 10:09:23 [PPID 2128 and PID 3093] Version:1.3.0
2022/10/09 10:09:23 Required at least 1 input and 1 output

Start servers

You can start echo server with the following command:

go run internal/cmd/main.go [port]

go run internal/cmd/main.go 8080
go run internal/cmd/main.go 8081

Or you can use docker compose to create two services on docker:

docker compose up -d

Shadow command

Now with the following command you can shadow http requests that are sent to localhost:8080 to localhost:8081.

sudo gor --input-raw :8080 --output-http http://localhost:8081

Now try to make http requests on localhost:8080.

curl localhost:8080

There are two log files named log8080.txt and log8081.txt. You can see that all requests that we send to first service is also being sent to other service.