goprep - Programmable REverse Proxy

This is a fast reverse proxy in Go which lets you modify the response in a Python-like language called Starlark.

Use Case

Wherever you think to yourself:

this existing API/service is amazing, if only it had feature x it would be perfect

This is where goprep is your friend. Just place goprep in front of your dream API and write a script to modify the response to your liking.

We include an example which sets the response header properly to make the proxied service accessible across domains.

Usage

goprep is meant to be used within Docker. The simplest way to run it is somehing like:

docker run \
    -p 6350:6350\
    -e SOURCE_URL=https://httpbin.org/\
    -v $PWD/examples/cors-allow-cookies/scripts/:/etc/goprep/scripts\
    codomatech/goprep

It can be used with Compose or your favourite docker orchestration environment in a similar manner.

Environment Variables

• SOURCE_URL: required. The full URL of the API/service which sits behind goprep.
• PORT: optional. Default=6350. The port which goprep will listen on.
• SCRIPTS_DIR: optional. Default='/etc/goprep/scripts'. The directory where your scripts are located.

Proxy Scripts

A proxy script is a script in Starlark which describes how the response should be modified.

The main function in the script is named modify with the following signature:

def modify(req, resp):
    # req is a dict of request parameters
    # resp is a dict of response parameters
    ...
    # modify can return override values for headers and body, both are optional
    return {
        'headers': {},  # dict of header overrides
        'body': ...,    # string of body replacement
    }

Please check the examples directory for more insights.

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goprep is a work of ❤️ by Codoma.tech.