Slack to Google Chat WebHook Proxy

This project is a simple server that accepts Slack-formatted webhook requests and transforms them into Google Chat webhook requests. It listens on the configured port and IP address and then forwards a transformed request to the configured Google Chat webhook URL.

This project was created when Slack is well supported in many third-party applications, but Google Chat is relatively new with little to no existing support. This project allows you to simply utilize a Slack-configurable webhook in a third-party application (provided it let's you set a custom URL) and have that webhook request routed to your Google Chat instead.

Configuration

The proxy is configured using environmental variables and/or a config.yaml file, it will also load environmental variables from a .env file present in the current directory if it is present.

YAML File

You can configure the proxy using a config.yaml file in the local directory. In the docker container, the full path is /srv/config.yaml. Using the YAML file gives you more flexibility than utilizing the environmental variables because you can setup multiple endpoints with differing target Google Chat webhooks.

Each endpoint is defined as a key-value object. The key is the route to accept the slack request, and the value is either an object defining key-values of channels and Google Chat endpoints, or just a Google Chat endpoint on it's own. If the value is empty or null, the default Google Chat endpoint (URL) is used. If you want to define the root route /, use an "_" key.

If any value is not found in the YAML file, it will fallback to the environmental variable value (if any), and then to the proxy default (if any).

Example YAML File A:

The following config file will set a specific port 4321 and host localhost to listen on, for any route request, then forward to the environmental variable's GOOGLE_CHAT_URL defined target.

port: 4321
host: localhost

Example YAML File B:

The following config file will set a specific port 3333 and host 192.168.1.1 to listen on, and use a differing webhook URL for different specific routes. In this case, a request to the proxy route /gotoTeamChannel will transform and forward to https://chat.google.com/XXXX123 whereas a request to /abc1235 would forward to https://chat.google.com/XXXXZXY. In the case of the /choose route, it will examine the slack request's channel value and send to the appropriately matching endpoint.

Any other route will result in a 404 error response.

port: 3333
host: 192.168.1.1
endpoints:
    - gotoTeamChannel: https://chat.google.com/XXXX123
    - choose: 
        Team Channel: https://chat.google.com/XXXXABC
        Tech Notify: https://chat.google.com/XXXX333
    - abc1235: https://chat.google.com/XXXXZXY

Environmental Variables

The following environmental variables are loaded if the values were not found in a config.yaml file.

ENV	Type	Default	Description
HOST	String	0.0.0.0	The IP address to listen on. Typically this is "0.0.0.0" for unix-based systems and "localhost" for Microsoft Windows.
PORT	Number	8080	The port number to listen on for the Slack-formatted webhook request.
GOOGLE_CHAT_URL	String		The Google Chat webhook URL endpoint to send the transformed request to.
DEBUG	Boolean	false	Enable the output of message data and results to STDOUT.

Running

This project can be run either as a docker container or by simply executing npm start to start listening.

Building

This project uses node.js to run and does not have an explicit build process.

Docker

This project can be made to run under a docker container (see Dockerfile in this project).
To build the docker image, run:

docker build -t chriseaton/slack-to-google-chat:latest .

If you want to test the docker image, start a container:

docker run -dp 8080:8080 \
    --name slack_to_google_proxy \
    --env GOOGLE_CHAT_URL="https://chat.google.com/XXXXXX" \
    chriseaton/slack-to-google-chat:latest

You can then kill and remove the container by running:

docker rm -f slack_to_google_proxy

If you are going to publish the image, use:

docker push chriseaton/slack-to-google-chat:latest

Code Documentation

You can generate a static JSDoc site under the docs/ path using the command npm run docs.

Testing

Run npm test to run jest unit tests.

Run npm run lint to run ESLint, optionally install the Visual Studio Code ESLint extension to have linting issues show in your "Problems" tab and be highlighted.

If you are writing unit tests, you may need to npm install @types/jest to get intellisense in Visual Studio Code if for some reason it did not get installed.