Post2Slack

Post2Slack posts to a Slack channel as the authorized user.

Running

For your .env file:

1. Set a PORT.
2. Set SLACK_CLIENT_ID to your Slack client ID.
3. Set SLACK_CLIENT_SECRET to your Slack client secret.
4. Set POST_SIGNING_SECRET to a base64-encoded 32-byte value After compiling this app (which is possible without the secrets), use mix post2_slack.gen.secret.
5. Set STATE_SIGNING_SECRET to another base64-encoded 32-byte value.
6. Set SLACK_REDIRECT_URI to your redirect URI. You can use ngrok for development. It should look something like https://my-host/oauth/slack/callback.

To start:

foreman start

Deploying

This can easily be deployed to Heroku via docker. First, set the above env vars, as well as MIX_ENV=prod, and excepting PORT.

1. heroku apps:create
2. heroku container:login
3. heroku container:push web
4. heroku container:release web

How it Works

Post2Slack uses Slack OAuth to get a token with chat:write:user scope, which is returned inside of an expiring, encrypted JWE token (this means that the token is not readable, and despite the fact that typical Slack access tokens don't expire, it expires in 1 week). Then, a normal Slack API chat.postMessage request can be sent to Post2Slack, along with a Authorization: Bearer $token header for authentication.