This extremely simple app solves a somewhat niche problem- letting your developers send notifications to Slack without needing them to manage webhooks. You deploy this app inside your network and have them send their messages to it, and then it forwards it on to Slack and returns the response.
The SLACK_WEBHOOK environmental variable needs to be set.
This proxy passes messages directly to the Slack Incoming Webhooks API, without modification. The only thing developers have to do is point their request at this service instead of the https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX URL.
This application can be found as a prebuild docker container on docker hub.