This is a simple proxy that receives alert messages from TrueNAS Scale via the Slack alert plugin and then passes those onward to a local ntfy server for immediate routing and display to the end-user.
TrueNAS Scale does not have an official means of developing a custom alert plugin, nor do any of the configurable alert plugins allow one to run a shell script. My best option was to use an existing plugin that accepted an incoming web-hook URL.
git clone https://github.com/syn-net/ntfy-webhooks.git ntfy-webhooks.git
cd ntfy-webhooks.git
npm install # install node_modules
cp -av .env.defaults .env
npm run start
WARNING: Although, I do my best to adhere to sane defaults for .env
, there will be times where you may need to review it and make modifications to suit your space.