Using dockered bbernhard/signal-cli-rest-api in Node-RED

The project https://github.com/bbernhard/signal-cli-rest-api provides a docker container with signal-cli and a REST API. The REST API can be used from Node-RED.

Please be aware that signal-cli-rest-api is not perfect. Specifically, because it uses signal-cli it fires up java engine for every command and therefore the speed is sub par compared to nodered-contrib-signal-client. Similarly, I did not find a way to subscribe permanently to signal for incoming messages. I ended up sending a poll request for new messages every 5 seconds.

Since I used nodered-contrib-signal-client before, I built some facade around bbernhard/signal-cli-rest-api, because I did not want to change all my flows that use signal.

Here is my steps how to replace nodered-contrib-signal-client with signal-cli-rest-api.

Setup docker with bbernhard/signal-cli-rest-api
- If you want to be able to send attachments that are stored on a filesystem (as required for nodered-contrib-signal-client), define a volume to which Node-RED and the new container have access.
- Assuming Node-RED runs in a container as well; in order for Node-RED to reach signal-cli-rest-api, you have to either add signal-cli-rest-api to the same stack as Node-RED, or you create it in another stack and let them use a shared network.
Create your signal account within signal-cli-rest-api
- Details about the API can be found here.
- Either link an existing account with qrcodelink or
- register a number from scratch. I used:
  
  a. curl -X 'POST' \\n 'http://signal-cli-rest-api:9880/v1/register/%2B491701234567' \\n -H 'accept: application/json' \\n -H 'Content-Type: application/json' \\n -d '{\n "captcha": "---fill captcha code here---",\n "use_voice": true\n}'
  
  b. curl -X 'POST' \\n 'http://signal-cli-rest-api:9880/v1/register/%2B491701234567/verify/---token from SMS or voice call---' \\n -H 'accept: application/json' \\n -H 'Content-Type: application/json' \\n -d '{\n "pin": "---enter PIN here---"\n}'
Create flow in Node-RED to replace nodered-contrib-signal-client (see example below).

Note: some third-party nodes may appear with blank styling, and not as they appear in the Node-RED Editor.

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