Alertmanager Signal Receiver

A Prometheus Alertmanager Webhook Receiver that forwards alerts to a group in Signal.

Heavily based on prometheus-am-executor.

Setup

Create a volume for signal-cli.

docker volume create signal-data

Start a temporary container with access to signal-cli.

docker run -it --rm -v signal-data:/app/data --entrypoint bash ghcr.io/dadevel/signal-receiver

Register a new phone number.

signal-cli --config ./data --username $YOUR_PHONE_NUMBER register
signal-cli --config ./data --username $YOUR_PHONE_NUMBER verify $CODE_RECEIVED_VIA_SMS

Create a new group (prints base64-encoded group id on success).

signal-cli --config ./data --username $YOUR_PHONE_NUMBER updateGroup --name Alerts --description 'Alertmanager notifications' --set-permission-send-messages only-admins --member $SOMEONES_PHONE_NUMBER $ANOTHER_PHONE_NUMBER

Send a test message.

signal-cli --config ./data --username $YOUR_PHONE_NUMBER send --group $GROUP_ID_FROM_ABOVE --message 'Hello World!'

Now that signal-cli is ready to go you can exit the temporary container and finally start the webhook receiver.

docker run -d -p 9709 -v signal-data:/app/data -e SIGNAL_RECEIVER_PHONE_NUMBER=$YOUR_PHONE_NUMBER -e SIGNAL_RECEIVER_GROUP_ID=$YOUR_GROUP_ID ghcr.io/dadevel/signal-receiver

Test it.

curl -i -d @- http://localhost:9709/alert << EOF
{
  "receiver": "default",
  "status": "firing",
  "alerts": [
    {
      "status": "firing",
      "labels": {
        "alertname": "HelloWorld",
        "instance": "localhost:1234",
        "job": "broken",
        "monitor": "world-monitor"
      },
      "annotations": {},
      "startsAt": "2016-04-07T18:08:52.804+02:00",
      "endsAt": "0001-01-01T00:00:00Z",
      "generatorURL": ""
    },
    {
      "status": "firing",
      "labels": {
        "alertname": "HelloWorld",
        "instance": "localhost:5678",
        "job": "broken",
        "monitor": "world-monitor"
      },
      "annotations": {},
      "startsAt": "2016-04-07T18:08:52.804+02:00",
      "endsAt": "0001-01-01T00:00:00Z",
      "generatorURL": ""
    }
  ],
  "groupLabels": {
    "alertname": "HelloWorld"
  },
  "commonLabels": {
    "alertname": "HelloWorld",
    "job": "broken",
    "monitor": "world-monitor"
  },
  "commonAnnotations": {},
  "externalURL": "http://localhost:9093",
  "version": "4",
  "groupKey": 9777663806026785000
}
EOF

Configure

Environment variable	Description
SIGNAL_RECEIVER_PHONE_NUMBER	phone number of signal account to send messages from, required
SIGNAL_RECEIVER_GROUP_ID	signal group id to send messages to, required
SIGNAL_RECEIVER_DATA_DIR	storage location used by signal-cli, defaults to ./data
SIGNAL_RECEIVER_LISTEN_ADDRESS	address and port to listen on, defaults to :9709
SIGNAL_RECEIVER_VERBOSE	enable verbose logging, off by default
SIGNAL_RECEIVER_MESSAGE_TEMPLATE	go template for messages, see source code for default value

Example configurations for Prometheus and Alertmanager can be found in the examples directory.

Build

Build the binary.

go build -o ./alertmanager-signal-receiver ./cmd/main.go

The Dockerfile is available under github.com/dadevel/dockerfiles.