flic-webhook-webpush/README.md

Flic to PWA WebPush Backend

This project provides a self-hosted backend service that listens for HTTP requests from Flic smart buttons and triggers Web Push notifications to specific Progressive Web App (PWA) instances. The goal is to allow a Flic button press (Single Click, Double Click, Hold) to trigger actions within the PWA via push messages handled by a Service Worker.

It's designed to be run as a Docker container and integrated with Traefik v3 for SSL termination and routing.

Features

• Receives GET requests on /webhook.
• Receives POST requests on /subscribe to manage button-PWA mappings.
• Uses HTTP headers Button-Name and Timestamp from the Flic request.
• Gets click_type from URL path.
• Looks up the target PWA push subscription based on the Button-Name header in a JSON file.
• Sends a Web Push notification containing the click details (action, button, timestamp) to the corresponding PWA subscription.
• Integrates with Traefik v3 via Docker labels.
• Configurable via environment variables (.env file).
• Optional Basic Authentication for securing the /webhook and /subscribe endpoints.
• CORS configuration for allowing requests (needed if your PWA management interface interacts with the /subscribe endpoint).

Prerequisites

• Docker: Install Docker
• Traefik: A running Traefik v3 instance configured with SSL (Let's Encrypt recommended) and connected to a Docker network named traefik. You need to know your certificate resolver name.
• Domain Name: A domain or subdomain pointing to your Traefik instance (e.g., webpush.virtonline.eu). This will be used for the webhook URL.
• Flic Hub/Service: Configured to send HTTP requests for button actions. You'll need the serial number(s) of your Flic button(s).
• Node.js & npm/npx (Optional): Needed only locally to generate VAPID keys easily. Not required for running the container.
• PWA Push Subscription Details: You need to obtain the Push Subscription object (containing endpoint, keys.p256dh, keys.auth) from your PWA after the user grants notification permission.

System Architecture

Subscription Flow

Interaction Flow

Project Structure

Setup

1. Clone the Repository:

   git clone https://gitea.virtonline.eu/2HoursProject/flic-webhook-webpush.git
   cd flic-webhook-webpush
   

2. Generate VAPID Keys: Web Push requires VAPID keys for security. Generate them once and store them into .env. You can use npx:

   npx web-push generate-vapid-keys
   

   This will output a Public Key and a Private Key.

3. Configure Environment Variables:

   • Copy the example .env file:

     cp .env.example .env
     

   • Edit the .env file with your specific values:
     • VAPID_PUBLIC_KEY: The public key generated in step 2. Your PWA will also need this key when it subscribes to push notifications.
     • VAPID_PRIVATE_KEY: The private key generated in step 2. Keep this secret!
     • VAPID_SUBJECT: A mailto: or https: URL identifying you or your application (e.g., mailto:admin@yourdomain.com). Used by push services to contact you.
     • PORT: (Default: 3000) The internal port the Node.js app listens on. Traefik will map to this.
     • SUBSCRIPTIONS_FILE: (Default: /app/subscriptions.json) The path inside the container where the button-to-subscription mapping is stored.
     • BASIC_AUTH_USERNAME: (Optional) Username for Basic Authentication. If set along with BASIC_AUTH_PASSWORD, authentication will be enabled for /webhook and /subscribe.
     • BASIC_AUTH_PASSWORD: (Optional) Password for Basic Authentication. If set along with BASIC_AUTH_USERNAME, authentication will be enabled.
     • ALLOWED_ORIGINS: Comma-separated list of domains allowed by CORS. Include your PWA's domain if it needs to interact directly (e.g., for setup). Example: https://my-pwa.com.
     • ALLOWED_METHODS: (Default: POST,OPTIONS) Standard methods needed.
     • ALLOWED_HEADERS: (Default: Content-Type,Authorization) Standard headers needed.
     • MAX_NOTIFICATION_RETRIES: (Default: 3) Number of retry attempts for failed push notifications. Must be a number.
     • INITIAL_RETRY_DELAY_MS: (Default: 1000) Initial delay in milliseconds before first retry. Must be a number.
     • DNS_TIMEOUT_MS: (Default: 5000) DNS resolution timeout in milliseconds. Must be a number.
     • HTTP_TIMEOUT_MS: (Default: 10000) HTTP request timeout in milliseconds. Must be a number.
     • LOG_LEVEL: (Default: info) Controls verbosity of logs. Valid values are error, warn, info, or debug. Use debug to see detailed header information and other diagnostic messages.
     • TRAEFIK_SERVICE_HOST: Your public domain for this service (e.g., webpush.virtonline.eu).
     • TRAEFIK_CERT_RESOLVER: The name of your TLS certificate resolver configured in Traefik (e.g., le, myresolver).

4. Configure Traefik Labels:

   • Copy the example labels file:

     cp labels.example labels
     

5. Prepare Subscription Mapping File:

   • Edit the subscriptions.json file
   • Add entries mapping your Flic button's serial number (as a lowercase string key) to the PWA PushSubscription object.

     {
       "game": { // <-- Replace with your actual Flic Button name (lowercase recommended)
         "endpoint": "https://your_pwa_push_endpoint...",
         "expirationTime": null,
         "keys": {
           "p256dh": "YOUR_PWA_SUBSCRIPTION_P256DH_KEY",
           "auth": "YOUR_PWA_SUBSCRIPTION_AUTH_KEY"
         }
       }
       // Add more entries for other buttons if needed
     }
     

   • Ensure this file contains valid JSON.

Running the Service

1. Build the Docker Image: Make sure you are in the flic-webhook-webpush directory.

   docker build -t flic-webhook-webpush:latest .
   

2. Run the Container: This command runs the container in detached mode (-d), names it, connects it to the traefik network, passes environment variables from the .env file, applies the Traefik labels from the labels file, and mounts the subscriptions.json file into the container.

   docker run -d --name flic-webhook-webpush \
     --network traefik \
     --env-file .env \
     --label-file labels \
     --mount type=bind,src=./subscriptions.json,dst=/app/subscriptions.json \
     flic-webhook-webpush:latest
   

3. Check Logs: Monitor the container logs to ensure it started correctly and to see incoming webhook requests or errors.

   docker logs -f flic-webhook-webpush
   

   You should see messages indicating the server started, configuration details, and subscription loading status.

4. Verify Traefik: Check your Traefik dashboard to ensure the flic-webhook-webpush service and router are discovered and healthy.

Flic Button Configuration

In your Flic app or Flic Hub SDK interface:

1. Select your Flic button.
2. Add an "Internet Request" action.
3. Fill in the following details:
   • Set GET method.
   • Set URL with query parameter: https://<your_domain>/webhook/SingleClick (Replace <your_domain> with your actual service domain, e.g., webpush.virtonline.eu).
   • If Basic Authentication is enabled:
     • Set the Username and Password fields to the values from your BASIC_AUTH_USERNAME and BASIC_AUTH_PASSWORD environment variables.
   • If Basic Authentication is disabled:
     • Leave the Username and Password fields empty.
   • Tap on Save action.
4. Repeat for Double Click and/or Hold events, changing the click_type parameter accordingly (e.g., /DoubleClick).

API Endpoints

• POST /subscribe

  • Description: Adds or updates the Web Push subscription associated with a specific Flic button ID.
  • Authentication: Optional Basic Authentication via Authorization header if BASIC_AUTH_USERNAME and BASIC_AUTH_PASSWORD are configured.
  • Request Body: JSON object containing:
    • button_id (string, required): The unique identifier for the Flic button (lowercase recommended, e.g., "game", "lights").
    • subscription (object, required): The PushSubscription object obtained from the browser's Push API.

    {
      "button_id": "game",
      "subscription": {
        "endpoint": "https://your_pwa_push_endpoint...",
        "expirationTime": null,
        "keys": {
          "p256dh": "YOUR_PWA_SUBSCRIPTION_P256DH_KEY",
          "auth": "YOUR_PWA_SUBSCRIPTION_AUTH_KEY"
        }
      }
    }
    

  • Responses:
    • 201 Created: Subscription saved successfully.
    • 400 Bad Request: Missing or invalid button_id or subscription object in the request body.
    • 401 Unauthorized: Missing or invalid Basic Authentication credentials (if authentication is enabled).
    • 500 Internal Server Error: Failed to save the subscription to the file.

• GET /webhook/:click_type

  • Description: Receives Flic button events.
  • Authentication: Optional Basic Authentication via Authorization header if BASIC_AUTH_USERNAME and BASIC_AUTH_PASSWORD are configured.
  • URL Parameters:
    • click_type (required): The type of button press (e.g., SingleClick, DoubleClick, or Hold).
  • Required Headers:
    • Button-Name (required): The identifier of the Flic button (sent by the Flic system).
  • Optional Headers:
    • Timestamp: Timestamp of the button event (sent by the Flic system).
    • Button-Battery-Level: The battery level percentage of the button (sent by the Flic system).
  • Push Notification Payload (data field): The service sends a JSON payload within the push notification. The client-side Service Worker can access this data via event.data.json(). The structure is:

    {
      "action": "SingleClick", // or DoubleClick, Hold
      "button": "game-button",       // Normalized button name (lowercase)
      "timestamp": "2024-03-28T15:00:00.000Z", // ISO 8601 timestamp or current server time
      "batteryLevel": 100     // Integer percentage (0-100) or 'N/A' if not provided
    }
    

  • Responses:
    • 200 OK: Webhook received, push notification sent successfully.
    • 400 Bad Request: Missing Button-Name header or click_type URL parameter.
    • 401 Unauthorized: Missing or invalid Basic Authentication credentials (if authentication is enabled).
    • 404 Not Found: No subscription found in subscriptions.json for the given Button-Name.
    • 410 Gone: The push subscription associated with the button was rejected by the push service (likely expired or revoked).
    • 500 Internal Server Error: Failed to send the push notification for other reasons.

Testing the Webhook

Once your service is up and running, you can test the webhook endpoint using curl or any API testing tool. This example assumes Basic Authentication is enabled.

Note: Replace <username>, <password>, <your_domain>, and <button_name> with your actual values.

# Generate Base64 credentials (run this once)
# echo -n '<username>:<password>' | base64

# Example using generated Base64 string (replace YOUR_BASE64_CREDS)
curl -X GET "https://<your_domain>/webhook/SingleClick" \
  -H "Authorization: Basic YOUR_BASE64_CREDS" \
  -H "Button-Name: <button_name>" \
  -H "Timestamp: $(date -u +%Y-%m-%dT%H:%M:%SZ)" \
  -H "Button-Battery-Level: 100" \

# Example using curl's built-in Basic Auth (-u)
curl -X GET "https://<your_domain>/webhook/SingleClick" \
  -u "<username>:<password>" \
  -H "Button-Name: <button_name>" \
  -H "Timestamp: $(date -u +%Y-%m-%dT%H:%M:%SZ)" \
  -H "Button-Battery-Level: 100" \

The expected response should be:

{"message":"Push notification sent successfully"}

If successful, the above response indicates that:

1. Your webhook endpoint is properly configured
2. The button ID was found in your subscriptions.json file
3. The web push notification was successfully sent to the registered PUSH API endpoint (e.g. https://jmt17.google.com/fcm/send/cf907M...)

If you receive a different response, refer to the Troubleshooting section below.

Troubleshooting

• Check Backend Logs: docker logs flic-webhook-webpush. Look for errors related to configuration, file access, JSON parsing, authentication, or sending push notifications.
  • To see detailed debug information including all headers received from the Flic button, set LOG_LEVEL=debug in your .env file.
• Check Traefik Logs: docker logs traefik. Look for routing errors or certificate issues.
• Verify .env: Ensure all required variables are set correctly, especially VAPID keys and Traefik settings.
• Verify labels: Double-check that variables were correctly substituted manually and match your .env and Traefik setup.
• Verify subscriptions.json: Ensure it's valid JSON and the button serial number (key) matches exactly what Flic sends (check backend logs for "Received webhook: Button=..."). Check if the subscription details are correct. Case sensitivity matters for the JSON keys (button serials).
• Check Flic Configuration: Ensure the URL, Method, click_type parameter, and authentication details (Username/Password if enabled) are correct in the Flic action setup. Use curl or Postman to test the endpoint manually first.
• PWA Service Worker: Remember that the PWA needs a correctly registered Service Worker to receive and handle the incoming push messages. Ensure the PWA subscribes using the same VAPID_PUBLIC_KEY configured in the backend's .env.