Add Docker workflow and docs (#1)

Co-authored-by: Priyanshubhartistm <bhartipriyanshustm@gmail.com>
Co-committed-by: Priyanshubhartistm <bhartipriyanshustm@gmail.com>

README.md

@@ -1,33 +1,62 @@
 # Video Thumbnail Service
 
-A lightweight microservice that generates video thumbnails by extracting a frame using ffmpeg.
+A lightweight microservice that generates JPEG thumbnails from video URLs using ffmpeg.
 
 ## Requirements
 
 - Node.js 18+
 - ffmpeg installed on the system
 
-## Setup
+## Environment Configuration
+
+Set environment variables in your shell, process manager, or deployment platform.
+
+| Variable | Default | Description |
+| --- | --- | --- |
+| `PORT` | `3100` | HTTP port used by the service |
+
+### Local Run
 
 ```bash
 npm install
-npm start
+PORT=3100 npm start
 ```
 
-The service runs on port 3100 by default. Set the `PORT` environment variable to change it.
+## Docker
+
+Build and run the service with Docker:
+
+```bash
+docker build -t vthumbs:local .
+docker run --rm -p 3100:3100 -e PORT=3100 vthumbs:local
+```
 
 ## Usage
 
-```
+```http
 GET /thumbnail?url=https://example.com/video.mp4
 ```
 
-Returns a JPEG image of the first frame (at 1 second).
+Returns a JPEG image extracted at 1 second.
 
-## Configuration
-
-Set `VITE_THUMBNAIL_URL` in the Flotilla `.env` file to the deployed service URL:
+## Health Check
 
+```http
+GET /health
 ```
-VITE_THUMBNAIL_URL=https://your-thumbnail-service.example.com
+
+Returns JSON:
+
+```json
+{"status":"ok"}
+```
+
+## Client Configuration
+
+Configure your client app with the base URL where this service is deployed.
+
+Example:
+
+```env
+THUMBNAIL_SERVICE_URL=https://your-thumbnail-service.example.com
 ```