Add technical documentation

Author: mariaob1201

_toc.yml

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 # Learn more at https://jupyterbook.org/customize/toc.html
 
 format: jb-book
-root: index
+root: index
+chapters:
+  - file: worker

worker.md

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+# Worker
+
+The OpenLambda **worker** is the core server-side component of a node. It listens for
+incoming HTTP requests, manages container lifecycle, and returns responses to callers.
+
+## Overview
+
+Each worker is a standalone Go binary that exposes a single HTTP endpoint:
+
+```
+POST /runLambda/<lambda-name>
+```
+
+When a request arrives the worker:
+
+1. Checks whether the lambda's container image is already present on the node; if not, pulls it from the registry.
+2. Starts a Linux container from the image.
+3. Passes the request payload to the lambda function running inside the container.
+4. Waits for the function to return a result, then forwards that result back to the caller.
+5. Optionally keeps the container warm for a short period to reduce cold-start latency on subsequent calls.
+
+## Configuration
+
+The worker is configured via a JSON file (default `config.json`) in the working directory.
+Key fields:
+
+| Field | Description | Default |
+|---|---|---|
+| `worker_port` | Port the HTTP server listens on | `8080` |
+| `registry` | URL of the lambda registry | `""` |
+| `sandbox` | Container backend (`docker` or `sock`) | `docker` |
+| `log_output` | Where to write logs (`stdout` or a file path) | `stdout` |
+
+## Starting the Worker
+
+```bash
+# From the repo root after building:
+./bin/worker --config config.json
+```
+
+The worker prints its listening address on startup. You can verify it is running with:
+
+```bash
+curl -w "\n" localhost:8080/status
+```
+
+## Deploying Multiple Workers
+
+Workers are stateless with respect to routing — each one operates independently. To scale
+horizontally, start one worker process per node and place a standard HTTP load balancer
+(Nginx, HAProxy, or similar) in front of them. No coordination between workers is required.
+
+```{note}
+A centralized **boss** component for cluster-wide management is currently under development.
+Until then, manual deployment behind a load balancer is the recommended approach for
+multi-node setups.
+```
+
+## Further Reading
+
+- [Quickstart guide](doc.htm) — get a single worker running locally in minutes
+- [SOCK: Rapid Task Provisioning with Serverless-Optimized Containers](https://www.usenix.org/conference/atc18/presentation/oakes) — the research paper describing the container backend.