> ## Documentation Index
> Fetch the complete documentation index at: https://docs.techulus.cloud/llms.txt
> Use this file to discover all available pages before exploring further.

# Service Discovery

> Internal DNS for service-to-service communication.

Services discover each other using `.internal` domain names. Every agent runs a built-in DNS server that resolves these names to container IP addresses over the [WireGuard mesh](/architecture#wireguard-mesh).

## How It Works

Each service gets a hostname like `my-service.internal`. The DNS server on every agent is configured with all service records pushed from the control plane.

When a container queries `my-service.internal`, the local DNS server resolves it to the container IPs of that service. If the service has multiple replicas, responses use round-robin across all healthy containers.

All DNS resolution happens over the private WireGuard network — no traffic leaves the mesh.

## Configuration

Service discovery works automatically. The DNS server:

* Listens on the container gateway IP (e.g., `10.200.1.1`).
* Configures `systemd-resolved` to forward `.internal` queries.
* Receives record updates from the control plane as part of expected state.

No manual configuration is needed. Services can reference each other by name immediately after deployment.

## Example

If you have an `api` service and a `web` service, the web service can connect to the API using:

```
http://api.internal:3000
```

For production databases, use an external managed database or another HA database setup. Techulus Cloud stateful volumes are single-server local storage and do not currently provide replicated storage or automatic failover.