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

# Registering a Service Proxy

> This article explains how to register a service proxy with Consul Connect for secure service communication.

Consul Connect, the built-in service mesh of Consul, uses sidecar proxies to secure and manage traffic between services. By registering a sidecar proxy alongside your application, Consul can automatically route and secure calls through TLS-encrypted channels.

<Callout icon="lightbulb" color="#1CB2FE">
  Registering a service proxy in Consul does **not** launch it. You still need to start the proxy process (either Consul’s built-in proxy or an external proxy such as [Envoy](https://www.envoyproxy.io)).
</Callout>

Key tasks:

| Task                  | Description                                                   |
| --------------------- | ------------------------------------------------------------- |
| 1. Register the proxy | Add a `connect.sidecar_service` stanza in your service config |
| 2. Start the proxy    | Launch with `consul connect proxy -sidecar-for <service>`     |

## 1. Registering via Configuration File

Instead of the [HTTP API](https://www.consul.io/api), declare your sidecar proxy in the same JSON or HCL file as your primary service. Include a `connect` block with an empty `sidecar_service` object:

```json theme={null}
{
  "service": {
    "name": "front-end-ecommerce",
    "port": 8080,
    "connect": {
      "sidecar_service": {}
    }
  }
}
```

* `"name"`: Service identifier (e.g., `front-end-ecommerce`).
* `"port"`: Port your application listens on.
* `"connect.sidecar_service": {}`: Signals Consul to register an integrated sidecar proxy.

Verify both the service and its proxy via the [Consul UI](https://www.consul.io/docs/commands/ui) or [API](https://www.consul.io/api).

## 2. Adding Upstream Dependencies

Declare downstream services under `proxy.upstreams` within the `sidecar_service` block:

```json theme={null}
{
  "service": {
    "id": "web-01",
    "name": "front-end-ecommerce",
    "tags": ["v7.05", "production"],
    "address": "",
    "port": 8080,
    "connect": {
      "sidecar_service": {
        "proxy": {
          "upstreams": [
            {
              "destination_name": "db01"
            }
          ]
        }
      }
    }
  }
}
```

* `"id"`: Unique instance identifier.
* `"tags"`: Metadata (version, environment).
* `"address"`: If empty, defaults to the local agent address.
* `"connect.sidecar_service.proxy.upstreams"`: List of target services.
  * `"destination_name"`: Consul-registered name of the downstream service.

<Callout icon="lightbulb" color="#1CB2FE">
  To add more dependencies, append additional objects to the `upstreams` list.
</Callout>

```json theme={null}
"upstreams": [
  { "destination_name": "db01" },
  { "destination_name": "api-service" }
]
```

## 3. Deploying and Starting the Sidecar Proxy

1. Place your JSON file in Consul’s configuration directory (e.g., `/etc/consul.d/`).
2. Reload or restart the Consul agent:
   * `consul reload`
   * or `systemctl restart consul`
3. Launch the proxy process:\
   consul connect proxy -sidecar-for front-end-ecommerce

After these steps, both the application and its sidecar proxy are registered and active. Verify connectivity in the [Consul UI](https://www.consul.io/docs/commands/ui), via the [CLI](https://www.consul.io/docs/commands), or using the [API](https://www.consul.io/api).

## References

* [Consul Connect Overview](https://www.consul.io/docs/connect)
* [Consul HTTP API](https://www.consul.io/api)
* [Envoy Proxy](https://www.envoyproxy.io)

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