# MiniDiscovery API Documentation

This document describes the HTTP API endpoints provided by MiniDiscovery.

## Authentication

Most API endpoints require authentication using an API token. Tokens must be passed in the `X-API-Token` HTTP header.

```http
GET /v1/catalog/services HTTP/1.1
Host: your-minidiscovery-host:8500
X-API-Token: your_secret_api_token
```

Tokens have associated permissions:

*   **`read`**: Allows reading service information (catalog, health).
*   **`write`**: Allows registering and deregistering services.
*   **`admin`**: Allows all `read` and `write` operations, plus managing ACL tokens.

The initial admin token is set using the `MINIDISCOVERY_ADMIN_TOKEN` environment variable on the *first* run when the database is empty. Subsequent tokens are managed via the API.

## Data Models

### `ServiceInstance`

This model represents a single instance of a registered service.

```json
{
  "id": "web-instance-1",
  "name": "web",
  "address": "192.168.1.100",
  "port": 80,
  "tags": ["frontend", "nginx"],
  "metadata": {
    "version": "1.2.3",
    "region": "us-east-1"
  },
  "health": "passing",
  "last_updated": 1678886400.123456
}
```

*   `id` (string, required): Unique identifier for this specific instance.
*   `name` (string, required): Logical name of the service (e.g., 'web', 'api', 'db').
*   `address` (string, required): IP address or resolvable hostname where the service listens.
*   `port` (integer, required): Port number (1-65535).
*   `tags` (array of strings, optional): List of tags for filtering/grouping. Defaults to `[]`.
*   `metadata` (object, optional): Key-value string pairs for arbitrary metadata. Defaults to `{}`.
*   `health` (string, optional): Current health status ('passing', 'failing', 'unknown'). Defaults to 'passing' on registration. Automatically updated by the health checker.
*   `last_updated` (float, internal): Unix timestamp of the last update (set automatically).

## Endpoints

### Agent Endpoints

These endpoints interact with the local agent state (registering/deregistering services).

#### Register Service

*   **`POST /v1/agent/service/register`**
*   **Description:** Registers a new service instance or updates an existing one with the same `id`. This operation is idempotent based on the service `id`.
*   **Authentication:** Requires `write` permission.
*   **Request Body:** `ServiceInstance` JSON object. The `health` and `last_updated` fields in the request body are ignored; health is managed internally, and `last_updated` is set automatically.
*   **Success Response:** `200 OK`
    ```json
    {
      "status": "registered",
      "service_id": "web-instance-1"
    }
    ```
*   **Error Responses:**
    *   `400 Bad Request`: Invalid request body format.
    *   `401 Unauthorized`: Missing `X-API-Token`.
    *   `403 Forbidden`: Invalid token or insufficient permissions.
    *   `500 Internal Server Error`: Database error during registration.
*   **`curl` Example:**
    ```bash
    curl -X POST http://localhost:8500/v1/agent/service/register \
      -H "X-API-Token: your_write_token" \
      -H "Content-Type: application/json" \
      -d '{
        "id": "api-instance-01",
        "name": "api",
        "address": "10.0.1.5",
        "port": 8080,
        "tags": ["backend", "v2"],
        "metadata": {"git_sha": "a1b2c3d"}
      }'
    ```

#### Deregister Service

*   **`PUT /v1/agent/service/deregister/{service_id}`**
    *(Note: Consul uses PUT here, although DELETE might feel more intuitive)*
*   **Description:** Removes a service instance by its ID.
*   **Authentication:** Requires `write` permission.
*   **Path Parameters:**
    *   `service_id` (string): The unique ID of the service instance to deregister.
*   **Success Response:** `200 OK`
    ```json
    {
      "status": "deregistered",
      "service_id": "api-instance-01"
    }
    ```
*   **Error Responses:**
    *   `401 Unauthorized`: Missing `X-API-Token`.
    *   `403 Forbidden`: Invalid token or insufficient permissions.
    *   `404 Not Found`: Service with the given `service_id` does not exist.
*   **`curl` Example:**
    ```bash
    curl -X PUT http://localhost:8500/v1/agent/service/deregister/api-instance-01 \
      -H "X-API-Token: your_write_token"
    ```

### Catalog Endpoints

These endpoints provide information about registered services across the system.

#### List Services

*   **`GET /v1/catalog/services`**
*   **Description:** Returns a map of all registered service names to a list of unique tags associated with instances of that service.
*   **Authentication:** Requires `read` permission.
*   **Success Response:** `200 OK`
    ```json
    {
      "web": ["frontend", "nginx"],
      "api": ["backend", "v2"],
      "db": []
    }
    ```
*   **Error Responses:**
    *   `401 Unauthorized`: Missing `X-API-Token`.
    *   `403 Forbidden`: Invalid token or insufficient permissions.
*   **`curl` Example:**
    ```bash
    curl http://localhost:8500/v1/catalog/services \
      -H "X-API-Token: your_read_token"
    ```

#### List Service Instances

*   **`GET /v1/catalog/service/{service_name}`**
*   **Description:** Returns a list of all registered instances for a given service name.
*   **Authentication:** Requires `read` permission.
*   **Path Parameters:**
    *   `service_name` (string): The name of the service (e.g., 'web', 'api').
*   **Query Parameters:**
    *   `tag` (string, optional): Filter instances by tag. Only instances with this tag will be returned.
*   **Success Response:** `200 OK` (Returns an array of `ServiceInstance` objects)
    ```json
    [
      {
        "id": "web-instance-1",
        "name": "web",
        "address": "192.168.1.100",
        "port": 80,
        "tags": ["frontend", "nginx"],
        "metadata": {"version": "1.2.3"},
        "health": "passing",
        "last_updated": 1678886400.123
      },
      {
        "id": "web-instance-2",
        "name": "web",
        "address": "192.168.1.101",
        "port": 80,
        "tags": ["frontend"],
        "metadata": {"version": "1.2.4"},
        "health": "failing",
        "last_updated": 1678886405.456
      }
    ]
    ```
    *   Returns `[]` if the service name is not found.
*   **Error Responses:**
    *   `401 Unauthorized`: Missing `X-API-Token`.
    *   `403 Forbidden`: Invalid token or insufficient permissions.
*   **`curl` Examples:**
    ```bash
    # Get all 'web' instances
    curl http://localhost:8500/v1/catalog/service/web \
      -H "X-API-Token: your_read_token"

    # Get 'web' instances tagged with 'nginx'
    curl http://localhost:8500/v1/catalog/service/web?tag=nginx \
      -H "X-API-Token: your_read_token"
    ```

### Health Endpoints

These endpoints provide service discovery filtered by health status.

#### List Healthy Service Instances

*   **`GET /v1/health/service/{service_name}`**
*   **Description:** Returns a list of service instances, similar to the catalog endpoint, but allows filtering by health status.
*   **Authentication:** Requires `read` permission.
*   **Path Parameters:**
    *   `service_name` (string): The name of the service.
*   **Query Parameters:**
    *   `tag` (string, optional): Filter instances by tag.
    *   `passing` (boolean, optional): If `true`, only return instances with a `passing` health status. Defaults to `false` (returns all instances regardless of health).
*   **Success Response:** `200 OK` (Returns an array of `ServiceInstance` objects)
    *   Response format is identical to `/v1/catalog/service/{service_name}` but filtered according to query parameters.
*   **Error Responses:**
    *   `401 Unauthorized`: Missing `X-API-Token`.
    *   `403 Forbidden`: Invalid token or insufficient permissions.
*   **`curl` Examples:**
    ```bash
    # Get all 'api' instances (healthy or not)
    curl http://localhost:8500/v1/health/service/api \
      -H "X-API-Token: your_read_token"

    # Get only healthy ('passing') 'api' instances
    curl http://localhost:8500/v1/health/service/api?passing=true \
      -H "X-API-Token: your_read_token"

    # Get only healthy 'api' instances tagged 'v2'
    curl 'http://localhost:8500/v1/health/service/api?passing=true&tag=v2' \
      -H "X-API-Token: your_read_token"
    ```

### ACL Token Endpoints

These endpoints manage API access tokens.

#### Create Token

*   **`POST /v1/acl/token`**
*   **Description:** Creates a new API token with specified permissions.
*   **Authentication:** Requires `admin` permission.
*   **Request Body:**
    ```json
    {
      "name": "my-app-token",
      "permissions": ["read", "write"]
    }
    ```
    *   `name` (string, required): A unique descriptive name for the token.
    *   `permissions` (array of strings, optional): List of permissions (`read`, `write`, `admin`). Defaults to `["read", "write"]`.
*   **Success Response:** `201 Created`
    ```json
    {
      "token": "YOUR_NEW_SECRET_TOKEN_VALUE",
      "name": "my-app-token",
      "permissions": ["read", "write"]
    }
    ```
    *   **IMPORTANT:** The `token` value is the actual secret token. It is **only shown once** in this response. Store it securely immediately.
*   **Error Responses:**
    *   `400 Bad Request`: Invalid request body or token name already exists.
    *   `401 Unauthorized`: Missing `X-API-Token`.
    *   `403 Forbidden`: Invalid token or insufficient permissions (not admin).
    *   `500 Internal Server Error`: Database error during token creation.
*   **`curl` Example:**
    ```bash
    curl -X POST http://localhost:8500/v1/acl/token \
      -H "X-API-Token: your_admin_token" \
      -H "Content-Type: application/json" \
      -d '{
        "name": "read-only-dashboard",
        "permissions": ["read"]
      }'
    ```

#### Revoke Token

*   **`DELETE /v1/acl/token/{token_to_revoke}`**
*   **Description:** Revokes (deletes) an existing API token.
*   **Authentication:** Requires `admin` permission.
*   **Path Parameters:**
    *   `token_to_revoke` (string): The **actual secret token value** of the token you want to revoke.
*   **Success Response:** `200 OK`
    ```json
    {
      "status": "revoked",
      "token_info": "Token revoked successfully"
    }
    ```
*   **Error Responses:**
    *   `401 Unauthorized`: Missing `X-API-Token`.
    *   `403 Forbidden`: Invalid token or insufficient permissions (not admin).
    *   `404 Not Found`: The token specified in the path does not exist or was already revoked.
*   **`curl` Example:**
    ```bash
    # Replace YOUR_OLD_SECRET_TOKEN_VALUE with the token to be deleted
    curl -X DELETE http://localhost:8500/v1/acl/token/YOUR_OLD_SECRET_TOKEN_VALUE \
      -H "X-API-Token: your_admin_token"
    ```

### DNS over HTTPS (DoH)

*   **`GET /dns-query`**
*   **Description:** Provides a simplified DNS-over-HTTPS interface (RFC 8484 GET format) for querying service addresses and SRV records. Primarily intended for simple DNS clients or scripts. **Note:** Requires service names to end with the configured DNS suffix (default: `.laiska.local`).
*   **Authentication:** None (typically).
*   **Query Parameters:**
    *   `name` (string, required): The DNS query name (e.g., `web.laiska.local`, `_frontend._tcp.web.laiska.local`).
    *   `type` (string, optional): The DNS record type (e.g., `A`, `SRV`, `TXT`). Defaults to `A`. Case-insensitive.
*   **Success Response:** `200 OK` (JSON object following RFC 8484 structure)
    *   **Example (A query for `web.laiska.local`):**
        ```json
        {
          "Status": 0, "TC": false, "RD": true, "RA": false, "AD": false, "CD": false,
          "Question": [{"name": "web.laiska.local.", "type": 1}],
          "Answer": [
            {"name": "web.laiska.local.", "type": 1, "TTL": 60, "data": "192.168.1.100"},
            {"name": "web.laiska.local.", "type": 1, "TTL": 60, "data": "192.168.1.101"}
          ]
        }
        ```
    *   **Example (SRV query for `_frontend._tcp.web.laiska.local`):**
        ```json
        {
          "Status": 0, "TC": false, "RD": true, "RA": false, "AD": false, "CD": false,
          "Question": [{"name": "_frontend._tcp.web.laiska.local.", "type": 33}],
          "Answer": [
            {"name": "_frontend._tcp.web.laiska.local.", "type": 33, "TTL": 60, "data": "0 10 80 web-instance-1.laiska.local."},
            {"name": "_frontend._tcp.web.laiska.local.", "type": 33, "TTL": 60, "data": "0 10 80 web-instance-2.laiska.local."}
          ],
          "Additional": [ // Note: MiniDiscovery doesn't currently populate Additional well for DoH
             // Ideally A records for targets would be here
          ]
        }
        ```
*   **Error/NXDOMAIN Response:** Returns JSON with `"Status"` other than `0` (e.g., `2` for NXDOMAIN, `4` for Not Implemented type).
*   **`curl` Example:**
    ```bash
    # Query for A records
    curl "http://localhost:8500/dns-query?name=web.laiska.local&type=A"

    # Query for SRV records
    curl "http://localhost:8500/dns-query?name=_frontend._tcp.web.laiska.local&type=SRV"
    ```

### Other Endpoints

#### Root

*   **`GET /`**
*   **Description:** Provides a basic entry point. Redirects browsers to `/status`. API clients receive a simple JSON message.
*   **Authentication:** None.
*   **Response (Browser):** HTTP 307 Redirect to `/status`.
*   **Response (API Client):** `200 OK`
    ```json
    {
      "message": "MiniDiscovery API Root. See /status for HTML view or /docs for API documentation."
    }
    ```

#### Status Page

*   **`GET /status`**
*   **Description:** Serves a simple HTML status page showing node health based on registered services. Useful for a quick visual overview. Automatically refreshes.
*   **Authentication:** None.
*   **Response:** `200 OK` with `Content-Type: text/html`.