device-api: Add v2/device/name endpoint

This endpoint returns the last known device name from the API. This
differs from the BALENA_DEVICE_NAME_AT_INIT env var because this will
not change throughout the runtime of the container.

Closes: #908
Change-type: minor
Signed-off-by: Cameron Diver <cameron@balena.io>

docs/API.md

@@ -1102,3 +1102,27 @@ Response:
 	"serviceName": "main"
 }
 ```
+
+### V2 Device Information
+
+#### Device name
+
+Added in supervisor version v9.11.0
+
+Get the last returned device name from the balena API. Note that this differs from the
+`BALENA_DEVICE_NAME_AT_INIT` environment variable provided to containers, as this will
+not change throughout the runtime of the container, but the endpoint will always return
+the latest known device name.
+
+From an application container:
+```
+$ curl "$BALENA_SUPERVISOR_ADDRESS/v2/device/name?apikey=$BALENA_SUPERVISOR_API_KEY"
+```
+
+Response:
+```json
+{
+	"status": "success",
+	"deviceName": "holy-wildflower"
+}
+```

src/device-api/v2.ts

@@ -436,4 +436,19 @@ export function createV2Api(router: Router, applications: ApplicationManager) {
 			release: currentRelease,
 		});
 	});
+
+	router.get('/v2/device/name', async (_req, res) => {
+		try {
+			const deviceName = await applications.config.get('name');
+			res.json({
+				status: 'success',
+				deviceName,
+			});
+		} catch (e) {
+			res.status(503).json({
+				status: 'failed',
+				message: messageFromError(e),
+			});
+		}
+	});
 }