http: api: implement vmm.ping

vmm.ping will help to check if http API server is up and
running.

This also removes the vmm.info endpoint.

Signed-off-by: Jose Carlos Venegas Munoz <jose.carlos.venegas.munoz@intel.com>

vmm/src/api/mod.rs

@@ -105,12 +105,20 @@ pub struct VmInfo {
     pub state: VmState,
 }
 
+#[derive(Clone, Deserialize, Serialize)]
+pub struct VmmPingResponse {
+    pub version: String,
+}
+
 pub enum ApiResponsePayload {
     /// No data is sent on the channel.
     Empty,
 
     /// Virtual machine information
     VmInfo(VmInfo),
+
+    /// Vmm ping response
+    VmmPing(VmmPingResponse),
 }
 
 /// This is the response sent by the VMM API server through the mpsc channel.
@@ -138,6 +146,9 @@ pub enum ApiRequest {
     /// Request the VM information.
     VmInfo(Sender<ApiResponse>),
 
+    /// Request the VMM API server status
+    VmmPing(Sender<ApiResponse>),
+
     /// Pause a VM.
     VmPause(Sender<ApiResponse>),
 
@@ -263,6 +274,22 @@ pub fn vm_info(api_evt: EventFd, api_sender: Sender<ApiRequest>) -> ApiResult<Vm
     }
 }
 
+pub fn vmm_ping(api_evt: EventFd, api_sender: Sender<ApiRequest>) -> ApiResult<VmmPingResponse> {
+    let (response_sender, response_receiver) = channel();
+
+    api_sender
+        .send(ApiRequest::VmmPing(response_sender))
+        .map_err(ApiError::RequestSend)?;
+    api_evt.write(1).map_err(ApiError::EventFdWrite)?;
+
+    let vmm_pong = response_receiver.recv().map_err(ApiError::ResponseRecv)??;
+
+    match vmm_pong {
+        ApiResponsePayload::VmmPing(pong) => Ok(pong),
+        _ => Err(ApiError::ResponsePayloadType),
+    }
+}
+
 pub fn vmm_shutdown(api_evt: EventFd, api_sender: Sender<ApiRequest>) -> ApiResult<()> {
     let (response_sender, response_receiver) = channel();