vmm: Deprecate cpu_template in /machine-config API

Signed-off-by: Takahiro Itazuri <itazur@amazon.com>

Author: zulinx86

src/api_server/src/request/machine_configuration.rs

@@ -20,11 +20,25 @@ pub(crate) fn parse_put_machine_config(body: &Body) -> Result<ParsedRequest, Err
         err
     })?;
 
+    // Check for the presence of deprecated `cpu_template` field.
+    let mut deprecation_message = None;
+    if config.cpu_template.is_some() {
+        // `cpu_template` field in request is deprecated.
+        METRICS.deprecated_api.deprecated_http_api_calls.inc();
+        deprecation_message = Some("PUT /machine-config: cpu_template field is deprecated.");
+    }
+
+    // Convert `MachineConfig` to `MachineConfigUpdate`.
     let config_update = MachineConfigUpdate::from(config);
 
-    Ok(ParsedRequest::new_sync(VmmAction::UpdateVmConfiguration(
-        config_update,
-    )))
+    // Construct the `ParsedRequest` object.
+    let mut parsed_req = ParsedRequest::new_sync(VmmAction::UpdateVmConfiguration(config_update));
+    // If `cpu_template` was present, set the deprecation message in `parsing_info`.
+    if let Some(msg) = deprecation_message {
+        parsed_req.parsing_info().append_deprecation_message(msg);
+    }
+
+    Ok(parsed_req)
 }
 
 pub(crate) fn parse_patch_machine_config(body: &Body) -> Result<ParsedRequest, Error> {
@@ -39,9 +53,22 @@ pub(crate) fn parse_patch_machine_config(body: &Body) -> Result<ParsedRequest, E
         return method_to_error(Method::Patch);
     }
 
-    Ok(ParsedRequest::new_sync(VmmAction::UpdateVmConfiguration(
-        config_update,
-    )))
+    // Check for the presence of deprecated `cpu_template` field.
+    let mut deprecation_message = None;
+    if config_update.cpu_template.is_some() {
+        // `cpu_template` field in request is deprecated.
+        METRICS.deprecated_api.deprecated_http_api_calls.inc();
+        deprecation_message = Some("PATCH /machine-config: cpu_template is deprecated.");
+    }
+
+    // Construct the `ParsedRequest` object.
+    let mut parsed_req = ParsedRequest::new_sync(VmmAction::UpdateVmConfiguration(config_update));
+    // If `cpu_template` was present, set the deprecation message in `parsing_info`.
+    if let Some(msg) = deprecation_message {
+        parsed_req.parsing_info().append_deprecation_message(msg);
+    }
+
+    Ok(parsed_req)
 }
 
 #[cfg(test)]

src/vmm/src/vmm_config/machine_config.rs

@@ -40,8 +40,8 @@ pub struct MachineConfig {
     #[serde(default, deserialize_with = "deserialize_smt")]
     pub smt: bool,
     /// A CPU template that it is used to filter the CPU features exposed to the guest.
-    #[serde(default, skip_serializing_if = "StaticCpuTemplate::is_none")]
-    pub cpu_template: StaticCpuTemplate,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub cpu_template: Option<StaticCpuTemplate>,
     /// Enables or disables dirty page tracking. Enabling allows incremental snapshots.
     #[serde(default)]
     pub track_dirty_pages: bool,
@@ -122,7 +122,7 @@ impl From<MachineConfig> for MachineConfigUpdate {
             vcpu_count: Some(cfg.vcpu_count),
             mem_size_mib: Some(cfg.mem_size_mib),
             smt: Some(cfg.smt),
-            cpu_template: Some(cfg.cpu_template),
+            cpu_template: cfg.cpu_template,
             track_dirty_pages: Some(cfg.track_dirty_pages),
         }
     }
@@ -212,7 +212,7 @@ impl From<&VmConfig> for MachineConfig {
             vcpu_count: value.vcpu_count,
             mem_size_mib: value.mem_size_mib,
             smt: value.smt,
-            cpu_template: (&value.cpu_template).into(),
+            cpu_template: Some((&value.cpu_template).into()),
             track_dirty_pages: value.track_dirty_pages,
         }
     }