Network binding plugin: Address compute container resource overhead

Signed-off-by: Orel Misan <[email protected]>

Author: orelmisan

design-proposals/network-binding-plugin/network-binding-plugin.md

@@ -303,6 +303,58 @@ Cons:
 - Additional point of failure.
 - Additional latency when creating VMs with network binding plugins.
 
+##### Compute Container Resource Requirements / Limits
+
+For some plugins, such as passt, there is a need to execute an additional binary in the compute container.
+Since this binary has its own CPU and memory limits, they should be somehow accounted for.
+
+Alternatives:
+1. Manually setting the VM's resources:
+The user can override KubeVirt's algorithms and set resource requirements.
+
+Pros:
+- Already implemented.
+
+Cons:
+- Error prune
+- The user does not take into account the overhead considerations KubeVirt takes when templating a virt-launcher pod.
+
+2. Additional API for compute container resource overhead:
+
+The network binding plugin API in the KubeVirt CR could receive an additional input field to specify the resource requirements overhead for the compute container:
+
+```yaml
+apiVersion: kubevirt.io/v1
+kind: KubeVirt
+metadata:
+  name: kubevirt
+  namespace: kubevirt
+spec:
+  configuration:
+    network:
+      binding:
+        mynetbindingplugin:
+          sidecarImage: quay.io/kubevirt/mynetbindingplugin
+          computeContainerResourceOverhead:
+            requests:
+              cpu: 200m
+              memory: 20Mi
+```
+
+Pros:
+- Cluster-wide definition of network binding plugin compute resource overhead per plugin.
+- Additional resources could be requested other than CPU and Memory.
+
+Cons:
+- Require an API change.
+- The API will probably evolve as additional plugins will be created.
+- May require cluster admins to adjust plugin resources during the plugin's lifecycle.
+
+3. Mutating for the virt-launcher pod:
+
+Same suggestion as in the sidecar section.
+
+The webhook will add the required resource overhead for the compute container. 
 
 #### Configure Pod netns