Merge pull request kubernetes#130512 from HirazawaUi/Clarify-cri-fields

Clarify the behavior when the host_port value is set to 0 in CRI

Author: k8s-ci-robot

staging/src/k8s.io/cri-api/pkg/apis/runtime/v1/api.pb.go

@@ -201,7 +201,16 @@ message PortMapping {
     Protocol protocol = 1;
     // Port number within the container. Default: 0 (not specified).
     int32 container_port = 2;
-    // Port number on the host. Default: 0 (not specified).
+    // Port number on the host to map the container port to.
+    //
+    // * Valid host port range is 1-65535.
+    // * The value 0 has explicit semantic meaning: it indicates NO host port should be allocated.
+    // * The value 0 does NOT indicate dynamic port allocation. Future implementations
+    //   of dynamic allocation will use different values/semantics.
+    // * Implementations MUST handle the case where this field is explicitly set to 0,
+    //   This field SHOULD be omitted when no port is required.
+    //
+    // Default: If omitted, container port will not be exposed on the host.
     int32 host_port = 3;
     // Host IP.
     string host_ip = 4;