Tests for snapshot network renames

Test that we can correctly parse configuration and API calls in a
backwards compatible way.

Signed-off-by: Andrew Laucius <[email protected]>
Signed-off-by: Babis Chalios <[email protected]>

Author: andrewla

src/firecracker/src/api_server/request/snapshot.rs

@@ -121,7 +121,7 @@ fn parse_put_snapshot_load(body: &Body) -> Result<ParsedRequest, RequestError> {
 
 #[cfg(test)]
 mod tests {
-    use vmm::vmm_config::snapshot::{MemBackendConfig, MemBackendType};
+    use vmm::vmm_config::snapshot::{MemBackendConfig, MemBackendType, NetworkOverride};
 
     use super::*;
     use crate::api_server::parsed_request::tests::{depr_action_from_req, vmm_action_from_request};
@@ -256,6 +256,45 @@ mod tests {
             VmmAction::LoadSnapshot(expected_config)
         );
 
+        let body = r#"{
+            "snapshot_path": "foo",
+            "mem_backend": {
+                "backend_path": "bar",
+                "backend_type": "Uffd"
+            },
+            "resume_vm": true,
+            "network_overrides": [
+                {
+                    "iface_id": "eth0",
+                    "host_dev_name": "vmtap2"
+                }
+            ]
+        }"#;
+        let expected_config = LoadSnapshotParams {
+            snapshot_path: PathBuf::from("foo"),
+            mem_backend: MemBackendConfig {
+                backend_path: PathBuf::from("bar"),
+                backend_type: MemBackendType::Uffd,
+            },
+            enable_diff_snapshots: false,
+            resume_vm: true,
+            network_overrides: vec![NetworkOverride {
+                iface_id: String::from("eth0"),
+                host_dev_name: String::from("vmtap2"),
+            }],
+        };
+        let mut parsed_request = parse_put_snapshot(&Body::new(body), Some("load")).unwrap();
+        assert!(
+            parsed_request
+                .parsing_info()
+                .take_deprecation_message()
+                .is_none()
+        );
+        assert_eq!(
+            vmm_action_from_request(parsed_request),
+            VmmAction::LoadSnapshot(expected_config)
+        );
+
         let body = r#"{
             "snapshot_path": "foo",
             "mem_file_path": "bar",

src/vmm/tests/integration_tests.rs

@@ -261,6 +261,7 @@ fn verify_load_snapshot(snapshot_file: TempFile, memory_file: TempFile) {
             },
             enable_diff_snapshots: false,
             resume_vm: true,
+            network_overrides: vec![],
         }))
         .unwrap();
 
@@ -344,6 +345,7 @@ fn verify_load_snap_disallowed_after_boot_resources(res: VmmAction, res_name: &s
         },
         enable_diff_snapshots: false,
         resume_vm: false,
+        network_overrides: vec![],
     });
     let err = preboot_api_controller.handle_preboot_request(req);
     assert!(

tests/framework/microvm.py

@@ -974,6 +974,7 @@ def restore_from_snapshot(
         snapshot: Snapshot,
         resume: bool = False,
         uffd_path: Path = None,
+        rename_interfaces: dict = None,
     ):
         """Restore a snapshot"""
         jailed_snapshot = snapshot.copy_to_chroot(Path(self.chroot()))
@@ -1001,11 +1002,27 @@ def restore_from_snapshot(
         # Adjust things just in case
         self.kernel_file = Path(self.kernel_file)
 
+        iface_overrides = []
+        if rename_interfaces is not None:
+            iface_overrides = [
+                {"iface_id": k, "host_dev_name": v}
+                for k, v in rename_interfaces.items()
+            ]
+
+        optional_kwargs = {}
+        if iface_overrides:
+            # For backwards compatibility ab testing we want to avoid adding
+            # new parameters until we have a release baseline with the new
+            # parameter. Once the release baseline has moved, this assignment
+            # can be inline in the snapshot_load command below
+            optional_kwargs["network_overrides"] = iface_overrides
+
         self.api.snapshot_load.put(
             mem_backend=mem_backend,
             snapshot_path=str(jailed_vmstate),
             enable_diff_snapshots=snapshot.is_diff,
             resume_vm=resume,
+            **optional_kwargs,
         )
         # This is not a "wait for boot", but rather a "VM still works after restoration"
         if snapshot.net_ifaces and resume:

tests/integration_tests/functional/test_snapshot_basic.py

@@ -2,19 +2,22 @@
 # SPDX-License-Identifier: Apache-2.0
 """Basic tests scenarios for snapshot save/restore."""
 
+import dataclasses
 import filecmp
 import logging
 import os
 import platform
 import re
 import shutil
 import time
+import uuid
 from pathlib import Path
 
 import pytest
 
 import host_tools.cargo_build as host
 import host_tools.drive as drive_tools
+import host_tools.network as net_tools
 from framework import utils
 from framework.microvm import SnapshotType
 from framework.properties import global_props
@@ -570,3 +573,29 @@ def test_physical_counter_reset_aarch64(uvm_nano):
                 break
     else:
         raise RuntimeError("Did not find CNTPCT_EL0 register in snapshot")
+
+
+def test_snapshot_rename_interface(uvm_nano, microvm_factory):
+    """
+    Test that we can restore a snapshot and point its interface to a
+    different host interface.
+    """
+    vm = uvm_nano
+    base_iface = vm.add_net_iface()
+    vm.start()
+    snapshot = vm.snapshot_full()
+
+    # We don't reuse the network namespace as it may conflict with
+    # previous/future devices
+    restored_vm = microvm_factory.build(netns=net_tools.NetNs(str(uuid.uuid4())))
+    # Override the tap name, but keep the same IP configuration
+    iface_override = dataclasses.replace(base_iface, tap_name="tap_override")
+
+    restored_vm.spawn()
+    snapshot.net_ifaces.clear()
+    snapshot.net_ifaces.append(iface_override)
+    restored_vm.restore_from_snapshot(
+        snapshot,
+        rename_interfaces={iface_override.dev_name: iface_override.tap_name},
+        resume=True,
+    )