test: enable serial console in integration tests

If SSH to guest is failing, we don't really get much useful in terms of
logs in our ci artifacts. Enable serial console so that we get guest
dmesg always.

Disable pylint's "too-many-statements" lint, because it started firing
in microvm.spawn()

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

tests/framework/microvm.py

@@ -254,6 +254,7 @@ def __init__(
 
         self.api = None
         self.log_file = None
+        self.serial_log_file = None
         self.metrics_file = None
         self._spawned = False
         self._killed = False
@@ -618,6 +619,7 @@ def add_pre_cmd(self, pre_cmd):
     def spawn(
         self,
         log_file="fc.log",
+        serial_log_file="serial.log",
         log_level="Debug",
         log_show_level=False,
         log_show_origin=False,
@@ -648,6 +650,12 @@ def spawn(
             if log_show_origin:
                 self.jailer.extra_args["show-log-origin"] = None
 
+        if serial_log_file is not None:
+            self.serial_log_file = Path(self.path) / serial_log_file
+            self.serial_log_file.touch()
+            self.create_jailed_resource(self.serial_log_file)
+            self.jailer.extra_args.update({"serial-out-path": serial_log_file})
+
         if metrics_path is not None:
             self.metrics_file = Path(self.path) / metrics_path
             self.metrics_file.touch()
@@ -789,10 +797,9 @@ def basic_config(
         The function checks the response status code and asserts that
         the response is within the interval [200, 300).
 
-        If boot_args is None, the default boot_args in Firecracker is
-            reboot=k panic=1 pci=off nomodule 8250.nr_uarts=0
-            i8042.noaux i8042.nomux i8042.nopnp i8042.dumbkbd
-
+        If boot_args is None, the default boot_args used in tests is
+            reboot=k panic=1 pci=off nomodule console=ttyS0
+        which differs from Firecracker's default only in the enabling of the serial console.
         Reference: file:../../src/vmm/src/vmm_config/boot_source.rs::DEFAULT_KERNEL_CMDLINE
         """
         self.api.machine_config.put(
@@ -816,6 +823,8 @@ def basic_config(
 
         if boot_args is not None:
             self.boot_args = boot_args
+        else:
+            self.boot_args = "reboot=k panic=1 pci=off nomodule console=ttyS0"
         boot_source_args = {
             "kernel_image_path": self.create_jailed_resource(self.kernel_file),
             "boot_args": self.boot_args,
@@ -1301,13 +1310,13 @@ def open(self):
             return
 
         attempt = 0
-        while not Path(self._vm.screen_log).exists() and attempt < 5:
+        while not Path(self._vm.serial_log_file).exists() and attempt < 5:
             time.sleep(0.2)
             attempt += 1
 
-        screen_log_fd = os.open(self._vm.screen_log, os.O_RDONLY)
+        serial_log_fd = os.open(self._vm.serial_log_file, os.O_RDONLY)
         self._poller = select.poll()
-        self._poller.register(screen_log_fd, select.POLLIN | select.POLLHUP)
+        self._poller.register(serial_log_fd, select.POLLIN | select.POLLHUP)
 
     def tx(self, input_string, end="\n"):
         # pylint: disable=invalid-name

tests/integration_tests/functional/test_api.py

@@ -1136,7 +1136,7 @@ def test_get_full_config_after_restoring_snapshot(microvm_factory, uvm_nano):
     expected_cfg["boot-source"] = {
         "kernel_image_path": uvm_nano.get_jailed_resource(uvm_nano.kernel_file),
         "initrd_path": None,
-        "boot_args": None,
+        "boot_args": "reboot=k panic=1 pci=off nomodule console=ttyS0",
     }
 
     # no ipv4_address or imds_compat specified during PUT /mmds/config so we expect the default

tests/integration_tests/functional/test_cmd_line_parameters.py

@@ -29,7 +29,7 @@ def test_describe_snapshot_all_versions(
         jailer_binary_path=firecracker_release.jailer,
     )
     # FIXME: Once only FC versions >= 1.12 are supported, drop log_level="warn"
-    vm.spawn(log_level="warn")
+    vm.spawn(log_level="warn", serial_log_file=None)
     vm.basic_config(track_dirty_pages=True)
     vm.start()
     snapshot = vm.snapshot_diff()

tests/integration_tests/functional/test_max_devices.py

@@ -12,7 +12,7 @@
 # On aarch64, IRQs are available from 32 to 127. We always use one IRQ each for
 # the VMGenID and RTC devices, so the maximum number of devices supported
 # at the same time is 94.
-MAX_DEVICES_ATTACHED = {"x86_64": 18, "aarch64": 94}.get(platform.machine())
+MAX_DEVICES_ATTACHED = {"x86_64": 18, "aarch64": 93}.get(platform.machine())
 
 
 def test_attach_maximum_devices(microvm_factory, guest_kernel, rootfs):

tests/integration_tests/functional/test_serial_io.py

@@ -173,13 +173,12 @@ def test_serial_block(uvm_plain_any):
     """
     test_microvm = uvm_plain_any
     test_microvm.help.enable_console()
-    test_microvm.spawn()
+    test_microvm.spawn(serial_log_file=None)
     # Set up the microVM with 1 vCPU so we make sure the vCPU thread
     # responsible for the SSH connection will also run the serial.
     test_microvm.basic_config(
         vcpu_count=1,
         mem_size_mib=512,
-        boot_args="console=ttyS0 reboot=k panic=1 pci=off",
     )
     test_microvm.add_net_iface()
     test_microvm.start()

tests/pyproject.toml

@@ -56,4 +56,5 @@ disable = [
     "too-many-positional-arguments",
     "too-few-public-methods",
     "too-many-branches",
+    "too-many-statements",
 ]