Traffic Control: Delaying Network Traffic

tc is a tool to manipulate network traffic control setting. This utility allows you to delay communication with target host which can simulate high network latencies or delays.

Note

tc tool must be installed on the system.

See also

See the API reference of LinuxTrafficControl for more information.

Note

Since the utility also performs some setup actions, you probably want to mark the utility with postpone_setup() so the setup method is called only if the tc tool is actually used. This way, it saves some resources in tests that do not utilize the traffic control.

Example: Adding tc utility to your role

from pytest_mh import MultihostHost
from pytest_mh.utils.tc import LinuxTrafficControl

class ExampleRole(MultihostHost[ExampleDomain]):
    def __init__(self, *args, **kwargs) -> None:
        super().__init__(*args, **kwargs)

        self.tc: LinuxTrafficControl = LinuxTrafficControl(self.host).postpone_setup()
        """
        Traffic control manipulation.
        """

Example: Delaying traffic to host

@pytest.mark.topology(...)
def test_tc(client: ClientRole, server: ServerRole):
    ...
    # Delay traffic between client and server by 1500ms
    client.tc.add_delay(server, 1500)
    ...