Conntrack Migrator

Introduction

This repository hosts the code for the conntrack-migrator process.

As of today, QEMU does not migrate any connection tracking entries for the VM. With the introduction of dbus-vmstate backend in QEMU, it enables any external helper process to sync data with respect to the VM across hypervisor during VM migration. The conntrack migrator process thus acts as a helper process to QEMU to migrate VM connection tracking entries.

Responsibilities:

• On the source host, conntrack-migrator process reads the conntrack entries for the VM’s IP address and transfer them to QEMU via D-Bus. Also, post migration cleanup of these migrated conntrack entries is performed.
• On the destination host, read the data from QEMU via D-Bus and program the entries in the kernel conntrack table.

Directory tree

.
+-- .
|   +-- include
|   +-- src
|   +-- tests
|   +-- build (auto-generated by make)
|   +-- gen (auto-generated by make)

Build

Build Requirements:

Following libraries are required and can be easily installed using yum.

• libnetfilter_conntrack, libnetfilter_conntrack-devel
• libmnl, libmnl-devel
• glib2, glib2-devel
• gcc, make, gdbus-codegen

Compile

To compile the conntrack-migrator source:

foo@bar:~$ make all

This will create the conntrack-migrator binary in the build folder.

Running on host.

On the source hypervisor (SAVE MODE):

foo@bar:~$ DBUS_SYSTEM_BUS_ADDRESS=<dbus address> conntrack_migrator 2 <helper-id> <num of ip address> <space separated list of ip addresses>
foo@bar:~$ DBUS_SYSTEM_BUS_ADDRESS=unix:path=/run/system_dbus_socket conntrack_migrator 2 id1 2 1.1.1.1 2.2.2.2

On the destination hypervisor (LOAD MODE):

foo@bar:~$ DBUS_SYSTEM_BUS_ADDRESS=<dbus address> conntrack_migrator 1 <helper-id>
foo@bar:~$ DBUS_SYSTEM_BUS_ADDRESS=unix:path=/run/system_dbus_socket conntrack_migrator 2 id1

Testing

Requirements

Check unit testing framework(https://libcheck.github.io/check/) is used for running the unit test.

Before starting the UTs, make sure check is installed using:

foo@bar:~$ yum install check

Running all unit tests

foo@bar:~$ make check

Running individual unit test

foo@bar:~$ make clean_secondary # cleans up the stale tests (optional)
foo@bar:~$ make build/tests/runner/<test-name>.out

For eg:

foo@bar:~$ make build/tests/runner/test_common.out

Unsupported features

Following features are not yet supported:

• Conntrack entries having IPv6 information will not be migrated.
• Conntrack entries having zone information will not be migrated since there is no guarantee that on the destination the same zone will be allocated for the VM.

LICENSE

Copyright 2021, Nutanix, Inc.

Conntrack-Migrator v.1.0 is dual licensed under the BSD 3 Clause License or the GNU General Public License version 2.

See LICENSE file for detailed terms and conditions.