7ac619b24e
Move the networking details out of the architecture doc and into a separate file. Partially fixes: #3246. Signed-off-by: James O. D. Hunt <james.o.hunt@intel.com>
2.3 KiB
Networking
See the networking document.
Containers will typically live in their own, possibly shared, networking namespace. At some point in a container lifecycle, container engines will set up that namespace to add the container to a network which is isolated from the host network, but which is shared between containers
In order to do so, container engines will usually add one end of a virtual
ethernet (veth) pair into the container networking namespace. The other end of
the veth pair is added to the host networking namespace.
This is a very namespace-centric approach as many hypervisors or VM
Managers (VMMs) such as virt-manager cannot handle veth
interfaces. Typically, TAP interfaces are created for VM
connectivity.
To overcome incompatibility between typical container engines expectations
and virtual machines, Kata Containers networking transparently connects veth
interfaces with TAP ones using Traffic Control:
With a TC filter in place, a redirection is created between the container network and the
virtual machine. As an example, the CNI may create a device, eth0, in the container's network
namespace, which is a VETH device. Kata Containers will create a tap device for the VM, tap0_kata,
and setup a TC redirection filter to mirror traffic from eth0's ingress to tap0_kata's egress,
and a second to mirror traffic from tap0_kata's ingress to eth0's egress.
Kata Containers maintains support for MACVTAP, which was an earlier implementation used in Kata. TC-filter is the default because it allows for simpler configuration, better CNI plugin compatibility, and performance on par with MACVTAP.
Kata Containers has deprecated support for bridge due to lacking performance relative to TC-filter and MACVTAP.
Kata Containers supports both CNM and CNI for networking management.
Network Hotplug
Kata Containers has developed a set of network sub-commands and APIs to add, list and remove a guest network endpoint and to manipulate the guest route table.
The following diagram illustrates the Kata Containers network hotplug workflow.
