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Merge pull request #4795 from liubin/fix/4794-update-limitation

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docs: add back host network limitation
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Archana Shinde 2022-08-05 23:00:47 +05:30 committed by GitHub
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docs/Limitations.md
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@ -60,17 +60,26 @@ This section lists items that might be possible to fix.
## OCI CLI commands
### Docker and Podman support
Currently Kata Containers does not support Docker or Podman.
Currently Kata Containers does not support Podman.
See issue https://github.com/kata-containers/kata-containers/issues/722 for more information.
Docker supports Kata Containers since 22.06:
```bash
$ sudo docker run --runtime io.containerd.kata.v2
```
Kata Containers works perfectly with containerd, we recommend to use
containerd's Docker-style command line tool [`nerdctl`](https://github.com/containerd/nerdctl).
## Runtime commands
### checkpoint and restore
The runtime does not provide `checkpoint` and `restore` commands. There
are discussions about using VM save and restore to give us a
`[criu](https://github.com/checkpoint-restore/criu)`-like functionality,
[`criu`](https://github.com/checkpoint-restore/criu)-like functionality,
which might provide a solution.
Note that the OCI standard does not specify `checkpoint` and `restore`
@ -93,6 +102,42 @@ All other configurations are supported and are working properly.
## Networking
### Host network
Host network (`nerdctl/docker run --net=host`or [Kubernetes `HostNetwork`](https://kubernetes.io/docs/reference/kubernetes-api/workload-resources/pod-v1/#hosts-namespaces)) is not supported.
It is not possible to directly access the host networking configuration
from within the VM.
The `--net=host` option can still be used with `runc` containers and
inter-mixed with running Kata Containers, thus enabling use of `--net=host`
when necessary.
It should be noted, currently passing the `--net=host` option into a
Kata Container may result in the Kata Container networking setup
modifying, re-configuring and therefore possibly breaking the host
networking setup. Do not use `--net=host` with Kata Containers.
### Support for joining an existing VM network
Docker supports the ability for containers to join another containers
namespace with the `docker run --net=containers` syntax. This allows
multiple containers to share a common network namespace and the network
interfaces placed in the network namespace. Kata Containers does not
support network namespace sharing. If a Kata Container is setup to
share the network namespace of a `runc` container, the runtime
effectively takes over all the network interfaces assigned to the
namespace and binds them to the VM. Consequently, the `runc` container loses
its network connectivity.
### docker run --link
The runtime does not support the `docker run --link` command. This
command is now deprecated by docker and we have no intention of adding support.
Equivalent functionality can be achieved with the newer docker networking commands.
See more documentation at
[docs.docker.com](https://docs.docker.com/network/links/).
## Resource management
Due to the way VMs differ in their CPU and memory allocation, and sharing