This is a follow up post to ["Joining libvirt {{<abbr short="VM" full="Virtual Machine" >}}s and Podman container in a common network"]({{<relref "2022-02-libvirt-podman-network-mesh.md" >}}).
Therefore I won't cover all the basics again and how to configure libvirt because nothing's changed on that side.
## Podman 4.0
Podman 4.0 comes with a completely new network stack replacing the previous [{{<abbr short="CNI" full="Container Network Interface" >}}](https://www.cni.dev/) stack:
There are [great resources](https://www.redhat.com/sysadmin/podman-new-network-stack) that explain the backgrounds of both tools and I don't think I could describe it better than the folks implementing it :smile: so if you're interested have a look at the aforementioned article or the [release post](https://podman.io/releases/2022/02/22/podman-release-v4.0.0.html).
## Netavark and libvirt
After reading the announcement I was most curious if I would be able to configure an equivalent setup for Netavark like I described it with Podman 3.x and CNI.
__Short answer:__ yes, it is possible! :tada:
_"But how?!"_ do you ask?
Well it's pretty much equivalent to the previous solution: you need to create a new Podman network I once more named it _'libvirt'_.
To get an idea how the config should look like and where it should placed.
I reused the CLI call from my previous article:
```bash
podman network create \
--disable-dns \
--internal \
--gateway 10.10.2.37 \
--ip-range 10.10.2.160/29 \
--subnet 10.10.2.0/24 \
libvirt
```
The configuration files are now obviously resided in `/etc/containers/networks/` and my (already modified) `libvirt.json` now looks like so:
_Side note: I'm really happy they dropped the `.conflist` extension because this way most editors offer really helpful syntax highlighting in the first place!_
Note that `"internal": false` is mandatory. Otherwise I wasn't able to establish communication between VM and container.
I also disabled the Aardvark {{<abbrshort="DNS"full="Domain Name System">}} server and IPv6 support because I don't need it and I also don't expect much benefit of it due to the fact that it can't be aware of the VMs present in the network same as `dnsmasq` won't be able to resolve containers in the libvirt network.
Having this in place I was again able to reuse the CLI command from my previous article:
```bash
podman run \
--rm \
-d \
--name nginx \
--network libvirt \
--ip 10.10.1.151 \
docker.io/nginx:alpine
```
to create a Nginx container that can be reached from a VM.
## Troubleshooting
Sometimes the communication between container and VM fails - don't know if I restarted the libvirt network previously or somehow fucked up the container network configuration but a:
```bash
podman network reload <containerID/containername>
```
often resolved the problem.
## Final thoughts
I haven't used _Netavark_ and _Aardvark_ a lot, yet.
But I already noticed a few **really awesome** things:
- the `docker-compose` support seems to be a lot better now because containers are actually able to talk to each other by _service name_, something I wasn't able to configure properly in Podman 3.x - at least not rootless.
- with _Netavark_ all the Podman configuration is now unified within `/etc/containers` or `$HOME/.config/containers` respectively
- the new configuration format is a little bit cleaner the the previous one due to the fact that _Netavark_ does not support plugins and with a `.json` extension editors do help a lot more without requiring extra "configuration"
