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4.5 KiB
Markdown
110 lines
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4.5 KiB
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author = "Peter Kurfer"
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title = "Libvirt & Podman: follow up for Podman 4.0 and netavark"
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date = "2022-02-24"
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description = "Joining libvirt VMs and containers with Podman 4.0's new network stack netavark"
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tags = [
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"podman",
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"libvirt",
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"netavark"
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]
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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" >}}).
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Therefore I won't cover all the basics again and how to configure libvirt because nothing's changed on that side.
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## Podman 4.0
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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:
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* [Netavark](https://github.com/containers/netavark)
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* [Aardvark](https://github.com/containers/aardvark-dns)
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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).
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## Netavark and libvirt
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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.
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__Short answer:__ yes, it is possible! :tada:
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_"But how?!"_ do you ask?
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Well it's pretty much equivalent to the previous solution: you need to create a new Podman network I once more named it _'libvirt'_.
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To get an idea how the config should look like and where it should placed.
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I reused the CLI call from my previous article:
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```bash
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podman network create \
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--disable-dns \
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--internal \
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--gateway 10.10.2.37 \
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--ip-range 10.10.2.160/29 \
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--subnet 10.10.2.0/24 \
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libvirt
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```
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The configuration files are now obviously resided in `/etc/containers/networks/` and my (already modified) `libvirt.json` now looks like so:
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```json
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{
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"name": "libvirt",
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"id": "0489e6e643b97003c47b27a9ce0a6f6a8dce7d5f08329603e79a0ba48ad5285f",
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"driver": "bridge",
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"network_interface": "conbr0",
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"created": "2022-04-05T09:18:48.198960971+01:00",
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"subnets": [
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{
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"subnet": "10.10.1.0/24",
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"gateway": "10.10.1.42",
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"lease_range": {
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"start_ip": "10.10.1.1",
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"end_ip": "10.10.1.10"
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}
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}
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],
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"ipv6_enabled": false,
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"internal": false,
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"dns_enabled": false,
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"ipam_options": {
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"driver": "host-local"
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}
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}
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```
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_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!_
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Note that `"internal": false` is mandatory. Otherwise I wasn't able to establish communication between VM and container.
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I also disabled the Aardvark {{<abbr short="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.
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Having this in place I was again able to reuse the CLI command from my previous article:
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```bash
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podman run \
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--rm \
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-d \
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--name nginx \
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--network libvirt \
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--ip 10.10.1.151 \
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docker.io/nginx:alpine
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```
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to create a Nginx container that can be reached from a VM.
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## Troubleshooting
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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:
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```bash
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podman network reload <container ID/container name>
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```
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often resolved the problem.
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## Final thoughts
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I haven't used _Netavark_ and _Aardvark_ a lot, yet.
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But I already noticed a few **really awesome** things:
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- 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.
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- with _Netavark_ all the Podman configuration is now unified within `/etc/containers` or `$HOME/.config/containers` respectively
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- 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" |