constellation/dev-docs/workflows/qemu.md

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# Local image testing with QEMU / libvirt
To create local testing clusters using QEMU, some prerequisites have to be met:
- [qcow2 constellation image](/image/README.md)
- [qemu-metadata-api container image](/hack/qemu-metadata-api/README.md)
Deploying the VMs requires `libvirt` to be installed and configured correctly.
You may either use [your local libvirt setup](#local-libvirt-setup) if it meets the requirements, or use a [containerized libvirt in docker](#containerized-libvirt).
## Containerized libvirt
Constellation will automatically deploy a containerized libvirt instance, if no connection URI is defined in the Constellation config file.
Follow the steps in our [libvirt readme](../../nix/container/README.md) if you wish to build your own image.
## Local libvirt setup
<details>
<summary>Ubuntu</summary>
### Install required packages
[General reference](https://ubuntu.com/server/docs/virtualization-libvirt)
```shell-session
sudo apt install qemu-kvm libvirt-daemon-system xsltproc
sudo systemctl enable libvirtd
sudo usermod -a -G libvirt $USER
# reboot
```
### Setup emulated TPM
Using a virtual TPM (vTPM) with QEMU only works if swtpm is version 0.7 or newer!
Ubuntu 22.04 currently ships swtpm 0.6.3, so you need to install swtpm [from launchpad](https://launchpad.net/~stefanberger/+archive/ubuntu/swtpm-jammy/).
1. Uninstall current version of swtpm (if installed)
```shell-session
sudo apt remove swtpm swtpm-tools
```
2. Add ppa (this command shows the ppa for Ubuntu 22.04 jammy but others are available)
```shell-session
sudo add-apt-repository ppa:stefanberger/swtpm-jammy
sudo apt update
```
3. Install swtpm
```shell-session
sudo apt install swtpm swtpm-tools
```
4. Patch configuration under `/etc/swtpm_setup.conf`
```shell-session
# Program invoked for creating certificates
create_certs_tool = /usr/bin/swtpm_localca
```
5. Patch ownership of `/var/lib/swtpm-localca`
```shell-session
sudo chown -R swtpm:root /var/lib/swtpm-localca
```
</details>
<details>
<summary>Fedora</summary>
```shell-session
sudo dnf install -y dnf-plugins-core
sudo dnf -y install qemu-kvm libvirt-daemon-config-network libvirt-daemon-kvm xsltproc swtpm
sudo usermod -a -G libvirt $USER
# reboot
```
</details>
### Update libvirt settings
Open `/etc/libvirt/qemu.conf` and change the following settings:
```shell-session
security_driver = "none"
```
Then restart libvirt
```shell-session
sudo systemctl restart libvirtd
```
### Connecting to a console
Once you created a cluster via constellation you can connect to the virtual machines using the following commands. First, run
```shell-session
virsh -c qemu+tcp://localhost:16599/system
```
which gives you a new `virsh` shell. In this shell, you can run
```shell-session
list
```
to see the created virtual machines, as well as their status. This should look something like this:
```txt
Id Name State
------------------------------------------
1 constell-control-plane-0 running
2 constell-worker-0 running
```
If you want to connect to one of those machines, run
```shell-session
console <ID>
```
where `<ID>` would be the id of your virtual machine as seen above (e.g. `1`). After that, press Enter another time and you should drop into a shell on the virtual machine.
Please note that connecting via `qemu+tcp` is not encrypted and should not be used in a security relevant environment.
## Troubleshooting
### VMs are not properly cleaned up after a failed `constellation create` command
Terraform may fail to remove your VMs, in which case you need to do so manually.
- List all domains: `virsh list --all`
- Destroy domains with nvram: `virsh undefine --nvram <name>`
### VMs have no internet access
`iptables` rules may prevent your VMs form properly accessing the internet.
Make sure your rules are not dropping forwarded packages.
List your rules:
```shell
sudo iptables -S
```
The output may look similar to the following:
```shell
-P INPUT ACCEPT
-P FORWARD DROP
-P OUTPUT ACCEPT
-N DOCKER
-N DOCKER-ISOLATION-STAGE-1
-N DOCKER-ISOLATION-STAGE-2
-N DOCKER-USER
```
If your `FORWARD` chain is set to `DROP`, you will need to update your rules:
```shell
sudo iptables -P FORWARD ACCEPT
```