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| title | date | draft | description | featured | toc | reply | categories | tags | |||||||||||
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| Automate Proxmox Packer Builds Github Actions | 2024-07-21 | true | This is a new post about... | false | true | true | Code |
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I recently shared how I set up Packer to build Proxmox templates in my homelab. That post covered storing (and retrieving) environment-specific values in Vault, the cloud-init configuration for definiting the installation parameters, the various post-install scripts for further customizing and hardening the template, and the Packer template files that tie it all together. By the end of the post, I was able to simply run ./build.sh ubuntu2204 to kick the build of a new Ubuntu 22.04 template without having to do any other interaction with the process.
That's pretty slick, but The Dream is to not have to do anything at all. So that's what this post is about: describing setting up a rootless self-hosted GitHub Actions Runner to perform the build, and the GitHub Actions workflows to trigger it.
Self-Hosted Runner
When a GitHub Actions workflow fires, it schedules the job(s) to run on GitHub's own infrastructure. That's easy and convenient, but can make things tricky when you need a workflow to interact with on-prem infrastructure. I've worked around that in the past by configuring the runner to connect to my tailnet, but given the amount of data that will need to be transferred during the Packer build I decided that a self-hosted runner would be a better solution.
I wanted my runner to execute the build inside of a Docker container so that I could control that environment a bit more, and I also wanted to ensure that it would run without elevated permissions. It took a bit of fiddling to get there, but I'm pretty pleased with the result!
I started by cloning a fresh Ubuntu 22.04 VM off of my new template. After doing the basic initial setup (setting the hostname and IP, connecting it Tailscale), I then created a user account for the runner to use. That account will need sudo privileges during the initial setup, but then I can revoke that access. I also set a password for the account.
sudo useradd -m -G sudo -s $(which bash) github # [tl! .cmd:1]
sudo passwd github
I then installed the systemd-container package so that I could use machinectl to log in as the new user (since sudo su won't work for the rootless setup).
sudo apt update # [tl! .cmd:2]
sudo apt install systemd-container
sudo machinectl shell github@
And I installed the uidmap package since rootless Docker requires newuidmap and newgidmap:
sudo apt install uidmap # [tl! .cmd]
At this point, I just followed the usual Docker installation instructions:
# Add Docker's official GPG key:
sudo apt-get update # [tl! .cmd:4]
sudo apt-get install ca-certificates curl
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc
# Add the repository to Apt sources:
echo \ # [tl! .cmd]
"deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
$(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update # [tl! .cmd]
sudo apt-get install \ # [tl! .cmd]
docker-ce \
docker-ce-cli \
containerd.io \
docker-buildx-plugin \
docker-compose-plugin
Then the actual rootless setup can begin. That starts by disabling the existing Docker service and socket and then running the dockerd-rootless-setuptool.sh script:
sudo systemctl disable --now docker.service docker.socket # [tl! .cmd:1]
sudo rm /var/run/docker.sock
dockerd-rootless-setuptool.sh install # [tl! .cmd]
After that, I started and enabled the service in the user context and enabled "linger" for the github user so that its systemd instance can continue to function even while the user is not logged in:
systemctl --user start docker # [tl! .cmd:2]
systemctl --user enable docker
sudo loginctl enable-linger $(whoami)
That should take care of setting up Docker, and I can quickly confirm by spawning the hello-world container:
docker run hello-world # [tl! .cmd]
Unable to find image 'hello-world:latest' locally # [tl! .nocopy:25]
latest: Pulling from library/hello-world
c1ec31eb5944: Pull complete
Digest: sha256:1408fec50309afee38f3535383f5b09419e6dc0925bc69891e79d84cc4cdcec6
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/