gitlab-runner-vm

This repository contains script that creates virtual machine disk (file).

Script creates temporary virtual machine, installs non-interactively Ubuntu Server 22.04 and latest gitlab-runner and commonly used tools in CI, deletes temporary virtual machine. The result of this script is disk image - file that can be later imported to emulator (qemu). This repository also contains script for creating secondary disk that will be used as build directory and also for files in directories: /tmp, /var/tmp, /var/lib/docker.

Idea is that you can have virtual machine with gitlab-runner already installed and the only thing left to do is to register gitlab-runner to the gitlab.com server.

Assumptions

I am assuming that you are using linux distribution (e.g. Ubuntu) for generating virtual machine. Packer supports different operating systems so if you tinker with configuration files you may make this work on Windows or macOS.

I am assuming that virtual machine will be run under qemu. Generated virtual machine will have package qemu-guest-agent installed. That package improves perfomance under qemu but may also cause problems under different emulator (e.g. VirtualBox). Packer supports different emulators so if you tinker with configuration files you may make this work under VirtualBox or VMware. Make sure to not install qemu-guest-agent and also install appropriate guest package.

Requirements

Creating virtual machine image:

• linux distribution (e.g. Ubuntu)
• internet access
• installed programs (here Ubuntu packages):
  • ansible
  • libvirt-daemon
  • virt-manager
  • libguestfs-tools
  • qemu
  • qemu-utils
  • qemu-kvm
  • packer
  • e2fsprogs
• 4 GB or more RAM
• 20 GB or more free space on disk
• CPU architecture: amd64 (x86_64)

Virtual machine:

• 1 GB or more RAM
• 2 CPU cores or more
• CPU architecture: amd64 (x86_64)
• internet access

Generate virtual machine image

Generate primary disk image with virtual machine:

packer build gitlab-runner.pkr.hcl

Image will be out/vm/gitlab-runner. It is qcow2 file format. Virtual disk size is 10 GB.

Generate secondary disk image used for building in CI:

chmod +x gitlab-runner-create-disk-builds.sh
sudo ./gitlab-runner-create-disk-builds.sh 50

Parameter 50 means disk size is 50 GB. Image will be out/gr-disk-builds-50G.qcow2. It is qcow2 file format. Disk is empty in the beginning so even if virtual size is 50 GB file will be only few megabytes. Size of file will grow over time.

Error "failed to handshake"

It is possible that generating virtual machine fails with error "failed to handshake". It is problem with packer. Packer by default uses outdated algorithms (disabled in official openssh release) when connecting through ssh. If you have recent ssh client version (you should have) then this error will appear.

As a workaround you can re-enable old algorithms when connecting. Edit file gitlab-runner.pkr.hcl and uncomment 3 lines with workaround near the end of file.

Original file:

    #ansible_ssh_extra_args = [
    #  "-oHostKeyAlgorithms=+ssh-rsa -oPubkeyAcceptedKeyTypes=+ssh-rsa"
    #]

After uncommenting:

    ansible_ssh_extra_args = [
      "-oHostKeyAlgorithms=+ssh-rsa -oPubkeyAcceptedKeyTypes=+ssh-rsa"
    ]

Generate virtual machine image again.

Error "failed to transfer file"

It is possible that generating virtual machine fails with error "failed to transfer file". It is problem with packer. Packer uses default ssh settings which have changed in openssh 9. If you have recent ssh client version (you should have) then this error will appear.

As a workaround you can re-enable old behaviour with additional parameters. Edit file gitlab-runner.pkr.hcl and append "--scp-extra-args", "'-O'" to extra_arguments.

Original file:

    extra_arguments = [
      "--extra-vars", "ansible_sudo_pass=user1"
    ]

With workaround:

    extra_arguments = [
      "--extra-vars", "ansible_sudo_pass=user1", "--scp-extra-args", "'-O'"
    ]

Generate virtual machine image again.

Run virtual machine

There are 2 user accounts configured: root (administrator) and user1 (normal account with ability to sudo as root). Password is the same as login.

Create virtual machine in virt-manager and import two generated disks. Run the machine. Login as root. Register gitlab-runner to gitlab server by running script:

/root/register-gitlab-runner.sh REGISTRATION_TOKEN

Script will register three tagged runners to gitlab.com server:

• linux, amd64, shell
• linux, amd64, docker
• linux, amd64, docker-privileged

When virtual machine is powered on and has internet access it will automatically connect to gitlab server and wait for next job to process.