bean

Creating a boot ISO with containerd/buildkitd, for lima.

Lima:

Lima launches Linux virtual machines, using QEMU.

An image has to satisfy the following requirements:

• systemd or OpenRC
• cloud-init
• The following binaries to be preinstalled:
  • sudo
  • sshfs
  • newuidmap and newgidmap (shadow)

Format:

• disk.img
  • kernel (bzImage)
  • rootfs (rootfs.ext4)
• cidata.iso
  • user-data (cloud-init)
  • generated by: limactl

Bootloader:

• UEFI (instead of BIOS)
• GRUB

Architecture:

• amd64 (x86_64)
• arm64 (aarch64)

Software:

• sshd
• containerd
• buildkitd
• nerdctl

Docker:

nerdctl is a Docker-compatible CLI for containerd. 🤓

nerdctl is a non-core sub-project of CNCF's containerd.

# nerdctl build -t foo .
# nerdctl run -it --rm foo

Toolbox:

The regular image does not have a package manager, but it is possible to install a toolbox container.

The default toolbox uses the alpine distribution. That makes it possible to install apk packages.

2.7M /var/lib/toolbox/alpine_latest.tar

Based on CoreOS Toolbox, but using nerdctl.

Design:

This OS follows a layered "three images" approach:

1. Base OS, based on musl/busybox (like Alpine)

2. "boot2nerdctl", adds containerd and buildkitd

3. Adding support for python3 and cloud-init

---

qemu

pstree

init-+-acpid
     |-buildkitd---5*[{buildkitd}]
     |-containerd---7*[{containerd}]
     |-klogd
     |-sshd---sshd---sshd-+-bash---pstree
     |                    `-2*[sshfs---3*[{sshfs}]]
     |-supervise-daemo---lima-guestagent---3*[{lima-guestagent}]
     |-2*[supervise-daemo---getty]
     |-syslogd
     |-udevd
     `-udhcpc

$ lima nproc
4
$ lima free -m
              total        used        free      shared  buff/cache   available
Mem:           3942          47        3761           3         133        3837
Swap:             0           0           0
$ lima df -h /
Filesystem                Size      Used Available Use% Mounted on
/dev/root                96.9G    269.4M     92.6G   0% /
$ lima sudo nerdctl version
Client:
 Version:	0.12.0
 Git commit:	<unknown>

Server:
 containerd:
  Version:	1.4.9
  GitCommit:

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Building all the required software is done using Buildroot.

The download is around 100 MB, with all batteries included.

98M	output/disk.img.gz

See https://github.com/afbjorklund/buildroot4containers

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There is currently no public release of Bean OS available.

Written by Anders F Björklund https://github.com/afbjorklund

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Green Beans image credit: Designed by macrovector / Freepik