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A BSD person tries Alpine Linux

Friday 26 April 2024

In February last year I wrote about running a FreeBSD desktop, and
concluded that sometimes you need to give yourself permission to
tinker.

Well recently I've started tinkering with Alpine Linux! It's been
recommended to me for years, so I'm finally getting around to
checking it out. There's a lot to like if you come from BSD, which
we'll dig into here.

Booting a new Alpine ISO on OrionVM

A potted history

The Alpine website describes it as:

    an independent, non-commercial, general purpose Linux
    distribution designed for power users who appreciate security,
    simplicity and resource efficiency.

Its small footprint and design decisions also make it more secure:

    All userland binaries are compiled as Position Independent
    Executables (PIE) with stack smashing protection. These proactive
    security features prevent exploitation of entire classes of
    zero-day and other vulnerabilities.

Natanael Copa discussed the genesis of the project back in 2005,
making it older than I realised. Like the BSDs, it's found its way
into embedded systems, routers, and mobile devices, as well as
general purpose servers and desktops.

Alpine is also a popular base for use in Linux containers, owing to
its compact size and limited dependencies. There are also toolchains
for easily running it in a chroot(8), which is interesting for
someone who uses NetBSD chroots(8) and FreeBSD jails extensively for
testing and deployments.

Installation

Alpine comes in a few different versions, including builds for ARM,
PPC64, x86, and x86_64.

I downloaded the Xen ISO image because I was booting it on a VM at
work, before realising I misread Dom0 as DomU. The former refers to a
Xen hypervisor, not a guest. Either way, it booted and installed the
same as a standard ISO.

The install process is about as simple as you could make it. You log
into the live environment with root and no password, then execute
setup-alpine.

You're asked basic questions for your keymap, networking, timezone,
and root authentication. You can also inject an SSH key from the
start, which is useful if you're deploying a fleet of VMs or servers
with an orchestration tool after the fact, or you're deploying to a
mediocre hosting provider that doesn't give you an OOB console.

You're also given the choice of a few different SSH servers and ntp
clients, which let me choose my preferred OpenSSH and openntpd. It
also correctly identified it was operating under Xen.

Screenshot of a portion of the Alpine Linux installer, showing the
mirror selection, user config, and Xen installation.

It can also configure an LVM, but I stuck with what Alpine calls
standard sys partitions for now. This uses ext4.

Post-install and exploration

Booting into Alpine for the first time, your given a hint as to why
it's special: dmesg(1) informs you you're running OpenRC! It's
portable, small, fast, efficient, transparent, and secure. It's also
very familiar to a BSD person used to writing rc scripts. /etc/
rc.conf and crond(8)!? Yes!!!

At the risk of embellishing my feelings about this, it is such a
relief that there are Linux distros like Devuan, Gentoo, and Alpine
using this. It's a breath of alpine air, and has legitimately made
Linux fun again.

Screenshot showing dmesg output on first boot.

Along with OpenRC, Alpine is bundled with musl, and runs busybox.
Both are obviously more limited than GCC and the GNU coreutils, but
they further contribute to the base system's smaller size and attack
surface. llvm is also available, as is the MirBSD Korn shell, one of
my two preferred interactive shells.

    Um, Ruben, I'd like to interject for a moment. What you are
    referring to as Linux, is in fact, GNU/Linux, or as I've recently
    taken to calling it, a GNU grilled cheese sandwich merely
    featuring Linux as the...

... nope!

Packages

Speaking of installing packages, let's take a look at that. Alpine's
default package manager is apk. As is normal on Linux, this handles
updating the base system and all packages, because it makes no
distinction. I'd be interested to see if I could also run an
unprivileged copy of this as I like to do on the BSDs, but I haven't
checked yet. There's also pkgsrc, so no biggie.

Configuration is in /etc/apk/repositories, where you can enable the
community repo by uncommenting the second URL supplied by the
installer. Alpine also has a testing repo, and you can add your own.

Usage is easy, though I've still been mistyping apt install instead
of apk add, because old habits die hard. There's an official web
interface, and Alpine repos are on pkgs.org.

A few packages later, and I had my "essentials" going, like I do on
my console-only laptop:

Alpine running tmux, htop, zpool, and cmatrix.

Perhaps the package I was most surprised about was zfs. It was
literally two commands to install and load the kernel module (though
obviously root on ZFS would be more involved). What that would look
like after an upgrade I'd have to see, but thus far I'm impressed.

# apk add zfs zfs-lts
# modprobe zfs

Conclusion

I've barely scratched the surface, but there's enough here for me to
seriously consider a switch to it as my primary Linux distro for
testing and servers. I love that htop(1) and lsof(1) only shows a
small list of recognisable processes, that it uses OpenRC, that
package management seems straight forward, and that it's so simple to
configure. I've wondered what a modern, functional "Occam's Linux"
would look like. This is it.

I'd be interested in seeing if uutils runs if I need something more
than busybox, but for a server I doubt it.

Alpine running the Alpine mail client

I heard you liked Alpine, so I etc...

  * Published: 2024-04-26 08:23:08 +1000 AEST
  * Tagged: software, alpine-linux, bsd, grilled-cheese-sandwiches,
    linux, openrc
  * Written in: Sydney

Me!

This was posted by Ruben Schade, a technical writer and IaaS engineer
in Sydney, Australia. Hi! You can shout me a coffee or send a comment
here.

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