Docker Official Images Are Moving to Alpine Linux

https://www.brianchristner.io/docker-is-moving-to-alpine-linux/

by infodroid • 10 years ago

246 124 10 years ago

brianchristner.io

Zekio• 10 years ago

Damn, the Alphine linux ISO is tiny

anon9872• 10 years ago

Red Hat's Project Atomic "installer ISO" is ~630mb and the uncompressed qcow2 is >900mb.

I was impressed with Atomic's size, but seeing how much smaller Alpine is, I can't help but wonder what all the additional size is in Red Hat's images.

rdtsc• 10 years ago

RHEL is an enterprise OS. It is designed to handle various drivers (video, network, storage). It has monitoring, auditing, reporting stuff. Some of those dependencies are bringing others (say the monitor needs a mail client to sent messages, ok, install the mail client, oh looks like that brings in perl, etc). Then there might be multiple version of said monitoring. And think they just never really try to make it small. That is just what their customers pay for.

If Alpine did what RHEL does out of the box it would be hundreds of MBs as well.

lisivka8• 10 years ago

Fedora 23 minimal image in docker: 43MB in archive.

With tons of packages available (with patches and live maintainers). With formal stabilization process. With well tested package management system (with hundreds of bug fixes in 20 years of use). Which can be used as host and as container (so you will need to learn well and support just one OS). With Systemd, which handles daemons well. With well supported LTS version (RHEL/CentOS). With option for paid support. With glibc, which is much faster and feature-richer than musl.

Why I should use Alpine, which cannot even handle versioned dependencies between packages? Literally, I cannot tell that package A needs package B >= 3.x or package C < 2.x, which causes serious troubles in complex systems.

JasonSage3• 10 years ago

Last I'd heard (I believe) the creator of Alpine Linux was looking for work and the future of the project was a bit uncertain. I'm happy to hear that he'll be able to continue working with Alpine Linux and that we'll still be able to make great Docker images with it.

fidget• 10 years ago

Wait, the future of Alpine is dependant on 1 person? I'll stick with Ubuntu I think

marshallford• 10 years ago

I agree, if that is the case those using Alpine in production should be wary.

JasonSage3• 10 years ago

Maybe "future of the project is a bit uncertain" was a bit too strong. Here's all I originally saw:

https://twitter.com/richfelker/status/662535718267392000

Either way, it seems it's now getting some backing by Docker. I can only imagine that the number of contributors and packages for it will grow and mature.

kev009• 10 years ago

Alpine makes me not totally hate Linux, and musl libc is just great code. Good to see them getting publicity and adoption!

lisivka8• 10 years ago

musl is about 2x slower than glibc: http://www.etalabs.net/compare_libcs.html . Other libraries are even worse.

hga• 10 years ago

Note that comparison is by the musl author, but it's several point releases old for it and glibc.

regecks• 10 years ago

That seems ... brave? I have used Alpine a few times in Docker images and it's fantastic, but we did run into incompatibilities due to musl.

gtaylor• 10 years ago

I've ran into this as well. Having a hard time remembering what the issue was. Maybe DNS-related?

stonogo• 10 years ago

These incompatibilities arose from software that was written to rely on glibc-specific name resolution quirks. Neither musl nor docker rely on these misplaced expectations, but unfortunately some projects have decided to blame a standards-compliant libc implementation rather than fix their own software.

coleca• 10 years ago

Looks like the DNS issue might finally be getting resolved:

https://github.com/gliderlabs/docker-alpine/issues/8

kylequest6• 10 years ago

Alpine is pretty nice though using it in containers you are not getting the best part of it: the hardened kernel. I'd say Alpine is a better fit for the host OS where you have a few moving parts.

It will be great for compiled language base images, but even there it might be tricky if you rely on 3rd party packages. Libc compatibility issues are also real. It's great that they are slowing addressing them though.

daxfohl• 10 years ago

Wouldn't CoreOS be the better host though, if just hosting containers is the only goal? Or are there things Alpine would do better?

GauntletWizard• 10 years ago

Great move by the docker team. The promise of containers has always been to make the environment that processes live in super lightweight, with a minimum of unnecessary binaries and permissions. Having a full ubuntu installation per container has been a major hazard to that, as it's required the use of overlays and other tricks to avoid having huge disk overhead per container. Moving to a much lighterweight base image means you need fewer overlays, because you can pay the 5mb cost for days. It also reduces the attack surface by a lot, for much greater security.

mverwijs3• 10 years ago

It was not the promise as I understood it. As I understood it the promise was to have my production environment run on my desktop.

I cannot run my production on Alpine.

(Yes, every startup I know can. But I work for a lot of older companies that have legacy systems. And that is a huge market that cannot use Alpine.)

auvi• 10 years ago

does this mean i can practically email a container? wow!

iso-8859-1• 10 years ago

What's with the weird comparison to the Windows start button? Is that if you encode the button as a BMP? Or is it the size of the compressed vector graphics? Or is it the size of the binary used to implement the start button? Does it include the shared libraries that binary uses? wtf.

mastazi• 10 years ago

Exactly what I thought while I was reading that sentence.

x5n1• 10 years ago

w00t

gtirloni• 10 years ago

Alpine is fine but it would be really nice to have smaller images from the RHEL/CentOS/Fedora or Debian/Ubuntu ecosystems, if that's possible.

sandGorgon5• 10 years ago

+1 I would love to have a stripped down Debian 8 base.

mverwijs3• 10 years ago

    sudo apt-get install debootstrap
    mkdir deb8
    sudo debootstrap jessie deb8

Combine that with apt-cacher-ng and whooosh. And now all you have to do is tell Ansible what needs to get done in that chroot. And you have a container that matches production one-on-one.

u320• 10 years ago

On fedora, you can do something like

  mkdir /tmp/myimage
  dnf --releasever=23 --installroot=/tmp/myimage install <package-name>
  rm -rf /tmp/myimage/var/cache/dnf
  tar zcvf - /tmp/myimage | docker import - myimage

Gives you an image that is ~30M (15M compressed) plus the size of whatever package you are installing. The advantage is that you get access to Fedora's package database with security updates.

This could probably be slimmed down further with custom versions of the base packages.

jmspring2• 10 years ago

Blog claims Alpine is based around being secure and light weight...but gives no indication on why it is secure. Oh, lightweight because of busy box? Is there scrutiny on packages installed? I don't see the security component.

Maybe Docker can reveal more there, though given how they iterate and things break, I'm not sure they are willing (or capable).

hiou• 10 years ago

From the article > 2. Security is improved as the image has a smaller footprint thus making the attack surface also smaller

Not saying you need to agree with that. But that does appear to be at least an "indication"

jmspring2• 10 years ago

Image footprint has nothing to do with the packages installed in that image.

This is complete hogwash from a security point of view.

Yes "smaller" could = "more secure", but, yeah, no.

viraptor• 10 years ago

From the Alpine linux site: "Alpine Linux was designed with security in mind. The kernel is patched with grsecurity/PaX out of the box, and 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."

I got excited, but then remembered - grsec will not affect containers. Neither will PaX unfortunately. PIE + stack smashing protection is already available in most serious distros. From the basic info I can find, I don't see a huge difference.

For comparison Ubuntu provides its list here: https://wiki.ubuntu.com/Security/Features It's similar to Fedora: https://fedoraproject.org/wiki/Security_Features_Matrix And to Arch (no nice table though) https://wiki.archlinux.org/index.php/DeveloperWiki:Security - Alpine doesn't seem to provide similar summary.

[edit: sorry, I stealth-edited the realisation]

kalmi10• 10 years ago

Containerization uses the host's kernel, so it doesn't matter what the kernel is in the image.

Edit: I see your edit. Yep.

jwatte2• 10 years ago

Having less crap in by default reduces the attack surface area. Having a smaller libc makes it easier to audit. (It still needs to actually be audited of course)

mverwijs3• 10 years ago

This does not give me a vote of confidence: http://lists.alpinelinux.org/alpine-security/

hogeland• 10 years ago

Good, using Ubuntu as a base for official images always seemed dumb.

bcook• 10 years ago

Explain (consisely).

infamouscow• 10 years ago

Because all you're really doing is increasing your attack surface and wasting storage space. If you have a need for a specific piece of software, you should be able to identify that and include that in your docker image. Starting with a kitchen sink is only good when you're too lazy to spend an hour to understand what your software depends on.

siliconc0w• 10 years ago

Ubuntu is great because people already understand it and probably already know how to install their apps on it which makes moving to Docker easy. Most businesses unsurprisingly don't like the idea of running on a OS they never heard of with tooling their engineers don't have experience with, limited community or enterprise support, or even internal repos.

Alpine may be the 'technically correct' choice but Ubuntu is easily a much better business choice.

vidarh3• 10 years ago

Nothing stops people from using the ubuntu images as the base for their own containers, so this is pretty much irrelevant.

sandGorgon5• 10 years ago

What worries me about Alpine is that it invents YET-ANOTHER package manager(apk) . I think it claims that it builds on top of Gentoo... But could someone explain why Deb or rpm could not be used.

Does using Deb or rpm screw up size or security in some way. We could also have gotten access to the Debian/Fedora repository in a pinch. Not all of us run statically compiled go executables and often have tons of dependencies that need to be installed for webapp.

P.S. And the package manager apk is unfortunately named to conflict with IMHO the biggest package repo in the world:Android. It is virtually impossible to Google anything meaningful without running into android.

monkmartinez4• 10 years ago

What is the fall back if a package is not available? For example, I was able to find an APK for python 3.5.1-r0. However, I can find nothing for Python 3.4 except a bug report and some hacky fixes.

Also, it looks like running anything that require binaries that have compiled against glibc will be wonky as hell.

jwatte2• 10 years ago

The whole point is: Do not run with glibc! If you need something that's not available, build it.

vidarh3• 10 years ago

What is the fall back if a package is not available?

Then use another distro if you're not prepared to invest the effort into it. The point of people wanting to move Docker images to distros like Alpine is to minimize size. That matters if you're going for massive density etc., but depending on your use cases, using e.g. Ubuntu or Debian or Centos as a base can be just fine.

It's worthwhile to move the official images to it because they are used so widely. It's not necessarily worth it for every random image someone puts together.

awinter-py• 10 years ago

There are even more exciting libs like numpy/scipy which rely on a system BLAS package before they can even compile (and take forever). This is a problem that Ubuntu has made less difficult but a better solution would be package managers for C and fortran.

If the 'alpine experiment' results in more work on portable build tools for complex projects, that's a win for the open source community.

JasonSage3• 10 years ago

Alpine uses the musl libc and the OpenRC init system. In order for a deb or rpm package to install correctly, the binary would have to be built for musl already and the necessary information to set up services on the init system be provided. I don't know how the latter works for other package managers, be it in a way compatible with OpenRC or not.

P.S. In my experience APK has been rock-solid and simple to use.

sandGorgon5• 10 years ago

this is a huge blocker - we are already in a world where RPM and DEB dont get released in tandem. And it has taken millions of man hours to resolve deep problems in dependency resolution, circular dependencies,etc.

For a startup like mine, I already estimate I'm installing hundreds of libraries (Ruby gems, Python wheels, etc). I'm pretty sure some of them are weird dependencies... but I have come to trust apt and dnf.

There is zero reason for me to trust Alpine's new package manager that is managed by a single dev. Disk space is cheap - my time is not.

This is the big blocker - if Alpine can figure out a way to co-exist with apt or dnf (pick your own poison), that makes it compelling.

But then again, I would ask - can something like Alpine be achieved with debian or centos. Even if it is 3X the size (30mb) ?

EDIT: I run a fat docker VM based on debian with nginx, rsyslog, postgresql and ruby+puma using supervisord. There is absolutely ZERO need for OpenRC. I have been running this in production for over 18 months since before Docker was this stable.

ape4• 10 years ago

The name conflict with Android make this the worse named piece of software. Any other name would be better.

digi_owl4• 10 years ago

From their wiki, the format itself it basically a tar.gz wrapped in a digital signature.

hharnisch• 10 years ago

Does DNS based service discovery work yet? If not these images don't play nice with kubernetes.

shykes• 10 years ago

Yes. And Docker 1.10 does DNS service discovery out of the box.

justincormack• 10 years ago

Based on my understanding of the threads on the Musl list, part of this was some features that are now implemented in Musl, and part was Kubernetes using DNS in ways that are incorrect.

steeve2• 10 years ago

Don't have the link here to musl added domain support on Jan 26 2016, so it's close :)

steilpass• 10 years ago

As far as I can see it's currently in master: http://git.musl-libc.org/cgit/musl/commit/?id=3d6e2e477ced37...

But has not been released yet: http://wiki.musl-libc.org/wiki/Roadmap#musl_1.1.13 http://git.musl-libc.org/cgit/musl/

gizi• 10 years ago

I agree with snubbing glibc, systemd, and apt-get. Seriously, it is about time to put an end to the bloated fatibubbul fest going on over there! I intend to move my dockers to alpine. I will only come back to debian after and not before they have downsized, trimmed and layed off all the useless fat around their bellies!

digi_owl4• 10 years ago

Dunno if it is about snubbing, but i get the impression that having systemd inside the container makes it damn hard to work it if you do not also have it outside the container. And at that point, systemd is likely to take over control completely rather than play nice with docker.

ownagefool2• 10 years ago

Na, that's not how it works at all. When you run a docker container, you'll be running your app directly, thus systemd won't be involved and isn't even needed within the container.

The problem with debian and centos is they weren't create with containers in mind, thus by default their base images pull in a lot of stuff that's required to actually init hardware.

We can see with fedora that efforts have been made to slim it down, I suspect as containers become a popular usecase we're going to see smaller base containers, except with access to 30,000 stable packages and a mainstream community.

dschiptsov• 10 years ago

So, that Alpine linux has more man-power and resources to maintain kernel and core libraries stability and binary compatibility than Ubuntu (with its huge community) or Fedora/RH/CentOS (with its money)?

Does Oracle runs on it?

ageofwant4• 10 years ago

Alpine is built by one guy, that now works for Docker. So I understand. I really hope I'm wrong.

uggedal3• 10 years ago

Alpine is not built by one guy. There is only one creator though.

RaleyField• 10 years ago

ls -l ~/.bashrc

ARothfusz• 10 years ago

Why does the size of a base image matter? What happened to the shared layers between images? Did the new file systems completely sacrifice that?

The original filesystem (AUFS) used shared read-only layers, so if two images used the same base image, only their differences contributed to disk usage. I know there has been a lot of work to move to filesystems supported by more kernels, but if shared layers have been sacrificed, that makes me sad.

vidarh3• 10 years ago

Why does the size of a base image matter? What happened to the shared layers between images?

It matters because when bootstrapping new hosts you still need to download all the base images, and because in many systems the base images can come to totally dominate the storage needs.

It still can often save a lot, but it's not enough for a lot of places where people want to use Docker.

icebraining4• 10 years ago

It matters because when bootstrapping new hosts you still need to download all the base images

Why not just put those images in the snapshot/installer you're using to initialize those hosts?

lisivka8• 10 years ago

If you need a library, you will download it anyway. But you can download it once, in base image, or multiple times. IMHO, the fatter _base_ image is, the better.

Ideally, base image must be full installation of everything, one large image for all. You will just download it, and it will just work.

ageofwant4• 10 years ago

This is silly nonsense. Before I care about image size or "security", I need to ship my products. After I've accomplished that, I make sure my firewall is still good and if necessary buy $20 more volume space.

You have "solved" a problem that no one has. I don't care about image size, and neither should you. I don't care about container security, and neither should you. How does struggling with a anaemic non-distribution hacked together by a handful of kids that believes software is about size and "security" help me accomplish shipping shit ? It does not.

This decision is ill-advised.

duaneb• 10 years ago

The base image size does not explain the switch in package manager. Why not use the ubuntu one, and simply trim the base image to minimal?

What a waste of energy for everyone so they can save a few cents on bandwidth.

tommis• 10 years ago

To you complaining "its just one guy maintaining the distro" etc. Did you not read the article?

Docker has hired the creator of Alpine Linux, Natanael Copa <

pepijndevos• 10 years ago

From the Alpine website, the iso is 82 MB. What's up with that?

profmonocle• 10 years ago

Well, the ISO includes the Linux kernel. A Docker image only comes with user space components since the host provides the kernel, so an ISO would need to be larger.

steeve2• 10 years ago

Boot2docker creator here (although I don't actively maintain it)

TCL is only 9 mb, oh which the kernel is 4mb if my memory serves me well. So most of the size is likely not due to the kernel (modules maybe?)

I'd like to see an Alpine based b2d though

diebir• 10 years ago

Awesome, can we now move Docker somewhere ever further, where it can't be seen or found all together?

gaius2• 10 years ago

Red Hat, Debian, Suse. Stood the test of time. Everything else is not a wise choice for anything but a personal system.

digi_owl4• 10 years ago

Slackware?

gaius2• 10 years ago

Sure, but my point stands. Will Alpine exist in 5 years, 10 years?

hackerboos2• 10 years ago

Has Alpine Linux solved the glibc problem? I recall you can't simply install Oracle Java 7+ on Alpine linux without a lot of setup first because of the dependency on glibc.

bleakgadfly• 10 years ago

Alpine Linux has a glibc solution. The glibc problem lies with other applications.

hackerboos2• 10 years ago

I think it's easier to get Alpine to fix the issue than Oracle. Until then the issue remains

https://github.com/gliderlabs/docker-alpine/issues/11

kylequest6• 10 years ago

Sort of... They have a glib package. Take a look at this Atlassian post to see how you can make your Oracle Java based apps run with Alpine: https://developer.atlassian.com/blog/2015/08/minimal-java-do...

I still prefer to use DockerSlim to shrink images. I'm too lazy to worry about the Alpine gotchas :)

tianon• 10 years ago

Primary curator of the program here (https://github.com/docker-library/official-images/blob/319cb...).

"Moving" is a bit of a strong word. It would be much more accurate to say "providing alternatives". For example, the "golang" image now has an "alpine" variant for each supported version (https://hub.docker.com/_/golang/), but the default variant is still Debian-based (especially given that switching the base outright would break far too many existing Dockerfiles). Additionally, the documentation calls out that there might be libc compatibility issues in the spirit of trying to ensure our users are properly informed about the potential problems they might run into in their quest for the smallest possible base: https://github.com/docker-library/docs/blob/b7b6b86124682ef1...

I would definitely welcome PRs to make this verbiage more accurate or more informative of pros and cons.

Docker Official Images Are Moving to Alpine Linux

Related Stories