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The thing I'm always interested in finding out is how people using lots of containers deal with security updates.

Do they go into every image and run the updates for the base image it's based on? Does that just mean you're now subject to multiple OS security and patching and best practices?

Do they think it doesn't matter and just get new images then they're published, which from what I can see is just when the overplayed software has an update and not the system anduvraries it relies on?

When glibc or zlib have a security update, what do you do? For RHEL and derivatives it looks line quay.io tries to help with that, but what's the best practice for the rest of the community?

We haven't really adopted containers at all at work yet, and to be honest this is at least part of the reason. It feels like we'd be doing all the patching we currently are, and then a bunch more. Sure, there are some gains, but if also feels like there's a lot more work involved there too?

You can use tools like Snyk to scan images for vulnerabilities (even the Docker(tm) cli tool has one now), you can do things like failing your CI pipeline if there are critica vulnerabilities.

You can also use Dependabot (and others) to update your images on a cronjob-like schedule.

This is a solved problem

This is a solution for the app developer, not for the users that might have to deal with older and unsupported apps.

I highly advise going with Trivy over Snyk or, as it's still in beta at the moment, Docker Scout.

Hadn't heard of Trivy, but glad to see another great product from AquaSec :^)

So i primarily use containers on my local machine walled off from the internet, so it's not a big concern for me. Watchtower [1] is popular among home server users too which automatically updates containers to the latest image.

For production uses I think companies generally build their own containers. They would have a common base linux container and build the other containers based off that with a typical CI/CD pipeline. So if glibc is patched, it's probably patched in the base container and the others are then rebuilt. You don't have to patch each container individually, just the base. Once the whole build pipeline is automated its not too hard to add checks for security updates and rebuild when needed. Production also minimizes the scope of containers with nothing installed except what's necessary so they have few dependencies.

[1] https://github.com/containrrr/watchtower

The gist of what I'm reading here and in other comments is that you either have a full build pipeline and rebuild nightly or on demand, and then roll out container updates too, along with OS updates that are needed? If so, that seems like the "a lot more work" I mentioned, because you still have to update all the systems, but now you have a separate process to follow for all the apps/containers on the systems too, and that's assuming you have a build pipeline.

Or is the assumption that it's all k8s so the container updates being applied part is automated as well? Because assuming k8s in a discussion about containers does seem to be a bad habit from both detractors and proponents of containers from what I've seen, so I wouldn't be that surprised...

(for home user stuff I'm not too worried about finding out if there's a newer image, but I am worried that the image is updated once a year because the publishers of it don't care about base image security)

On a single system with `docker compose`, redeploying containers is just `docker compose down && docker compose up`. On clusters you could use k8s or you could use the same orchestration tools you would use to manage a cluster without Docker like Chef/Puppet to run these same commands. Like whatever orchestration system you have for restarting applications without docker, could be used with Docker as well.

Personally I do think `k8s` is poorly documented and hard to use so I stay away from it. I don't know if there are good alternatives for production uses though.

Don’t use glibc…

I am of course partially joking.

But seriously, use musl libc, build static binaries, build the images from scratch, and have a CI server handle it for you to keep it updated.

Alternatively use a small image like Alpine as base if you want some tools in the image for debugging.

> ...how people using lots of containers deal with security updates.

TL/DR: they don't. #yolo, don't be a square.

We use What's Up Docker [1] to monitor for new versions of docker containers that are created by others (eg. self hosted apps).

For containers we create ourselves, we automatically rebuild them each night which pulls the latest security updates.

[1] https://github.com/fmartinou/whats-up-docker

This is what I get for making a comment on my phone and then watching a movie until the the edit window is closed.

s/overplayed/overlaid/

s/anduvraries/and libraries/

s/looks line/looks like/

As one of those people: we don’t do much, if anything at all. I use containers to try things out behind a VPN like Tailscale. I use containers at work to deploy software but there it is put behind some kind of SSO proxy and lots of different rules apply. Even if I deploy something externally facing, 3rd party containers are going to be on a private docker network - much easier setup than dealing with allow/blocklists and/or firewall rules. Of course I need to take care of my code’s security but that is true with or without containers. For the situations where you deploy 3rd party services facing externally there are solutions (like Watchtower) that I can run and be more confident that this update would not ripple through the system with unknown (and sometimes hidden) consequences.

I build docker images with Nix, so I just update the library by updating my nix flake.

> Whats the alternative to running a big project like say Sourcegraph through a docker compose instance? You have to get set up ~10 services yourself including Redis, Postgres, some logging thing blah blah. I do not believe this is ever easier than `docker compose up -d`.

Even with Docker, it's not as easy as `docker compose up -d`.

You need to setup backups too. How do you backup all these containers? Do they even support it? Meanwhile I already have Postgres and Redis tuned, running, and backuped. I'd even have a warm Postgres replica if I could figure how to make that work.

Then you need to monitor them for security updates. How are you notified your Sourcegraph container and its dependencies' containers need to be updated and restarted? If they used system packages, I'd already have this solved with Munin's APT plugin and/or Debian's unattended-upgrades. So you need to install Watchtower or equivalent. Which can't tell the difference between a security update and other updates, so you might have your software updated with breaking changes at any point.

Alternatively, you can locate and subscribe to the RSS feed for the repository of every Dockerfile involved (or use one of these third-party services providing RSS feeds for Dockerhub) and hope they contain a changelog. If I installed from Debian I wouldn't need that because I'm already subscribed to debian-security-announce@lists.debian.org

I don't back up containers, why would you? I back up the attached volumes, or, more often, their state is fully in a database, which isn't in a container (it doesn't need to be), so I just back the database up.

I meant backing up volumes.

Number one advice for using docker volumes: Don't use docker volumes. Just mount directories or files from the host file system. I have never had a situation where I didn't regret docker volumes but where I regretted host FS mounts.

How do you backup a directory? You tell me, because I have to use a multi gigabyte software package that, mind you, is a pain to install since it consists of like two dozen packages.

UID mapping?

Long lived data is stored as a volume which is just a directory on the host. You just backup the directory like you would any other.

I feel like people are misunderstanding.. containers are a wrapper. You can run whatever APT plugin or unattended-upgrades on the container as well its just linux. You can then even snapshot this new state of the container into a new image if you want to persist them. Like you can fully simulate the usual workflow of a regular server if you really want. They don't take away any functionality.

Another thing is docker is not necessarily the be-all end-all way to deploy things especially in production. If I was running Sourcegraph seriously in production, I might not use it. But it does make it so much easier to just try things out or run them as a hobbyist.

> You can run whatever APT plugin or unattended-upgrades on the container as well its just linux.

Only if the software inside was installed with APT. When you just do `docker compose up -d` you have no idea how software inside is installed so you need to poke around as if you had installed it without docker.

> Another thing is docker is not necessarily the be-all end-all way to deploy things especially in production. If I was running Sourcegraph seriously in production, I might not use it.

But containers are increasingly the only supported method, because developers assume every production's constraints/preferences look like their own. For example https://docs.sourcegraph.com/admin/deploy only lists the following options:

* VMs

* "install script" unsuitable for use outside a dedicated VM: (re)installs k3s (as a one-off without updates as far as I can tell), overwrites existing config files, disables firewall

* k8s

* Docker-Compose

> But it does make it so much easier to just try things out or run them as a hobbyist.

Sure, I definitely agree with that

I really don't know what other production methods you would expect to find before docker.. install scripts and READMEs is pretty much all there is or ever was for complex software with many interlocking components. I don't really think there's ever been a way to install an entire stack like that from a single apt command. It's always been bespoke scripts and procedures with a lot of manual steps.

What I expect is a list of dependencies I can install myself, instructions to compile the code, and a description of config files to write/edit, eg. to point the main software to its dependencies' URLs. Like this, for example: https://docs.joinmastodon.org/admin/install/

So basically, you want a Dockerfile.

Yes this is called a Dockerfile. Better yet, its not just a list, its working code so you don't have to run through the list manually.

While a readable Dockerfile can work as documentation, there are a few caveats:

* the application needs to be designed to work outside containers (so, no hardcoded URLs, ports, or paths). Also, not directly related to containers, but it's nice if it can be easily compiled in most environments and not just on the base image.

* I still need a way to be notified of updates; if the Dockerfile just wgets a binary, this doesn't help me.

* The Dockerfiles need to be easy to find. Sourcegraph's don't seem to be referenced from the documentation, I had to look through their Github repos to find https://github.com/sourcegraph/sourcegraph/tree/main/docker-... (though most are bazel scripts instead of Dockerfiles, but serve the same purpose)

Wait wait wait. Docker has two use cases and you're conflating them. The original use case is:

Project Foo uses libqxt version 7. Project Bar uses libqxt version 8. They are incompatible so I'd need two development workstations (or later two LXC containers). This is slow and heavy on diskspace; docker solves that problem. This is a great use of docker.

The second use case that it has morphed into is:

I've decided stack management is hard and I can't tell my downstream which libraries they need because even I'm no longer sure. So I'll just bundle them all as this opaque container and distribute it that way and now literally nobody knows what versions of what software they are running in production. This is a very harmful use case of docker that is unfortunately nearly universal at this point.

> Project Foo uses libqxt version 7. Project Bar uses libqxt version 8

Pretty much fixed by asdf or any sane manager.. Also, two containers aren't slow at all, but rebuilding one completely from scratch is.

The latter is a good use case. No big deal to include a commit/version number, and a list of packages / libraries used in a lock file..

The problems with docker I have are: no lock files to pin versions. No integration with other package management tools. For example, I want to install my dependencies as a step in Docker. I don't want to manually copy over the list of dependencies from my lockfiles (gemfile, package, etc). The reason why I'd want this is that it speeds up builds.

I don't understand how stack management without Docker is any better. As far as I can tell, the alternative without Docker is the same. A list of `apt install`s with no versions listed or no mention of dependencies at all. If you used a lockfile in a language package manager, you can use the same lockfile in the docker too.

So, as an example, 20 years ago when we started a project the devs and I (the sysadmin) would sit down and have a meeting where they would talk about what libraries they wanted to use (think CPAN or PEAR) and I would tell them what versions were compatible with our servers and those are the versions they would use for the lifetime of the project. Docker came about because devs got tired of hearing "no" to upgrades and admins got tired of saying it. But in 2023 if there was a zero day (though we didn't call them that back then) for libqxt7.2 (but not 7.0 or 8.1) I could tell you immediately if we were impacted. In 2023 I can't even tell you how many versions of OpenSSL are on my laptop right now as I type.

Stack management is a bullshit job, and the downstream will hit the libqxt-7 vs libqxt-8 problem anyway.

Exactly, Docker + Compose is the best way of running server software these days.

I keep my compose files in source control and I have got a CI server building images for anything that doesn’t have first party images available.

Updates are super easy as well, just update the pinned version at the top of the compose file (if not using latest), then ’docker-compose pull’ followed by ’docker-compose up -d’

The entire thing is so much more stable and easier to manage than the RedHat/Ubuntu/FreeBSD systems I used to manage.

(I use Alpine Linux + ZFS for the host OS)

I spent the last couple of days trying to set up some software waddling though open source repositories, fixing broken deps, pinning minor versions, browsing SO for obscure errors... I wish I had a Docker container instead.

> `apt remove` will often leave other things lying around.

If you mean configuration files, then this is by design.

`apt purge` removes those as well.

I just found about a half a gigabyte of files from programs I uninstalled two laptops ago on my machine, and files from a Steam game I got a refund for because it would crash after fifteen minutes. It’s frustrating.

> Whats the alternative to running a big project like say Sourcegraph through a docker compose instance? You have to get set up ~10 services yourself including Redis, Postgres, some logging thing blah blah. I do not believe this is ever easier than `docker compose up -d`.

Maybe my recollection is just fuzzy, but it seems to me back in the day many projects just had fewer dependencies and more of them were optional. "For larger installations and/or better performance, here's where to configure your redis instance."

Instead now you try and run someone's little self-hosted bookmark manager and it's "just" docker-compose up to spin up the backend API, frontend UI, Postgres, redis, elasticsearch, thumbor, and a KinD container that we use to dynamically run pods for scraping your bookmarked websites!

I'd almost _rather_ that sort of setup be reserved for stuff where it's worth investing the time to set it up.

All of this complexity is easier to get up this way, but that doesn't make it easier to properly manage or a _good_ way to do things. I'd much rather run _one_ instance of Postgres, set up proper backups _once_, perform upgrades _once_, etc. Even if I don't care about the hardware resource usage, I do care about my time. How do I point this at an external postgres instance? Unfortunately, the setup instructions for many services these days start _and end_ at `docker-compose up`.

And this idea of "dockerfiles as documentation" should really die. There are often so many implicit assumptions baked into them as to make them a complete minefield for use as a reference. And unless you're going to dig into a thousand lines of bash scripts, they're not going to answer the questions you actually need answers to like "how do I change this configuration option?".

> figured out how to uninstall a piece of software. `apt remove` will often leave other things lying around.

What's the Docker way of uninstall? In most cases Docker packaged software uses some kind of volume or local mount to save data. Is there a way to remove these when you remove the container? What about networks? (besides running prune on all available entities)

You can `docker rm -v <container>` to remove a ccontainer + its volumes. For larger stuff typically I just read the docker-compose file with all of that listed in one place, so its pretty easy to just `docker rm` the volumes and networks. With apt I have no idea what files were added or modified and there's no simple "undo".

I wasn't aware of '-v' so thanks for that.

You can list package content with 'dpkg -L', although, granted, it doesn't cover files that were somehow created by the install script. Also 'apt purge' removes all files including config.

It’s very nice, although I had a hard time getting the btrfs driver to actually remove the backing store a year or so back.

> All the traditional distribution methods have barely even figured out how to uninstall a piece of software. `apt remove` will often leave other things lying around.

Sounds like an issue that needs to be fixed instead of working around it. Also dependency hell. Few distros manage those hard problems nicely but they do exist.

> A week ago I wanted to learn more about data engineering - got a whole Apache Airflow cluster setup with a single compose file, took a few minutes.

Off-topic, but how did you like it? Tried it out a couple of years ago and felt like it overcomplicates things for probably 99% of use cases, and the overhead is huge.

Over-complicated, I agree. "This cluster could have been a Makefile"

There probably are good reasons to use it when you have complex distributed DAGs though.

> All the traditional distribution methods have barely even figured out how to uninstall a piece of software.

The most traditional way is to compile under /usr/local/application_name, and symlinking to /usr/local/(s)bin. Remove the folder and the links, and you're done.

> `apt remove` will often leave other things lying around.

"remove" is designed to leave config and database files in place, assuming that you might want to install it later without losing data. apt has "purge" option for the last decade which removes anything and everything completely.

> Whats the alternative to running a big project like say Sourcegraph through a docker compose instance? You have to get set up ~10 services yourself including Redis, Postgres, some logging thing blah blah. I do not believe this is ever easier than `docker compose up -d`.

Install in a single or on a couple of pet servers. Configure them, forget them. If you fancy, spawn a couple of VMs, and snapshot them daily. While it takes a bit more time, for a single time job, I won't mind.

Docker's biggest curse is it enables many bad practices and advertises as best practices. Why enable SSL on a service while I can add a SSL terminating container? Why tune a piece of software if I can spawn five more copies of that for scaling?, etc.

Docker is nice when it's packaged and documented well, and good for packaging stable meta-utilities (e.g.: A documenting pipeline which runs daily and terminates), but using it as a silver bullet and accepting its bad practices as gold standards is wasting resources, space, time; and creating security problems at the same time.

Basically you are okay with installing containers blindly but not installing services and learning apt purge. it just comes down to familiarity.

Obligatory XKCD: https://xkcd.com/1988/