The cost of complexity showing itself.
A sysadmin friend of mine is totally against docker and his reason is that he wants as little complexity as is needed on his systems. Complexity, he says, leads to emergent behavior.
A sysadmin friend of mine is totally against docker and his reason is that he wants as little complexity as is needed on his systems. Complexity, he says, leads to emergent behavior.
- If you throw the box out, you know you did no harm to other boxes.
- If you change your floor, you know you didn't wipe out something useful.
- Aaand you can `git switch` to a well known state
Ofcourse it's not 100% like that, in reality you still have to have some kind of consistency on where you put your docker-compose file, Dockerfiles for all the boxes, where you mount your volumes (in some folder or scattered all over system), maybe dealing with host firewall, dealing with not-commiting secrets into git etc.
But overall, it's very positive - docker-compose is (almost) one-stop file you need to see all your references to volumes, Dockerfile, network configurations, environment files with secrets.
It seems less complex to manage a bunch of systemd services than one pile of systemd services that are managed and logged one way and bunch of docker services that are managed and logged another way.
If your standard is dealing with systemd units, it may make sense to make your containers conform to that (thereby deviating from the most common way of managing containers). Maybe it's what I'd do in a larger operation. For my personal use I find it the most pragmatic to just use Docker since it's reasonably well documented, has reasonably low friction in usage and is very easy to set up.
Howevre looking at the whole chain of process:
I can deploy service/app on my local machine, including dependencies, along with other independent services/apps.
So, I can reuse what I have for production. But ofcourse, local development stuff will have different env variables, some docker-compose etc.
But it is a joy, when you can:
1. git clone something
2. set some env variables
3. docker-compose up -d
And your app, along with database, elasticsearch, whatnot - is running
So for development purposes it really helps. For deployment purposes - if that box is dedicated to something, then yeah, many of the good use cases not necessary.
(just not from the system perspective, but from the "reasoning about it" perspective)
Even container security and compliance around it is a measurable loss on its own which is trivially solved if you have bare EC2 instances and a patch cycle.
The emergent behavior of containerization has had an overall positive effect, even if it has annoying costs.
They were also better organized. Ebay and Amazon were leaner and more pleasant to use.
Citation needed. There were a lot less sites, maintenance windows in the hours weren't uncommon, there was no security to speak of (SQL injections, no SSL/TLS, etc.), and sites could do maybe 1% of what today's sites can (not saying that all of it is good or necessary, bit i quite like a non-insignificant amount of those new features like native video, audio, graphics, dynamism, etc.).
When was the last time you saw a weekly "Our website is down for maintenance for the next 2 days" message, other than for some government website still running COBOL on a mainframe? When was the last time you saw 500 errors? Used to be a daily thing.
Source? Sounds bullshit
It could be triggered by other complex applications that use kernel container features.
This is when I introduce them to something called VirtualBox and then their eyes go bright with wonder on how simple that works.
Well, If I'd have a workhorse with loads of RAM... I'd still choose docker, because how FAST it starts/restarts. And because it is easy to recreate everything with docker - a VM may get messy when installing stuff for APP #1, #2, #x, "works on my machine!" etc.
Not to mention, if you want to "natively" pack something for Windows and macOS, containers won't even solve that problem, as they only run on Linux. Only reason you can use Docker on macOS is because of virtualization.
Mac .app files are not just binary (MACH-O), they can include libraries, "frameworks", etc that will override what's loaded from the system. AppImage is even worse [1]. .exe are usually setup with an installer that trigger the side-by-side assembly mechanism, pretending that the system is using the version of the libraries that you included (and growing your WinSXS folder forever). JAR files usually include all their required transitive dependencies rather than "dynamic linking" with other JARs.
[1]: AppImage official documentation: "Do not depend on system-provided resources" https://docs.appimage.org/introduction/concepts.html#do-not-...
I don’t think that it uses virtualisation on windows or Mac is very bad. I think that it’s an advantage for simplicity that everything is Linux (I pretend that windows containers do not exist).
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[1] I have a couple of bits running via LCX but otherwise use VMs to split services out
[2] One large VM running many containers³, or sometimes a couple of VMs, perhaps separating them performance-wise across drives or with CPU core affinity where that was/seemed easier, or just so in case of disaster they could concentrate on getting the higher priority VM+containers restored and back up first.
[3] Obviously one VM per container would defeat the container benefits, though I've seen this done where docker was the only officially supported install option and they wanted to run a service in a VM.
Either way, I dont think they understand what Docker is, what it's for, and why it makes things less complicated.