Does this mean we're admitting defeat with shared libraries and we're going back to static libraries again?
So now we have the issue that you have lots of applications running on the same server, and how do we make sure the right version of some shared lib is on there. And that we won't break another program by updating it.
Containers solve that. No more worrying if that java 8 upgrade will break some old application.
So now every application stack is a static application.
...this applies only software developed and run internally, which is a small fraction of all the software running in the world.
This has literally zero to do with containers and everything to do with an automated deployment pipeline.
As a quick FYI: Those are not unique to containers.
As one very minor point, it turns vulnerability tracking in to an accounting exercise, which sounds like a good idea until you take a look at the dexterity with which most engineering firms manage their AWS accounts. (Sure, just get better at it and it won't be a problem. That advice works with everything else, right?)
One's choice of deployment tools may slap a bandaid on some things, but that is not the same thing as solving a problem; that is automated bandaid application.
And odd pronouncements like any given container shouldn't be long lived are... odd. I guess if all you do is serve CRUD queries with them, that's probably OK.
As a final point, I feel like the container advocates are selling an engineer's view of how ops should work. As with most things, neutral to good ideas end up wrapped up with a lot of rookie mistakes, not to mention typical engineer arrogance[1]. Just the same thing you get anywhere amateurs lecture the pros, but the current hype train surrounding docker is enough to let it actually cause problems[2].
My takeaway is still the same as it was when the noise started. Docker has the potential to be a nice bundling of Linux capabilities as an evolution of a very old idea that solves some real problems in some situations, and I look forward to it growing up. In the mean time, I'm bored with this engineering fad; can we get on with the next one already?
[1] One very simple example, because I know someone will ask: Kubernetes logging is a stupid mess that doesn't play well with... well, anything. And to be fair, ops engineers are no better with the arrogance.
[2] Problems like there being not even a single clearly production-ready host platform out of the box. Centos? Not yet. Ubuntu? Best of the bunch, but still hacky and buggy. CoreOS? I thought one of the points was a unified platform for dev and prod.
Signed jars are a little painful to use (you can't easily bundle them), but that's a minor issue.
Page sharing can also depend on the storage driver; overlayfs support page cache sharing and brtfs does not.
But there are more benefits like Jessie touches upon in her blog post, wrt flexibility and patterns you can use with multiple containers sharing some namespaces, etc. And from the perspective of languages that do not compile to a native binary the containers offer a uniform way to package and deploy an application.
When I was at QuizUp and we decided to switch our deployment units to docker containers we had been deploying using custom-baked VM's (AMI's). When we first started doing that it was due to our immutable infrastructure philosophy, but soon it became a relied-upon and necessary abstraction to homogeneously deploy services whether they were written in python, java, scala, go, or c++.
Using docker containers allowed us to keep that level of abstraction while reducing overheads significantly, and due to the dockers being easy to start and run anywhere we became more infrastructure agnostic at the same time.
And that's great news. Immutable deployment artifacts let us reason about our systems much more coherently.