Ask HN: What is the actual purpose of Docker?

Post by [deleted] » Tue, Jul 07, 2015, 1:21 PM UTC

ageofwant wrote: post #20

KaiserPro wrote: post #13

docker and openVZ aim to do the same thing. docker is a glorified chroot and cgroup wrapper. There is also a library of prebuilt docker images (think of it as a tar of a chroot) and a library of automated build instructions. The library is the most compelling part of docker. everything else is basically a question of preference. You will hear a lot about build once, deploy anywhere. whilst true in theory, your mileag…

> docker and openVZ aim to do the same thing. docker is a process container not a system container. > docker is a glorified chroot and cgroup wrapper. that is fairly immaterial, suffice to say that the underlying linux core tech that enables docker has matured enough lately to enable a tool like docker. I built many containers and I never thought about them in terms of the underlying tech. > There is also a library o…

Post by grhmc » Tue, Jul 07, 2015, 1:22 PM UTC

crdoconnor wrote: post #18

grhmc wrote: post #7

For me, it is the ultimate in the idea in Continuous Delivery of "build once." I can be very confident that the docker image I build in the first stage of my pipeline will operate correctly in production. This is because that identical image was used for unit tests, to integration and functional testing, to the staging environment and finally production. There is no difference than configuration. This is the core tha…

I get this by using vagrant + ansible rather than docker. Easy to spin up or destroy the environment in the same way in a VM, staging server or live environment. I don't really see the point of lightweight virtualization. It provides an illusion of isolation which will likely come crashing down at some probably very inconvenient point (e.g. when you discover a bug caused by a different version of glibc or a different…

Post by grhmc » Tue, Jul 07, 2015, 1:27 PM UTC

odiroot wrote: post #10

grhmc wrote: post #7

For me, it is the ultimate in the idea in Continuous Delivery of "build once." I can be very confident that the docker image I build in the first stage of my pipeline will operate correctly in production. This is because that identical image was used for unit tests, to integration and functional testing, to the staging environment and finally production. There is no difference than configuration. This is the core tha…

How do you handle different configurations then? Especially if you need to provide N values (or structured data). Also, how do you manage your containers in production?

Post by grhmc » Tue, Jul 07, 2015, 1:33 PM UTC

danesparza wrote: post #26

I'm stunned that nobody has brought up the idea of 'immutable architecture' -- the idea that you create an image and deploy it, and then there is no change of state after it's deployed. If you want a change to that environment, you create a new image and deploy that instead. Docker gives you the ability to version your architecture and 'roll back' to a previous version of a container.

Post by grhmc » Tue, Jul 07, 2015, 1:41 PM UTC

crdoconnor wrote: post #28

grhmc wrote: post #23

Earlier quoted context omitted.

The problem is Vagrant + Ansible violates the rule of "build once." I don't care about the isolation for isolation sake, I care about it for the artifact sake.

I don't care so much for this rule. It sounds like a figleaf covering for broken build scripts. I care about tracking down issues before they reach production. Meaning that I want an environment that mirrors production as closely as possible. Meaning heavyweight not lightweight virtualization.