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Docker does different things than VM's, but they work together perfectly. I run my all my Docker hosts on a VMWare infrastructure, which gives me best of both w

Docker does different things than VM's, but they work together perfectly. I run my all my Docker hosts on a VMWare infrastructure, which gives me best of both worlds. Yes - for some things, VMWare can't be beaten - but that's the nice thing: they are not mutually exclusive. Both are very handy tools in my toolbox, and neither are a one-stop solution. Docker sure adds complexity - but also a huge amount of flexibility. Once you understand the power of it all, and how to think with Docker (which isn't that obvious) - it's pretty damn good. Not that there are no downsides or things that could be improved, but nothing is perfect. And then: 1) The problem is hugely exaggerated. It only applies to badly written software. And make sure we don't lose syslog? Seriously? just mount /dev/log into your container (it's a unix socket after all) and you're done. 2) Arguably faster? Try booting up 15 instances of app X. With docker, that's achieved in less than a second. On VMWare this has a huge memory and CPU overhead, not to mention boot-up times. 3) Try versioning VM's. Good luck. I have 100% reproducible, versioned images generated and tested in our CI system, that I can easily deploy in a VM on my laptop where I will have 100% the same setup as it will in test/qa/prod. To deploy the new version, start new instance, point load balancer/proxy/whatever to the new instance (happens automagically btw). Everything goes well? Stop old instance. Something goes wrong? Point proxy to old instance, and kill the badly-behaving. If everything went well: zero downtime. If you detect something goes wrong, it's nearly instant to switch back to the previous version. Also, testing this is a lot easier than with VM's. Sure you could do that with VM's too - but the overhead is massive, and takes a lot more time. My ideal setup would be a hypervisor infrastructure with a bunch of VM's running only Docker applications.

shykes 12y ago
> My ideal setup would be a hypervisor infrastructure with a bunch of VM's running only Docker applications. You should take a look at https://github.com/docker/machine https://github.com/docker/machine and https://github.com/docker/swarm https://github.com/docker/swarm , they were designed with exactly that goal in mind!
- KaiserPro 12y ago
  Sadly, it still lags behind even KVM, it can't hot migrate, which means zero downtime maintenance is impossible, along with transparent HA.
dordoka 12y ago
Care to share your CI tech stack? Specially the deployment bit automagically updating the balancer. We are internally building that kind of setup at the moment and some insight from experienced people like you would be very helpful. Thanks.
- koffiezet 12y ago
  CI is Jenkins, which uses the Docker plugin for creating slaves on-the-fly. The plugin has it's share of problems, so I don't use it to build the images itself - I do this using a generalized bash script, which also pushes it to our private repo. For automatically updating the load-balancer, check out docker-gen (https://github.com/jwilder/docker-gen https://github.com/jwilder/docker-gen). I hacked together setup that detects the latest version and points to this-one when a container comes up or goes down. It assumes a lot of things specific to my setup though (versioning of the containers, env vars, ...)

shykes 12y ago

> My ideal setup would be a hypervisor infrastructure with a bunch of VM's running only Docker applications. You should take a look at https://github.com/docker/machine https://github.com/docker/machine and https://github.com/docker/swarm https://github.com/docker/swarm , they were designed with exactly that goal in mind!

KaiserPro 12y ago
Sadly, it still lags behind even KVM, it can't hot migrate, which means zero downtime maintenance is impossible, along with transparent HA.

dordoka 12y ago

Care to share your CI tech stack? Specially the deployment bit automagically updating the balancer. We are internally building that kind of setup at the moment and some insight from experienced people like you would be very helpful. Thanks.

koffiezet 12y ago
CI is Jenkins, which uses the Docker plugin for creating slaves on-the-fly. The plugin has it's share of problems, so I don't use it to build the images itself - I do this using a generalized bash script, which also pushes it to our private repo. For automatically updating the load-balancer, check out docker-gen (https://github.com/jwilder/docker-gen https://github.com/jwilder/docker-gen). I hacked together setup that detects the latest version and points to this-one when a container comes up or goes down. It assumes a lot of things specific to my setup though (versioning of the containers, env vars, ...)