Can people elaborate on when it would be better to use a virtual machine and when it would be beneficial to use a container?
Ask HN: Why use Docker and what are the business cases for using it?
21–30 of 137 posts
Re: Ask HN: Why use Docker and what are the business cases for using it?
#22We have a shitload of servers running CentOS for historical reasons. We can't change the distribution because all the services running on this servers are tight to the quirks and special cases of this distribution. So we need to live with CentOS. Some of our newer services need a up to date version of glibc and a lot of other dependencies CentOS can't provide. So we use docker to boot up Ubuntu 14.04 containers and r…
>running CentOS for historical reasons
Is CentOS not the state-of-the-art Linux distro to run for servers (besides RHEL for support)?
Re: Ask HN: Why use Docker and what are the business cases for using it?
#23There are many ways of using Docker and obviously different companies could come up with their own business cases for adopting the technology. So let me focus on one scenario and we can talk about whether it makes sense for your environment. Software engineering is often difficult because programmers have to deal with inconsistent environments for development and for production execution of their products. Due to mis…
Great, but what are the benefits of running Docker in AWS? You are still running VMs and you are being charged for running them. With Docker you are simply putting yet another layer of complexity, because now you have to run more beefier VMs, you now have problem with network communication between containers running on different hosts. So you will most likely need to use overlay network. You also decrease resiliency, because now when AWS terminated a single VM, all apps running on that node suddenly disappear.
I also don't get the argument about running the same container in dev/test/prod. For example my company is working on going Docker and one of the problem with these environments is that app running there has different configuration. So the idea to solve it is to create three different versions of the same container. Genius! But now are you really running the same thing in dev/test/prod? How is it different to what we did in the past? Especially that before Docker through our continuous delivery we actually were using exact same artifact on machines set up with chef that were configured the same way as in prod, while with Docker now we plan to use three different containers.
Re: Ask HN: Why use Docker and what are the business cases for using it?
#24If you're familiar with Java, think of a docker container like a WAR or EAR, except it can contain ANY dependency, not just Java code. Database, binaries, cache server, you name it. The implementation is vastly different, but the effect is a deployment artifact that can be configured at build time, and easily deployed to multiple servers.
Re: Ask HN: Why use Docker and what are the business cases for using it?
#25lol
Re: Ask HN: Why use Docker and what are the business cases for using it?
#26lol
Re: Ask HN: Why use Docker and what are the business cases for using it?
#27To get some additional viewpoints on containerization, you could also take a look at what has been said about similar, preceeding technologies:
* Solaris Zones, see also SmartOS Zones based on that
* FreeBSD jails
Re: Ask HN: Why use Docker and what are the business cases for using it?
#28I'm a sysadmin for a private K-8 school.
I use docker because of the ease of deploying and upgrading a large number of tools on a limited number of servers.
I've used puppet for several years to manage our infrastructure, and puppet is still managing all our staff and student laptops, but for servers, I've switched everything to CoreOS + Docker.
Re: Ask HN: Why use Docker and what are the business cases for using it?
#29Can people elaborate on when it would be better to use a virtual machine and when it would be beneficial to use a container?
Virtual machines have a much higher level of isolation than the LXC used currently for containers. In a container all it takes to get access to the whole system is a privilege escalation exploit. Such exploits are fairly common.
Re: Ask HN: Why use Docker and what are the business cases for using it?
#30There are many ways of using Docker and obviously different companies could come up with their own business cases for adopting the technology. So let me focus on one scenario and we can talk about whether it makes sense for your environment. Software engineering is often difficult because programmers have to deal with inconsistent environments for development and for production execution of their products. Due to mis…
- maintain consistent dev/test/prod environments
We're pretty heavily invested in Docker. To this point, it's really nice knowing that all the developers are operating in consistent environments.
An additional bonus is that using Docker makes it really easy to propagate infrastructure changes to the rest of your team for use in development. And, more importantly, know those infrastructure changes are consistent across local dev setups.
As an example, I recently incorporated Sphinx search into a project we were working on. I didn't want to require devs to install Sphinx on their own machines and get it up and running for search to function properly. I also didn't want devs to have the overhead of running Sphinx for search on their local boxes unless they were actively working on something related to search. Basically, I wanted search to be optionally configured to run on startup.
I used a DockerFile to setup Sphinx in its own container, pushed the DockerFile to a Tools source repository we use, and then incorporated the build and running of that container into our startup scripts (just some simple orchestration stuff for the local machine written in bash). Now, if a dev wants a containerized search mechanism they run a simple bash script to build that container, then run another command to spin up our dockerized web app with a connection to a running sphinx search container. We do this for all of our services: mysql, redis, sphinx, the web app itself, and anything else we might need.
As an added bonus, all the Docker CLI work and orchestration of our application is easily hidden behind a shell script. If a dev wants to run the webapp, they simply run: app server dev. If they want the app with search they run: app server dev search from the command line. Developers never need to know what's going on under the hood to get their job done. From their perspective, it just works.