- Simon Waight
The release this week of the Windows Server 2016 Technical Preview 3 which includes the first public release of Microsoft's Docker-compatible container implementation is sure to bring additional focus onto an already hot topic.
I was going to write a long introductory post about why containers matter, but Azure CTO Mark Russinovich beat me to it with his great post this week over on the Azure site.
Instead, here's a TL;DR summary on containers and the Windows announcement this week.
- A Container isn't a Virtual Machine it's a Virtual Operating System. Low-level services are provided by a Container Host which manages resource allocation (CPU / RAM / Disk). Some smarts around filesystem use means a Container can effectively share most of the underlying Container Host's filesystem and only needs to track delta changes to files.
- Containers are not just a cloud computing thing: they can run anywhere you can run a Linux or Windows server.
- Containers are, however well suited to cloud computing because they offer:
- faster startup times (they aren't an entire OS on their own)
- easier duplication and snapshotting (no need to track an entire VM any more)
- higher density of hosting (though noisy neighbour control still needs solving)
- easier portability: anywhere you have a compatible Container Host you can run your Container. The underlying virtualisation platform no longer matters, just the OS.
- Docker is supported on all major tier one public clouds. Azure, AWS, GCP, Bluemix and Softlayer.
- A Linux Container can't run on a Windows Host (and vice versa): the Container Host shares its filesystem with a Container so it's not possible to mix and match them!
- Containers are well suited to use in microservices architectures where a Container hosts a single service.
- Docker isn't the only Container tech about (but is the best known and considered most mature) and we can hold out hope of good interoperability in the Container space (for now) thanks to the Open Container Initiative (OCI).
Containers offer great value for DevOps-type custom software development and delivery, but can also work for standard off-the-shelf software too. I fully expect we will see Microsoft offer Containers for specific roles for their various server products.
As an example, for Exchange Server you may see Containers available for each Exchange role: Mailbox, Client Access (CAS), Hub Transport (Bridgehead), Unified Messaging and Edge Transport. You apply minimal configuration to the Container but can immediately deploy it into an existing or new Exchange environment. I would imagine this would make a great deal of sense to the teams running Office 365 given the number of instances of these they would have to run.
So, there we have it, hopefully an easily digestable intro and summary of all things Containers. If you want to play with the latest Windows Server release you can spin up a copy in Azure if you want. If you don't have a subscription sign up for a trial. Alternatively, Docker offers some good introductory resources and training is available in Australia*.
- Disclaimer: Cevo is a sister company of my employer Kloud Solutions.