Over the past months, I had multiple conversations on why you would want to virtualize containers or Kubernetes. The “containers are somewhat providing virtualization – why should I do it at the server level as well?” myth has been around for some time now. Before I start addressing this, let me take a quick step back here. When I started my career roughly 10 years ago in datacenter operations, virtualization wasn’t mainstream in many environments. I learned a lot about operating physical machines before I got to work on virtual infrastructures at scale. I also worked with multiple vendors and used several “Lights Out Management” solutions and their basic automation capabilities to get my hardware up and running. But it was always a “yes, it’s getting easier from now on” moment when vSphere was ready for configuration. While I enjoyed working in operations, I was always happy to set something up without plugging cables in or working on a server in the datacenters.
I have worked with customers that fully embraced virtualization and have been 100% virtualized for years. They have benefited so much from this move and were able to simplify so many of their operational tasks while doing this. Even if they chose a 1:1 mapping for few extremly demanding VMs to a given host, this was still the better option. Having a consistent infrastructure and operational framework outpaces the potential drawbacks or “virtualization overhead” (another myth) if you look at the bigger picture. Even though I haven’t been working in operations for some time now, I still remember what it means to be called during the night or deal with spontaneous changes in plans/projects all the time. And businesses and therefore IT are only moving faster – automation, “software-defined” and constant improvements should be part of everyone’s daily business in operations.
For me, this applies to all workloads – from your traditional legacy applications to modern application runtime frameworks such as Kubernetes or event-driven architectures that are leveraging Functions-as-a-Service capabilities. Most of them co-exist all the time and it’s not a one-or-the-other conversation but an AND conversation. Even highly demanding workloads such as core telco applications are put on virtual infrastructure these days, enabled by automation and Open Source API definitions. All of these can be operated on a consistent infrastructure layer with a consistent operational model. Infrastructure silos have been broken down over the past decade and VMware has invested a lot to make vSphere a platform for all workloads. So when someone mentions bare-metal these days all I can ask myself is “why would I ever want to go back”? I sometimes wonder if all the challenges that virtualization took away have simply been forgotten – it just ran too well.
So what are my personal reasons to run containers on a virtual infrastructure & vSphere in specific?
- Agility, Independence & Abstraction: scale, repair, lifecycle & migrate underlying components independently from your workloads; if you ever worked in operations, this is daily business (datacenter move, new server vendor selected, major storage upgrades, … there are tons of reasons why this is still a thing)
- Density: run multiple k8s clusters/tenants on same hardware cluster, avoid idle servers e.g. due to N+1 availability concepts
- Availability and QoS: you can plan for failures without compromising density, you can even ensure SLOs/SLAs by enforcing policies (networking, storage, compute, memory) that will also be enforced during outages (NIOC, SIOC, Resource Pools, Reservations, Limits, …)
- Performance: better-than-physical performance & resource management (core ESXi scheduling, DRS & vMotion, vGPUs, …)
- Infrastructure as Code: automate all the things on an API-driven Software Defined Datacenter stack
- Security & Isolation: yep, still a thing
- Fun fact: even Google demoes K8s on vSphere as part of their “GKE on-prem” offering 😉
There has been a ton of material published around this topic recently (and some awesome foundational work by Michael Gasch incl. his KubeCon talk), I want to list a few of the public resources here:
So, no matter what your favorite Kubernetes framework is these days – I am convinced it runs best on a virtual infrastructure and of course even better on vSphere. Friends don’t let friends run Kubernetes on bare-metal. And what hashtag could summarize this better than something short and crips like #vK8s ? I liked this idea so much that I created some “RUN vK8s” images (inspired by my colleagues Frank Denneman and Duncan Epping – guys, it’s been six years since RUN DRS!) that I want to share with all of you. You can find the repository on GitHub – feel free to use them whereever you like.