Kubernetes 18+ ways – yes, you can have it your way

By Rob Hirschfeld

Lately, I’ve been talking about the general concept of hybrid DevOps adding composability, orchestration and services to traditional configuration. It’s time add a concrete example because the RackN team is deliving it with Digital Rebar and Kubernetes.

So far, we enabled a single open platform to install over 18 different configurations of Kubernetes simply by changing command line flags [videos below].

By taking advantage of the Digital Rebar underlay abstractions and orchestration, we are able to use open community installation playbooks for a wide range of configurations.

So far, we’re testing against:

  • Three different clouds (AWS, Google and Packet) not including the option of using bare metal.
  • Two different operating systems (Ubuntu and Centos)
  • Three different software defined networking systems (Flannel, Calico and OpenContrail)

Those 18 are just the tip of the iceberg that we are actively testing. The actual matrix is much deeper.


The composable architecture of Digital Rebar means that all of these variations are isolated. We are not creating 18 distinct variations; instead, the system chains options together and abstracts the differences between steps.

That means that we could add different logging options, test sequences or configuration choices into the deployment with minimal coupling of previous steps. This enables operator choice and vendor injection in a way to allows collaboration around common components. By design, we’ve eliminated fragile installation monoliths.

All it takes is a Packet, AWS or Google account to try this out for yourself!

DevOps workers, you mother was right: always bring a clean Underlay.

Why did your mom care about underwear? She wanted you to have good hygiene. What is good Ops hygiene? It’s not as simple as keeping up with the laundry, but the idea is similar. It means that we’re not going to get surprised by something in our environment that we’d taken for granted. It means that we have a fundamental level of control to keep clean. Let’s explore this in context.

l_1600_1200_9847591C-0837-4A7D-A69D-54041685E1C6.jpegI’ve struggled with the term “underlay” for infrastructure of a long time. At RackN, we generally prefer the term “ready state” to describe getting systems prepared for install; however, underlay fits very well when we consider it as the foundation for a more building up a platform like Kubernetes, Docker Swarm, Ceph and OpenStack. Even more than single operator applications, these community built platforms require carefully tuned and configured environments. In my experience, getting the underlay right dramatically reduces installation challenges of the platform.

What goes into a clean underlay? All your infrastructure and most of your configuration.

Just buying servers (or cloud instances) does not make a platform. Cloud underlay is nearly as complex, but let’s assume metal here. To turn nodes into a cluster, you need setup their RAID and BIOS. Generally, you’ll also need to configure out-of-band management IPs and security. Those RAID and BIOS settings specific to the function of each node, so you’d better get that right. Then install the operating system. That will need access keys, IP addresses, names, NTP, DNS and proxy configuration just as a start. Before you connect to the wide, make sure to update to your a local mirror and site specific requirements. Installing Docker or a SDN layer? You may have to patch your kernel. It’s already overwhelming and we have not even gotten to the platform specific details!

Buried in this long sequence of configurations are critical details about your network, storage and environment.

Any mistake here and your install goes off the rails. Imagine that your building a house: it’s very expensive to change the plumbing lines once the foundation is poured. Thankfully, software configuration is not concrete but the costs of dealing with bad setup is just as frustrating.

The underlay is the foundation of your install. It needs to be automated and robust.

The challenge compounds once an installation is already in progress because adding the application changes the underlay. When (not if) you make a deploy mistake, you’ll have to either reset the environment or make your deployment idempotent (meaning, able to run the same script multiple times safely). Really, you need to do both.

Why do you need both fast resets and component idempotency? They each help you troubleshoot issues but in different ways. Fast resets ensure that you understand the environment your application requires. Post install tweaks can mask systemic problems that will only be exposed under load. Idempotent action allows you to quickly iterate over individual steps to optimize and isolate components. Together they create resilient automation and good hygiene.

In my experience, the best deployments involved a non-recoverable/destructive performance test followed by a completely fresh install to reset the environment. The Ops equivalent of a full dress rehearsal to flush out issues. I’ve seen similar concepts promoted around the Netflix Chaos Monkey pattern.

If your deployment is too fragile to risk breaking in development and test then you’re signing up for an on-going life of fire fighting. In that case, you’ll definitely need all the “clean underwear” you can find.

We need DevOps without Borders! Is that “Hybrid DevOps?”

The RackN team has been working on making DevOps more portable for over five years.  Portable between vendors, sites, tools and operating systems means that our automation needs be to hybrid in multiple dimensions by design.

Why drive for hybrid?  It’s about giving users control.

launch!I believe that application should drive the infrastructure, not the reverse.  I’ve heard may times that the “infrastructure should be invisible to the user.”  Unfortunately, lack of abstraction and composibility make it difficult to code across platforms.  I like the term “fidelity gap” to describe the cost of these differences.

What keeps DevOps from going hybrid?  Shortcuts related to platform entangled configuration management.

Everyone wants to get stuff done quickly; however, we make the same hard-coded ops choices over and over again.  Big bang configuration automation that embeds sequence assumptions into the script is not just technical debt, it’s fragile and difficult to upgrade or maintain.  The problem is not configuration management (that’s a critical component!), it’s the lack of system level tooling that forces us to overload the configuration tools.

What is system level tooling?  It’s integrating automation that expands beyond configuration into managing sequence (aka orchestration), service orientation, script modularity (aka composibility) and multi-platform abstraction (aka hybrid).

My ops automation experience says that these four factors must be solved together because they are interconnected.

What would a platform that embraced all these ideas look like?  Here is what we’ve been working towards with Digital Rebar at RackN:

Mono-Infrastructure IT “Hybrid DevOps”
Locked into a single platform Portable between sites and infrastructures with layered ops abstractions.
Limited interop between tools Adaptive to mix and match best-for-job tools.  Use the right scripting for the job at hand and never force migrate working automation.
Ad hoc security based on site specifics Secure using repeatable automated processes.  We fail at security when things get too complex change and adapt.
Difficult to reuse ops tools Composable Modules enable Ops Pipelines.  We have to be able to interchange parts of our deployments for collaboration and upgrades.
Fragile Configuration Management Service Oriented simplifies API integration.  The number of APIs and services is increasing.  Configuration management is not sufficient.
 Big bang: configure then deploy scripting Orchestrated action is critical because sequence matters.  Building a cluster requires sequential (often iterative) operations between nodes in the system.  We cannot build robust deployments without ongoing control over order of operations.

Should we call this “Hybrid Devops?”  That sounds so buzz-wordy!

I’ve come to believe that Hybrid DevOps is the right name.  More technical descriptions like “composable ops” or “service oriented devops” or “cross-platform orchestration” just don’t capture the real value.  All these names fail to capture the portability and multi-system flavor that drives the need for user control of hybrid in multiple dimensions.

Simply put, we need devops without borders!

What do you think?  Do you have a better term?