A Detailed Overview of Rancher's Architecture

This newly-updated, in-depth guidebook provides a detailed overview of the features and functionality of the new Rancher: an open-source enterprise Kubernetes platform.

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I’m not gonna tell you how to live your life—that’s for your doctor to do. What I am gonna tell you is how a beautifully poetic dynamic duo of DevOps delightfulness can make your next project shine brighter than the sun and give you more marketable skills. We live in a world where everything is becoming more modular. From your phone to your Keurig coffee maker to your USB type-C laptop setup, modularity allows you to do more and rearrange components of your life to best suit your needs.

Why should your software be any different?

Containerization is the basis of modular software development, and it really opens your eyes to how easy and properly cost scaling deployment can be when your applications remain agnostic to the OS, hardware, and network on which they run. Of course, the modern software developer now builds services to run on top of containers and, although services offer a neat solution to a lot of problems introduced through basic containers, deploying services out into the world through our favorite cloud platforms can be difficult to say the least. I needed a cloud that suited all of my conditions: it’s at the right price point, has the features, instances, extra services I love to use, and doesn’t tie me down to one particular company. I should be able to pick and choose from all the cloud providers what kind of instance I want, utilize the massive array of regions that spans every popular cloud provider from New York to Australia, and even manage DNS across multiple instances on multiple clouds.

The nature of the cloud market is interesting because, for most developers, we pick one provider and tend to stick with it. A provider may change its policies or jack up its prices whenever it wants, and we’re forced to go along with it because migrating to a new cloud takes a lot of hours and effort.

What if there were some platform, independent of a cloud provider, that would let us, the developers, be agnostic to a cloud provider and focus on the product?

Enter Rancher. Rancher is a cloud-agnostic deployment engineering platform for services. It offers a one-stop shop for all your deployment needs. Rancher provides a handful of orchestration options including Kubernetes, Swarm, and its own Cattle, all of which allow you to deploy your application, your way, on your cloud. With features like multihost spawning via cloud API, baked-in networking with load-balancing, and terminal-free interaction with your hosts, Rancher is a compelling platform for managing your cloud-based project. DigitalOcean is my favorite infrastructure cloud. I say this wholeheartedly because they provide sensible options for sensible people who aren’t trying to run their own Netflix on someone else’s hardware.

In modern development, the only thing that should be persistent is your database and configurations, where DigitalOcean’s new Spaces really shines. Managing and monitoring container hosts through the dashboard of your DigitalOcean account can be a challenge, however, as you really don’t know what is consuming resources or what workloads look like unless you SSH into each of your hosts and check the Docker stats. While this may be doable for a project running only one or two containers on a single host, what happens if you want to scale it at all? How do you handle the monitoring, stratified deployment, and scaling of your services? Sure, DigitalOcean offers some load-balancing techniques, but that’s on a machine level, not on a service level. Running Rancher on top of DigitalOcean sticks the infrastructure behind a layer of abstraction that you, the developer, don’t need to worry about. Instead of managing hosts, all you have to worry about are your services.

So, why do Rancher and DigitalOcean complement each other so well? Where’s the magic, and why does it matter?

Rancher’s design philosophy is such that no matter how the hardware configuration changes, you can move services around and they’ll stay alive as long as one host is available. Rancher aims to allow quick changes to hardware architecture without compromising on availability. Provisioning a running host can happen in under three minutes in most cases. This sounds pretty darn fast but, in reality, bringing up the host on your cloud provider can take a while if it’s not built to let you rapidly spin up instances through an API. Thankfully, DigitalOcean offers SSD-based droplets that you can spin up in under 30 seconds. Yeah, that’s right. Under 30 seconds. That means you can deploy a new host and scale your service onto that host in under five minutes, and you can perform upgrades and infrastructure changes with ease. The DigitalOcean API is an incredibly powerful tool for DevOps. Not only can you create an instance from the API, but you can generate and upload secure SSH keys for each host, configure DNS for the load balancers, and even reverse the process, destroying droplets and getting rid of DNS records and SSH keys.

The power of DigitalOcean’s API enables Rancher to automate all of these tasks for you in a simple interface. When you want to create a new droplet, all you have to specify is the number, size, hostnames (which can follow patterns for multi-droplet creations), and Linux image. All the SSH key distribution, provisioning, networking, and security is automated by Rancher in the few minutes it takes to spin up and adopt an instance. Rancher offers a single interface to connect with all of your clouds, so the process is more or less the same no matter what infrastructure you’re running.

Essentially, learning Rancher through an affordable and quick cloud provider like DigitalOcean enables you to deploy on AWS, Google Cloud Platform, OpenStack, and any other production infrastructure that industry leaders are running in their datacenters. For now, though, let’s stick with DigitalOcean. In an upcoming post, I’ll continue guiding you through the process of getting started with DigitalOcean on Rancher.

Next, we’ll cover Terraforming your environment so spin up and spin down are as easy as terraform < apply|destroy >.

Eric Volpert

Eric Volpert is a student at the University of Chicago and works as an evangelist, growth hacker, and writer for Rancher Labs. He enjoys any engineering challenge. He’s spent the last three summers as an internal tools engineer at Bloomberg and a year building DNS services for the Secure Domain Foundation with CrowdStrike. Eric enjoys many forms of music ranging from EDM to High Baroque, playing MOBAs and other action-packed games on his PC, and late-night hacking sessions, duct taping APIs together so he can make coffee with a voice command.