Kubernetes is a container orchestration system that originated at Google, and is now being maintained by the Cloud Native Computing Foundation. In this post, I am going to dissect some Kubernetes internals—especially, Deployments and how gradual rollouts of new containers are handled.

What Is a Deployment?

This is how the Kubernetes documentation describes Deployments:

A Deployment controller provides declarative updates for Pods and ReplicaSets.

A Pod is a group of one or more containers which can be started inside a cluster. A pod started manually is not going to be very useful though, as it won't automatically be restarted if it crashes. A ReplicaSet ensures that a Pod...

Rails 5 will be the easiest release ever to get running on Heroku. You can get it going in just five lines:

$ rails new myapp -d postgresql $ cd myapp $ git init . ; git add . ; git commit -m first $ heroku create $ git push heroku master 

These five lines (and a view or two) are all you need to get a Rails 5 app working on Heroku — there are no special gems you need to install, or flags you must toggle. Let's take a peek under the hood, and explore the interfaces baked right into Rails 5 that make it easy to deploy your app on any modern container-based platform.

Production Web Server as the Default

Before Rails 5, the default web server that you get when you run $ rails server is...

Developers want to spend less time setting up applications so they can start working with the code sooner. Setting up applications is error-prone, time-consuming, and interruptive to the development flow. Often, there are several steps to go from your code to a running application that you can continue to work on. Enter the app.json application manifest, which allows developers to automate complex set-up processes and deploy to Heroku faster.

The Heroku app.json manifest enables developers to define their applications' details, setup configurations and runtime environments in a structured way. Instead of providing step-by-step instructions, you can add an app.json application manifest...

Last summer, Heroku became a polyglot platform, with official support for Ruby, Node.js, Clojure, Java, Python, and Scala. Building a platform that works equally well for such a wide variety of programming languages was a unique technical design challenge.

We knew from the outset that maintaining siloed, language-specific products – a Heroku for Ruby, a Heroku for Node.js, a Heroku for Clojure, and so on – wouldn't be scalable over the long-term.

Instead, we created Cedar: a single, general-purpose stack with no native support for any language. Adding support for any language is a matter of layering on a build-time adapter that can...