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 and 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 or other samples and templates that you find in repositories online, to a running application that you can continue to work on.

Today, we are excited to introduce the app.json manifest. app.json 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 now add app.json files to your applications' source code. You...

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...