This post is going to help save you money if you're running a Rails server. It starts like this: you write an app. Let's say you're building the next hyper-targeted blogging platform for medium length posts. When you login, you see a paginated list of all of the articles you've written. You have a Post model and maybe for to do tags, you have a Tag model, and for comments, you have a Comment model. You write your view so that it renders the posts:

<% @posts.each do |post| %> <%= link_to(post, post.title) %> <%= teaser_for(post) %> <%= "#{post.comments.count} comments" <% end %> <%= pagination(@posts) %> 

See any problems with...

We are happy to announce the general availability of Automated Certificate Management (ACM) for all paid Heroku dynos. With ACM, the cumbersome and costly process of provisioning and managing SSL certificates is replaced with a simple experience that is free for all paid Dynos on Heroku’s Common Runtime. Creating secure web applications has never been more important, and with ACM and the Let’s Encrypt project, never easier.

ACM handles all aspects of SSL/TLS certificates for custom domains; you no longer have to purchase certificates, or worry about their expiration or renewal. ACM builds directly on our recent release of Heroku Free SSL to make encryption the default for web applications...

The most innovative apps augment our human senses, intuition, and logic with machine learning. Deep learning, modelled after the neural networks of the human brain, continues to grow as one of the most powerful types of machine learning. When applied to images, deep learning enables powerful computer vision features like visual search, product identification, and brand detection.

Today, we bring you the Einstein Vision add-on (beta), allowing Heroku developers to easily connect to and use Einstein Vision, a set of powerful new APIs for building AI-powered apps. With this release, Salesforce is making it easy for you to embed image recognition directly into your apps. Rather than building...

Choices are an important part of a healthy open source software community. That’s why we’re excited about Yarn, a new package manager that addresses many of the problems with Node’s default package manager, npm. While npm has done a fantastic job creating a large and vibrant JavaScript ecosystem, I want to share why Yarn is an important addition to the Node.js ecosystem, how it will improve your Node.js development experience, and how Heroku has incorporated it into the build process for your Heroku apps.

We began testing Yarn almost immediately after it was released, and began fully supporting it on December 16.

About Yarn

Yarn was released in October 2016 and made a big splash...

Heroku bumped its Bundler version to 1.13.7 almost a month ago, and since then we've had a large number of support tickets opened, many a variant of the following:

Your Ruby version is <X>, but your Gemfile specified <Y> 

I wanted to talk about why you might get this error while deploying to Heroku, and what you can do about it, along with some bonus features provided by the new Bundler version.

Why?

First off, why are you getting this error? On Heroku in our Ruby Version docs, we mention that you can use a Ruby directive in your Gemfile to specify a version of Ruby. For example if you wanted 2.3.3 then you would need this:

# Gemfile ruby "2.3.3" 

This is still...