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How I Broke `git push heroku main`

Incidents are inevitable. Any platform, large or small will have them. While resiliency work will definitely be an important factor in reducing the number of incidents, hoping to remove all of them (and therefore reach 100% uptime) is not an achievable goal. We should, however, learn as much as we can from incidents, so we can avoid repeating them. In this post, we will look at one of those incidents, #2105, see how it happened (spoiler: I messed up), and what we’re doing to avoid it from happening again (spoiler: I’m not fired). Git push inception Our Git server is…

The Life-Changing Magic of Tidying Ruby Object Allocations

Your app is slow. It does not spark joy. This post will use memory allocation profiling tools to discover performance hotspots, even when they're coming from inside a library. We will use this technique with a real-world application to identify a piece of optimizable code in Active Record that ultimately leads to a patch with a substantial impact on page speed. In addition to the talk, I've gone back and written a full technical recap of each section to revisit it any time you want without going through the video. I make heavy use of theatrics here, including a Japanese…

Let’s Debug a Node.js Application

There are always challenges when it comes to debugging applications. Node.js' asynchronous workflows add an extra layer of complexity to this arduous process. Although there have been some updates made to the V8 engine in order to easily access asynchronous stack traces, most of the time, we just get errors on the main thread of our applications, which makes debugging a little bit difficult. As well, when our Node.js applications crash, we usually need to rely on some complicated CLI tooling to analyze the core dumps. In this article, we'll take a look at some easier ways to debug your…

Ground Control to Major TOML: Why Buildpacks Use a Most Peculiar Format

YAML files dominate configuration in the cloud native ecosystem. They’re used by Kuberentes, Helm, Tekton, and many other projects to define custom configuration and workflows. But YAML has its oddities, which is why the Cloud Native Buildpacks project chose TOML as its primary configuration format. TOML is a minimal configuration file format that's easy to read because of its simple semantics. You can learn more about TOML from the official documentation, but a simple buildpack TOML file looks like this: api = "0.2" [buildpack] id = "heroku/maven" version = "1.0" name = "Maven" Unlike YAML, TOML doesn’t rely on significant…

Making Time to Save You Time: How We Sped Up Time-Related Syscalls on Dynos

I work on Heroku’s Runtime Infrastructure team, which focuses on most of the underlying compute and containerization here at Heroku. Over the years, we’ve tuned our infrastructure in a number of ways to improve performance of customer dynos and harden security. We recently received a support ticket from a customer inquiring about poor performance in two system calls (more commonly referred to as syscalls) their application was making frequently: clock_gettime(3) and gettimeofday(2). In this customer’s case, they were using a tool to do transaction tracing to monitor the performance of their application. This tool made many such system calls to…

A Fast Car Needs Good Brakes: How We Added Client Rate Throttling to the Platform API Gem

When API requests are made one-after-the-other they'll quickly hit rate limits and when that happens: If you provide an API client that doesn't include rate limiting, you don't really have an API client. You've got an exception generator with a remote timer. — Richard Schneeman Stay Inside (@schneems) June 12, 2019 That tweet spawned a discussion that generated a quest to add rate throttling logic to the platform-api gem that Heroku maintains for talking to its API in Ruby. If the term "rate throttling" is new to you, read Rate limiting, rate throttling, and how they work together The Heroku…

Building a GraphQL API in JavaScript

Over the last few years, GraphQL has emerged as a very popular API specification that focuses on making data fetching easier for clients, whether the clients are a front-end or a third-party. In a traditional REST-based API approach, the client makes a request, and the server dictates the response: $ curl https://api.heroku.space/users/1 { “id”: 1, “name”: “Luke”, “email”: “luke@heroku.space”, “addresses”: [ { “street”: “1234 Rodeo Drive”, “city”: “Los Angeles”, “country”: “USA” } ] } But, in GraphQL, the client determines precisely the data it wants from the server. For example, the client may want only the user’s name and email,…

From Project to Productionized with Python

This blog post is based on From Project to Productionized, a talk given at PyCon 2020 at the height of the COVID-19 pandemic. You can use this post today to learn how to deploy a Python application on Heroku. More specifically, we’ll show you how to deploy Django apps, including setting up your Django configuration, building continuous delivery pipelines, adding middleware, and everything else that goes into deploying Django on Heroku. If you’d prefer a generic guide explaining how to deploy a Python application on Heroku, check out Getting Started on Heroku with Python. https://www.youtube.com/embed/1923eduj0Gg Imagine that you’ve just spent the last…

Evolving Alongside your Tech Stack

This blog post is adapted from a discussion during an episode of our podcast, Code[ish]. Over the last twenty years, software development has advanced so rapidly that it's possible to create amazing user experiences, powerful machine learning algorithms, and memory efficient applications with incredible ease. But as the capabilities tech provides has changed, so too have the requirements of individual developers morphed to encompass a variety of skills. Not only should you be writing efficient code; you need to understand how that code communicates with all the other systems involved and make it all work together. In this post, we'll…

Building and Scaling a Global Chatbot using Heroku + Terraform

Text-based communication has a long history weaved into the evolution of the Internet, from IRC and XMPP to Slack and Discord. And where there have been humans, there have also been chatbots: scriptable programs that respond to a user’s commands, like messages in a chat room. Chatbots don't require much in terms of computational power or disk storage, as they rely heavily on APIs to send actions and receive responses. But as with any kind of software, scaling them to support millions of user’s requests across the world requires a fail-safe operational strategy. Salesforce offers a Live Agent support product…

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