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Working at FusionAuth

FusionAuth adds login, registration, SSO, MFA, and a bazillion other features to your app in days – not months.

Tech stack


How engineering works at FusionAuth

How are the teams structured?

We have a small and agile dev team of about 8 people. We don’t divide ourselves into rigid teams or roles, but rather work collaboratively on every aspect of a feature, from design to implementation to testing to documentation. We also take turns to handle customer support, both on Zendesk and Slack, and to be on-call for any urgent issues. This way, we get to know our customers better and understand their needs and challenges. We believe this makes us more empathetic and effective as developers.

What tools do engineers use?

  • Product Design: Markdown files and GitHub Issues
  • Issue Tracking: GitHub Issues
  • Internal Documentation: GitHub Wiki and Markdown files
  • External Documentation: AsciiDoc, Markdown, Astro
  • Incident Management: Zendesk and Slack
  • Internal Communication: Slack and Email
  • Build Pipeline: JetBrains TeamCity
  • Deployments: GitHub Actions
  • Monitoring: Prometheus, AWS CloudWatch, Grafana, and StatusCake

Can developers pick their own tools?

The developers do have some flexibility in choosing tools, but we also have some standards to ensure consistency. For the core product development, we all use JetBrains IntelliJ as our IDE and each developer is issued a Macbook Pro for their dev machine. This makes it easier for us to train and pair with new engineers and to collaborate on the primary codebase.

The DevRel team, which works on various other languages and projects can use whatever tools they prefer, such as Visual Studio, Vim or any other text editor. We also don’t restrict anyone from installing other tools on their laptops if they find them useful. We try to balance the freedom of choice with the efficiency of teamwork.

How does the development process work? What's the process for working through bugs, features and tech debt?

We have a flexible and customer-driven development process. We use GitHub for issue tracking and a simple kanban board for prioritization. As developers finish tasks, we assign them new ones or they can pick something themselves. We always try to prioritize bugs – if an engineer needs a break while doing feature dev they may shelve those changes and quickly fix a bug for a quick dopamine hit.

For everything else, both our customers and community help drive our priority. For instance, if we're going to sign a big customer and they say, "Hey, it'd be really nice if the product did X-Y or Z," and the X-Y or Z was already on the roadmap anyway, that's a pretty easy decision to prioritize this work for that customer. If a security researcher lets us know that they found a vulnerability, that's always a super high priority.

We always have a roadmap of the next six to twelve months of development work that we'd like to do, but it is pretty fluid because there's lots of things that can be prioritized ahead of anything on the roadmap. From a core engineering perspective, I don’t love roadmaps because you can plan all you want and priorities often change.

How does code get reviewed, merged, and deployed?

When a developer picks up a bug, fixes it, puts up a pull request, one or more developers will review that pull request. A code owner has to sign-off, so there could be one or many reviews, but ultimately myself or another code owner has to provide final approval. At that point it's approved and we can merge that into the master branch.

Once coe is in the mainline build, it'll just go out when we cut that next release – releases are all automated. Once released, this new version will show up on the customer's dashboard in FusionAuth Cloud as an upgrade target, so they could then choose to make that upgrade.

If the bug was reported by a customer that we're working with, we would then communicate, "Hey, this is available for you to test now." We might even volunteer to upgrade their environments for them so that they can begin testing and confirming that that bug has been resolved before they roll it to their production.

If you're a customer and you choose to have us host for you, which means you're in FusionAuth Cloud, you might think we pool resources to serve multiple customers, but we never commingle – if you host in FusionAuth Cloud, you get dedicated compute, storage and database within your own security group. In a typical SaaS offering that uses a continuous integration deployment mode, software is always upgrading and you may not even notice. But if you're hosting in FusionAuth Cloud, you have to opt into an upgrade. There are pros and cons to this strategy, but we find most larger clients prefer this opt-in approach.

We do oftentimes help our larger customers to give them more of a white glove service, but fundamentally it's just a self service option. You can log into FusionAuth Cloud and say, "I want to upgrade," and you pick your version.

For those that do want to use FusionAuth Cloud as a traditional SaaS offering and not even worry about upgrades, we plan to roll out a fully managed option yet this year.

What is the QA process?

We don't have an official QA team. We basically put this responsibility on every developer – a developer can't just write code and throw it over the fence to another team and say, "Make sure it works." We write an extraordinary amount of tests. So we've actually spent a significant amount of time and energy into how we write tests, particularly for the core product. The HTTP server and the MVC software that we run are all open source, but we own them, and we contribute to them. We've built what we call a simulator, but it's not even really a simulator, it's just a test harness that provides an HTTP server, HTTP client, and a User-Agent.

All of our tests are written from the end user perspective, which is to say we don't test internal services, we only test APIs or front end workflows. Tests are usually like, "Set this environment up, call this API with this input, and expect this result in a JSON output, and then also then assert the database state." FusionAuth is fundamentally users and applications and logins, users logging into applications, so we write tests using a fluent API that uses these same nouns and verbs.

Every time we run a test, nothing is mocked. We're calling the real API over HTTP, we're opening sockets to an HTTP server that accepts that request, calls a database, and then makes an assertion. That level of comprehensive testing allows us to be confident when we ship a feature that we have not introduced regression.

We clearly communicate to every developer that there are no fences, and each feature must be comprehensively tested.

Each test that we write functionally becomes a specification. If I have a user API that says I have to validate an email address, there's a test that calls the user API and validates the email address in every possible validation methodology we have in the API. The goal is to build a fully comprehensive test suite.

What are some recent examples of interesting development challenges solved by internal teams as part of building the product?

As we've expanded the company, our code base has expanded as well – we have the core product, but then we also have FusionAuth account management to manage licenses and payment, and FusionAuth Cloud that's interacting with AWS which manages the lifecycle of a FusionAuth instance in the cloud.

Today, if you buy FusionAuth Cloud and you want your own custom URL, we kick off a job that will create you a certificate then assign that to your service. We do that all through AWS cloud services, however Amazon puts quotas and limits on every possible thing you can think of. We have customers that white label FusionAuth, so they have one-to-many custom URLs per client so they may require thousands or hundreds of thousands of URLs. This scale quickly breaks down within the AWS quota model.

To solve this, we built a micro service that replaces Amazon services such as ACM and ALBs so that we can offer our clients one to many thousands of certificates and names per service. We built this solution on top of Caddy which is a popular open source HTTP server written in Go. We love supporting software that we use, so FusionAuth is now sponsoring Caddy to support their continued development.

Implementing this was fun and way more complicated than you’d think. The basics were really simple but the devil was in the details due to the DNS and routing requirements when switching service between AWS regions in a disaster recovery scenario. But the final solution is great and it allows us to dynamically provision certificates for new URLs.

For clients that will utilize this new capability, they can just log into their FusionAuth account, create a new record indicating the URL they wish to utilize. That’s it, now the first time we see that traffic on that URL, it is routed through FusionAuth Cloud and the certificate is dynamically provisioned using Let's Encrypt. It's an extremely low friction way for customers to add new service URLs in FusionAuth Cloud.

How does on-call work?

I know every developer kind of hates being on-call. But we are just up-front during the hiring process to let the candidate know, "You're going to be on-call and that's just part of the gig." I'm the CTO, and I’m still on-call, nobody gets a free pass. Everybody has to participate.

The way it works is, you're basically on-call every sixth or seventh week and that means during the day you're helping the support engineer, you're looking at Slack, helping customers through their issues.

If you have downtime, we don't really want that developer to be doing feature dev work during that week because then your head's not in the game for customer support. But if you have downtime, the goal is for that engineer to either fix a small bug or go fix some documentation or work on smaller items on the backlog just to stay busy.

I think it has a huge benefit, every engineer we've ever had, even though they might not enjoy it, has provided excellent feedback about how much it's both helped them be confident with the customer and just how much more quickly they learn about the product

You can be on feature dev duty for months and still only work in one part of the codebase, but when you're trying to help a customer integrate FusionAuth into their business, you're looking everywhere because now they're using dozens of APIs and you're having to figure out how they work together. It's a great learning experience. I don't want to separate support and engineering because I think it makes us better engineers; it's otherwise too easy as an engineer to just write code and then ignore the voice of the customer. The customer may not always be right, but you still have to have empathy and go through that process with them.

Hiring process at FusionAuth

How does the application process work? What are the stages and what is the timeline?

The job application process is broadly divided into following steps:

  • Initial call to check fit and expectations
  • Technical screen with Java and object oriented questions
  • Take home test or pairing exercise based on preference of the applicant
  • In-person whiteboarding and meet and greet. This helps us get to know the candidate, and see how they think and solve problems. We put an emphasis on communication skills because every engineer has to participate in customer support. If someone is uncomfortable with that, then it is a disqualifier. If the developer is remote, we would generally fly them to Denver for this final step of the interview.

What is the career progression framework? How are promotions and performance reviews managed?

We do have a framework in practice, the average tenure of an engineer is short enough where most people never progress. In my experience, most engineers don't stay more than two years.

Internally we’ve created a document that outlines every title of an engineer and expectations and growth areas and inhibitors. An inhibitor might be like, "Hey, if you're a staff level engineer and you're not helping your peers, that's going to be an inhibitor to you progressing."

We've outlined each promotion level and what's expected, so that way we can walk that through with engineers during one-on-ones and review cycles just so they know what's expected of them.

In practice, everybody still participates in most aspects, which is to say even if you're a staff level or a junior, you're still going to be doing design work, which is good for the engineer. It's just that you're probably not going to be doing it alone – you're going to be working with a more senior engineer to work with you.

We really don't have any entry level engineers. Our support engineer is more of an entry level code school grad. They primarily perform customer support and if possible complete smaller coding projects just to work their way up. Our core engineering team are all very experienced.

So in theory, we do have a progression framework, but in practice everybody's in a similar bucket where everyone's expected to be able to do design and implementation and work successfully with the team.

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