Note: This article was originally published on August 23, 2017. Following DrupalCon Nashville, we are republishing some of our key articles on decoupled or "headless" Drupal as the community as a whole continues to explore this approach further. Comments from the original will appear unmodified.
Decoupled Drupal has been well understood at a technical level for many years now. While the implementation details vary, most Drupal teams can handle working on decoupled projects. However, we’ve heard the following from many of our clients:
- We want a decoupled site. Why is this web project so expensive compared to sites I worked on in the past?
- Why do our decoupled projects seem so unpredictable?
- If we decide to invest in decoupled technologies, what can we expect in return?
Let’s dive into these questions.
Why Can Decoupled Sites Cost More?
Before getting too much into the details of decoupled versus full-stack, I like to ask stakeholders:
“What does your website need to do today that it didn't 5 years ago?”
Often, the answer is quite a lot! Live video, authenticated traffic, multiple mobile apps, and additional advertising deals all add to more requirements, more code, and more complexity. In many cases, the costs that are unique to decoupling are quite small compared to the costs imposed by the real business requirements.
However, I have worked on some projects where the shift to a decoupled architecture is fundamentally a technology shift to enable future improvements, but the initial build is very similar to the existing site. In those cases, there are some very specific costs of decoupled architectures.
Decoupling means forgoing Drupal functionality
Many contributed modules provide the pre-built functionality we rely on for Drupal site builds. For example, the Quickedit module enables in-place editing of content. In a decoupled architecture, prepare to rewrite this functionality. Website preview (or even authenticated viewing of content) has to be built into every front-end, instead of using the features we get for free with Drupal. Need UI localization? Content translation? Get ready for some custom code. Drupal has solved a lot of problems over the course of its evolution, so you don’t have to—unless you decouple.
Decoupling is shorthand for Service Oriented Architectures
For many organizations, a decoupled website is their first foray into Service Oriented Architectures. Most full-stack Drupal sites are a single application, with constrained integration points. In contrast, a decoupled Drupal site is best conceived of as a “content service,” accessed by many disparate consumers.
I’ve found that the “black-boxing” of a decoupled Drupal site is a common stumbling block for organizations and a driver behind the increased costs of decoupling. To properly abstract a system requires up-front systems design and development that doesn’t always fit within the time and budget constraints of a web project. Instead, internal details end up being encoded into the APIs Drupal exposes, or visual design is reflected in data structures, making future upgrades and redesigns much more expensive. Writing good APIs is hard! To do it well, you need a team who is capable of handling the responsibility—and those developers are harder to find and cost more.
Scalable systems and network effects
- Drupal for content management
- A CouchDB application to serve content over an API
- A second CouchDB application to support internal content preview
- A React app for the site front-end
- Disqus for commenting
Compared to the sites our clients need, lullabot.com is a simple site. In other words, as you build, expect to be building a web of systems, and not just a “decoupled” website. It’s possible to have a consumer request Drupal content directly, especially in Drupal 8, but expect your tech teams to push for smaller “micro” services as they get used to decoupling.
Building and testing a network of systems requires a lot of focus and discipline. For example, I’ve worked with APIs that expose internal traces of exceptions instead of returning something usable to API consumers. Writing that error handling code on the service is important, but takes time! Is your team going to have the bandwidth to focus on building a robust API, or are they going to be focusing on the front-end features your stakeholders prioritize?
I’ve also seen decoupled systems end up requiring a ton of human intervention in day-to-day use. For example, I’ve worked with systems where not only is an API account created manually, but manual configuration is required on the API end to work properly. The API consumer is supposed to be abstracted from these details, but in the end, simple API calls are tightly coupled to the behind-the-scenes configuration. A manual set up might be OK for small numbers of clients, but try setting up 30 new clients at once, and a bottleneck forms around a few overworked developers.
Another common mistake is not to allow API consumers to test their integrations in “production.” Think about Amazon’s web services—even if your application is working from a QA instance, as far as Amazon is concerned there are only production API calls available. Forcing other teams to use your QA or sandbox instance means that they won’t be testing with production constraints, and they will have production-only bugs. It’s more difficult to think about clients creating test content in production—but if the API doesn't have a good way to support that (such as with multiple accounts), then you’re missing a key set of functionality.
It’s also important to think about error conditions in a self-serve context. Any error returned by an API must make clear if the error is due to an error in the API, or the request made of the API. Server-side errors should be wired up to reporting and monitoring by the API team. I worked with one team where client-side errors triggered alerts and SMS notifications. This stopped the client-side QA team from doing any testing where users entered bad data beyond very specific cases. If the API had been built to validate inbound requests (instead of passing untrusted data through its whole application), this wouldn't have been a problem.
There's a lot to think about when it comes to decoupled Drupal sites, but it’s the only way to build decoupled architectures that are scalable and lead to faster development. Otherwise, decoupling is going to be more expensive and slower, leaving your stakeholders unsatisfied.
Why are decoupled projects unpredictable?
When clients are struggling with decoupled projects, we’ve often found it’s not due to the technology at all. Instead, poor team structure and discipline lead to communication breakdowns that are compounded by decoupled architectures.
The team must be strong developers and testers
Building decoupled sites means teams have to be self-driving in terms of automated testing, documentation, and REST best practices. QA team members need to be familiar with testing outside of the browser if they are going to test APIs. If any of these components are missing, then sprints will start to become unpredictable. The riskiest scenario is where these best practices are known, but ignored due to stakeholders prioritizing “features.” Unlike one-off, full-stack architectures, there is little room to ignore these foundational techniques. If they’re ignored, expect the team to be more and more consumed by technical debt and hacking code instead of solving the actual difficult business problems of your project.
The organizational culture must prioritize reliable systems over human interactions
The real value in decoupled architectures comes not in the technology, but in the effects on how teams interact with each other. Ask yourself: when a new team wants to consume an API, where do they get their information? Is it primarily from project managers and lead developers, or documentation and code examples? Is your team focused on providing “exactly perfect” APIs for individual consumers, or a single reusable API? Are you beholden to a single knowledge holder?
This is often a struggle for teams, as it significantly redefines the role of project managers. Instead of knowing the who of different systems the organization provides, it refocuses on the what - documentation, SDKs, and examples. Contacting a person and scheduling a meeting becomes a last resort, not a first step. Remember, there’s no value in decoupling Drupal if you’ve just coupled yourself to a lead developer on another team.
- HTTP servers
- Deployment scripts
- Testing and automation tools
- Caching and other performance tools
- Local development for all of the above
All of this means that it’s very difficult for a team to estimate how long it will take to build out such an infrastructure, and maintenance after a launch can be unpredictable as well. Having strong DevOps expertise on hand (and not outsourced) is critical here.
What’s important here is to remember that this instability isn't due to decoupling—it’s due to front-end architecture decisions. There’s nothing that stops a team from building a decoupled front-end in PHP with Twig, as another Drupal site, or anything else.
If we invest in Decoupled Drupal, what’s the payoff?
It’s not all doom and decoupled gloom. I’ve recommended and enjoyed working on decoupled projects in the past, and I continue to recommend them in discoveries with clients. Before you start decoupling, you need to know what your goals are.
With full-stack Drupal, it’s easy to create and show content that is impossible to view on mobile or set-tops apps. By decoupling the Drupal front-end, and using the same APIs as every other app, it forces CMS teams to develop with an API-first mentality. It puts all consumers on an equal playing field, simplifying the development effort in adding a new app or platform. That, on its own, might be a win for your organization.
Scaling large teams?
Most large Drupal sites, even enterprise sites, have somewhere between 5-10 active developers at a time. What if your team has the budget to grow to 30 or 50 developers?
In that case, decoupled Drupal is almost the only solution to keep individuals working smoothly. However, decoupled Drupal isn’t enough. Your team will need to completely adopt an SOA approach to building software. Otherwise, you’ll end up paying developers to build a feature that takes them months instead of days.
Decoupling with your eyes open
The most successful decoupled projects are those where everyone is on board—developers, QA, editorial, and stakeholders. It’s the attitude towards decoupling that can really push teams to the next level of capability. Decoupling is a technical architecture that doesn't work well when the business isn't buying in as well. It’s worth thinking about your competitors too—because if they are tech companies, odds are they are already investing in their teams and systems to fully embrace decoupling.