5 Tips to Build a Scalable Multisite on Drupal 8

A Drupal 8 multisite is like an upscale condominium complex. The different units may have different layouts, different square footage and may be decorated by their owners in completely different ways, but certain things are the same throughout—the types of windows, the floors, architectural aspects, common areas.

The different condos are sites on the platform. Each site or condo has its own creative identity, so much so that one to one they may look completely different, but all are built on an infrastructure of shared components.

Gain speed and simplify with a multisite

A multisite enables you to spin up new sites quickly and inexpensively, especially for larger companies that oversee marketing for a collection of subsidiaries. A new branded site is possible in days, not months, using shared components and libraries, a shared UI kit, single sign-on, and shared content.

Another use-case for a multisite may be a single brand that operates in different global markets. In this case, each of the sites might be more or less the same but with certain regional differences.

Whatever the goal, planned correctly, a Drupal multisite can simplify and consolidate digital marketing operations and website maintenance, and operate as a sound platform for the future digital growth of the organization.

How do multisites work?

In a Drupal 8 multisite installation, each site has its own database and therefore its own entire set of configuration (which modules are enabled, what theme it is using, what content it has and which users can edit). Web requests coming into Drupal are routed to the appropriate site based either on domain (ex. site1.theawesome.com, site2.theawesome.com, theexcellent.com) or path (ex. theawesome.com/site1, theawesome.com/site2).

Since all of the sites share a codebase, they inherit access to all of the themes and modules therein and can turn on/off functionality as meets their needs on a particular site. What this entails for the dev team is that instead of thinking in terms of a single site, we think of building components and features for a community of sites. Planned and executed correctly, a Drupal 8 multisite gives an organization a platform with some punch: a powerful shared library of reusable integrations, functionality, UI components, and workflows.

Plan your Drupal 8 multisite

First, ask the question: why are we building a multisite or what outcome does the organization hope to accomplish with a multisite? Keeping this goal in mind will help guide the decisions that need to be made during the planning process.

Here are some good answers to that question:

• We need to run several websites that are somewhat similar in functionality but different in terms of theme/UI/UX, content, and editorial staff. 
• The engineering teams want the simplicity of managing one master codebase to reuse common code components across multiple site experiences. 
• We want to build a platform that other business units don’t manage directly to have an easy-to-use consistent, platform.
• We want our IT department to be able to maintain a single, highly secure code base of modules and features that comply with our security compliance rules and government regulations that are approved for use by all of our business units, who need a platform they can use to power their own, disparate marketing efforts.

5 tips to build a functional Drupal 8 multisite

Here are five important checkpoints when designing a new Drupal 8 multisite platform.

1. Reusability starts at the design table. It doesn’t naturally happen on its own. In order to build a Drupal 8 multisite platform that is useful to an organization the Design, UI/UX and Engineering teams all need to make practical decisions about which front end components should be built for all sites on the platform and which components should just be a customization to a specific site. This isn’t strictly limited to frontend components. There is an equal opportunity to share backend components such as content types, admin workflows, and integrations (Salesforce, Marketo). Be creative, but also don’t try to make everything reusable. It is perfectly acceptable to make site-specific customizations.
2. Build a UI kit. Decide what page components the multisite will offer to all of its tenants. Document the platform application's UI features. If you are working with an agency, ask them to do this for you. An example multisite might have a hero component, a video component, a blog component et. al. Come up with creative names for your reusable components that resonate with the marketing team. One of our clients who is building a multisite designed a reusable CTA component that could be configured to display with different degrees subtlety (ranging from a big bold button a less prominent link). The marketing team had a bit of fun with it and now when editors make a CTA on their platform they can select a “whisper”, a “buzz” or a “shout”. Thoughtful naming of components helps encourage editor engagement as well as editing uniformity throughout the platform. 
3. Build reusable features as Drupal modules. Use themes for site-specific customizations. As the name implies, modules in Drupal are intended to be independent units that can be used to construct a more complex structure. Most organizations will build a new theme for their website every couple of years but only make minor updates to their modules during the same period of time. Looking at modules and themes this way helps clearly delineate what code is for reuse and what are one-offs.
4. Plan on using single sign-on (SSO) throughout the platform whether that be using Drupal itself as the identity provider (IdP) or another system available to the organization. Managing access and permissions throughout a multisite platform in a decentralized manner quickly becomes untenable. Fortunately, Drupal 8 is very mature in regard to SSO and has robust support for common protocols like SAML.
5. Decide whether you’ll need to share content between the sites. This is actually quite feasible in Drupal 8 using its native REST services combined with the Deploy module. On a multisite with Deploy, admins can share menus, sets of categories, landing pages et. al. with each other as needed via Drupal without contacting a developer. Deploy can also be used as a content moderation tool where Admins can control content on all of the sites in a multisite platform from a single Drupal “Content Hub” instance.