PADI Axelerant
padi.com Enterprise Architecture
v1.1 · 6 November 2026
Work in progress · Version 1.1, last updated 6 November 2026
Systems

padi.com and Drupal

A Next.js frontend on Acquia Front End Hosting reads a headless Drupal CMS over JSON:API. Cloudflare sits in front of both.

Summary

Layer Technology Repository and Acquia application
Frontend Next.js App Router, React, next-intl, Tailwind, standalone output on Node.js padi.com on padifrontend
CMS Drupal, PHP, MySQL, Memcache drupal.padi.com on padicom
Contract JSON:API with jsonapi_extras, jsonapi_views and menu items; decoupled_router for path resolution. No GraphQL.
Legacy Drupal 10 serving www.padi.com until cutover Legacy Acquia application

Rendering

  • Partial prerendering. Each page is a static shell built ahead of time, with Drupal content streamed into it at request time.
  • Build-time prerender of the default locale only. Other locales render on their first request and are then cached at the edge.
  • URL shape /{country}/{language}/…, for example /us/en/courses or /fr/fr/blog.
  • Page classes decide edge caching: A (content), A0 (content whose page could not be identified in time, tagged coarsely), B (listings and finder places), C (not found), N (never shared: account, MyPADI, sign-in, search, preview, any request with a session).
  • HTML is cached only at Cloudflare. Pages leave the frontend marked private (no-cache for shareable pages so the browser can restore them on back and forward, no-store for personal pages), so Acquia Varnish never stores HTML. Cloudflare reads separate Cloudflare-CDN-Cache-Control and environment-prefixed Cache-Tag headers.

Components (C4 level 3)

Figure 7. Next.js components.
Figure 7. Next.js components.
Figure 8. Drupal components.
Figure 8. Drupal components.

Page request

An anonymous page view is usually answered by Cloudflare. On a miss, Next.js serves the prebuilt shell and streams content from Drupal, whose JSON:API responses are cached in Varnish.

Figure 9. Page request, including how it degrades. The circuit breaker opens when half of 10 reads in 10 s fail across at least 3 paths.
Figure 9. Page request, including how it degrades. The circuit breaker opens when half of 10 reads in 10 s fail across at least 3 paths.

Publish and purge

Publishing invalidates Drupal cache tags. Varnish is banned by tag and Cloudflare is purged by environment-prefixed tag twice: immediately, and again 6 minutes later to catch servers that rendered from older data. Next.js menus, footers and banners refresh on their own within about a minute.

Figure 10. Publish and purge.
Figure 10. Publish and purge.

A frontend deploy invalidates all HTML for its environment. A Drupal deploy purges everything only when code or configuration changed.

Content model

Figure 11. Drupal content model.
Figure 11. Drupal content model.
Group Members
Node types (16) marketing page, page, article, blog article, blog page, Pros blog article, Pros blog page, ambassadiver, consumer alert, course, FAQ, gear, offer, promo, notification bar, testimonial
Paragraph types (34) Hero banners, carousels, content and information cards, journey cards, MyPADI component, text sections, split and promotional cards, tabs, FAQ, video, gallery, testimonials, statistics, views, library items and others
Vocabularies (16) Blog and Pros blog categories and tags, content category and collection, certification, credential, discipline, equipment, experience level, FAQ category, PADI office, region, tags, ambassadiver hometown
Media Acquia DAM image, video, audio, PDF, document, archive, spinset and generic assets, plus core media types
Regions Domain records www_padi_com (US), uk, australia, japan, padi_com_cn. The go-live model serves the first three.
Workflow One editorial workflow; see Editorial workflow

Editorial workflow

All 16 node types and 4 block types share one moderation workflow. New content starts as a draft; only the Published state is visible on the site. Most steps send an email notification, and 13 node types can be scheduled to publish or unpublish.

Figure 12. Editorial workflow. Reviewers can also return content to draft from any review state, send published content back to translation, and restore archived content.
Figure 12. Editorial workflow. Reviewers can also return content to draft from any review state, send published content back to translation, and restore archived content.
Role Can do
Content editor, blog author, Pros blog author Create drafts and submit them for review
Global content manager, blog editor, Pros blog editor Every step: review, send to translation, publish, archive, restore
Blog admin Every step, including publishing straight from initial review

Send to translate creates Crowdin jobs (Localisation); publishing purges the edge and Varnish caches (Publish and purge).

Resilience in code (C4 level 4)

Figure 13. The classes behind
Figure 13. The classes behind "serve stale rather than fail".

Runtime switches

Operational switches let the team change behaviour without a code deploy.

Switch Values Production setting Effect
Edge cache off, shadow, on on Cloudflare caches HTML by page class
Edge TTL 60 s to 3 days 24 h Edge lifetime of content and listing pages
Coarse invalidation off, shadow, on on Clears all pages of an environment for changes that tags cannot reach
Private pages no-store, no-cache, off no-cache Keeps Varnish from storing HTML; shareable pages may be restored from the browser's back and forward cache; personal pages stay no-store
Telemetry 0 or unset unset (on) Turns all telemetry off when 0
Load shedding thresholds numbers defaults Returns 503 with Retry-After 5 when a server is saturated
Fault injection fault spec refused Used to test resilience on dev and stage

Three small Node.js preloads ship with the frontend: one exposes metrics for Acquia autoscaling, one sends runtime metrics to Datadog every minute, and one trims response headers because Acquia returns 502 above about 22 KiB of headers.