Watcher

Port: :4040
Source: apps/workers/watcher/

The watcher keeps the Redis cache in sync with MongoDB. It consumes change stream events from Kafka and writes or removes the relevant entities in Redis so that other workers and services can perform fast in-memory lookups without hitting the database on every request.

Responsibilities

For each Kafka change event the watcher:

1. Determines the operation type (create, update, delete).
2. Writes the updated entity to Redis (for create/update) or removes it (for delete).
3. Applies availability checks — only active/available entities are cached.

Watched Entities

Module	Entity	Redis Usage
auth	Grants	ABAC permission grants stored via abacl-redis RedisDriver
auth	APTs	Auth Personal Tokens cached for fast API key validation
domain	Clients	OAuth client records cached for token validation
identity	Users	User records cached for identity resolution
context	Configs	CQRS webhook configs read by the dispatcher
career	Products	Product records cached for business logic lookups
conjoint	Messages	Message records cached for real-time delivery
content	Posts	Post records cached for content delivery

Grant Caching (ABAC)

Grants are handled specially through abacl-redis:

The isAvailable() check ensures only active, non-expired grants are stored. Inactive or expired grants are removed immediately.

Infrastructure Dependencies

Dependency	Usage
Kafka	Consumes MongoDB change stream events
Redis	Write target — all watched entities land here
MongoDB	Source of truth (via Kafka change events)

Key Files

File	Purpose
modules/auth/grants/grants.service.ts	ABAC grant cache sync via abacl-redis
modules/auth/apts/apts.service.ts	APT (API key) cache sync
modules/domain/clients/clients.service.ts	OAuth client cache sync
modules/identity/users/users.service.ts	User record cache sync
modules/context/configs/configs.service.ts	CQRS config cache sync
modules/career/products/products.service.ts	Product cache sync
modules/conjoint/messages/messages.service.ts	Message cache sync
modules/content/posts/posts.service.ts	Post cache sync