feat(cache): implement read and write handlers for Redis #24
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Currently, the redis cache handler is reading and writing from the primary endpoint which is causing throttling from the primary instance. Instead, reads should come from read-only replicas and writes go to the primary. This changes the caching pattern to eventual consistency, but this is acceptable for the marketing sites. - Added separate read and write handlers for Redis caching. - Updated constructor to initialize handlers based on environment variables. - Modified methods to use new handlers for cache operations.
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Pull Request Overview
This PR implements separate read and write handlers for Redis caching to reduce throttling on the primary Redis instance. Reads are now directed to read-only replicas while writes go to the primary endpoint, implementing an eventual consistency pattern suitable for marketing sites.
Key changes:
- Split Redis connection into separate read and write endpoints using environment variables
- Refactored cache handler to use dedicated handlers for read and write operations
- Updated infrastructure configuration to provide both primary and reader endpoint URLs
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| apps/marketing/cicd/3-app/template.yml.erb | Updated environment variables to provide separate Redis read and write endpoints |
| apps/marketing/cache-handler.mjs | Refactored cache handler class to use separate read/write handlers with new endpoint configuration |
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snickell
approved these changes
Nov 14, 2025
| const isRedisCacheEnabled = | ||
| process.env.REDIS_URL && process.env.NODE_ENV === 'production'; | ||
| process.env.REDIS_READ_URL && | ||
| process.env.REDIS_WRITE_URL && |
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Might (or not?) be worth warning if only one of these is set, as I could see only setting one and expecting redis to be enabled. Very much your call.
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Currently, the redis cache handler is reading and writing from the primary endpoint which is causing throttling from the primary instance. Instead, reads should come from read-only replicas and writes go to the primary. This changes the caching pattern to eventual consistency, but this is acceptable for the marketing sites.
Verified on
https://csforall.marketing-sites.test-code.org/