I have a use case in which Microservice A has to do some heavy computation periodically and stores the result in Cache (redis) – something like k8s cron job.
Microservice B depends on the Cache written by A.(B only reads. never modifies cache).
But it looks like db is being shared here. Is this a good design?
(This aws doc shows 2 different services using same redis)
2
Answers
The contents of redis should be treated as ephemeral, not permanent. It’s a cache. There is nothing wrong with your design as long as your microservices, especially Microservice B, behave gracefully if they do not find what they expect in redis.
This is actually a very common practice in projects using Redis (for example its the exact way you setup Redis to act as a message broker. One end writes the message and the other reads it.)
Databases are meant do be shared, especially in the modern days where a program can consist of hundreds of micro-parts.
You shouldn’t have any issues related to Redis, BUT you HAVE to implement a fallback mechanism for Micro-service B, to handle the case in which no value is found, for example using a timeout and then read again, or getting some default value and using that.