GCP cloud run send a request to all running instances

user_15040818 0
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I have a rest API running on cloud run that implements a cache, which needs to be cleared maybe once a week when I update a certain property in the database. Is there any way to send a HTTP request to all running instances of my application? Right now my understanding is even if I send multiple requests and there are 5 instances, it could all go to one instance. So is there a way to do this?

google-cloud-run google-cloud-functions google-cloud-platform
2 Answers

Let's go back to basics:

Cloud Run instances start based on a revision/image.

If you have the above use case, where suppose you have 5 instances running and you suddenly need to re-start them as restarting the instances resolves your use case, such as clearing/rebuilding the cache, what you need to do is:

Trigger a change in the service/config, so a new revision gets created.

This will automatically replace, so will stop and relaunch all your instances on the fly.

You have a couple of options here, choose which is suitable for you:

  1. if you have your services defined as yaml files, the easiest is to run the replace service command:

    gcloud beta run services replace myservice.yaml

  2. otherwise add an Environmental variable like a date that you increase, and this will yield a new revision (as a change in Env means new config, new revision) read more.

    gcloud run services update SERVICE --update-env-vars KEY1=VALUE1,KEY2=VALUE2

As these operations are executed, you will see a new revision created, and your active instances will be replaced on their next request with fresh new instances that will build the new cache.

user_2437820

You can't reach directly all the active instance, it's the magic (and the tradeoff) of serverless: you don't really know what is running!! If you implement cache on Cloud Run, you need a way to invalidate it.

  • Either based on duration; when expired, refresh it
  • Or by invalidation. But you can't on Cloud Run.

The other way to see this use case is that you have a cache shared between all your instance, and thus you need a shared cache, something like memory store. You can have only 1 Cloud Run instance which invalidate it and recreate it and all the other instances will use it.

user_113725930
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