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From Markus Thömmes <>
Subject Re: Proposal on a future architecture of OpenWhisk
Date Sun, 19 Aug 2018 11:04:29 GMT
Hi Dave,
Am Sa., 18. Aug. 2018 um 17:01 Uhr schrieb David P Grove <

> [ Discussion about cluster singleton or not for the ContainerManager]
> fwiw, I believe for Kubernetes we do not need to attempt to deal with fault
> tolerance for the ContainerManager state ourselves.  We can use labels to
> replicate all the persistent metadata for a container (prewarm or not, the
> ContainerRouter it is assigned to) in the Kube objects representing the
> pods in Kube's etcd metadata server.  If we need to restart a
> ContainerManager, the new instance can come up "instantly" and start
> servicing requests while recovering the state of the previous instance via
> querries against etcd to discover the pre-existing containers it owned.

Note that there is also state it has about ContainerRouters (how many are
there and which own which containers). We could make that queryable as
well, so as soon as a fallback happens, the fallback component queries the
state of all routers to get into consistent state.

I agree we should replicate as little state as possible and in the
Kubernetes case, we already have state about containers through pods and
their labels.

> We'll need to validate the performance of this is acceptable (should be,
> since it is just some asynchronous labeling operations when (a) the
> container is created and (b) on the initial transition from stemcell to
> warm), but it is going to be pretty simple to implement and makes good
> usage of the underlying platform's capabilities.

Agreed, good point.

> --dave

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