[EnMasse] Enmasse + UnifiedPush + Operator Feedback and request for help

Wed Jul 31 12:40:46 UTC 2019

On Wed, Jul 31, 2019 at 1:27 PM Camila Macedo <cmacedo at redhat.com> wrote:

> Hi @Summers,
>
> Regards the items 2 and 3, could we not implement these actions in the UPS
> operators instead of the expected implementation on enmasse?
> Regards item 4 shows that a new release was made 10 hours ago with this
> fix[1](0.29.0[2]). So, could not it be solved by using this version?
>

I would hope we would not do that. Simply because that means a bit (or a
lot) of effort, but only solves to the problem for one consumer of enmasse.
However others (even the IoT components of enmasse) face the same issue.
And we would need to invest some time there as well.

So I would prefer some solution, which fixes the root cause, rather than
working around the issue in various other locations.

>
> [1] - https://github.com/EnMasseProject/enmasse/issues/2927
> [2] - https://github.com/EnMasseProject/enmasse/releases/tag/0.29.0
>
>
> CAMILA MACEDO
>
> SR. SOFTWARE ENGINEER, RED HAT CLOUD SERVICES
>
> Red Hat UK <https://www.redhat.com/>
>
> IM: cmacedo
>
> Phone: +44 7853500035
> <https://red.ht/sig>
>
>
> On Mon, Jul 29, 2019 at 4:07 PM Summers Pittman <supittma at redhat.com>
> wrote:
>
>> I'm cross posting this on the AeroGear(
>> https://groups.google.com/forum/#!forum/aerogear) and the enmasse (
>> https://www.redhat.com/mailman/listinfo/enmasse) mailing lists.
>>
>> In the past few months we've been adding the ability to use an external
>> broker with the Unified Push Server[UPS] (
>> https://github.com/aerogear/aerogear-unifiedpush-server).  We've added
>> support for external AMQP connections to the UPS container image, as well
>> as added support for connecting to enmasse using the UPS operator (
>> https://github.com/aerogear/unifiedpush-operator).  Following are our
>> experiences with enmasse as well as some problems we encountered.
>>
>> 1: The creation of enmasse resources using the UPS operator (based on
>> client-go https://github.com/kubernetes/client-go) worked pretty much as
>> expected.  The only downside was that the golang bindings from enmasse were
>> out of date, but the team accepted our PR's and released a new version with
>> updated bindings.  Much appreciated!
>>
>> 2: The enmasse controllers for address, addresspaces, and messagingusers
>> do not implement k8s watches, nor do they throw an exception if you try to
>> watch a resource.  This causes a lot of errors to be logged in the UPS
>> operator as we need to watch and maintain those resources to keep our
>> service running.  There is an open enmasse issue here that describes the
>> issue : https://github.com/EnMasseProject/enmasse/issues/1280
>>
>> 3: Enmasse doesn't block owner deletion nor implement a finalizer to
>> handle being orphaned.  This means that when our operator deletes a UPS
>> server, the addresses and addressspace resources we create don't get
>> deleted, nor do we get a notification that they aren't being deleted.
>>
>> 4: Enmasse has no way to configure delivery failures.  Usually with a
>> message broker we want failed messages to be retried, then retried with a
>> backoff, and eventually retired to a dead letter queue.  In enmasse the
>> default behavior is to retry immediately and infinitely.  There is very
>> little we can use the broker for to get an alert that this is happening.
>> In the case of a production error this means that enmasse will death star
>> our service with an infinite stream of doomed messages.  We are researching
>> workarounds, but per this issue (
>> https://github.com/EnMasseProject/enmasse/issues/2927) it seems like
>> there is little we can do at the level of address resource configuration.
>>
>> 5: Creation of resources (addresses, addressspaces, messaging users) and
>> getting their respective information into our deployment using our operator
>> was really straight forward.  Like amazingly simple and directly straight
>> forward.
>>
>> Feel free to reply inline to the points.  Now for my actual question :
>>
>> We're trying to find workaround to #4 and are actively soliciting ideas.
>> Right now we're looking at implementing more aggressive messaging handling
>> so messages will always be consumed even if we would prefer them to be
>> retried (for instance if the network connection to our push service was
>> unavailable for a moment, a credential expired etc).
>>
>> This doesn't help for unexpected errors in the UPS code (who doesn't love
>> a good NPE), and for that we might want to have the UPS operator keep an
>> eye out for extreme message re deliveries and auto-manually delete those
>> messages, but that would be better handled by a DLQ mechanism.
>>
>> Thoughts on the potential workarounds?
>>
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>>
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