Local MQTT/Pub/Sub - to notify component crashes

[chandar1]

I have 2 apps running as green grass components.

when one of the apps crashes for some reason, the other app/component should be notified via local pub/sub mechanism - but the crashing app cannot "publish" its status here.
Is there a way that Green Grass nucleus notifies such status changes, crashes of components, to other running components?
Need to use pub-sub model here and NOT direct http rest api calls.

How to achieve this in aws green grass?

Any help is appreciated!
Thanks.

[jmklix]

You will want to use IoT lifecycle events. If you subscribe to this topic: $aws/events/presence/disconnected/clientId, you will get notified when a specific clientId is disconnected.

[bretambrose]

You will want to use IoT lifecycle events. If you subscribe to this topic: $aws/events/presence/disconnected/clientId, you will get notified when a specific clientId is disconnected.

I don't think that applies to local pub/sub on GG.

[jmklix]

I believe you can use lifecycle events, as Michael Dombrowski suggested it here:

Hi,

You cannot configure a will for Greengrass. Why do you want a will to be set? If you'd like to know when Greengrass connects and disconnects you can use IoT lifecycle events for that: https://docs.aws.amazon.com/iot/latest/developerguide/life-cycle-events.html

Cheers,

Michael

[bretambrose]

I believe you can use lifecycle events, as Michael Dombrowski suggested it here:

Hi,
You cannot configure a will for Greengrass. Why do you want a will to be set? If you'd like to know when Greengrass connects and disconnects you can use IoT lifecycle events for that: https://docs.aws.amazon.com/iot/latest/developerguide/life-cycle-events.html
Cheers,
Michael

They're not asking for GG connectivity they're wondering about component stability.

[jmklix]

Thanks @bretambrose for pointing this out, my above suggestion won't work for your situation. Still looking for a solution

[joysl]

you can subscribe to component events: https://docs.aws.amazon.com/greengrass/v2/developerguide/ipc-component-lifecycle.html#ipc-operation-subscribetocomponentupdates

[jmklix]

The only local solution is to use GetComponentDetails to get the status of each component. This might not fix your exact use case because it's something that you have check yourself. Please let me know if you have any questions about this