Add unique id to events

[bafonins]

Summary:

We need to uniquely identify events. References: https://github.com/TheThingsNetwork/lorawan-stack/pull/570

Why do we need this?

Currently a combination of time and name is used as the key, however this can cause overlaps.

What is already there? What do you see now?

1. The Event proto, see https://github.com/TheThingsNetwork/lorawan-stack/blob/master/api/events.proto

What is missing? What do you want to see?

1. The id entry that uniquely identifies the event

Environment:

stack

Can you do this yourself and submit a Pull Request?

I can do that with guidance from someone who is familiar with the way events work.

[kschiffer]

As far as I can see, events with the exact same timestamp should not happen, meaning that

• we can use the timestamp as event key
• the occasional events with duplicate timestamps need to be addressed in the backend (#3209)
• we can use logic in the console to check for events with duplicate timestamps and discard those (#3098)
• we might want to close this issue

cc @johanstokking

[johanstokking]

My proposal would be:

• Add a new field to Event proto
• Fill that when creating the event: https://github.com/TheThingsNetwork/lorawan-stack/blob/3c1ab3a4e8a443e8e28883bc05df27369e110c4a/pkg/events/builder.go#L45-L50
• With an ID that's like correlation ID: ulid.MustNew(ulid.Now(), rand.Reader).String()