this issue aims to track progress on harbor eventing system

we could add everything in a separate notifier package, which will handle all communication from satellite to outside world.

1. requirements :

• When images are on edge location ensure Image is ready to run
• Status of connectivity to upstream harbor
• states like sync started, sync completed, sync failed, config changed
• more tbd

2. Usecases :

The events by satellite can be emitted to
a. ground control
b. user defined endpoint(probably as webhooks)

The user can then decide what to do when those events are triggered

3. Event format :

• chosen spec : https://cloudevents.io/
• Allows to define general schema/format for events and also version them
• Already used in upstream harbor.

4. Status reporting(satellite to ground control) :

• satellite will report its state to ground control in periodic intervals, as to understand whether the satellite is working smoothly

endpoint on ground control : /satellites/sync

chosen request format :

{
  Name: satellite1,
  State: “pulling images”,
  Next update: “in 5 mins”,
  Next config update: “in 10mins”,
  Next state update: “in 5 mins”,
  Memory: “<how much memory are you currently using>”,
  Storage: “<how much storage is satellite using>”,
  Cpu: “<how much cpu is using>”,
  Request created time(optional): “timestamp of created request”
}

5. Event notification :
   tbd