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Edge Controller

Edge Controller Overview

 EdgeController is the bridge between Kubernetes Api-Server and edgecore

Operations Performed By Edge Controller

The following are the functions performed by Edge controller:

  • Downstream Controller: Sync add/update/delete event to edgecore from K8s Api-server
  • Upstream Controller: Sync watch and update the status of resource and events(node, pod and configmap) to K8s Api-server and also subscribe message from edgecore
  • Controller Manager: Creates manager interface which implements events for managing ConfigmapManager, LocationCache and podManager

Downstream Controller:

Sync add/update/delete event to edge

  • Downstream controller: Watches K8S Api-server and sends updates to edgecore via cloudHub
  • Sync (pod, configmap, secret) add/update/delete event to edge via cloudHub
  • Creates Respective manager (pod, configmap, secret) for handling events by calling manager interface
  • Locates configmap and secret should be send to which node

Downstream Controller

Upstream Controller:

Sync watch and update status of resource and events

  • UpstreamController receives messages from edgecore and syncs the updates to K8S-Api-server
  • Creates stop channel to dispatch and stop event to handle pods, configMaps, node and secrets
  • Creates message channel to update Nodestatus, Podstatus, Secret and configmap related events
  • Gets pod condition information like Ready, Initialized, Podscheduled and Unschedulable details
  • Below is the information for PodCondition    - Ready: PodReady means the pod is able to service requests and should be added to the load balancing pools for all matching services    - PodScheduled: It represents the status of the scheduling process for this pod    - Unschedulable: It means the scheduler cannot schedule the pod right now, maybe due to insufficient resources in the cluster    - Initialized: It means that all Init containers in the pod have started successfully    - ContainersReady: It indicates whether all containers in the pod are ready
  • Below is the information for PodStatus    - PodPhase: Current condition of the pod    - Conditions: Details indicating why the pod is in this condition    - HostIP: IP address of the host to which pod is assigned    - PodIp: IP address allocated to the Pod    - QosClass: Assigned to the pod based on resource requirement

   Upstream Controller

Controller Manager:

Creates manager interface and implements ConfigmapManager, LocationCache and podManager

  • Manager defines the interface of a manager, ConfigManager, Podmanager, secretmanager implements it
  • Manages OnAdd, OnUpdate and OnDelete events which will be updated to the respective edge node from the K8s Api-server
  • Creates an eventManager(configMaps, pod, secrets) which will start a CommonResourceEventHandler, NewListWatch and a newShared Informer for each event to sync(add/update/delete)event(pod, configmap, secret) to edgecore via cloudHub
  • Below is the List of handlers created by the controller Manager    - CommonResourceEventHandler: NewcommonResourceEventHandler creates CommonResourceEventHandler which is used for Configmap and pod Manager    - NewListWatch: Creates a new ListWatch from the specified client resource namespace and field selector    - NewSharedInformer: Creates a new Instance for the Listwatcher