Edge Controller

Edge Controller Overview

EdgeController is the bridge between Kubernetes Api-Server and edgecore

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: 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

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

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