Edge Controller

Edge Controller Overview

Controller(also known as 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 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

Downstream Controller

UpstreamController receives messages from edgecore and sync 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 Podcondition 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 status of the scheduling process for this pod
- Unschedulable: It means scheduler cannot schedule the pod right now, may be due to insufficient resources in the cluster
- Initialized: It means that all Init containers in the pod have started sucessfully
- 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 requirementUpstream Controller

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 controller Manager
- CommonResourceEventHandler: NewcommonResourceEventHandler creates CommonResourceEventHandler 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