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 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
Upstream Controller:
Sync watch and Update status of resource and events
- 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 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
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 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