Merge pull request #154 from vaamarnath/update-arch-doc

Design document update with MS Teams support

docs/design.md

@@ -1,32 +1,41 @@
 # Kubewatch
 
-Kubewatch contains three components: client, config, handler
+Kubewatch contains three components: controller, config, handler
 
 ![Kubewatch Diagram](kubewatch.png?raw=true "Kubewatch Overview")
 
-## Client
-
-The client gets events from `kube-apiserver`, filtering and applying handler to event.
-
-It contains a config object and embedded with a k8s client.
-
 ## Config
 
 The config object contains `kubewatch` configuration, like handlers, filters.
 
 A config object is used to creating new client.
 
+## Controller
+
+The controller initializes using the config object by reading the `.kubewatch.yaml` or command line arguments.
+If the parameters are not fully mentioned, the config falls back to read a set of standard environment variables.
+
+Controller creates necessary `SharedIndexInformer`s provided by `kubernetes/client-go` for listening and watching
+resource changes. Controller updates this subscription information with Kubernetes API Server.
+
+Whenever, the Kubernetes Controller Manager gets events related to the subscribed resources, it pushes the events to
+`SharedIndexInformer`. This in-turn puts the events onto a rate-limiting queue for better handling of the events.
+
+Controller picks the events from the queue and hands over the events to the appropriate handler after
+necessary filtering.
+
 ## Handler
 
 Handler manages how `kubewatch` handles events.
 
 With each event get from k8s and matched filtering from configuration, it is passed to handler. Currently, `kubewatch` has 2 handlers:
 
  - `Default`: which just print the event in JSON format
- - `Slack`: which send notification to Slack channel based on information from config
+ - `Flock`: which send notification to Flock channel based on information from config
  - `Hipchat`: which send notification to Hipchat room based on information from config
  - `Mattermost`: which send notification to Mattermost channel based on information from config
- - `Flock`: which send notification to Flock channel based on information from config
+ - `MS Teams`: which send notification to MS Team incoming webhook based on information from config
+ - `Slack`: which send notification to Slack channel based on information from config
 
 More handlers will be added in future.