新增learn-kubernetes（https://github.com/yyong-brs/learn-kubernetes）相关文件

learn/learn-kubernetes-master/kiamol/ch21/lab/README.md

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+# Ch20 lab
+
+## Setup
+
+Deploy Knative with Contour:
+
+```
+kubectl apply -f lab/knative/
+```
+
+Deploy the to-do app:
+
+```
+kubectl apply -f lab/todo-list/
+```
+
+Get the ingress URL:
+
+```
+kubectl get svc -n contour-external envoy -o jsonpath='http://{.status.loadBalancer.ingress[0].*}:80'
+```
+
+> Map your `hosts` file to use the Contour IP for `todo.kiamol.local` and `api.todo.kiamol.local`
+
+
+## Solution
+
+I've used a [Knative Service custom resource](./solution/todo-api.yaml) which specifies the API container image.
+
+```
+kubectl apply -f lab/solution/todo-api.yaml
+```
+
+Check the Knative Service is running:
+
+```
+kubectl get ksvc -n todo
+```
+
+Invoke the function:
+
+```
+curl --data 'Write KIAMOL ch22' http://api.todo.kiamol.local/todos
+```
+
+Print the function logs - you should see the event being published:
+
+```
+kubectl -n todo logs -l serving.knative.dev/service=api -c user-container
+```
+
+Print the save handler logs - you should see the new item being saved:
+
+```
+kubectl -n todo logs -l component=save-handler
+```
+
+> Browse to http://todo.kiamol.local to see the new item