add README and reference

Author: tomkukral

trouble/README.md

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+This repository containers common Kubernetes problems. Each YAML file (or directory) contains broken deployment.
+
+* `clean.sh` will clean everything in `default` namespaces and fix broken nodes.
+
+
+# Easy
+
+* U01 - Scaled to 0 replicas
+* U02 - Wrong service selector (application instead of app)
+* U03 - Typo in container image
+* U09 - Nodes unschedulable
+
+# Medium
+
+* U04 - ConfigMap missing
+* U05 - Persistent volume claim missing
+* U06 - Missing node label (nodeSelector)
+* U08 - Service port mismatch
+* U09 - Nodes unschedulable
+* U10 - Nodes tainted
+* U11 - InitContainer failing
+* U12 - Liveness probe not working (port mismatch)

trouble/reference.yml

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+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: kad
+spec:
+  selector:
+    app: kad
+  ports:
+    - protocol: TCP
+      targetPort: 5000
+      port: 80
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: redis
+spec:
+  type: ClusterIP
+  clusterIP: None
+  selector:
+    app: redis
+  ports:
+    - protocol: TCP
+      port: 6379
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: kad
+data:
+  config.yml: |
+    abc: 123
+    password: LinuxDays
+  option.color: red
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: credentials
+type: Opaque
+data:
+  username: YWRtaW4=
+  password: TGludXhEYXlz
+---
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: kad
+spec:
+  replicas: 1
+  template:
+    metadata:
+      labels:
+        app: kad
+    spec:
+      containers:
+      - name: app
+        image: tomkukral/kad
+        imagePullPolicy: Always
+        ports:
+        - containerPort: 5000
+        command: ["/bin/kad", "--color", "$(COLOR)", "--user", "$(USERNAME)"]
+        env:
+        # static configuration from yaml
+        - name: REDIS_SERVER
+          value: redis-0.redis:6379
+        # configuraiton from downward API
+        - name: NODE_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: spec.nodeName
+        # variable form configmap
+        - name: COLOR
+          valueFrom:
+            configMapKeyRef:
+              name: kad
+              key: option.color
+        # variables from secret
+        - name: USERNAME
+          valueFrom:
+            secretKeyRef:
+              name: credentials
+              key: username
+        - name: PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: credentials
+              key: password
+        volumeMounts:
+        - name: config
+          mountPath: /etc/kad/
+      volumes:
+      - name: config
+        configMap:
+          name: kad
+          items:
+          - key: config.yml
+            path: config.yml
+---
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: redis
+spec:
+  selector:
+    matchLabels:
+      app: redis
+  serviceName: redis
+  replicas: 1
+  template:
+    metadata:
+      labels:
+        app: redis
+      annotations:
+        sidecar.istio.io/inject: "true"
+    spec:
+      containers:
+      - name: redis
+        image: redis
+        resources:
+          limits:
+            memory: 128Mi
+        ports:
+        - containerPort: 6379
+        volumeMounts:
+          - mountPath: "/data"
+            name: redis-disk
+  volumeClaimTemplates:
+  - metadata:
+      name: redis-disk
+    spec:
+      accessModes: ["ReadWriteOnce"]
+      resources:
+        requests:
+          storage: 1Gi