Created 3 new scenarios for troubleshooting

scenarios/README.md

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+
+
+
+### 3. Persistent Volume Issues
+
+#### Overview
+Applications might face issues when trying to mount persistent volumes, which can be due to misconfigurations or underlying storage issues.
+
+#### Tasks
+- **Creating the Problem**:
+  1. Create a persistent volume with incorrect access modes.
+  2. Create a persistent volume claim that references the volume.
+  3. Create a pod that mounts the persistent volume claim.
+  4. Apply all configurations and observe the pod failing to start.
+
+- **Fixing the Problem**:
+  1. Update the persistent volume to have the correct access modes.
+  2. Apply the updated configuration: `kubectl apply -f persistent-volume.yaml`.
+  3. Delete and recreate the pod to attempt mounting the volume again.
+
+---
+
+### 4. Resource Limitations
+
+#### Overview
+Setting appropriate resource requests and limits is crucial to ensure that your applications have the resources they need to run effectively.
+
+#### Tasks
+- **Creating the Problem**:
+  1. Create a pod with very low resource limits.
+  2. Apply the configuration: `kubectl apply -f pod-definition.yaml`.
+  3. Observe that the pod might be evicted or fail to run effectively.
+
+- **Fixing the Problem**:
+  1. Update the pod definition to have more reasonable resource limits.
+  2. Apply the updated configuration: `kubectl apply -f pod-definition.yaml`.
+  3. Observe that the pod is now running effectively.
+
+---
+
+### 5. Security and RBAC Issues
+
+#### Overview
+Role-Based Access Control (RBAC) in Kubernetes helps in defining what actions users or applications can perform. Misconfigurations can lead to access issues.
+
+#### Tasks
+- **Creating the Problem**:
+  1. Create a Role and RoleBinding (or ClusterRole and ClusterRoleBinding) with very limited permissions.
+  2. Try to perform an action that requires more permissions and observe the failure.
+
+- **Fixing the Problem**:
+  1. Update the Role (or ClusterRole) to include the necessary permissions.
+  2. Apply the updated configuration: `kubectl apply -f role-definition.yaml`.
+  3. Retest the action and observe that it now succeeds.
+
+---
+
+### 6. ConfigMap and Secret Issues
+
+#### Overview
+Applications might fail if they cannot access the necessary configuration data or secrets.
+
+#### Tasks
+- **Creating the Problem**:
+  1. Create a ConfigMap or Secret with incorrect data.
+  2. Mount the ConfigMap or Secret in a pod.
+  3. Apply all configurations and observe the application failing.
+
+- **Fixing the Problem**:
+  1. Update the ConfigMap or Secret with the correct data.
+  2. Apply the updated configuration: `kubectl apply -f configmap-or-secret.yaml`.
+  3. Delete and recreate the pod to mount the updated ConfigMap or Secret.
+
+---
+
+### 7. Upgrade Issues
+
+#### Overview
+Upgrading Kubernetes or applications can sometimes lead to issues if not done carefully.
+
+#### Tasks
+- **Creating the Problem**:
+  1. Upgrade your Kubernetes cluster or application without checking compatibility.
+  2. Observe any issues that arise post-upgrade.
+
+- **Fixing the Problem**:
+  1. Roll back to the previous version if necessary.
+  2. Check compatibility and perform any required pre-upgrade steps.
+  3. Retry the upgrade.
+
+---
+
+### 8. High Availability and Failover
+
+#### Overview
+Ensuring high availability and seamless failover is crucial for production applications.
+
+#### Tasks
+- **Creating the Problem**:
+  1. Set up an application with a single replica.
+  2. Simulate a node failure or delete the pod and observe downtime.
+
+- **Fixing the Problem**:
+  1. Update the deployment to use multiple replicas spread across different nodes.
+  2. Apply the updated configuration: `kubectl apply -f deployment.yaml`.
+  3. Retest node failure or pod deletion and observe reduced downtime.
+
+---
+
+### 9. Monitoring and Logging
+
+#### Overview
+Proper monitoring and logging are essential for troubleshooting and maintaining the health of your applications.
+
+#### Tasks
+- **Creating the Problem**:
+  1. Set up an application without any monitoring or logging solutions in place.
+  2. Try to troubleshoot an issue without sufficient logs or metrics.
+
+- **Fixing the Problem**:
+  1. Set up and configure a monitoring and logging solution such as Prometheus, Grafana, and ELK stack.
+  2. Ensure logs and metrics are being collected.
+  3. Retest troubleshooting with the available logs and metrics.
+
+---
+
+### 10. Resource Leaks and Orphaned Resources
+
+#### Overview
+Over time, Kubernetes clusters might accumulate unused or orphaned resources, leading to resource wastage.
+
+#### Tasks
+- **Creating the Problem**:
+  1. Create and delete numerous resources without cleaning up associated resources.
+  2. Observe the accumulation of orphaned resources.
+
+- **Fixing the Problem**:
+  1. Identify and manually delete orphaned resources.
+  2. Use tools like `kubectl-prune` to automate the cleanup of unused resources.
+
+---
+
+Each section provides a basic guide on how to create a specific problem in a Kubernetes environment and steps to resolve it. Adjustments may be needed based on the specific Kubernetes setup and application configurations.

scenarios/connectivity/README.md

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+### Service Connectivity Issues
+
+
+#### Overview
+Services in Kubernetes provide a way for pods to communicate with each other. Misconfigurations or network policies can lead to connectivity issues.
+
+In this scenario, we have an `nginx` deployment that has a service assosiated with it. The goal is to get connectivity between the `probe` pod and the `nginx` pod through the service.
+
+#### Tasks
+- **Creating the Problem**:
+  1. run `bash setup.sh`
+  1. Execute into the `probe` pod and see that you can connect to the nginx deployment through the service with a curl call: `curl nginx-service:80`
+
+- **Fixing the Problem**:
+
+<details>
+<summary> Hint </summary>
+It is clear that the connection is not working.
+Try to describe the service and see if you can find the problem.
+</details>
+
+<details>
+<summary> Hint </summary>
+
+A service describes it's endpoints under the `Endpoints` section. Is there any there?
+
+</details>
+
+<summary> Hint </summary>
+
+The service is not assosiated with any pods, because the selector does not match any labels. 
+Make sure that the labels on both service and deployment/pod are the same.
+
+</details>
+
+### Clean up
+
+Remove the pod by executing `kubectl delete -f .` in the folder

scenarios/connectivity/deployment.yaml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: nginx
+spec:
+  selector:
+    matchLabels:
+      app: myapp
+  template:
+    metadata:
+      labels:
+        app: myapp
+    spec:
+      containers:
+      - name: myapp
+        image: nginx
+        resources:
+          limits:
+            memory: "128Mi"
+            cpu: "500m"
+        ports:
+        - containerPort: 80

scenarios/connectivity/pod.yaml

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+apiVersion: v1
+kind: Pod
+metadata:
+  name: probe
+  labels:
+    name: probe
+spec:
+  containers:
+  - name: probe
+    image: ghcr.io/eficode-academy/network-multitool
+    resources:
+      limits:
+        memory: "128Mi"
+        cpu: "500m"
+    ports:
+      - containerPort: 80

scenarios/connectivity/service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx-service
+spec:
+  selector:
+    app: app
+  ports:
+  - port: 80
+    targetPort: 80

scenarios/connectivity/setup.sh

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+#!/bin/bash
+# apply the configuration to your Kubernetes cluster
+kubectl apply -f .
+
+echo "setup completed"

scenarios/limits/README.md

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+### 3. Limits
+
+#### Overview
+Apps should have boundaries on what type of resources they can take up
+
+#### Tasks
+- **Creating the Problem**:
+  1. run `bash setup.sh`
+  1. Observe that the pod is failing to start.
+
+- **Fixing the Problem**:
+
+<details>
+<summary> Hint </summary>
+
+`kubectl get pods` will show you
+</details>
+
+<details>
+
+
+### Clean up
+
+Remove the pod by executing `kubectl delete -f .` in the folder

scenarios/limits/pod.yaml

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+apiVersion: v1
+kind: Pod
+metadata:
+  name: mysql-pod
+spec:
+  containers:
+  - name: mysql
+    image: mysql:5.7
+    env:
+      - name: MYSQL_ROOT_PASSWORD
+        value: "my-secret-pw"
+    ports:
+      - containerPort: 3306
+    volumeMounts:
+      - mountPath: /var/lib/mysql
+        name: my-volume
+    resources:
+      limits:
+        memory: "128Mi"
+        cpu: "500m"
+  volumes:
+  - name: my-volume
+    persistentVolumeClaim:
+      claimName: my-pvc

scenarios/limits/setup.sh

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+#!/bin/bash
+# apply the configuration to your Kubernetes cluster
+kubectl apply -f .
+
+echo "setup completed"

scenarios/persistency/README.md

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+### 3. Persistency Issues
+
+#### Overview
+Applications might face issues when trying to mount persistent volumes, which can be due to misconfigurations or underlying storage issues.
+
+Note that this scenario only works on AWS clusters, as persistency is very cloud provider specific.
+
+#### Tasks
+- **Creating the Problem**:
+  1. run `bash setup.sh`
+  1. Observe that the pod is failing to start.
+
+- **Fixing the Problem**:
+
+<details>
+<summary> Hint </summary>
+
+`kubectl get pods` will show you
+</details>
+
+<details>
+<summary> Hint </summary>
+
+A service describes it's endpoints under the `Endpoints` section. Is there any there?
+
+</details>
+
+<summary> Hint </summary>
+
+The service is not assosiated with any pods, because the selector does not match any labels. 
+Make sure that the labels on both service and deployment/pod are the same.
+
+</details>
+
+### Clean up
+
+Remove the pod by executing `kubectl delete -f .` in the folder

scenarios/persistency/pod.yaml

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+apiVersion: v1
+kind: Pod
+metadata:
+  name: mysql-pod
+spec:
+  containers:
+  - name: mysql
+    image: mysql:5.7
+    env:
+      - name: MYSQL_ROOT_PASSWORD
+        value: "my-secret-pw"
+    ports:
+      - containerPort: 3306
+    volumeMounts:
+      - mountPath: /var/lib/mysql
+        name: my-volume
+    resources:
+      limits:
+        memory: "512Mi"
+        cpu: "500m"
+  volumes:
+  - name: my-volume
+    persistentVolumeClaim:
+      claimName: my-pvc

scenarios/persistency/pvc.yaml

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+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: my-pvc
+spec:
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 1Gi
+  storageClassName: standard

scenarios/persistency/setup.sh

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+#!/bin/bash
+# apply the configuration to your Kubernetes cluster
+kubectl apply -f .
+
+echo "setup completed"