IntoTheDevOps: Add End-to-End Kubernetes content

Signed-off-by: NotHarshhaa <reddyharshhaa12@gmail.com>

topics/kubernetes/exercises/kustomize_common_labels/exercise.md

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+# Kustomize - Common Labels
+
+## Requirements
+
+1. Running Kubernetes cluster
+2. Kubctl version 1.14 or above
+
+## Objectives
+
+In the current directory there is an app composed of a Deployment and Service.
+
+1. Write a kustomization.yml file that will add to both the Service and Deployment the label "team-name: aces"
+2. Execute a kustomize command that will generate the customized k8s files with the label appended
+
+## Solution
+
+Click [here](solution.md) to view the solution

topics/kubernetes/exercises/kustomize_common_labels/solution.md

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+# Kustomize - Common Labels
+
+## Requirements
+
+1. Running Kubernetes cluster
+2. Kubctl version 1.14 or above
+
+## Objectives
+
+In the current directory there is an app composed of a Deployment and Service.
+
+1. Write a kustomization.yml file that will add to both the Service and Deployment the label "team-name: aces"
+2. Execute a kustomize command that will generate the customized k8s files with the label appended
+
+## Solution
+
+1. Add the following to kustomization.yml in someApp directory:
+
+```
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+commonLabels:
+  team-name: aces
+
+resources:
+  - service.yml
+  - deployment.yml
+```
+
+2. Run `kubectl apply -k someApp`

topics/kubernetes/exercises/kustomize_common_labels/someApp/deployment.yml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: nginx-deployment
+  labels:
+    app: nginx
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app: nginx
+  template:
+    metadata:
+      labels:
+        app: nginx
+    spec:
+      containers:
+      - name: nginx
+        image: nginx:1.14.2
+        ports:
+        - containerPort: 80

topics/kubernetes/exercises/kustomize_common_labels/someApp/service.yml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: my-service
+spec:
+  selector:
+    app: nginx
+  ports:
+    - protocol: TCP
+      port: 80
+      targetPort: 9376

topics/kubernetes/exercises/labels_and_selectors/exercise.md

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+# Labels and Selectors 101
+
+## Objectives
+
+1. How to list all the Pods with the label "app=web"?
+2. How to list all objects labeled as "env=staging"?
+3. How to list all deployments from "env=prod" and "type=web"?
+
+## Solution
+
+Click [here](solution.md) to view the solution.

topics/kubernetes/exercises/labels_and_selectors/solution.md

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+# Labels and Selectors 101
+
+## Objectives
+
+1. How to list all the Pods with the label "app=web"?
+2. How to list all objects labeled as "env=staging"?
+3. How to list all deployments from "env=prod" and "type=web"?
+
+## Solution
+
+`k get po -l app=web`
+`k get all -l env=staging`
+`k get deploy -l env=prod,type=web`

topics/kubernetes/exercises/node_selectors/exercise.md

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+# Node Selectors
+
+## Objectives
+
+1. Apply the label "hw=max" on one of the nodes in your cluster
+2. Create and run a Pod called `some-pod` with the image `redis` and configure it to use the selector `hw=max`
+3. Explain why node selectors might be limited
+
+
+## Solution
+
+Click [here](solution.md) to view the solution

topics/kubernetes/exercises/node_selectors/solution.md

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+# Node Selectors
+
+## Objectives
+
+1. Apply the label "hw=max" on one of the nodes in your cluster
+2. Create and run a Pod called `some-pod` with the image `redis` and configure it to use the selector `hw=max`
+3. Explain why node selectors might be limited
+
+
+## Solution
+
+Click [here](solution.md) to view the solution
+
+1. `kubectl label nodes some-node hw=max`
+2. 
+
+```
+kubectl run some-pod --image=redis --dry-run=client -o yaml > pod.yaml
+
+vi pod.yaml
+
+spec:
+  nodeSelector:
+    hw: max
+
+kubectl apply -f pod.yaml
+```
+
+3. Assume you would like to run your Pod on all the nodes with with either `hw` set to max or to min, instead of just max. This is not possible with nodeSelectors which are quite simplified and this is where you might want to consider `node affinity`.

topics/kubernetes/exercises/taints_101/exercise.md

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+# Taints 101
+
+## Objectives
+
+1. Check if one of the nodes in the cluster has taints (doesn't matter which node)
+2. Create a taint on one of the nodes in your cluster with key of "app" and value of "web" and effect of "NoSchedule"
+   1. Explain what it does exactly
+   2. Verify it was applied
+3. Run a Pod that will be able to run on the node on which you applied the taint
+
+## Solution
+
+Click [here](solution.md) to view the solution.

topics/kubernetes/exercises/taints_101/solution.md

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+# Taints 101
+
+## Objectives
+
+1. Check if one of the nodes in the cluster has taints (doesn't matter which node)
+2. Create a taint on one of the nodes in your cluster with key of "app" and value of "web" and effect of "NoSchedule"
+   1. Explain what it does exactly
+   2. Verify it was applied
+
+## Solution
+
+1. `kubectl describe no minikube | grep -i taints`
+2. `kubectl taint node minikube app=web:NoSchedule`
+   1. Any resource with "app=web" key value will not be scheduled on node `minikube`
+   2. `kubectl describe no minikube | grep -i taints`
+3. 
+
+```
+kubectl run some-pod --image=redis
+kubectl edit po some-pod
+```
+
+```
+ - effect: NoSchedule
+    key: app
+    operator: Equal
+    value: web
+```
+
+Save and exit. The Pod should be running.

topics/kubernetes/killing_containers.md

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+## "Killing" Containers
+
+1. Run Pod with a web service (e.g. httpd)
+2. Verify the web service is running with the `ps` command
+3. Check how many restarts the pod has performed
+4. Kill the web service process
+5. Check how many restarts the pod has performed
+6. Verify again the web service is running
+
+## After you complete the exercise
+
+* Why did the "RESTARTS" count raised?

topics/kubernetes/pods_01.md

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+## Pods 01
+
+#### Objective
+
+Learn how to create pods
+
+#### Instructions
+
+1. Choose a container image (e.g. redis, nginx, mongo, etc.)
+2. Create a pod (in the default namespace) using the image you chose
+3. Verify the pod is running

topics/kubernetes/replicaset_01.md

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+## ReplicaSet 101
+
+#### Objective
+
+Learn how to create and view ReplicaSets
+
+#### Instructions
+
+1. Create a ReplicaSet with 2 replicas. The app can be anything.
+2. Verify a ReplicaSet was created and there are 2 replicas
+3. Delete one of the Pods the ReplicaSet has created
+4. If you'll list all the Pods now, what will you see?
+5. Remove the ReplicaSet you've created
+6. Verify you've deleted the ReplicaSet

topics/kubernetes/replicaset_02.md

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+## ReplicaSet 102
+
+#### Objective
+
+Learn how to operate ReplicaSets
+
+#### Instructions
+
+1. Create a ReplicaSet with 2 replicas. The app can be anything.
+2. Verify a ReplicaSet was created and there are 2 replicas
+3. Remove the ReplicaSet but NOT the pods it created
+4. Verify you've deleted the ReplicaSet but the Pods are still running

topics/kubernetes/replicaset_03.md

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+## ReplicaSet 103
+
+#### Objective
+
+Learn how labels used by ReplicaSets
+
+#### Instructions
+
+1. Create a ReplicaSet with 2 replicas. Make sure the label used for the selector and in the Pods is "type=web"
+2. Verify a ReplicaSet was created and there are 2 replicas
+3. List the Pods running
+4. Remove the label (type=web) from one of the Pods created by the ReplicaSet
+5. List the Pods running. Are there more Pods running after removing the label? Why?
+6. Verify the ReplicaSet indeed created a new Pod

topics/kubernetes/services_01.md

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+## Services 01
+
+#### Objective
+
+Learn how to create services
+
+#### Instructions
+
+1. Create a pod running ngnix
+2. Create a service for the pod you've just created
+3. Verify the app is reachable

topics/kubernetes/solutions/killing_containers.md

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+## "Killing" Containers - Solution
+
+1. Run Pod with a web service (e.g. httpd) - `kubectl run web --image registry.redhat.io/rhscl/httpd-24-rhel7`
+2. Verify the web service is running with the `ps` command - `kubectl exec web -- ps`
+3. Check how many restarts the pod has performed - `kubectl get po web`
+4. Kill the web service process -`kubectl exec web -- kill 1`
+5. Check how many restarts the pod has performed - `kubectl get po web`
+6. Verify again the web service is running - `kubectl exec web -- ps`
+
+## After you complete the exercise
+
+* Why did the "RESTARTS" count raised? - `because we killed the process and Kubernetes identified the container isn't running properly so it performed restart to the Pod`

topics/kubernetes/solutions/pods_01_solution.md

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+## Pods 01 - Solution
+
+```
+kubectl run nginx --image=nginx --restart=Never
+kubectl get pods
+```

topics/kubernetes/solutions/replicaset_01_solution.md

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+## ReplicaSet 01 - Solution
+
+1. Create a ReplicaSet with 2 replicas. The app can be anything.
+
+```
+cat >> rs.yaml <<EOL
+apiVersion: apps/v1
+kind: ReplicaSet
+metadata:
+  name: web
+  labels:
+    app: somewebapp
+    type: web
+spec:
+  replicas: 2
+  selector:
+    matchLabels:
+      type: web
+  template:
+    metadata:
+      labels:
+        type: web
+    spec:
+      containers:
+      - name: httpd
+        image: registry.redhat.io/rhscl/httpd-24-rhel7
+EOL
+
+kubectl apply -f rs.yaml
+```
+
+2. Verify a ReplicaSet was created and there are 2 replicas
+
+```
+kubectl get rs
+# OR a more specific way: kubectl get -f rs.yaml
+```
+
+3. Delete one of the Pods the ReplicaSet has created
+
+```
+kubectl delete po <POD_NAME>
+```
+
+4. If you'll list all the Pods now, what will you see?
+
+```
+The same number of Pods. Since we defined 2 replicas, the ReplicaSet will make sure to create another Pod that will replace the one you've deleted.
+```
+
+5. Remove the ReplicaSet you've created
+
+```
+kubectl delete -f rs.yaml
+```
+
+6. Verify you've deleted the ReplicaSet
+
+```
+kubectl get rs
+# OR a more specific way: kubectl get -f rs.yaml
+```