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...-exercises/CKAD-Exam-Tips-kubectl-exercises-009-expose-nodeport-delete-lines.md
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| Original file line number | Diff line number | Diff line change |
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| --- | ||
| title: kubectl for CKAD - exercise 9 - expose a pod with NodePort service, delete lines in Vim | ||
| date: 2025-01-14 | ||
| --- | ||
| #### First things first | ||
| Put your mouse away, forget you have a touchpad and **keep your hands on the keyboard**. | ||
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| In this exercise we will learn how to create a NodePort service with `kubectl expose`. | ||
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| Also - we will learn to delete unwanted lines in a yaml file, which is a very important skill for the CKAD and other CK* exams. | ||
| For resources which can not be created with `kubectl` we must copy yaml definitions from kubernetes.io. We will have to delete unwanted lines in Vim - and, you guessed it - we need to be **fast and effective** deleting them. | ||
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| ### Scenario | ||
| Expose a running pod `nginxpod` on a node through a NodePort service named `nginx-service` on port `30100`. Let’s look at how using different `--dry-run` modes affects the generated YAML. | ||
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| #### Run a pod | ||
| Run an `nginxpod` using the `kubectl` command with port `80` specified. | ||
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| ``` | ||
| kubectl run nginxpod --image=nginx:alpine --port=80 | ||
| ``` | ||
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| #### Create a NodePort service for the nginxpod,using `kubectl expose`. | ||
| ``` | ||
| k expose pod nginxpod --name=nginx-service --type=NodePort --port=80 --dry-run=client -o yaml | vim - | ||
| ``` | ||
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| #### To include the nodePort field, let `kubectl` create it for you with `--dry-run=server` | ||
| ``` | ||
| k expose pod nginxpod --name=nginx-service --type=NodePort --port=80 --dry-run=server -o yaml | vim - | ||
| ``` | ||
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| Observe that `--dry-run=server` creates the `nodePort`field and populates it with a random port number. | ||
| ``` | ||
| ... | ||
| spec: | ||
| ports: | ||
| - nodePort: 34567 | ||
| port: 80 | ||
| protocol: TCP | ||
| targetPort: 80 | ||
| ... | ||
| ``` | ||
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| #### Replace the autoassigned port with the specified one: `30100`. | ||
| ``` | ||
| /34567 # start searching from top, replace 34567 with the generated number you see in your nodePort: | ||
| Enter | ||
| C # 'C'lear (delete) everything from the cursor to the end of this line and start writing | ||
| 30100 | ||
| ESC # 'ESC'ape from INSERT mode | ||
| :w nginx-service.yaml # Save the YAML definition | ||
| ``` | ||
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| There is one more little problem, let us apply the yaml to see it. | ||
| #### Apply the yaml - without leaving Vim! | ||
| ``` | ||
| :!kubectl apply -f % # Run `kubectl apply` directly from inside Vim | ||
| ``` | ||
| #### If you have already set up the bash variable / shortcut `ka` in the previous exercise, use it like this: | ||
| ``` | ||
| :!$ka -f % | ||
| ``` | ||
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| #### It throws an error: | ||
| ``` | ||
| The Service "nginx-service" is invalid: spec.clusterIPs: Invalid value: ... | ||
| shell returned 1 | ||
| Press ENTER or type command to continue | ||
| ``` | ||
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| The error tells us that by using `--dry-run=server -o yaml` we created some unwanted lines we now need to delete. So press Enter to return to Vim. | ||
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| #### For fast navigation, set Vim up to show line ***nu***mbers and ***r***elative line ***nu***mbers | ||
| ``` | ||
| :set nu # show 'nu'mbers | ||
| :set rnu # show 'r'elative 'nu'mbers | ||
| ``` | ||
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| Or do it in one line | ||
| ``` | ||
| :set nu rnu | ||
| ``` | ||
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| Line `1` is the one with the cursor so it shows the real line number, all others are relative line numbers, which we will use to make our navigation in Vim **fast and effective**! | ||
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| ``` | ||
| 1 apiVersion: v1 | ||
| 1 kind: Service | ||
| 2 metadata: | ||
| 3 creationTimestamp: "2025-01-14T18:27:29Z" | ||
| 4 labels: | ||
| 5 run: nginxpod | ||
| 6 name: nginx-service | ||
| 7 namespace: default | ||
| 8 uid: 0d175654-b5d4-4306-85c3-924c6f64e62f | ||
| 9 spec: | ||
| 10 clusterIP: 10.96.0.0 | ||
| 11 clusterIPs: | ||
| 12 - 10.96.0.0 | ||
| 13 externalTrafficPolicy: Cluster | ||
| 14 internalTrafficPolicy: Cluster | ||
| 15 ipFamilies: | ||
| 16 - IPv4 | ||
| 17 ipFamilyPolicy: SingleStack | ||
| 18 ports: | ||
| 19 - nodePort: 32769 | ||
| 20 port: 80 | ||
| 21 protocol: TCP | ||
| 22 targetPort: 80 | ||
| ... | ||
| ``` | ||
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| We need to delete lines from`10 clusterIP: 10.96.0.0` down to (including) `17 ipFamilyPolicy: SingleStack` | ||
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| #### 10 lines ***j***umpdown, to the first line we want to delete | ||
| ``` | ||
| 10j # 10 lines 'j'umpdown | ||
| ``` | ||
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| We landed on the line with the real **nu**mber 11. | ||
| ``` | ||
| 10 apiVersion: v1 | ||
| 9 kind: Service | ||
| 8 metadata: | ||
| 7 creationTimestamp: "2025-01-14T18:27:29Z" | ||
| 6 labels: | ||
| 5 run: nginxpod | ||
| 4 name: nginx-service | ||
| 3 namespace: default | ||
| 2 uid: 0d175654-b5d4-4306-85c3-924c6f64e62f | ||
| 1 spec: | ||
| 11 clusterIP: 10.96.0.0 | ||
| 1 clusterIPs: | ||
| 2 - 10.96.0.0 | ||
| 3 externalTrafficPolicy: Cluster | ||
| 4 internalTrafficPolicy: Cluster | ||
| 5 ipFamilies: | ||
| 6 - IPv4 | ||
| 7 ipFamilyPolicy: SingleStack | ||
| 8 ports: | ||
| 9 - nodePort: 32769 | ||
| 10 port: 80 | ||
| 11 protocol: TCP | ||
| 12 targetPort: 80 | ||
| ``` | ||
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| #### ***D***elete 7 lines ***j***umping down, including the current line | ||
| ``` | ||
| d7j # 'd'elete 7 lines 'j'umping down | ||
| ``` | ||
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| ``` | ||
| 10 apiVersion: v1 | ||
| 9 kind: Service | ||
| 8 metadata: | ||
| 7 creationTimestamp: "2025-01-14T18:27:29Z" | ||
| 6 labels: | ||
| 5 run: nginxpod | ||
| 4 name: nginx-service | ||
| 3 namespace: default | ||
| 2 uid: 0d175654-b5d4-4306-85c3-924c6f64e62f | ||
| 1 spec: | ||
| 11 ports: | ||
| 1 - nodePort: 32769 | ||
| 2 port: 80 | ||
| 3 protocol: TCP | ||
| 4 targetPort: 80 | ||
| ... | ||
| ``` | ||
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| With the unwanted lines deleted we can now apply the service yaml. | ||
| #### Save and apply the yaml - again - without leaving Vim! | ||
| ``` | ||
| ESC # 'ESC'ape from INSERT mode | ||
| :w nginx-service.yaml # Save the YAML definition | ||
| :!kubectl apply -f % # Run `kubectl apply` directly from inside Vim | ||
| ``` | ||
| #### If you have already set up the bash variable / shortcut `ka` in the previous exercises use it like this: | ||
| ``` | ||
| ESC # 'ESC'ape from INSERT mode | ||
| :w nginx-service.yaml # Save the YAML definition | ||
| :!$ka -f % # Run `kubectl apply` directly from inside Vim | ||
| ``` | ||
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| #### If everything is fine with the yaml definition, nginx-service.yaml gets applied, service is created. | ||
| ``` | ||
| k get svc -o wide # view the service, -o wide shows more info about resources | ||
| ``` | ||
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| #### Don't forget to define a shortcut for `--dry-run=server -o yaml` in your `.bashrc`: | ||
| ``` | ||
| vim ~/.bashrc | ||
| G # Go to the last line | ||
| i # Switch to INSERT mode | ||
| export drys='--dry-run=server -o yaml' # use your own shortcut, if you don't like 'drys' | ||
| ``` | ||
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| #### ***w***rite (save), ***q***uit, ***source*** (reload) the `.bashrc` | ||
| ``` | ||
| ESC | ||
| :wq | ||
| source ~/.bashrc | ||
| ``` | ||
| #### Congratulations! | ||
| You have learned how to use `--dry-run=server` effectively to expose a pod with a `nodePort` service. You also learned how to navigate in Vim as fast as a lightning and how to delete unwanted lines in yaml definitions. Practice, practice, practice... |