Kubernetes Lab📜

Lab Overview📜

In this lab we will interact with our kubernetes cluster by creating a namespace, and a pod. Next will use
kubectl port-forward to create a network connection from our laptop to the pod running in the cluster.

Kubectl Basics📜

Note

sshuttle is expected to be running in a background
sshuttle -vr bastion --dns 10.10.0.0/16 --ssh-cmd 'ssh -i ~/.ssh/bb-onboarding-attendees.ssh.privatekey'

Add kubectl completion📜

Typing kubectl gets old, everyone uses a shortcuts published in the kubernetes docs bash-completion package should be installed first

echo "source <(kubectl completion bash)" >> ~/.bashrc # add autocomplete permanently to your bash shell.
echo "alias k=kubectl" >> ~/.bashrc
echo "complete -F __start_kubectl k" >> ~/.bashrc
source ~/.bashrc

Now you can use k instead of typing kubectl and after typing 3-4 letters of the command use tab key to complete command
Test completion works:
k get dep  # <----- press tab, the word `deployments.apps` should fill in

Updating Bash on macOS📜

Note

Completion may fail with this error on macOS:

-bash: completion: function `__start_kubectl' not found

This happens because macOS ships with Bash 3.2, and tab completion for kubectl requires a minimum Bash version of 4.1, first released in 2009. If this happens, switch to a new version of Bash:

brew install bash
echo /usr/local/bin/bash | sudo tee -a /etc/shells
chsh -s /usr/local/bin/bash

Then either close your terminal and open a new one, or run exec /usr/local/bin/bash -il if you want to stay in your existing terminal.

Creating a Pod📜

Now that we have access to the kubernetes cluster let’s deploy something

kubectl create namespace refresher
kubectl get namespaces
kubectl get ns

Quick exercise to build some background docker knowledge:

Note

docker.io is an implicit default that gets put in front of images so iahmad/ubi8-nginx-high-port:8.1 is actually docker.io/iahmad/ubi8-nginx-high-port:8.1

Try running in terminal:

    docker pull docker.io/iahmad/ubi8-nginx-high-port:8.1
    # Downloading...

    # Then
    docker pull iahmad/ubi8-nginx-high-port:8.1
    # ... Image is up to date ...
    # (This knowledge will be important for future Open Policy Agent Image Registry Filtering Constraints)

Create a folder to work in:

mkdir -p ~/day1refresher
cd ~/day1refresher

Copy and paste the contents into a file

apiVersion: v1
kind: Pod
metadata:
  name: simple-nginx-app
  namespace: refresher
spec:
  containers:
  - name: simple-nginx-app
    image: iahmad/ubi8-nginx-high-port:8.1
    ports:
    - containerPort: 7000 # This correlates to the port in the nginx.conf

vi pod.yml
# Press i for insert mode, then Paste
# escape : qw! Enter to save
cat pod.yml
# Verify the file saved correctly/looks right

Run the following command to deploy the pod into the cluster
```
kubectl apply -f pod.yml
```
Validate the pod deployed correctly
```
kubectl get pods -n refresher
```
RECORD your pod-name

Open another terminal and run the following command:

kubectl port-forward <your-pod-name> 8080:7000 --namespace=refresher
# the 8080:7000 in the command means your laptop's
# localhost:8080 --redirects to--> pod's port 7000

Tip

The above command will not return you your terminal prompt, until you ctrl+c

In a new terminal window: Use the curl command to reach the following URL from your Laptop:
```
curl localhost:8080
```

Note

kubectl port-forward will crash after ~1-3 minutes, so if you’re slow on the above command you may need to rerun the port forward

Once you’ve been able to hit your application delete your pod

# You can go back to the original terminal that was running the kubectl port-forward command and use Ctrl + C to break out of it.
cd ~/day1refresher
kubectl delete -f pod.yml

Lab Summary📜

You have been able to create a pod that deploys an instance of a nginx container inside your pod.
You also used the kubectl port-forward command, a debug tool, to open a port on your server to a port on the nginx pod in the cluster.
You then used this tunnel to send a curl command to the pod and validate your pod is up and running, and accepting traffic over this tunnel.