Pods

Lab Objectives

In this lab we will configure a Kubernetes Pod hosting a mysql database from the command-line. We’ll also log into the container we deploy into this lab using the mysql-client. We’ll expose the pod in a follow-up lab.

Lab Structure - Overview

  1. Run a command to deploy a pod from the command-line
  2. Run a command to deploy a pod sourced from a YAML file
  3. Run a command to exec a shell into a Kubernetes hosted container
  4. Run a command to exec directly into the mysql-client from the command-line

Execute on the Leader node

The following commands should all be executed in the VS Code window connected to the leader node.

Deploy a Pod from the command-line

  1. Show the nodes of the cluster 
    kubectl get nodes
  2. Show information about the cluster 
    kubectl cluster-info
  3. Dump information about the cluster 
    kubectl cluster-info dump
  4. Show all Pods in the kube-system namespace 
    kubectl get pods -n kube-system
  5. Deploy nginx Pod 
    kubectl run nginx-pod-lab --image=nginx:alpine --port=80 --restart=Never

    Note: The --restart=Never flag ensures this creates a Pod (not a Deployment)

  6. Confirm Pod is running’ 
    kubectl get pods
  7. Get information about Pod in json format 
    kubectl get pod nginx-pod-lab -o json
  8. Now get info about it in YAML syntax 
    kubectl get pod nginx-pod-lab -o yaml
  9. Delete the pod. 
    kubectl delete pod nginx-pod-lab

Create Pod from manifest

  1. Enter the lab directory.
cd $HOME/core-k8s/labs/pods
  1. In the manifests directory, you will find nginx-kube.yml . This file will launch a simple nginx server. Deploy it with the following:
kubectl apply -f manifests/nginx-kube.yml
  1. Show the deployed Pods
kubectl get pods

You should see something like this:

NAME                            READY   STATUS    RESTARTS   AGE
nginx-pod-lab                   1/1     Running   0          18m
nginx-web                       1/1     Running   0          15s
  1. Cleanup everything
kubectl delete pods --all

Create a Pod with 2 containers

  1. In the manifests directory you will find two-containers.yml. Review the manifest and see if you can figure out what it is doing, then deploy it: 
    kubectl apply -f manifests/two-containers.yml
  2. Show the deployed Pods 
    kubectl get pods
  3. Look at the details of the Pod 
    kubectl describe pod two-containers

Sample output:

Name:         two-containers
Namespace:    default
Priority:     0
Node:         ip-192-168-29-163.us-west-2.compute.internal/192.168.29.163
Start Time:   Tue, 27 Aug 2019 22:38:37 -0700
Labels:       <none>
Annotations:  kubectl.kubernetes.io/last-applied-configuration:
                {"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"name":"two-containers","namespace":"default"},"spec":{"containers":[{"image"...
              kubernetes.io/psp: eks.privileged
Status:       Running
IP:           192.168.22.118
Containers:
  nginx-container:
    Container ID:   docker://d5f34b906d03eddc2521c3860558d14174d2e63b786a22471a3c818cb5e5ad73
<snip>...
  1. Log into the nginx container of the two-containers Pod: 
    kubectl exec -it two-containers -c nginx-container -- bash
  2. Validate nginx is running in the container: 
    apt-get update && apt-get install -y procps && ps aux

Sample output:

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.1  10624  5412 ?        Ss   05:38   0:00 nginx: master process nginx -g daemon off;
nginx        7  0.0  0.0  11096  2604 ?        S    05:38   0:00 nginx: worker process
root         8  0.0  0.0   3868  3244 pts/0    Ss   05:49   0:00 bash
root       338  0.0  0.0   7640  2672 pts/0    R+   05:49   0:00 ps aux
  1. Install curl inside the container 
    apt install -y curl
  2. Check the default nginx page is loading using curl. 
    curl localhost

Output:

Hello from the debian container
  1. Exit the nginx container 
    exit

Deploy MySQLDB and connect to the client

  1. Deploy a MySQL DB image 
    kubectl run mysql-demo --image=mysql:5.7 --port=3306 --env="MYSQL_ROOT_PASSWORD=password" --restart=Never
  2. Show all of the running Pods, and note the name of the Pod you just created 
    kubectl get pods

Sample output:

NAME             READY   STATUS     RESTARTS   AGE
mysql-demo       1/1     Running    0          3m24s
two-containers   1/2     NotReady   0          4m54s
  1. Log into the new MySQL container: 
    kubectl exec -it mysql-demo -- mysql -ppassword
  2. Look around 
    SHOW DATABASES;

SELECT * FROM mysql.user LIMIT 1\G
  1. Exit MySQL:
quit
  1. Exit the container
exit

Clean up

Run the following to delete resources created in this lab:

kubectl delete --ignore-not-found=true manifests

Lab complete