Skip to content

Latest commit

 

History

History
187 lines (138 loc) · 5.36 KB

intro-to-kubernetes-package-manager.md

File metadata and controls

187 lines (138 loc) · 5.36 KB
Raw

The Kubernetes package manager

Learning goal

  • Try the Helm cli to spin up a chart

Introduction

Enter Helm - the answer to how to package multi-container applications, and how to easily install packages on Kubernetes.

Helm helps you to:

  • Achieve a simple (one command) and repeatable deployment
  • Manage application dependency, using specific versions of other application and services
  • Manage multiple deployment configurations: test, staging, production and others
  • Execute post/pre deployment jobs during application deployment
  • Update/rollback and test application deployments

Using Helm charts

Helm uses a packaging format called charts. A Chart is a collection of files that describe k8s resources.

Charts can be simple, describing something like a standalone web server but they can also be more complex, for example, a chart that represents a full web application stack included web servers, databases, proxies, etc.

Instead of installing k8s resources manually via kubectl, we can use Helm to install pre-defined Charts faster, with less chance of typos or other operator errors.

When you install Helm, it does not have a connection to any default repositories. This is because Helm wants to decouple the application to the repository in use.

One of the largest Chart Repositories is the BitNami Chart Repository, which we will be using in these exercises.

Helm chart repositories are very dynamic due to updates and new additions. To keep Helm's local list updated with all these changes, we need to occasionally run the repository update command.

Exercise

Overview

  • Add a chart repository to your Helm cli
  • Install Nginx chart
  • Access the Nginx load balanced service
  • Look at the status of the deployment with helm ls
  • Clean up the chart deployment

Step by step

More details

Add a chart repository to your Helm cli

To install the Bitnami Helm Repo and update Helm's local list of Charts, run:

helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update

Install Nginx Chart

We use the Nginx chart because it is fast and easy to install, and allows us to access the Nginx webserver from our browser to verify that it was deployed.

helm install my-release bitnami/nginx --version=15.0.0 --set service.type=NodePort

This command creates a release called my-release with the bitnami/nginx chart.

The command will output information about your newly deployed nginx setup similar to this:

NAME: my-release
LAST DEPLOYED: Wed Sep 27 09:21:48 2023
NAMESPACE: student-3
STATUS: deployed
REVISION: 1
TEST SUITE: None
NOTES:
CHART NAME: nginx
CHART VERSION: 15.3.1
APP VERSION: 1.25.2

** Please be patient while the chart is being deployed **
NGINX can be accessed through the following DNS name from within your cluster:

    my-release-nginx.student-3.svc.cluster.local (port 80)

To access NGINX from outside the cluster, follow the steps below:

1. Get the NGINX URL by running these commands:

    export NODE_PORT=$(kubectl get --namespace student-3 -o jsonpath="{.spec.ports[0].nodePort}" services my-release-nginx)
    export NODE_IP=$(kubectl get nodes --namespace student-3 -o jsonpath="{.items[0].status.addresses[0].address}")
    echo "http://${NODE_IP}:${NODE_PORT}"

Access the Nginx NodePort service

Get the external port of Nginx with the following commands:

kubectl get services

  • Note down the external port of the Nginx service, it should be in the range of 30000-32767

  • Note down one of the external IP addresses of the nodes in the cluster

kubectl get nodes -o wide

result:

NAME                                            STATUS   ROLES    AGE     VERSION   INTERNAL-IP      EXTERNAL-IP     OS-IMAGE             KERNEL-VERSION    CONTAINER-RUNTIME
ip-192-168-83-125.eu-north-1.compute.internal   Ready    <none>   4h29m   v1.26.8   192.168.83.125   13.51.165.230   Ubuntu 20.04.6 LTS   5.15.0-1045-aws   cri-o://1.26.1
ip-192-168-85-161.eu-north-1.compute.internal   Ready    <none>   4h29m   v1.26.8   192.168.85.161   13.53.106.222   Ubuntu 20.04.6 LTS   5.15.0-1045-aws   cri-o://1.26.1
  • Open a browser and enter the IP address and port of the Nginx service, e.g. http://<node-ip>:<node-port>

Look at the status of the deployment with helm and kubectl

Running helm ls will show all current deployments.

  • Run helm ls and observe that you have a release named my-release
  • Run kubectl get pods,deployments,svc and look at a few of the kubernetes objects the release created.

💡 As said before Helm deals with the concept of charts for its deployment logic. bitnami/nginx was a chart, found here that describes how helm should deploy it. It interpolates values into the deployment, which for nginx looks like this. The charts describe which values can be given for overwriting default behavior, and there is an active community around it.

Clean up the chart deployment

To remove the my-release release run:

helm uninstall my-release