Helm One Shot

Don’t think helm is hard. It’s the same for K8s, what’s apt for Linux (Debian). That’s it!

Remember when you install something on Ubuntu, you just say apt install nginx and boom, done? Nobody sits and downloads ten different files and puts them one by one. Kubernetes people were doing exactly that, deployment.yaml first, then service.yaml, then this yaml, then that yaml. I got tired of it, then I found Helm. This is my little diary of how it went.

So What Is Helm?

Helm is the package manager for Kubernetes. Same idea as apt or dpkg on Linux, but for your cluster.

A chart is just all your yaml manifests tied up in one bundle. A release is one installed copy of that chart in your cluster.

Where Do Charts Live?

Every popular app already has a chart, like Redis, nginx and so on. People put them in a repo and you just download from there.

Bitnami is not the only one, it is just very common. And you can make your own repo for your company, or even for your customers.

Start Here

Add a repo:

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

See what repos you have:

helm repo list

Just like apt update, refresh the repo once in a while:

helm repo update bitnami

Search inside the repo:

helm search repo bitnami

Only the one you want:

helm search repo bitnami | grep nginx

Install:

helm install my-nginx bitnami/nginx

Here bitnami/nginx is the chart and my-nginx is the release name, your choice.

See it running:

helm list
kubectl get pods

Remove it:

helm uninstall my-nginx

That is it. One shot install, one shot uninstall. No yaml chasing.

Make Your Own Chart

Create the template:

helm create login-app-busybox

You get a folder like this:

Chart.yaml  charts  templates  values.yaml

rm -rf login-app-busybox/templates/*

Now put your own manifest inside. The {{ }} parts get filled from values.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-{{ .Chart.Name }}-{{ .Values.name }}-deployment
  labels:
    app: {{ .Values.name | quote }}
spec:
  replicas: {{ .Values.spec.replicas }}
  selector:
    matchLabels:
      app: {{ .Values.name | quote }}
  template:
    metadata:
      labels:
        app: {{ .Values.name | quote }}
    spec:
      containers:
        - name: {{ .Values.name | quote }}
          image: busybox
          command:
            - sh
            - -c
            - {{ printf "echo %s; sleep 3600" (.Values.message | quote) | quote }}

Replace the whole values.yaml with this:

name: login-app
spec:
  replicas: 2
message: Hello From Login App!

Before packing, check it is not broken:

helm lint login-app-busybox/
helm template test login-app-busybox/

helm template just prints the final yaml on your screen, nothing gets installed. Handy for seeing what your {{ }} turned into.

Want to try it right now, no repo needed?

helm install login-app ./login-app-busybox
kubectl get pods
helm uninstall login-app

Pack It And Make A Repo

Pack the chart:

helm package login-app-busybox/

You get login-app-busybox-0.1.0.tgz. The version comes from Chart.yaml.

Create the index.yaml (this is the file that tells Helm what charts are in the repo):

helm repo index .

Now your folder looks like this:

.
├── index.yaml
├── login-app-busybox
│   ├── Chart.yaml
│   ├── charts
│   ├── templates
│   │   └── deploy.yaml
│   └── values.yaml
└── login-app-busybox-0.1.0.tgz

Host It On GitHub Pages

Push this to a GitHub repo and turn on GitHub Pages for it. Done, that same repo is now a Helm repo. No server, no money.

Now anyone can use it:

helm repo add my-helm-repo https://xyizlop.github.io/helm-repo-online/
helm search repo my-helm-repo
helm install login-app my-helm-repo/login-app-busybox

Clean up when you are done playing:

helm uninstall login-app
helm repo remove my-helm-repo

That is how I went from chasing yaml files to typing one command. Pretty sweet deal.