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Create helm-demo.md #180

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201 changes: 201 additions & 0 deletions package-managers/helm/helm-demo.md
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## Helm demo
*This demo will user the ingress on bare-metal using the Nginx Ingress Controller and metalLB.*

In my `helm-demo` folder, I have the `templates` directory and the `Chart` and `values` YAML files :
```bash
k8s-master@master:~/helm-demo$ ls
Chart.yaml templates values.yaml
```
Inside the Chart.yaml file :
```YAML
name: my-first-demo
version: 1.0.0
description: easy helm demo
maintainers:
- name: Siwar
```
This is the metadata to describe each deployment.

Now inside the templates directory :
```bash
k8s-master@master:~/helm-demo/templates$ ls
deployment.yaml ingress.yaml service.yaml
```
The depoyment.yaml file contains a simple nginx deployment :
```YAML
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-nginx-deployment
spec:
selector:
matchLabels:
app: nginx
replicas: 3
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.14.2
ports:
- containerPort: 80

```
And the service.yaml file :
``` YAML
apiVersion: v1
kind: Service
metadata:
name: my-nginx-service
spec:
selector:
app: nginx
ports:
- name: main
protocol: TCP
port: 80
```
And the ingress.yaml :
```YAML
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: my-nginx-ingress
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
http.port: "443"
spec:
ingressClassName: nginx
rules:
- http:
paths:
- path: /testpath
pathType: Prefix
backend:
service:
name: my-nginx-service
port:
number: 80

```
We're exposing port 443 on our ingress.

Next is `helm install`:
```bash
k8s-master@master:~$ helm install --generate-name helm-demo/
NAME: helm-demo-1660310990
LAST DEPLOYED: Fri Aug 12 06:29:50 2022
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None
```
So now with Helm and thanks to only one command line tool `helm install`, we were able to deploy our app very easily and very fast.
```bash
k8s-master@master:~$ kubectl get all
NAME READY STATUS RESTARTS AGE
pod/my-nginx-deployment-9456bbbf9-c74rs 0/1 ContainerCreating 0 11s
pod/my-nginx-deployment-9456bbbf9-k4cdb 0/1 ContainerCreating 0 11s
pod/my-nginx-deployment-9456bbbf9-mm7dm 0/1 ContainerCreating 0 11s

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 22m
service/my-nginx-service ClusterIP 10.100.146.193 <none> 80/TCP 11s

NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/my-nginx-deployment 0/3 3 0 11s

NAME DESIRED CURRENT READY AGE
replicaset.apps/my-nginx-deployment-9456bbbf9 3 3 0 11s
```
We can check our app running in the browser using the ingress ip `192.168.1.240` and specifying the path `/testpath`:

<img src="nginx.png" width=50% height=50%>

The usual way to do this with kubectl is by executing the `kubectl apply` command line for every resource.

Another important feature in Helm are placeholders!
so if we look at another deployment.yaml file for example :
```Yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-nginx-deployment
spec:
selector:
matchLabels:
app: nginx
replicas: {{.Values.scale}}
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.14.2
ports:
- containerPort: 80
```
The `{{.Values.scale}}`placeholder makes it possible to modify the configuration without having to edit the actual manifest file every time.

So whatever the value of scale is in `values.yaml` file is going to be the value of the configuration file.

The `values.yaml` file :
```bash
k8s-master@master:~/helming-once-more$ cat values.yaml
scale: 3
```

And now let's install our app again :
```bash
k8s-master@master:~$ helm install another-demo helming-once-more/
NAME: another-demo
LAST DEPLOYED: Fri Aug 12 11:48:53 2022
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None
```
Just to check that we have our pods up and running :
```bash
k8s-master@master:~$ kubectl get pods
NAME READY STATUS RESTARTS AGE
my-nginx-deployment-9456bbbf9-mx45n 1/1 Running 0 3m9s
my-nginx-deployment-9456bbbf9-rqkmw 1/1 Running 0 3m9s
my-nginx-deployment-9456bbbf9-tl4wj 1/1 Running 0 3m9s
```
So thanks to the scale value in the values.yaml file, we now have 3 pods.

For some reason or another, we needed to scale up our up :
```bash
k8s-master@master:~$ helm upgrade --set scale=5 another-demo ./helming-once-more/
Release "another-demo" has been upgraded. Happy Helming!
NAME: another-demo
LAST DEPLOYED: Fri Aug 12 11:55:14 2022
NAMESPACE: default
STATUS: deployed
REVISION: 2
TEST SUITE: None
```
```bash
k8s-master@master:~$ kubectl get pod
NAME READY STATUS RESTARTS AGE
my-nginx-deployment-9456bbbf9-7ddlm 1/1 Running 0 95s
my-nginx-deployment-9456bbbf9-mx45n 1/1 Running 0 8m9s
my-nginx-deployment-9456bbbf9-rqkmw 1/1 Running 0 8m9s
my-nginx-deployment-9456bbbf9-tl4wj 1/1 Running 0 8m9s
my-nginx-deployment-9456bbbf9-tpsqv 1/1 Running 0 96s
```

To finish off, we will delete our app :
```bash
k8s-master@master:~$ helm list
NAME NAMESPACE REVISION UPDATED STATUS CHART APP VERSION
another-demo default 2 2022-08-12 11:55:14.913503686 -0700 PDT deployed another-demo-1.0.0
k8s-master@master:~$ helm uninstall another-demo
release "another-demo" uninstalled
```