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deepak gupta edited this page Dec 15, 2020 · 9 revisions

Helm_Lab_0

Before You Begin

Prerequisites

  • Kubectl

Installing Kubectl

Allows us to run commands against Kubernetes clusters to deploy applications, inspect and manage cluster resources, and view logs.

We can follow the instructions from Install and Set Up kubectl. We'll install kubectl binary with curl:

  • Download the latest release with the command:
$ curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl
  • Make the kubectl binary executable.
$ chmod +x ./kubectl
  • Move the binary in to your PATH.
$ sudo mv ./kubectl /usr/local/bin/kubectl
  • Test to ensure the version you installed is up-to-date
$ kubectl version --client
Client Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.4", 
GitCommit:"d360454c9bcd1634cf4cc52d1867af5491dc9c5f", GitTreeState:"clean", 
BuildDate:"2020-11-11T13:17:17Z", GoVersion:"go1.15.2", Compiler:"gc", Platform:"linux/amd64"}

Deploying app on Kubernetes

Before starting, let's take a quick look

You can create and manage a Deployment by using the Kubernetes command-line interface, Kubectl. Kubectl uses the Kubernetes API to interact with the cluster. In this module, you'll learn the most common Kubectl commands needed to create Deployments that run your applications on a Kubernetes cluster.

OK, so now that we’ve got the basics out of the way, let’s look at putting this to use. We’re going to first create the first Pod of MySql, then a Deployment, using YAML.

Create Kube Config file

Create kubernetes config file in your home directory ~/.kube/config

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUJWekNCL3FBREFnRUNBZ0VBTUFvR0NDcUdTTTQ5QkFNQ01DTXhJVEFmQmdOVkJBTU1HR3N6Y3kxelpYSjIKWlhJdFkyRkFNVFl3TnpReE1UUTRNVEFlRncweU1ERXlNRGd3TnpFeE1qRmFGdzB6TURFeU1EWXdOekV4TWpGYQpNQ014SVRBZkJnTlZCQU1NR0dzemN5MXpaWEoyWlhJdFkyRkFNVFl3TnpReE1UUTRNVEJaTUJNR0J5cUdTTTQ5CkFnRUdDQ3FHU000OUF3RUhBMElBQkhaS0xwWEVuWVJMeTRSa1FJYmptaHNiNGdwcjJ5ZmlLVVU5QXQwRDVnNS8KY0lxLzJ5THliYnVqVXNrSzhGWEQrZStiK0xIUGNKRWlhSzBDTjZSVE1yZWpJekFoTUE0R0ExVWREd0VCL3dRRQpBd0lDcERBUEJnTlZIUk1CQWY4RUJUQURBUUgvTUFvR0NDcUdTTTQ5QkFNQ0EwZ0FNRVVDSVFDTFR2UjVYMzVlCmVweW1KeEd5WTI3UHllb244ZHNZUjRBWEVSb0N5T1FCMlFJZ1dESlZzYnJwWGkzNUY2endpNFRKb1hRUitiaFMKN3AxZy9MbVdRWnM0TjlrPQotLS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==
    server: https://91.211.152.138:6443
  name: helm-poc
contexts:
- context:
    cluster: helm-poc
    namespace: sandy
    user: helm-poc
  name: helm-poc
current-context: helm-poc
kind: Config
preferences: {}
users:
- name: helm-poc
  user:
    password: 0864eeafb41906e5797fc1aad1ff60e2
    username: admin

Validate if connectivity with kubernetes cluster is in place or not

$kubectl cluster-info
Kubernetes master is running at https://91.211.152.138:6443
CoreDNS is running at https://91.211.152.138:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
Metrics-server is running at https://91.211.152.138:6443/api/v1/namespaces/kube-system/services/https:metrics-server:/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

Create NameSpace

$ kubectl create namespace <Team Namespace>

Set team namespace as default namespace

$ kubectl config set-context $(kubectl config current-context) --namespace=<team_name>; 
i.e kubectl config set-context $(kubectl config current-context) --namespace=ethanhunt

Creating the MySql Pod YAML file

  • Step 1: Create file mysql.yaml
Here we creating MySql pod as a micro service keeping environment variable of database as: 

* MYSQL_ROOT_PASSWORD:password
* MYSQL_USER:root
* MYSQL_DATABASE:employeedb
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: mysql
  name: mysql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:5.7.30
        ports:
        - containerPort: 3306
          name: mysql
          protocol: TCP
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: password
        - name: MYSQL_USER
          value: root
        - name: MYSQL_DATABASE
          value: employeedb
  • Step 2: Now applying the pod using YAML file
$ kubectl apply -f mysql.yaml
deployment.apps/mysql created
  • Step 3: Verify the pod is up and running
$ kubectl get pods

NAME                     READY   STATUS    RESTARTS   AGE
mysql-68cdc487d5-d2w9l   1/1     Running   0          28s

Wait !! Don't you think

Pods are nonpermanent resources? If you use a Deployment to run your app, it can create and destroy Pods dynamically. Kubernetes Pods are created and destroyed to match the state of your cluster

Each Pod gets its own IP address, however in a Deployment, the set of Pods running in one moment in time could be different from the set of Pods running that application a moment later.

This leads to a problem: if some set of Pods (call them "backends") provides functionality to other Pods (call them "frontends") inside your cluster, how do the frontends find out and keep track of which IP address to connect to, so that the frontend can use the backend part of the workload?

Here comes the Savior Services.

In Kubernetes, a Service is an abstraction which defines a logical set of Pods and a policy by which to access them.

Creating the MySql-Service YAML file

  • Step 1: Create file mysql-svc.yaml
apiVersion: v1
kind: Service
metadata:
  labels:
    app: mysql
  name: mysql-svc
spec:
  ports:
  - name: mysql
    port: 3306
    protocol: TCP
    targetPort: mysql
  selector:
    app: mysql
  type: ClusterIP
  • Step 2: Now applying the service using YAML file
$ kubectl apply -f mysql-svc.yaml
service/mysql-svc created
  • Step 3: Verify the service is up and running
$ kubectl get svc

NAME         TYPE        CLUSTER-IP        EXTERNAL-IP   PORT(S)    AGE
mysql-svc    ClusterIP   192.168.174.136   <none>        3306/TCP   15s

Creating the Pod and Service file for application deployment

  • Step 1: Create file deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app.kubernetes.io/name: app
  name: goweb-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: app
  template:
    metadata:
      labels:
        app.kubernetes.io/name: app
    spec:
      containers:
      - env:
        - name: DB_URL
          value: mysql-svc
        - name: DB_PORT
          value: "3306"
        - name: DB_USER
          value: root
        - name: DB_PASSWORD
          value: password
        image: opstreedevops/ot-go-webapp:v1
        name: goweb-app
        ports:
        - containerPort: 8080
          name: http
          protocol: TCP
  • Step 2: Now applying the pod using YAML file
$ kubectl apply -f deployment.yaml
  • Step 3: Now creating the service YAML file

Create deployment-svc.yaml file

apiVersion: v1
kind: Service
metadata:
  labels:
    app.kubernetes.io/name: app
  name: goweb-app
spec:
  ports:
  - name: http
    port: 8080
    protocol: TCP
    targetPort: http
  selector:
    app.kubernetes.io/name: app
  type: ClusterIP
  • Step 4: Now applying the service file
$ kubectl apply -f deployment-svc.yaml

Creating Ingress YAML file

  • Step 1: Create file ingress.yaml
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  labels:
    app.kubernetes.io/name: app
  name: goweb-app
spec:
  rules:
  - host: opstree.com
    http:
      paths:
      - backend:
          serviceName: goweb-app
          servicePort: 8080
        path: /
        pathType: ImplementationSpecific
  • Step 2: Now applying the ingress using YAML file
$ kubectl apply -f ingress.yaml

To check on web enter the details in /etc/hosts file depicting hostname and IP Address:-

91.211.152.138 opstree.com

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