{"id":6143,"date":"2021-03-23T15:44:28","date_gmt":"2021-03-23T10:14:28","guid":{"rendered":"https:\/\/opstree.com\/blog\/\/?p=6143"},"modified":"2021-03-23T18:26:55","modified_gmt":"2021-03-23T12:56:55","slug":"create-your-first-helm-chart-part-03","status":"publish","type":"post","link":"https:\/\/opstree.com\/blog\/2021\/03\/23\/create-your-first-helm-chart-part-03\/","title":{"rendered":"Create Your First Helm Chart (Part 03)"},"content":{"rendered":"\r\n

Bonjour! So we’ve had our minikube cluster up and running<\/a> and tried setting up MySQL application onto our cluster using publicly available Helm Charts in our previous blog<\/a>. In case, you haven\u2019t, I suggest you go through the link before reading this blog.<\/p>\r\n\r\n\r\n\r\n

This guide walks us through the process of creating our first-ever chart, explaining what goes inside these packages and the tools we use to develop them. By the end of it we should have an understanding of the advantages of using and creating our Helm Charts to deliver our own applications to the K8s cluster.<\/p>\r\n\r\n\r\n\r\n

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Case: Deploying a Golang Application using our own Helm Charts<\/h5>\r\n\r\n\r\n\r\n

The best way to get started with a new chart is to use the helm create<\/code> command, which helps to understand the directory structure of a Chart in Helm. It is nothing but a packaged version of your application that follows some specifications for describing the resources to be installed into K8s.<\/p>\r\n\r\n\r\n\r\n

$ helm create gowebapp<\/pre>\r\n\r\n\r\n\r\n
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Chart.yaml : <\/strong>It provides the information about the chart version, name, description, etc. or, in another words, the metadata of our chart.<\/p>\r\n\r\n\r\n\r\n
Templates :<\/strong> The most important piece in the puzzle of Helm is the templates\/<\/code> directory. This is where Helm finds the YAML definitions for our Services, Deployments, and other K8s objects.<\/p>\r\n\r\n\r\n\r\n
values.yaml :<\/strong> This file can’t be shrugged off as it contains the default values for the chart. These values may be overridden by us to manage our K8s objects.<\/p>\r\n\r\n\r\n\r\n
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Building a Helm Chart<\/h6>\r\n\r\n\r\n\r\n
As we have already created the default structure for our application as shown above, we’ll proceed with building our resource files under gowebapp\/<\/code> directory. We have some database dependencies for our application which helps to bring up the UI. To resolve those dependencies, we mention it under Chart.yaml<\/code> as shown below<\/p>\r\n\r\n\r\n\r\n
apiVersion: v2\r\nname: gowebapp\r\ndescription: A Helm chart for GoWebApp\r\ntype: application\r\nversion: 0.1.0\r\nappVersion: 1.16.0\r\ndependencies:\r\n- name: mysql\r\n  version: \"1.6.9\"\r\n  repository: \"https:\/\/charts.helm.sh\/stable\"\r\n- name: redis\r\n  version: \"10.5.7\"\r\n  repository: \"https:\/\/charts.helm.sh\/stable\"<\/pre>\r\n\r\n\r\n\r\n
Before, updating the dependencies we can list out to check do we have any or not, as shown :<\/p>\r\n\r\n\r\n\r\n
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Now, to update the application dependencies we have to follow some steps keeping ourselves under the gowebapp<\/code> directory :<\/p>\r\n\r\n\r\n\r\n
$ helm dependency list\r\n$ helm dependency update<\/pre>\r\n\r\n\r\n\r\n
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As the dependencies are downloaded, it’s time for adding resource files. For our Golang Application all we need is deployment, service, and ingress resources. The other resources created by default like, service account, _helpers.tpl, etc. can be deleted.<\/p>\r\n\r\n\r\n\r\n
Here, we passed some default values of database, labels, matchlabels, and containers specs to the Chart with the help of values.yaml file as below :<\/p>\r\n\r\n\r\n\r\n
mysql:\r\n  mysqlDatabase: employeedb\r\n  mysqlRootPassword: password\r\n  persistence:\r\n    enabled: false\r\n\r\nredis:\r\n  usePassword: false\r\n  cluster:\r\n    enabled: false\r\n  master:\r\n    persistence:\r\n      enabled: false\r\n\r\nlabels:\r\n  app.kubernetes.io\/name: app\r\n  app.kubernetes.io\/instance: goweb-app\r\n  app.kubernetes.io\/version: \"1.16.0\"\r\n\r\nmatchLabels:\r\n  app.kubernetes.io\/name: app\r\n  app.kubernetes.io\/instance: goweb-app\r\n\r\ncontainers:\r\n  name: goweb-app\r\n  image: opstreedevops\/ot-go-webapp\r\n  tag: \"v1\"<\/pre>\r\n\r\n\r\n\r\n
Now, we can start adding the resource file values under the template\/<\/code> directory in the deployment, service, and ingress resource files as below :<\/p>\r\n\r\n\r\n\r\n
apiVersion: apps\/v1\r\nkind: Deployment\r\nmetadata:\r\n  name: goweb-app\r\n  {{- if .Values.labels }}\r\n  labels:\r\n    {{- toYaml .Values.labels | nindent 4 }}\r\n  {{- end }}\r\nspec:\r\n  replicas: 1\r\n  selector:\r\n    matchLabels:\r\n      {{- toYaml .Values.matchLabels | nindent 6 }}\r\n  template:\r\n    metadata:\r\n      {{- if .Values.matchLabels }}\r\n      labels:\r\n        {{- toYaml .Values.matchLabels| nindent 8 }}\r\n      {{- end }}\r\n    spec:\r\n      containers:\r\n        - name: {{ .Values.containers.name }}\r\n          image: \"{{ .Values.containers.image }}:{{ .Values.containers.tag }}\"\r\n          imagePullPolicy: IfNotPresent\r\n          ports:\r\n          - name: http\r\n            containerPort: 8080\r\n            protocol: TCP\r\n          env:\r\n          - name: DB_URL\r\n            value: goweb-app-mysql\r\n          - name: DB_PORT\r\n            value: \"3306\"\r\n          - name: DB_USER\r\n            value: \"root\"\r\n          - name: DB_PASSWORD\r\n            value: password\r\n          - name: REDIS_HOST\r\n            value: \"goweb-app-redis-headless\"\r\n          - name: REDIS_PORT\r\n            value: \"6379\"<\/pre>\r\n\r\n\r\n\r\n
apiVersion: v1\r\nkind: Service\r\nmetadata:\r\n  name: goweb-app\r\n  {{- if .Values.labels }}\r\n  labels:\r\n    {{- toYaml .Values.labels | nindent 4 }}\r\n  {{- end }}\r\nspec:\r\n  type: ClusterIP\r\n  ports:\r\n    - port: 8080\r\n      targetPort: http\r\n      protocol: TCP\r\n      name: http\r\n{{- if .Values.matchLabels }}\r\n  selector:\r\n        {{- toYaml .Values.matchLabels| nindent 4 }}\r\n      {{- end }}<\/pre>\r\n\r\n\r\n\r\n
apiVersion: networking.k8s.io\/v1beta1\r\nkind: Ingress\r\nmetadata:\r\n  name: goweb-app\r\n  {{- if .Values.labels }}\r\n  labels:\r\n    {{- toYaml .Values.labels | nindent 4 }}\r\n  {{- end }}\r\nspec:\r\n  rules:\r\n    - host: \"ethanhunt.com\"\r\n      http:\r\n        paths:\r\n          - path: \/\r\n            backend:\r\n              serviceName: goweb-app\r\n              servicePort: 8080<\/pre>\r\n\r\n\r\n\r\n
Let\u2019s validate the manifest content by running helm template<\/code> command, which will list out all the resource files with the configured values which will be needed to install our application using Helm Chart onto our K8s cluster.<\/p>\r\n\r\n\r\n\r\n
$ helm template gowebapp\/<\/pre>\r\n\r\n\r\n\r\n
To make it more clear let’s understand the flow when Helm Chart is installed into Kubernetes :<\/p>\r\n\r\n\r\n\r\n