Intro To Helm

Intro to Helm

Helm is the best way to find, share and use software built for Kubernetes.

To use, download the Helm client.

To run, use helm init.

Helm uses a packaging format call charts.

Helm commands

Installing Helm

curl https://raw.githubusercontent.com/helm/helm/master/scripts/get > get_helm.sh
chmod 700 get_helm.sh
./get_helm.sh
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Alternatively:

curl https://raw.githubusercontent.com/helm/helm/master/scripts/get | bash
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Linux Distro Install

wget https://kubernetes-helm.storage.googleapis.com/helm-v2.11.0-linux-amd64.tar.gz
tar -xzvf helm-v2.11.0-linux-amd64.tar.gz
sudo mv linux-amd64/helm /usr/local/bin/helm
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Adding to cluster

# helm-rbac.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  name: tiller
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: tiller
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
  - kind: ServiceAccount
    name: tiller
    namespace: kube-system
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kubectl apply -f helm-rbac.yaml
helm init --service-account tiller
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Creating your own helm charts

This is the recommended way to deploy applications.

# creates director mychart/
helm create mychart
ls mychart
# Displays Chart.yaml  charts  templates  values.yaml
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values.yaml will control things such as replicas, image etc.

# Default values for test.
# This is a YAML-formatted file.
# Declare variables to be passed into your templates.

replicaCount: 1

image:
  repository: nginx
  tag: stable
  pullPolicy: IfNotPresent

nameOverride: ""
fullnameOverride: ""

service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false
  annotations:
    {}
    # kubernetes.io/ingress.class: nginx
    # kubernetes.io/tls-acme: "true"
  paths: []
  hosts:
    - chart-example.local
  tls: []
  #  - secretName: chart-example-tls
  #    hosts:
  #      - chart-example.local

resources:
  {}
  # We usually recommend not to specify default resources and to leave this as a conscious
  # choice for the user. This also increases chances charts run on environments with little
  # resources, such as Minikube. If you do want to specify resources, uncomment the following
  # lines, adjust them as necessary, and remove the curly braces after 'resources:'.
  # limits:
  #  cpu: 100m
  #  memory: 128Mi
  # requests:
  #  cpu: 100m
  #  memory: 128Mi

nodeSelector: {}

tolerations: []

affinity: {}
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Inside the mychart/templates folder we have...

ls mychart/templates
# shows NOTES.txt  _helpers.tpl  deployment.yaml  ingress.yaml  service.yaml  tests
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Looking at the deployment.yaml we see the following:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "test.fullname" . }}
  labels:
    app.kubernetes.io/name: {{ include "test.name" . }}
    helm.sh/chart: {{ include "test.chart" . }}
    app.kubernetes.io/instance: {{ .Release.Name }}
    app.kubernetes.io/managed-by: {{ .Release.Service }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app.kubernetes.io/name: {{ include "test.name" . }}
      app.kubernetes.io/instance: {{ .Release.Name }}
  template:
    metadata:
      labels:
        app.kubernetes.io/name: {{ include "test.name" . }}
        app.kubernetes.io/instance: {{ .Release.Name }}
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          ports:
            - name: http
              containerPort: 80
              protocol: TCP
          livenessProbe:
            httpGet:
              path: /
              port: http
          readinessProbe:
            httpGet:
              path: /
              port: http
          resources:
            {{- toYaml .Values.resources | nindent 12 }}
      {{- with .Values.nodeSelector }}
      nodeSelector:
        {{- toYaml . | nindent 8 }}
      {{- end }}
    {{- with .Values.affinity }}
      affinity:
        {{- toYaml . | nindent 8 }}
    {{- end }}
    {{- with .Values.tolerations }}
      tolerations:
        {{- toYaml . | nindent 8 }}
    {{- end }}
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These values will be filled out when deployed.

The spec values are generally defined by the earlier values.yaml.

The mychart/service.yaml also templates how the service file will be created:

apiVersion: v1
kind: Service
metadata:
  name: { { include "test.fullname" . } }
  labels:
    app.kubernetes.io/name: { { include "test.name" . } }
    helm.sh/chart: { { include "test.chart" . } }
    app.kubernetes.io/instance: { { .Release.Name } }
    app.kubernetes.io/managed-by: { { .Release.Service } }
spec:
  type: { { .Values.service.type } }
  ports:
    - port: { { .Values.service.port } }
      targetPort: http
      protocol: TCP
      name: http
  selector:
    app.kubernetes.io/name: { { include "test.name" . } }
    app.kubernetes.io/instance: { { .Release.Name } }
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From here, you can directly install the helm chart using helm install mychart/.

Using the default chart, there is a nginx configuration you then port forward and curl.

kubectl port-forward 80:8080
# Press ^z here
bg # set to background
curl localhost:8080
# result should be default nginx html
fg # bring port-forward back to foreground
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Demo with a Nodejs app

Create a chart and update the required value for your image etc.

# Default values for test.
# This is a YAML-formatted file.
# Declare variables to be passed into your templates.

replicaCount: 1

image:
  repository: okeeffed/repo
  tag: latest
  pullPolicy: IfNotPresent

# Could also be LoadBalancer
service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false
  annotations:
    {}
    # kubernetes.io/ingress.class: nginx
    # kubernetes.io/tls-acme: "true"
  paths: []
  hosts:
    - chart-example.local
    # this could also be whatever.domain.com
  tls: []
  #  - secretName: chart-example-tls
  #    hosts:
  #      - chart-example.local

resources:
  {}
  # We usually recommend not to specify default resources and to leave this as a conscious
  # choice for the user. This also increases chances charts run on environments with little
  # resources, such as Minikube. If you do want to specify resources, uncomment the following
  # lines, adjust them as necessary, and remove the curly braces after 'resources:'.
  # limits:
  #  cpu: 100m
  #  memory: 128Mi
  # requests:
  #  cpu: 100m
  #  memory: 128Mi

nodeSelector: {}

tolerations: []

affinity: {}
# Here you can add dependencies
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If your helm has depencies, these can be defined in a requirements.yaml file. Example:

dependencies:
  - name: mariadb
    version: 4.x.x
    repository: https://kubernetes-charts.storage.googleapis.com/
    condition: mariadb.enabled
    tags:
      - node-app-database
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Ensure you update the chart if you need to change the containerPort or env variables etc.

Once the chart is up and running, you can update charts which will update the orchestration. Use helm update <OPTIONS> <CHART> path/to/chart

Rollbacks can easily be done as well.

Use helm history <CHART> to get a history of deployments. Say we want to rollback to revision one, we can then just run helm rollback <CHART> 1.

Setting up Helm Repo with S3

If you have charts stored on S3:

# Install plugin
helm plugin install https://github.com/hypnoglow/helm-s3.git

# Initialise s3 bucket
helm s3 init s3://helm-bucket/charts

# Add report to helm
helm repo add my-charts s3://helm-bucket/charts
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