Use Helm variables in entrypoint script

Question

I'm struggling to use Helm variables within my entry script for my container, when deploying to AKS. Running locally work perfectly fine, as I'm specifying them as docker -e arguement. How do I pass arguments, either specified as helm variables and/or overwrited when issuing the helm install command?

Entry script start.sh

#!/bin/bash

GH_OWNER=$GH_OWNER
GH_REPOSITORY=$GH_REPOSITORY
GH_TOKEN=$GH_TOKEN

echo "variables"
echo $GH_TOKEN
echo $GH_OWNER
echo $GH_REPOSITORY
echo ${GH_TOKEN}
echo ${GH_OWNER}
echo ${GH_REPOSITORY}
env

Docker file

# base image
FROM ubuntu:20.04

#input GitHub runner version argument
ARG RUNNER_VERSION
ENV DEBIAN_FRONTEND=noninteractive

# update the base packages + add a non-sudo user
RUN apt-get update -y && apt-get upgrade -y && useradd -m docker

# install the packages and dependencies along with jq so we can parse JSON (add additional packages as necessary)
RUN apt-get install -y --no-install-recommends \
    curl nodejs wget unzip vim git azure-cli jq build-essential libssl-dev libffi-dev python3 python3-venv python3-dev python3-pip

# cd into the user directory, download and unzip the github actions runner
RUN cd /home/docker && mkdir actions-runner && cd actions-runner \
    && curl -O -L https://github.com/actions/runner/releases/download/v${RUNNER_VERSION}/actions-runner-linux-x64-${RUNNER_VERSION}.tar.gz \
    && tar xzf ./actions-runner-linux-x64-${RUNNER_VERSION}.tar.gz

# install some additional dependencies
RUN chown -R docker ~docker && /home/docker/actions-runner/bin/installdependencies.sh

# add over the start.sh script
ADD scripts/start.sh start.sh

# make the script executable
RUN chmod +x start.sh

# set the user to "docker" so all subsequent commands are run as the docker user
USER docker

# set the entrypoint to the start.sh script
ENTRYPOINT ["/start.sh"]

Helm values

replicaCount: 1

image:
  repository: somecreg.azurecr.io/ghrunner
  pullPolicy: Always
  # tag: latest  

imagePullSecrets: []
nameOverride: ""
fullnameOverride: ""

env:
  GH_TOKEN: "SET"
  GH_OWNER: "SET"
  GH_REPOSITORY: "SET"
   
serviceAccount:
  create: true
  annotations: {}
  name: ""

podAnnotations: {}

podSecurityContext: {}


securityContext: {}

service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false
  className: ""
  annotations: {}
  hosts:
    - host: chart-example.local
      paths:
        - path: /
          pathType: ImplementationSpecific
  tls: []


resources: {}

autoscaling:
  enabled: false
  minReplicas: 1
  maxReplicas: 100
  targetCPUUtilizationPercentage: 80
  # targetMemoryUtilizationPercentage: 80

nodeSelector: {}
tolerations: []
affinity: {}

Deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "hostedrunner.fullname" . }}
  labels:
    {{- include "hostedrunner.labels" . | nindent 4 }}
spec:
  {{- if not .Values.autoscaling.enabled }}
  replicas: {{ .Values.replicaCount }}
  {{- end }}
  selector:
    matchLabels:
      {{- include "hostedrunner.selectorLabels" . | nindent 6 }}
  template:
    metadata:
      {{- with .Values.podAnnotations }}
      annotations:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      labels:
        {{- include "hostedrunner.selectorLabels" . | nindent 8 }}
    spec:
      {{- with .Values.imagePullSecrets }}
      imagePullSecrets:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      serviceAccountName: {{ include "hostedrunner.serviceAccountName" . }}
      securityContext:
        {{- toYaml .Values.podSecurityContext | nindent 8 }}
      containers:
        - name: {{ .Chart.Name }}
          securityContext:
            {{- toYaml .Values.securityContext | nindent 12 }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
          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 }}

Console output for helm install

Helm command (tried both with set and set-string and values to get substituted correctly)

helm install --set-string env.GH_TOKEN="$env:pat" --set-string env.GH_OWNER="SomeOwner" --set-string env.GH_REPOSITORY="aks-hostedrunner" $deploymentName .helm/ --debug

I thought the helm variables might be passed as environment variables, but that's not the case. Any input is greatly appreciated

Harsh Manvar · Answer

You can add and update your deployment template with

env:
    {{- range $key, $val := .Values.env }}
    - name: {{ $key }}
      value: {{ $val }}
    {{- end }}

so it will add the env block into your deployment section and your shell script when will run inside the docker, it will be able to access the Environment variables

Deployment env example

containers:
  - name: envar-demo-container
    image: 
    env:
    - name: DEMO_GREETING
      value: "Hello from the environment"
    - name: DEMO_FAREWELL
      value: "Such a sweet sorrow"

Ref : https://kubernetes.io/docs/tasks/inject-data-application/define-environment-variable-container/#define-an-environment-variable-for-a-container

If you will implement above one those variables will get set as Environment variables and Docker will be able to access it(shell script inside the container).

You can also use the configmap and secret of Kubernetes to set values at Env level.

Use Helm variables in entrypoint script

1 Answers