azure-devops | aks | helm

Azure DevOps - CI/CD Pipeline involving Helm 3, ACR & AKS

Setup Continuous Integration in Azure DevOps which push Docker image, Helm 3 chart to ACR, and Continuous Deployment pipeline that deploys the chart to AKS.

Abhith Rajan
Abhith RajanAugust 18, 2020 · 8 min read · Last Updated:

Azure is my favorite cloud provider. We use Azure for most of the infra & services. Our code goes to Azure DevOps, we use Azure Container Registry (ACR) to host our docker container images and our Kubernetes clusters running in Azure Kubernetes Service (AKS).

We configured the CI/CD pipelines in Azure DevOps. In my case, we have a monorepo that contains several ASP.NET Core microservices and the folder structure looks like below, which we inherited from eShopOnContainers.

- build
  - azure-devops
    - common
      - ci-steps-template.yml
      - ci-vars-template.yml
    - project-one
      - ci-pipeline.yml
    - project-two
- deploy

  - azure-devops
    - common
      - cd-steps-template.yml
      - cd-steps-template-prod.yml
      - cd-vars-template.yml
    - project-one
      - cd-pipeline.yml
    - project-two
  - k8s
    - helm
      - project-one
      - project-two

- src
  - Services
    - Project-One
    - Project-Two

One of the great articles that helped me to initial setup the CI/CD is given below. Its kind of outdated now since it is using az acr helm commands which were deprecated later. But it is still worth reading. So definitely check it out.

👉 Tutorial: Using Azure DevOps to setup a CI/CD pipeline and deploy to Kubernetes

CI Pipeline

The CI pipeline does the following,

  • Build a Docker image and push to ACR
  • Build Helm chart and push to ACR

Prerequisites

  • Helm chart for your project. Here my chart directory is located at deploy > k8s > helm. To create a new chart for your project, refer Helm Create.
  • acr-connection-name: ACR service connection in Azure DevOps. You can add it under Azure DevOps > Project > Project Settings > Service Connections.

The ACR credentials I stored in the Azure DevOps Variable Groups (acr-variable-group).

NameValue
registryNameYour ACR name
registryLoginACR login
registryPasswordACR password
Variable group definition
Variable group definition

Common

ci-vars-template.yml

parameters:
  projectName: ""
  dockerRegistryServiceConnectionName: ""
  dockerfile: ""
  buildContext: ""

variables:
  helmVersion: 3.2.3
  HELM_EXPERIMENTAL_OCI: 1
  registryServerName: "$(registryName).azurecr.io"
  dockerRegistryServiceConnectionName: ${{ parameters.dockerRegistryServiceConnectionName }}
  dockerfile: ${{ parameters.dockerfile }}
  buildContext: ${{ parameters.buildContext }}
  projectName: ${{ parameters.projectName }}
  imageName: ${{ parameters.projectName }}
  imageTag: $(build.sourceBranchName)
  helmChartVersion: $(build.sourceBranchName)
  helmfrom: $(Build.SourcesDirectory)/deploy/k8s/helm
  helmto: $(Build.ArtifactStagingDirectory)/deploy/k8s/helm

Few things to note here,

  • HELM_EXPERIMENTAL_OCI is to enable OCI support in the Helm 3 client. Currently, this support is experimental.
  • build.sourceBranchName as the image tag and chart version is handy if you are following Gitflow (which we follow) or similar git branching convention, so each release (eg, refs/tags/project-one/2.2.6) will generate Docker image and Helm chart with the same version.

ci-steps-template.yml

steps:
  - task: Docker@2
    displayName: Build and push an image to container registry
    inputs:
      command: buildAndPush
      repository: $(imageName)
      dockerfile: $(dockerfile)
      containerRegistry: $(dockerRegistryServiceConnectionName)
      buildContext: $(buildContext)
      tags: |
        $(imageTag)

  - task: HelmInstaller@1
    displayName: "install helm"
    inputs:
      helmVersionToInstall: $(helmVersion)
  - bash: |
      echo $(registryPassword) | helm registry login $(registryName).azurecr.io --username $(registryLogin) --password-stdin
      cd deploy/k8s/helm/
      helm chart save $(helm package --app-version $(imageTag) --version $(helmChartVersion) ./$(projectName) | grep -o '/.*.tgz') $(registryName).azurecr.io/charts/$(projectName):$(imageTag)
      helm chart push $(registryName).azurecr.io/charts/$(projectName):$(helmChartVersion)
      echo $(jq -n --arg version "$(helmChartVersion)" '{helmChartVersion: $version}') > $(build.artifactStagingDirectory)/variables.json
    failOnStderr: true
    displayName: "helm package"
  - task: CopyFiles@2
    inputs:
      sourceFolder: $(helmfrom)
      targetFolder: $(helmto)
  - publish: $(build.artifactStagingDirectory)
    artifact: build-artifact

The steps in the CI pipeline we moved to a common template file ci-steps-template.yml so that we can reuse it on other pipelines as well, and the steps include,

  1. Build and push the docker image

  2. Installs Helm client

  3. A series of script which does

    • Authenticate to ACR
    • Creates and push Helm chart to ACR.
    • Creates variables.json which contain the newly created Helm chart version. Which we will use to fetch the right chart version during CD.
  4. Copy some additional files to the artifact. Which we can use to override Helm chart values.

ci-pipeline.yml

trigger:
  branches:
    include:
      - refs/tags/project-one/*
  paths:
    include:
      - src/Services/ProjectOne/*

pr: none

pool:
  vmImage: "ubuntu-latest"

variables:
  - group: acr-variable-group
  - template: ../common/ci-vars-template.yml
    parameters:
      projectName: "project-one"
      dockerRegistryServiceConnectionName: "acr-connection-name"
      dockerfile: "src/Services/Project-One/Dockerfile"
      buildContext: "$(System.DefaultWorkingDirectory)"

steps:
  - template: ../common/ci-steps-template.yml

If everything went well, you will have two repositories under your ACR.

  • project-one which contains the Docker image
  • chart/project-one for the Helm chart

CD Pipeline

The CD pipeline will install the Helm chart on AKS. The CD pipeline stage requires following details,

NameValue
aksAKS name
rgAKS resource group
aksSpTenantIdSubscription tenant id
aksSpIdService principal Id
aksSpSecretService principal password

These credentials I stored in another varible group named aks-variable-group.

Helpful commands

Service principal credentials

Create new service principal aks-name-deploy by

az ad sp create-for-rbac -n aks-name-deploy --scopes aks-resource-id --role "Azure Kubernetes Service Cluster User Role" --query password -o tsv

Where aks-resource-id is,

az aks show -n $aks -g $rg --query id -o tsv

The above command will output service principal password aksSpSecret.

To get service principal id aksSpId,

az ad sp show --id http://aks-name-deploy --query appId -o tsv

Also we need to attach ACR with AKS so that AKS can pull our private docker images from our ACR.

Attach ACR with AKS

az aks update -g $rg -n $aks --attach-acr acr-resource-id

Where acr-resource-id is the output of,

az acr show -n $registryName -g acr-resource-group-name --query id -o tsv

Get Azure Tenant Id

To get tenantId aksSpTenantId,

az account show --query tenantId -o tsv

Now lets explore the pipeline YAML files.

Common

cd-vars-template.yml

parameters:
  projectName: ""

variables:
  helmVersion: 3.2.3
  HELM_EXPERIMENTAL_OCI: 1
  registryServerName: "$(registryName).azurecr.io"
  projectName: ${{ parameters.projectName }}

cd-steps-template.yml

steps:
  - checkout: none
  - task: HelmInstaller@1
    displayName: "install helm"
    inputs:
      helmVersionToInstall: $(helmVersion)
  - download: ci-pipeline
    artifact: build-artifact
  - bash: |
      az login \
           --service-principal \
           -u $(aksSpId) \
           -p '$(aksSpSecret)' \
           --tenant $(aksSpTenantId)
       az aks get-credentials \
           -n $(aks) \
           -g $(rg)
       echo $(registryPassword) | helm registry login $(registryServerName) --username $(registryLogin) --password-stdin
       helmChartVersion=$(jq .helmChartVersion $(pipeline.workspace)/ci-pipeline/build-artifact/variables.json -r)
       helm chart pull $(registryServerName)/charts/$(projectName):$helmChartVersion
       helm chart export $(registryServerName)/charts/$(projectName):$helmChartVersion --destination $(pipeline.workspace)/install
       helm upgrade \
           --namespace $(k8sNamespace) \
           --create-namespace \
           --install \
           --wait \
           --version $helmChartVersion \
           --set image.repository=$(registryServerName)/$(projectName) \
           -f $(pipeline.workspace)/ci-pipeline/build-artifact/deploy/k8s/helm/app.yaml \
           -f $(pipeline.workspace)/ci-pipeline/build-artifact/deploy/k8s/helm/inf.yaml \
           $(projectName) \
           $(pipeline.workspace)/install/$(projectName)
    failOnStderr: true
    displayName: "deploy helm chart"

The common CD steps include a series of script which does,

  • Authenticate to Azure using the service principal credentials
  • Set the specified AKS cluster as the context.
  • Authenticate ACR with the ACR credentials (The same credentials we used in CI pipeline defined in the acr-variable-group)
  • Extract the Helm chart version that need to install
  • Pulls the Helm chart and installs (or upgrade) it. Here we are overriding the chart image repository to our ACR repository and some additional common values (app.yaml & inf.yaml).

cd-pipeline.yml

trigger: none
pr: none

# define variables: registryName, registryLogin and registryPassword in the Azure pipeline UI definition
variables:
  - group: acr-variable-group
  - template: ../common/cd-vars-template.yml
    parameters:
      projectName: "project-one"
  - name: k8sNamespace
    value: myteam

resources:
  pipelines:
    - pipeline: ci-pipeline
      source: "project-one-ci"
      trigger:
        enabled: true
        branches:
          include:
            - refs/tags/project-one/*

# define 5 variables: aks, rg, aksSpId, aksSpSecret and aksSpTenantId in the Azure pipeline UI definition
stages:
  - stage: test
    displayName: test
    jobs:
      - deployment: test
        variables:
          - group: aks-variable-group
        displayName: deploy helm chart into AKS
        pool:
          vmImage: ubuntu-latest
        environment: test-$(projectName)
        strategy:
          runOnce:
            deploy:
              steps:
                - template: ../common/cd-steps-template.yml
  - stage: production
    displayName: production
    jobs:
      - deployment: production
        variables:
          - group: aks-prod-variable-group
        displayName: deploy helm chart into AKS
        pool:
          vmImage: ubuntu-latest
        environment: production-$(projectName)
        strategy:
          runOnce:
            deploy:
              steps:
                - template: ../common/cd-steps-template-prod.yml

In the CD pipeline above, I have defined two stages, one for TEST and one for PROD. The main difference between them is in the variable group used. aks-variable-group has the TEST cluster values and you guessed right, aks-prod-variable-group has the PROD cluster values. And the difference between cd-steps-template.yml and cd-steps-template-prod.yml is that prod file has some additional chart value overrides with respect to our PRODUCTION environment.

cd-steps-template-prod.yml

steps:
  - checkout: none
  - task: HelmInstaller@1
    displayName: "install helm"
    inputs:
      helmVersionToInstall: $(helmVersion)
  - download: ci-pipeline
    artifact: build-artifact
  - bash: |
      az login \
           --service-principal \
           -u $(aksSpId) \
           -p '$(aksSpSecret)' \
           --tenant $(aksSpTenantId)
       az aks get-credentials \
           -n $(aks) \
           -g $(rg)
       echo $(registryPassword) | helm registry login $(registryServerName) --username $(registryLogin) --password-stdin
       helmChartVersion=$(jq .helmChartVersion $(pipeline.workspace)/ci-pipeline/build-artifact/variables.json -r)
       helm chart pull $(registryServerName)/charts/$(projectName):$helmChartVersion
       helm chart export $(registryServerName)/charts/$(projectName):$helmChartVersion --destination $(pipeline.workspace)/install
       helm upgrade \
           --namespace $(k8sNamespace) \
           --create-namespace \
           --install \
           --wait \
           --version $helmChartVersion \
           --set image.repository=$(registryServerName)/$(projectName) \
           -f $(pipeline.workspace)/ci-pipeline/build-artifact/deploy/k8s/helm/app.yaml \
           -f $(pipeline.workspace)/ci-pipeline/build-artifact/deploy/k8s/helm/inf.yaml \
           -f $(pipeline.workspace)/ci-pipeline/build-artifact/deploy/k8s/helm/inf-prod.yaml \
           -f $(pipeline.workspace)/ci-pipeline/build-artifact/deploy/k8s/helm/$(projectName)/values-prod.yaml \
           $(projectName) \
           $(pipeline.workspace)/install/$(projectName)
    failOnStderr: true
    displayName: "deploy helm chart"

Few more Notes

  • CD pipeline is also YAML based (You gonna like it), hence create it like a regular pipeline (Not as RELEASE) in the Azure DevOps, and choose the cd-pipeline.yml after choosing to create pipeline based on Existing Azure Pipelines YAML file.
  • Once you create the CD pipeline, check the Environments under Azure DevOps Pipelines. There will be two environments as per the above example, test-project-one and production-project-one. Inside each, you can configure the approvals and more for the respective CD stages.

A sample reference source code is also pushed to here.

If you have any grey area in this article, feel free to shoot it in the comments below 👇, I will try to shed some light on that part.


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Abhith Rajan

Written byAbhith Rajan
Abhith Rajan is a software engineer by day and a full-stack developer by night. He's coding for almost a decade now. He codes 🧑‍💻, write ✍️, learn 📖 and advocate 👍.
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