flux2/docs/guides/image-update.md

Automate image updates to Git

This guide walks you through configuring container image scanning and deployment rollouts with Flux.

For a container image you can configure Flux to:

• scan the container registry and fetch the image tags
• select the latest tag based on the defined policy (semver, calver, regex)
• replace the tag in Kubernetes manifests (YAML format)
• checkout a branch, commit and push the changes to the remote Git repository
• apply the changes in-cluster and rollout the container image

!!! warning "Alpha version" Note that the image update feature is currently alpha, see the roadmap for more details.

For production environments, this feature allows you to automatically deploy application patches (CVEs and bug fixes), and keep a record of all deployments in Git history.

Production CI/CD workflow

• DEV: push a bug fix to the app repository
• DEV: bump the patch version and release e.g. v1.0.1
• CI: build and push a container image tagged as registry.domain/org/app:v1.0.1
• CD: pull the latest image metadata from the app registry (Flux image scanning)
• CD: update the image tag in the app manifest to v1.0.1 (Flux cluster to Git reconciliation)
• CD: deploy v1.0.1 to production clusters (Flux Git to cluster reconciliation)

For staging environments, this features allow you to deploy the latest build of a branch, without having to manually edit the app deployment manifest in Git.

Staging CI/CD workflow

• DEV: push code changes to the app repository main branch
• CI: build and push a container image tagged as ${GIT_BRANCH}-${GIT_SHA:0:7}-$(date +%s)
• CD: pull the latest image metadata from the app registry (Flux image scanning)
• CD: update the image tag in the app manifest to main-2d3fcbd-1611906956 (Flux cluster to Git reconciliation)
• CD: deploy main-2d3fcbd-1611906956 to staging clusters (Flux Git to cluster reconciliation)

Prerequisites

You will need a Kubernetes cluster version 1.16 or newer and kubectl version 1.18. For a quick local test, you can use Kubernetes kind. Any other Kubernetes setup will work as well.

In order to follow the guide you'll need a GitHub account and a personal access token that can create repositories (check all permissions under repo).

Export your GitHub personal access token and username:

export GITHUB_TOKEN=<your-token>
export GITHUB_USER=<your-username>

Install Flux

!!! hint "Enable image automation components" If you bootstrapped Flux before without the --components-extra= argument, you need to add --components-extra=image-reflector-controller,image-automation-controller to your bootstrapping routine as image automation components are not installed by default.

Install Flux with the image automation components:

flux bootstrap github \
  --components-extra=image-reflector-controller,image-automation-controller \
  --owner=$GITHUB_USER \
  --repository=flux-image-updates \
  --branch=main \
  --path=clusters/my-cluster \
  --token-auth \
  --personal

The bootstrap command creates a repository if one doesn't exist, and commits the manifests for the Flux components to the default branch at the specified path. It then configures the target cluster to synchronize with the specified path inside the repository.

!!! hint "GitLab and other Git platforms" You can install Flux and bootstrap repositories hosted on GitLab, BitBucket, Azure DevOps and any other Git provider that support SSH or token-based authentication. When using SSH, make sure the deploy key is configured with write access. Please see the installation guide for more details.

Deploy a demo app

We'll be using a tiny webapp called podinfo to showcase the image update feature.

Clone your repository with:

git clone https://github.com/$GITHUB_USER/flux-image-updates
cd flux-image-updates

Add the podinfo Kubernetes deployment file inside cluster/my-cluster:

curl -sL https://raw.githubusercontent.com/stefanprodan/podinfo/5.0.0/kustomize/deployment.yaml \
> ./clusters/my-cluster/podinfo-deployment.yaml

Commit and push changes to main branch:

git add -A && \
git commit -m "add podinfo deployment" && \
git push origin main

Tell Flux to pull and apply the changes or wait one minute for Flux to detect the changes on its own:

flux reconcile kustomization flux-system --with-source

Print the podinfo image deployed on your cluster:

$ kubectl get deployment/podinfo -oyaml | grep 'image:'
image: ghcr.io/stefanprodan/podinfo:5.0.0

Configure image scanning

Create an ImageRepository to tell Flux which container registry to scan for new tags:

flux create image repository podinfo \
--image=ghcr.io/stefanprodan/podinfo \
--interval=1m \
--export > ./clusters/my-cluster/podinfo-registry.yaml

The above command generates the following manifest:

apiVersion: image.toolkit.fluxcd.io/v1alpha1
kind: ImageRepository
metadata:
  name: podinfo
  namespace: flux-system
spec:
  image: ghcr.io/stefanprodan/podinfo
  interval: 1m0s

For private images, you can create a Kubernetes secret in the same namespace as the ImageRepository with kubectl create secret docker-registry. Then you can configure Flux to use the credentials by referencing the Kubernetes secret in the ImageRepository:

kind: ImageRepository
spec:
  secretRef:
    name: regcred

!!! hint "Storing secrets in Git" Note that if you want to store the image pull secret in Git, you can encrypt the manifest with Mozilla SOPS or Sealed Secrets.

Create an ImagePolicy to tell Flux which semver range to use when filtering tags:

flux create image policy podinfo \
--image-ref=podinfo \
--select-semver=5.0.x \
--export > ./clusters/my-cluster/podinfo-policy.yaml

The above command generates the following manifest:

apiVersion: image.toolkit.fluxcd.io/v1alpha1
kind: ImagePolicy
metadata:
  name: podinfo
  namespace: flux-system
spec:
  imageRepositoryRef:
    name: podinfo
  policy:
    semver:
      range: 5.0.x

!!! hint "semver ranges" A semver range that includes stable releases can be defined with 1.0.x (patch versions only) or >=1.0.0 <2.0.0 (minor and patch versions). If you want to include pre-release e.g. 1.0.0-rc.1, you can define a range like: ^1.x-0 or >1.0.0-rc <2.0.0-rc.

!!! hint "Other policy examples" For policies that make use of CalVer, build IDs or alphabetical sorting, have a look at the examples.

Commit and push changes to main branch:

git add -A && \
git commit -m "add podinfo image scan" && \
git push origin main

Tell Flux to pull and apply changes:

flux reconcile kustomization flux-system --with-source

Wait for Flux to fetch the image tag list from GitHub container registry:

$ flux get image repository podinfo
NAME   	READY	MESSAGE                       	LAST SCAN
podinfo	True 	successful scan, found 13 tags	2020-12-13T17:51:48+02:00

Find which image tag matches the policy semver range with:

$ flux get image policy podinfo
NAME   	READY	MESSAGE                   
podinfo	True 	Latest image tag for 'ghcr.io/stefanprodan/podinfo' resolved to: 5.0.3

Configure image updates

Edit the podinfo-deployment.yaml and add a marker to tell Flux which policy to use when updating the container image:

spec:
  containers:
  - name: podinfod
    image: ghcr.io/stefanprodan/podinfo:5.0.0 # {"$imagepolicy": "flux-system:podinfo"}

Create an ImageUpdateAutomation to tell Flux which Git repository to write image updates to:

flux create image update flux-system \
--git-repo-ref=flux-system \
--git-repo-path="./clusters/my-cluster" \
--checkout-branch=main \
--push-branch=main \
--author-name=fluxcdbot \
--author-email=fluxcdbot@users.noreply.github.com \
--commit-template="{{range .Updated.Images}}{{println .}}{{end}}" \
--export > ./clusters/my-cluster/flux-system-automation.yaml

The above command generates the following manifest:

apiVersion: image.toolkit.fluxcd.io/v1alpha1
kind: ImageUpdateAutomation
metadata:
  name: flux-system
  namespace: flux-system
spec:
  checkout:
    branch: main
    gitRepositoryRef:
      name: flux-system
  commit:
    authorEmail: fluxcdbot@users.noreply.github.com
    authorName: fluxcdbot
    messageTemplate: '{{range .Updated.Images}}{{println .}}{{end}}'
  interval: 1m0s
  push:
    branch: main
  update:
    path: ./clusters/my-cluster
    strategy: Setters

Commit and push changes to main branch:

git add -A && \
git commit -m "add image updates automation" && \
git push origin main

Note that the ImageUpdateAutomation runs all the policies found in its namespace at the specified interval.

Tell Flux to pull and apply changes:

flux reconcile kustomization flux-system --with-source

In a couple of seconds, Flux will push a commit to your repository with the latest image tag that matches the podinfo policy:

$ git pull && cat clusters/my-cluster/podinfo-deployment.yaml | grep "image:"
image: ghcr.io/stefanprodan/podinfo:5.0.3 # {"$imagepolicy": "flux-system:podinfo"}

Wait for Flux to apply the latest commit on the cluster and verify that podinfo was updated to 5.0.3:

$ watch "kubectl get deployment/podinfo -oyaml | grep 'image:'"
image: ghcr.io/stefanprodan/podinfo:5.0.3

You can check the status of the image automation objects with:

flux get images all --all-namespaces

Configure image update for custom resources

Besides Kubernetes native kinds (Deployment, StatefulSet, DaemonSet, CronJob), Flux can be used to patch image tags in any Kubernetes custom resource stored in Git.

The image policy marker format is:

• {"$imagepolicy": "<policy-namespace>:<policy-name>"}
• {"$imagepolicy": "<policy-namespace>:<policy-name>:tag"}

HelmRelease example:

apiVersion: helm.toolkit.fluxcd.io/v2beta1
kind: HelmRelease
metadata:
  name: podinfo
  namespace: default
spec:
  values:
    image:
      repository: ghcr.io/stefanprodan/podinfo
      tag: 5.0.0  # {"$imagepolicy": "flux-system:podinfo:tag"}

Tekton Task example:

apiVersion: tekton.dev/v1beta1
kind: Task
metadata:
  name: golang
  namespace: default
spec:
  steps:
    - name: golang
      image: docker.io/golang:1.15.6 # {"$imagepolicy": "flux-system:golang"}

Flux Kustomization example:

apiVersion: kustomize.toolkit.fluxcd.io/v1beta1
kind: Kustomization
metadata:
  name: podinfo
  namespace: default
spec:
  images:
    - name: ghcr.io/stefanprodan/podinfo
      newName: ghcr.io/stefanprodan/podinfo
      newTag: 5.0.0 # {"$imagepolicy": "flux-system:podinfo:tag"}

Kustomize config (kustomization.yaml) example:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- deployment.yaml
images:
- name: ghcr.io/stefanprodan/podinfo
  newName: ghcr.io/stefanprodan/podinfo
  newTag: 5.0.0 # {"$imagepolicy": "flux-system:podinfo:tag"}

Push updates to a different branch

With .spec.push.branch you can configure Flux to push the image updates to different branch than the one used for checkout. If the specified branch doesn't exist, Flux will create it for you.

apiVersion: image.toolkit.fluxcd.io/v1alpha1
kind: ImageUpdateAutomation
metadata:
  name: flux-system
spec:
  checkout:
    branch: main
    gitRepositoryRef:
      name: flux-system
  push:
    branch: image-updates

You can use CI automation e.g. GitHub Actions such as create-pull-request to open a pull request against the checkout branch.

This way you can manually approve the image updates before they are applied on your clusters.

Configure the commit message

The .spec.commit.messageTemplate field is a string which is used as a template for the commit message.

The message template is a Go text template that lets you range over the objects and images e.g.:

apiVersion: image.toolkit.fluxcd.io/v1alpha1
kind: ImageUpdateAutomation
metadata:
  name: flux-system
spec:
  commit:
    messageTemplate: |
      Automated image update

      Automation name: {{ .AutomationObject }}

      Files:
      {{ range $filename, $_ := .Updated.Files -}}
      - {{ $filename }}
      {{ end -}}

      Objects:
      {{ range $resource, $_ := .Updated.Objects -}}
      - {{ $resource.Kind }} {{ $resource.Name }}
      {{ end -}}

      Images:
      {{ range .Updated.Images -}}
      - {{.}}
      {{ end -}}      
    authorEmail: flux@example.com
    authorName: flux

Trigger image updates with webhooks

You may want to trigger a deployment as soon as a new image tag is pushed to your container registry. In order to notify the image-reflector-controller about new images, you can setup webhook receivers.

First generate a random string and create a secret with a token field:

TOKEN=$(head -c 12 /dev/urandom | shasum | cut -d ' ' -f1)
echo $TOKEN

kubectl -n flux-system create secret generic webhook-token \	
--from-literal=token=$TOKEN

Define a receiver for DockerHub:

apiVersion: notification.toolkit.fluxcd.io/v1beta1
kind: Receiver
metadata:
  name: podinfo
  namespace: flux-system
spec:
  type: dockerhub
  secretRef:
    name: webhook-token
  resources:
    - kind: ImageRepository
      name: podinfo

The notification-controller generates a unique URL using the provided token and the receiver name/namespace.

Find the URL with:

$ kubectl -n flux-system get receiver/podinfo

NAME      READY   STATUS
podinfo   True    Receiver initialised with URL: /hook/bed6d00b5555b1603e1f59b94d7fdbca58089cb5663633fb83f2815dc626d92b

Log in to DockerHub web interface, go to your image registry Settings and select Webhooks. Fill the form "Webhook URL" by composing the address using the receiver LB and the generated URL http://<LoadBalancerAddress>/<ReceiverURL>.

!!! hint "Note" Besides DockerHub, you can define receivers for Harbor, Quay, Nexus, GCR, and any other system that supports webhooks e.g. GitHub Actions, Jenkins, CircleCI, etc. See the Receiver CRD docs for more details.

Incident management

Suspend automation

During an incident you may wish to stop Flux from pushing image updates to Git.

You can suspend the image automation directly in-cluster:

flux suspend image update flux-system

Or by editing the ImageUpdateAutomation manifest in Git:

kind: ImageUpdateAutomation
metadata:
  name: flux-system
  namespace: flux-system
spec:
  suspend: true

Once the incident is resolved, you can resume automation with:

flux resume image update flux-system

If you wish to pause the automation for a particular image only, you can suspend/resume the image scanning:

flux suspend image repository podinfo

Revert image updates

Assuming you've configured Flux to update an app to its latest stable version:

flux create image policy podinfo \
--image-ref=podinfo \
--select-semver=">=5.0.0"

If the latest version e.g. 5.0.1 causes an incident in production, you can tell Flux to revert the image tag to a previous version e.g. 5.0.0 with:

flux create image policy podinfo \
--image-ref=podinfo \
--select-semver=5.0.0

Or by changing the semver range in Git:

kind: ImagePolicy
metadata:
  name: podinfo
  namespace: flux-system
spec:
  policy:
    semver:
      range: 5.0.0

Based on the above configuration, Flux will patch the podinfo deployment manifest in Git and roll out 5.0.0 in-cluster.

When a new version is available e.g. 5.0.2, you can update the policy once more and tell Flux to consider only versions greater than 5.0.1:

flux create image policy podinfo \
--image-ref=podinfo \
--select-semver=">5.0.1"

ImageRepository cloud providers authentication

If relying on a cloud provider image repository, you might need to do some extra work in order to configure the ImageRepository resource credentials. Here are some common examples for the most popular cloud provider docker registries.

!!! warning "Workarounds" The examples below are intended as workaround solutions until native authentication mechanisms are implemented in Flux itself to support this in a more straightforward manner.

AWS Elastic Container Registry

We can create a deployment that frequently refreshes an image pull secret into our desired namespace.

Create a directory in your control repository and save this kustomization.yaml:

# kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- git@github.com/fluxcd/flux2//manifests/integrations/registry-credentials-sync/aws
patchesStrategicMerge:
- config-patches.yaml

Save and configure the following patch -- note the instructional comments for configuring matching AWS resources:

# config-patches.yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: credentials-sync
data:
  ECR_REGION: us-east-1  # set the region
  ECR_REGISTRY: <account id>.dkr.ecr.<region>.amazonaws.com  # fill in the account id and region
  KUBE_SECRET: ecr-credentials  # does not yet exist -- will be created in the same Namespace
  SYNC_PERIOD: "21600"  # 6hrs -- ECR tokens expire every 12 hours; refresh faster than that

# Bind IRSA for the ServiceAccount 
#  If using IRSA, make sure the role attached to the service account has
#  readonly access to ECR. The AWS managed policy
#  `arn:aws:iam::aws:policy/AmazonEC2ContainerRegistryReadOnly` 
#  can be attached to the role.
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: credentials-sync
  namespace: flux-system
  annotations:
    eks.amazonaws.com/role-arn: <role arn>  # set the ARN for your role

## If not using IRSA, set the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables
## Store these values in a Secret and load them in the container using envFrom.
## For managing this secret via GitOps, consider using SOPS or SealedSecrets and add that manifest in a resource file for this kustomize build.
##   https://toolkit.fluxcd.io/guides/mozilla-sops/
##   https://toolkit.fluxcd.io/guides/sealed-secrets/
# ---
# apiVersion: apps/v1
# kind: Deployment
# metadata:
#   name: credentials-sync
#   namespace: flux-system
# spec:
#   template:
#     spec:
#       containers:
#       - name: sync
#         envFrom:
#           secretRef:
#             name: $(ECR_SECRET_NAME)  # uncomment the var for this in kustomization.yaml

Verify that kustomize build . works, then commit the directory to you control repo.

Flux will apply the Deployment and it will use the workload identity for that Pod to regularly fetch ECR tokens into your configured KUBE_SECRET name. Reference the KUBE_SECRET value from any ImageRepository objects for that ECR registry.

This example uses the fluxcd/flux2 github archive as a remote base, but you may copy the ./manifests/integrations/registry-credentials-sync/aws folder into your own repository or use a git submodule to vendor it if preferred.

GCP Container Registry

Using access token [short-lived]

Pre-requisites

Workload Identity

Your GCP cluster will need Workload Identity enabled.

Setting up authentication on GCP

Create a GCP service account to access the container registry

$ gcloud iam service-accounts create GSA_NAME

Create an IAM policy binding between the GCP service account and the Kubernetes service account.

$ gcloud iam service-accounts add-iam-policy-binding \
    --role roles/iam.workloadIdentityUser \
    --member "serviceAccount:PROJECT_ID.svc.id.goog[flux-system/credentials-sync]" \
    GSA_NAME@PROJECT_ID.iam.gserviceaccount.com

Creating Deployment to refresh image-pull secret

Once we have workload identity enabled, GCP service account created, and IAM policy binding setup, we can create a deployment that frequently refreshes an image pull secret into our desired namespace.

Create a directory in your control repository and save this kustomization.yaml:

# kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- git@github.com/fluxcd/flux2//manifests/integrations/registry-credentials-sync/gcp
patchesStrategicMerge:
- config-patches.yaml

Save and configure the following patch -- note the instructional comments for configuring matching GCP resources:

# config-patches.yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: credentials-sync
data:
  GCR_REGISTRY: gcr.io  # set the registry
  KUBE_SECRET: gcr-credentials  # does not yet exist -- will be created in the same Namespace
  SYNC_PERIOD: "1800"  # 30m -- GCR tokens expire every hour; refresh faster than that
# Bind to the GCP service-account
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: credentials-sync
  namespace: flux-system
  annotations:
    iam.gke.io/gcp-service-account: <gsa-name>@<project-id>.iam.gserviceaccount.com # set the GCP service-account

Verify that kustomize build . works, then commit the directory to you control repo.

Flux will apply the Deployment and it will use the workload identity for that Pod to regularly fetch GCR tokens into your configured KUBE_SECRET name. Reference the KUBE_SECRET value from any ImageRepository objects for that GCR registry.

This example uses the fluxcd/flux2 github archive as a remote base, but you may copy the ./manifests/integrations/registry-credentials-sync/gcp folder into your own repository or use a git submodule to vendor it if preferred.

Using a JSON key [long-lived]

!!! warning "Less secure option" From Google documentation on authenticating container registry > A user-managed key-pair that you can use as a credential for a service account. > Because the credential is long-lived, it is the least secure option of all the available authentication methods. > When possible, use an access token or another available authentication method to reduce the risk of > unauthorized access to your artifacts. If you must use a service account key, > ensure that you follow best practices for managing credentials.

A JSON key doesn't expire, which makes the need for a deployment to refresh tokens redundant. All that is needed is to create the secret and reference it in the ImagePolicy.

Follow steps 1-3 of the official GCP documentation regarding JSON key file Authentication method. This will guide you through creating a service account, and obtaining a JSON key file that can access GCR.

Generate a Kubernetes secret manifest with kubectl:

$ kubectl create secret docker-registry <secret-name> \
    --docker-server=<GCR-REGISTRY> \ # e.g gcr.io
    --docker-username=_json_key \
    --docker-password="$(cat <downloaded-json-file>)" \
    --dry-run=client \
    -o yaml > registry-credentials.yaml

Encrypt it using Mozilla SOPS or Sealed Secrets. Once encrypted commit and push the encrypted file to git.

Azure Container Registry

AKS clusters are not able to pull and run images from ACR by default. Read Integrating AKS /w ACR as a potential pre-requisite before integrating Flux ImageRepositories with ACR.

Note that the resulting ImagePullSecret for Flux could also be specified by Pods within the same Namespace to pull and run ACR images as well.

Generating Tokens for Managed Identities [short-lived]

As a pre-requisite, your AKS cluster will need AAD Pod Identity installed.

Once we have AAD Pod Identity installed, we can create a Deployment that frequently refreshes an image pull secret into our desired Namespace.

Create a directory in your control repository and save this kustomization.yaml:

# kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- git@github.com/fluxcd/flux2//manifests/integrations/registry-credentials-sync/azure
patchesStrategicMerge:
- config-patches.yaml

Save and configure the following patch -- note the instructional comments for configuring matching Azure resources:

# config-patches.yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: credentials-sync
data:
  ACR_NAME: my-registry
  KUBE_SECRET: my-registry  # does not yet exist -- will be created in the same Namespace
  SYNC_PERIOD: "3600"  # ACR tokens expire every 3 hours; refresh faster than that

# Create an identity in Azure and assign it a role to pull from ACR  (note: the identity's resourceGroup should match the desired ACR):
#     az identity create -n acr-sync
#     az role assignment create --role AcrPull --assignee-object-id "$(az identity show -n acr-sync -o tsv --query principalId)"
# Fetch the clientID and resourceID to configure the AzureIdentity spec below:
#     az identity show -n acr-sync -otsv --query clientId
#     az identity show -n acr-sync -otsv --query resourceId
---
apiVersion: aadpodidentity.k8s.io/v1
kind: AzureIdentity
metadata:
  name: credentials-sync  # name must match the stub-resource in az-identity.yaml
  namespace: flux-system
spec:
  clientID: 4ceaa448-d7b9-4a80-8f32-497eaf3d3287
  resourceID: /subscriptions/8c69185e-55f9-4d00-8e71-a1b1bb1386a1/resourcegroups/stealthybox/providers/Microsoft.ManagedIdentity/userAssignedIdentities/acr-sync
  type: 0  # user-managed identity

Verify that kustomize build . works, then commit the directory to you control repo. Flux will apply the Deployment and it will use the AAD managed identity for that Pod to regularly fetch ACR tokens into your configured KUBE_SECRET name. Reference the KUBE_SECRET value from any ImageRepository objects for that ACR registry.

This example uses the fluxcd/flux2 github archive as a remote base, but you may copy the ./manifests/integrations/registry-credentials-sync/azure folder into your own repository or use a git submodule to vendor it if preferred.

Using Static Credentials [long-lived]

!!! info Using a static credential requires a Secrets management solution compatible with your GitOps workflow.

Follow the official Azure documentation for Creating an Image Pull Secret for ACR.

Instead of creating the Secret directly into your Kubernetes cluster, encrypt it using Mozilla SOPS or Sealed Secrets, then commit and push the encrypted file to git.

This Secret should be in the same Namespace as your flux ImageRepository object. Update the ImageRepository.spec.secretRef to point to it.

It is also possible to create Repository Scoped Tokens.

!!! warning Repository Scoped Tokens are in preview and do have limitations.