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helm-operator-integration.md

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Integration with the Helm operator

You can release charts to your cluster via "GitOps", by combining Flux and the Helm operator.

The essential mechanism is this: the declaration of a Helm release is represented by a custom resource, specifying the chart and its values. If you put such a resource in your git repo as a file, Flux will apply it to the cluster, and once it's in the cluster, the Helm Operator will make sure the release exists by installing or upgrading it.

Upgrading images in a HelmRelease using Flux

If the chart you're using in a HelmRelease lets you specify the particular images to run, you will usually be able to update them with Flux, the same way you can with Deployments and so on.

Note: for automation to work, the repository and tag should be defined (either as a whole string, or under separate keys), as Flux determines image updates based on what it reads in the .spec.values of the HelmRelease.

Automated image detection

Flux interprets certain commonly used structures in the values section of a HelmRelease as referring to images, at least an image key needs to be specified. The following are understood (showing just the values section):

values:
  image: repo/image:version
values:
  image: repo/image
  tag: version
values:
  registry: docker.io
  image: repo/image
  tag: version
values:
  image:
    repository: repo/image
    tag: version
values:
  image:
    registry: docker.io
    repository: repo/image
    tag: version

These can appear at the top level (immediately under values:), or in a subsection (under a key, itself under values:). Other values may be mixed in arbitrarily. Here's an example of a values section that specifies two images, along with some other configuration:

values:
  persistent: true

  # image that will be labeled "chart-image"
  image: repo/image1:version

  subsystem:
    # image that will be labeled "subsystem"
    image:
      repository: repo/image2
      tag: version
      imagePullPolicy: IfNotPresent
    port: 4040

Annotations

If Flux does not automatically detect your image, it is possible to map the image paths by alias with YAML dot notation annotations. An alias overrules a detected image.

The following annotations are available, you need to at least specify the repository.fluxcd.io annotation:

Annotation
registry.fludcd.io/<alias> sub.reg
repository.fluxcd.io/<alias> sub.repo
tag.fluxcd.io/<alias> sub.tag
filter.fluxcd.io/<alias> glob: master-*

Two images specified in a HelmRelease as an example:

metadata:
  annotations:
    # image and tag
    repository.fluxcd.io/app: appImage
    tag.fluxcd.io/app: appTag
    filter.tag/app: 'glob: *'
    # nested image with registry and tag
    registry.fluxcd.io/submarine: sub.marinesystem.reg
    repository.fluxcd.io/submarine: sub.marinesystem.img
    tag.fluxcd.io/submarine: sub.marinesystem.tag

spec:
  values:
    # image and tag
    appImage: repo/image1
    appTag: version
    sub:
      marinesystem:
        # nested image with registry and tag
        reg: domain.com
        img: repo/image2
        tag: version

Filter

You can use the same annotations in the HelmRelease as you would for a Deployment or other workload, to control updates and automation. For the purpose of specifying filters, the container name is either chart-image (if at the top level), the key under which the image is given (e.g., "subsystem" from the example above), or the alias you are using in your annotations.

Top level image example:

kind: HelmRelease
metadata:
  annotations:
    fluxcd.io/automated: "true"
    fluxcd.io/tag.chart-image: semver:~4.0
spec:
  values:
    image:
      repository: bitnami/mongodb
      tag: 4.0.3

Sub-section images example:

kind: HelmRelease
metadata:
  annotations:
    fluxcd.io/automated: "true"
    fluxcd.io/tag.prometheus: semver:~2.3
    fluxcd.io/tag.alertmanager: glob:v0.15.*
    filter.fluxcd.io/nats: regex:^0.6.*
spec:
  values:
    prometheus:
      image: prom/prometheus:v2.3.1
    alertmanager:
      image: prom/alertmanager:v0.15.0
    nats:
      image:
        repository: nats-streaming
        tag: 0.6.0