On this page you get a quick intro on the Kubernetes custom resources that Flux uses.
Flux uses several Kubernetes Custom Resources Definitions (CRDs) to configure the automation process. In this section, you will get a picture of what those are and what they are used for.
In short, GitRepository points Flux to a git repository and to credentials to get the yamls.
From the Core Concepts of FluxCD
A Source defines the origin of a repository containing the desired state of the system and the requirements to obtain it (e.g. credentials, version selectors). For example, the latest
1.xtag available from a Git repository over SSH. [...]
The origin of the source is checked for changes on a defined interval, if there is a newer version available that matches the criteria, a new artifact is produced.
All sources are specified as Custom Resources in a Kubernetes cluster, examples of sources are
From the Core Concepts of FluxCD
Kustomizationcustom resource represents a local set of Kubernetes resources (e.g. kustomize overlay) that Flux is supposed to reconcile in the cluster. The reconciliation runs every one minute by default, but this can be changed with
.spec.interval. If you make any changes to the cluster using
kubectl edit/patch/delete, they will be promptly reverted. You either suspend the reconciliation or push your changes to a Git repository.
While the official documentation talks about Kustomize resources, the
Kustomization resource simply points to a path in a
GitRepository to apply yamls from. Technically, it uses Kustomize to render the yamls from that location, but it can deploy plain Kubernetes yamls too. This is what Gimlet uses it for.
HelmRelease resource let's you install Helm Charts of given versions with the specified values.yaml file.
This CRD makes it possible to deploy Helm charts from gitops, thus making the procedural
helm install and
helm upgrade commands declarative. So it allows you to manage the helm chart and its values with git. Flux will take care of the installation, upgrade, and rollback.
helm install to the HelmRelease CRD
A typcal two command Helm install process looks like this:
helm repo add grafana https://grafana.github.io/helm-charts
helm install my-release grafana/grafana -f values.yaml
The HelmRelease CRD describes two important things:
spec.chartpoints to a Helm chart and its version
spec.valuesis where you can move here the contents of your values.yaml as they are. With the right indentation of course.
The HelmRepository resource captures the information from the
helm repo add grafana https://grafana.github.io/helm-charts command, then the HelmRelease resource refers to it.
One last thing to locate is the exact chart version. Either you find it in the chart's source code, locate the
version field in
Chart.yaml. Or you can get it from the
helm show chart grafana/grafana command's output.
- secretName: tls-grafana
Alert CRD, you can send notifications of a given gitops automation to a list of
Provider resources. You can read more about various CRDs and their configuration options in the Flux documentation.
Verifying Flux in action
Check Flux's custom resources on the cluster to verify the gitops automation.
Flux uses the
gitrepository custom resource to point to git repository locations and credentials. Flux's source controller periodically checks the content of the git repositories, and you can validate their status as follows:
➜ kubectl get gitrepositories -A
NAMESPACE NAME URL AGE READY STATUS
flux-system gitops-repo-gimlet-bootstraping-tutorial ssh://firstname.lastname@example.org/gimlet/gimlet-bootstraping-tutorial 125m True stored artifact for revision 'main/f4a2a676bbcc04f38120b24463ca1c66cc099ab4'
If the git repositories are in ready state, validate the
kustomization custom resources. These resources point to a path in a git repository to apply yamls from. If they are in ready state, you can be sure the Flux applied your latest manifests.
➜ kubectl get kustomizations -A
NAMESPACE NAME AGE READY STATUS
flux-system gitops-repo-gimlet-bootstraping-tutorial 127m True Applied revision: main/f4a2a676bbcc04f38120b24463ca1c66cc099ab4
flux-system gitops-repo-gimlet-bootstraping-tutorial-dependencies 127m True Applied revision: main/f4a2a676bbcc04f38120b24463ca1c66cc099ab4
Now that the gitops automation is in place, every manifest you put in the gitops repositories will be applied on the cluster by the gitops controller.
Need to debug Flux?
gitrepositories are not in ready state, you get an error message in their status.
If you need to further debug their behavior, you can check Flux logs in the
kubectl logs -f deploy/kustomize-controller -n flux-system
kubectl logs -f deploy/source-controller -n flux-system