GitOps using FluxCD (v2)
FluxCD is a GitOps operator for Kubernetes. It synchronizes the status of the cluster from manifests allocated in different repositories (Git or Helm). This approach fits perfectly with External Secrets on clusters which are dynamically created, to get credentials with no manual intervention from the beginning.
This approach has several advantages as follows:
- Homogenize environments allowing developers to use the same toolset in Kind in the same way they do in the cloud provider distributions such as EKS or GKE. This accelerates the development
- Reduce security risks, because credentials can be easily obtained, so temptation to store them locally is reduced.
- Application compatibility increase: Applications are deployed in different ways, and sometimes they need to share credentials. This can be done using External Secrets as a wire for them at real time.
- Automation by default oh, come on!
FluxCD is composed by several controllers dedicated to manage different custom resources. The most important ones are Kustomization (to clarify, Flux one, not Kubernetes' one) and HelmRelease to deploy using the approaches of the same names.
External Secrets can be deployed using Helm as explained here. The deployment includes the
CRDs if enabled on the
values.yaml, but after this, you need to deploy some
SecretStore to start
getting credentials from your secrets manager with External Secrets.
The idea of this guide is to deploy the whole stack, using flux, needed by developers not to worry about the credentials, but only about the application and its code.
This can sound easy, but External Secrets is deployed using Helm, which is managed by the HelmController,
and your custom resources, for example a
ClusterSecretStore and the related
Secret, are often deployed using a
kustomization.yaml, which is deployed by the KustomizeController.
Both controllers manage the resources independently, at different moments, with no possibility to wait each other.
This means that we have a wonderful race condition where sometimes the CRs (
to be deployed before than the CRDs needed to recognize them.
Let's see the conditions to start working on a solution:
- The External Secrets operator is deployed with Helm, and admits disabling the CRDs deployment
- The race condition only affects the deployment of
CustomResourceDefinitionand the CRs needed later
- CRDs can be deployed directly from the Git repository of the project using a Flux
- Required CRs can be deployed using a Flux
Kustomizationtoo, allowing dependency between CRDs and CRs
- All previous manifests can be applied with a Kubernetes
Create the main kustomization
To have a better view of things needed later, the first manifest to be created is the
apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization resources: # Deploy the Vault access secret - namespace.yaml - secret-token.yaml # Deploy the repositories - repositories.yaml # Deploy the CRDs - deployment-crds.yaml # Deploy the operator - deployment.yaml # Deploy default Custom Resources from 'crs' directory # INFO: This depends on the CRDs deployment. Will happen after it - deployment-crs.yaml
Create the secret
To access your secret manager, External Secrets needs some credentials. They are stored inside a Secret, which is intended
to be deployed by automation as a good practise. This time, a placeholder called
secret-token.yaml is show as an example:
# The namespace.yaml first apiVersion: v1 kind: Namespace metadata: name: external-secrets
apiVersion: v1 kind: Secret metadata: name: vault-token-global namespace: external-secrets stringData: # This token must be patched by overlays. Not here for security reasons token: change-me-placeholder
Creating the references to repositories
Create a manifest called
repositories.yaml to store the references to external repositories for Flux
# Reference to Helm repository apiVersion: source.toolkit.fluxcd.io/v1beta1 kind: HelmRepository metadata: name: external-secrets namespace: flux-system spec: interval: 10m url: https://charts.external-secrets.io --- apiVersion: source.toolkit.fluxcd.io/v1beta1 kind: GitRepository metadata: name: external-secrets namespace: flux-system spec: interval: 10m ref: branch: main url: http://github.com/external-secrets/external-secrets
Deploy the CRDs
As mentioned, CRDs can be deployed using the official Helm package, but to solve the race condition, they will be deployed
from our git repository using a Kustomization manifest called
deployment-crds.yaml as follows:
--- apiVersion: kustomize.toolkit.fluxcd.io/v1beta2 kind: Kustomization metadata: name: external-secrets-crds namespace: flux-system spec: interval: 10m path: ./deploy/crds prune: true sourceRef: kind: GitRepository name: external-secrets
Deploy the operator
The operator is deployed using a HelmRelease manifest to deploy the Helm package, but due to the special race condition,
the deployment must be disabled in the
values of the manifest called
deployment.yaml, as follows:
# How to manage values files. Ref: https://fluxcd.io/docs/guides/helmreleases/#refer-to-values-inside-the-chart # How to inject values: https://fluxcd.io/docs/guides/helmreleases/#cloud-storage --- apiVersion: helm.toolkit.fluxcd.io/v2beta1 kind: HelmRelease metadata: name: external-secrets namespace: flux-system spec: # Override Release name to avoid the pattern Namespace-Release # Ref: https://fluxcd.io/docs/components/helm/api/#helm.toolkit.fluxcd.io/v2beta1.HelmRelease releaseName: external-secrets targetNamespace: external-secrets interval: 10m chart: spec: chart: external-secrets version: 0.3.9 sourceRef: kind: HelmRepository name: external-secrets namespace: flux-system values: installCRDs: false # Ref: https://fluxcd.io/docs/components/helm/api/#helm.toolkit.fluxcd.io/v2beta1.Install install: createNamespace: true
Deploy the CRs
Now, be ready for the arcane magic. Create a Kustomization manifest called
deployment-crs.yaml with the following content:
--- apiVersion: kustomize.toolkit.fluxcd.io/v1beta2 kind: Kustomization metadata: name: external-secrets-crs namespace: flux-system spec: dependsOn: - name: external-secrets-crds interval: 10m path: ./infrastructure/external-secrets/crs prune: true sourceRef: kind: GitRepository name: flux-system
There are several interesting details to see here, that finally solves the race condition:
- First one is the field
dependsOn, which points to a previous Kustomization called
external-secrets-crds. This dependency forces this deployment to wait for the other to be ready, before start being deployed.
- The reference to the place where to find the CRs
Custom Resources will be searched in the relative path
path: ./infrastructure/external-secrets/crs sourceRef: kind: GitRepository name: flux-system
./infrastructure/external-secrets/crsof the GitRepository called
flux-system, which is a reference to the same repository that FluxCD watches to synchronize the cluster. With fewer words, a reference to itself, but going to another directory called
Of course, allocate inside the mentioned path
./infrastructure/external-secrets/crs, all the desired CRs to be deployed,
for example, a manifest
clusterSecretStore.yaml to reach your Hashicorp Vault as follows:
apiVersion: external-secrets.io/v1alpha1 kind: ClusterSecretStore metadata: name: vault-backend-global spec: provider: vault: server: "https://vault.your-domain.com" path: secret version: v2 auth: # points to a secret that contains a vault token # https://www.vaultproject.io/docs/auth/token tokenSecretRef: name: "vault-token-global" key: "token" namespace: external-secrets
At the end, the required files tree is shown in the following picture: