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In this guide, you’ll learn how to use Flux CD’s Source Controller to fetch Kubernetes manifests from an S3-compatible bucket (for example, MinIO). We assume you have a bucket named k8s-manifests with two subfolders, app-A and app-B, each containing its own manifests. By the end, you will:
  1. Store MinIO credentials in a Kubernetes Secret
  2. Register the bucket as a Flux Bucket source
  3. Apply the app-A manifests via a Flux Kustomization

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Prerequisites

  • A running Kubernetes cluster
  • Flux CD installed (Source and Kustomize Controllers)
  • A MinIO (or other S3-compatible) endpoint
  • A bucket named k8s-manifests containing app-A/ and app-B/

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1. Create the MinIO Credentials Secret

Store your MinIO access key and secret key as a Kubernetes Secret in the flux-system namespace: 
kubectl -n flux-system create secret generic minio-crd \
  --from-literal=accesskey=minioadmin \
  --from-literal=secretkey=minioadmin
Expected output: 
secret/minio-crd created
Ensure your credentials are scoped to the least-privileged user on your S3 endpoint.

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2. Register the Flux Bucket Source

Define a Flux Bucket resource that points to your S3-compatible endpoint. Replace the --endpoint value with your MinIO service address if different. 
flux create source bucket minio-bucket \
  --bucket-name k8s-manifests \
  --endpoint minio.minio-dev.svc.cluster.local:9000 \
  --provider generic \
  --insecure \
  --secret-ref minio-crd
Sample output: 
► generating Bucket source
✔ Bucket source updated
⟳ waiting for Bucket source reconciliation
✔ Bucket source reconciliation completed
fetched revision: b3642f24daf09a297b6237b345a6a
This creates a Bucket named minio-bucket in the flux-system namespace, which tars and retrieves all contents under k8s-manifests.
Using --insecure disables TLS verification. Only use this flag in trusted environments or testing scenarios.

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3. Apply Manifests with Flux Kustomization

Now that Flux can fetch the bucket contents, configure a Kustomization to build and apply the app-A manifests: 
flux create kustomization kust-app-a \
  --source Bucket/minio-bucket \
  --path "./app-A" \
  --prune=true \
  --interval=10m
Sample output: 
► generating Kustomization
✔ Kustomization updated
⟳ waiting for Kustomization reconciliation
✔ Kustomization kust-app-a is ready
✔ applied revision b3642f24daf09a297b6237b345a6a
Flux will now periodically reconcile and apply the contents of app-A to your cluster.

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Summary of Resources

ResourcePurposeFlux Command
SecretStore MinIO S3 credentialskubectl create secret generic minio-crd …
Bucket (Source)Fetch objects from k8s-manifestsflux create source bucket minio-bucket …
KustomizationBuild & apply manifests from app-Aflux create kustomization kust-app-a …

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