Source Controller S3 Bucket

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

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/

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

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.

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.

Summary of Resources

Links and References

• Flux Source Controller
• Flux Bucket Source
• Flux Kustomization
• Kubernetes Secrets
• MinIO Documentation