Kubernetes Configuration Recovery: Retrieving and Cleaning Deployed YAML

This document outlines the technical facts regarding configuration storage in Kubernetes and provides a reliable method for technical leads to retrieve the current, deployed resource configurations, which closely resemble the original YAML files.

1. Kubernetes Does Not Store the Original YAML File Path

When a user executes kubectl apply -f [yaml file], Kubernetes does not record the actual location of the original file. Instead, it only stores the desired state of the resources, as defined in the YAML, within its internal database, etcd.

2. Obtaining the Resource's Current Configuration from the Cluster

While the original YAML file itself cannot be located within the cluster, the cluster holds the complete current configuration of the deployed resource, which is highly similar to the source file.

Steps to Retrieve the Deployed Resource Configuration:

A. Identify the Resource Name, Type, and Namespace

You must first determine the resource's Kind, Name, and its Namespace (if applicable).

Resource Type	Command to List Resources	Notes
StorageClass (SC)	kubectl get sc	Typically cluster-scoped (no specific Namespace).
PersistentVolume (PV)	kubectl get pv	Cluster-scoped.
PersistentVolumeClaim (PVC)	kubectl get pvc --all-namespaces	Use -n <namespace> if the Namespace is known. e.g., for Elasticsearch.
Workload (e.g., Elasticsearch)	kubectl get statefulset --all-namespaces kubectl get deployment --all-namespaces	Identify the name (e.g., elasticsearch-master) and its Namespace. (Workloads are usually StatefulSet or Deployment).

B. Export the Resource's YAML Configuration

Once the resource is identified, use kubectl get with the -o yaml flag to export its current configuration.

Resource Type	Example Command
StorageClass	kubectl get sc <sc-name> -o yaml > storageclass-<sc-name>.yaml (e.g., kubectl get sc netapp-trident-sc -o yaml > netapp-trident-sc.yaml)
PersistentVolume (PV)	kubectl get pv <pv-name> -o yaml > pv-<pv-name>.yaml
PersistentVolumeClaim (PVC)	kubectl get pvc <pvc-name> -n <namespace> -o yaml > pvc-<pvc-name>.yaml
Elasticsearch StatefulSet/Deployment	# Assuming StatefulSet kubectl get statefulset <es-statefulset-name> -n <namespace> -o yaml > es-statefulset.yaml

🚨 Critical Note: Cleaning the Exported YAML

The exported YAML files will contain numerous fields automatically added by Kubernetes during runtime. These include: status, creationTimestamp, resourceVersion, uid, and lengthy metadata.annotations (especially kubectl.kubernetes.io/last-applied-configuration).

If a "clean" YAML file is required for subsequent kubectl apply commands or for version control, these system-generated fields must be manually removed or stripped.

• Priority Fields to Delete (Top-Level): status, metadata.creationTimestamp, metadata.resourceVersion, metadata.uid, metadata.selfLink (if present), and often metadata.generation.
• For Deployment/StatefulSet, review and clean any unnecessary auto-generated annotations and labels within spec.template.metadata.

C. Using the last-applied-configuration Annotation (If Applicable)

If the initial kubectl apply command was executed without the --save-config=false flag, Kubernetes stores a copy of the successfully applied YAML content in a metadata.annotations field called kubectl.kubernetes.io/last-applied-configuration.

This configuration is typically closer to the original YAML (e.g., it lacks the status block) than the full kubectl get -o yaml output.

You can retrieve this clean configuration using tools like jq or yq:

# Retrieve for a StatefulSet, outputting JSON and piping to jq
kubectl get statefulset <es-statefulset-name> -n <namespace> -o jsonpath='{.metadata.annotations."kubectl\.kubernetes\.io/last-applied-configuration"}' | jq . > clean-es-statefulset.json

# Alternative: Retrieve for a StatefulSet, using yq to output clean YAML (requires yq)
# kubectl get statefulset <es-statefulset-name> -n <namespace> -o yaml | yq '.metadata.annotations."kubectl\.kubernetes\.io/last-applied-configuration"' -r | yq -P > clean-es-statefulset.yaml

Summary for Technical Management

The most robust method to reconstruct the configuration is:

1. Use kubectl get <resource_type> -n <namespace> -o yaml to export the resource.
2. Manually clean or use scripting tools to strip the exported YAML of status and system-generated metadata, rendering it a re-applyable configuration file.

Concurrently, the new administration must establish a mandatory process to store all future configuration files in a version control system (e.g., Git) and document the file location corresponding to each deployed resource, preventing recurrence of this "missing file" issue.