> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Garbage Collection

> This guide shows how to label and prune unused resources to keep your namespace clean.

When you use Kustomize’s `configMapGenerator` or `secretGenerator`, each modification produces a brand-new ConfigMap or Secret. Over time, this leads to multiple stale objects cluttering your cluster. This guide shows how to label and prune unused resources to keep your namespace clean.

## The Problem: Stale ConfigMaps & Secrets

Run the following command to list all ConfigMaps:

```bash theme={null}
kubectl get configmap
```

You might see output like this:

```bash theme={null}
NAME                       DATA   AGE
db-cred-b6fhfd8c67         1      38h
db-cred-bf778fgm5h         1      2m13s
db-cred-mh7c9fbtfc         1      2m5s
kube-root-ca.crt           1      9d
redis-cred-229bkfk6cd      1      82s
redis-cred-b6fhfd8c67      1      38h
redis-cred-kh464kfbf2      1      118s
```

Here, you can spot three versions each of `db-cred` and `redis-cred`, but only the most recent ones are actually in use. The rest are stale leftovers.

## Solution Overview: `kubectl apply --prune`

By adding a shared label to all generated ConfigMaps/Secrets and running `kubectl apply --prune`, Kubernetes will automatically delete any resource with that label that is no longer part of your current build.

### Step 1: Add a Common Label

In your `kustomization.yaml`, include identical labels under `options` for each generator:

```yaml theme={null}
# kustomization.yaml
configMapGenerator:
  - name: db-cred
    literals:
      - password=password122
    options:
      labels:
        app-config: my-config
  - name: redis-cred
    literals:
      - password=password122
    options:
      labels:
        app-config: my-config
```

### Step 2: Update Your Generator

When you change a literal—e.g., updating the password—keep the same label:

```yaml theme={null}
# kustomization.yaml (after update)
configMapGenerator:
  - name: db-cred
    literals:
      - password=password1224
    options:
      labels:
        app-config: my-config
  - name: redis-cred
    literals:
      - password=password1224
    options:
      labels:
        app-config: my-config
```

### Step 3: Apply with Prune

Use the `--prune` flag along with `-l` to target your shared label:

```bash theme={null}
kubectl apply -k k8s/overlays/prod/ --prune -l app-config=my-config
```

<Callout icon="triangle-alert" color="#FF6B6B">
  `kubectl apply --prune` will delete **any** resource in the namespace matching the label selector that isn’t in the current Kustomize output. Make sure only intended resources use this label.
</Callout>

### Step 4: Verify Cleanup

After pruning, run:

```bash theme={null}
kubectl get configmap
```

You should now see only the active ConfigMaps:

```bash theme={null}
NAME                      DATA   AGE
db-cred-44h89htdm7        1      27m
kube-root-ca.crt          1      9d
redis-cred-c6k6d6bh64     1      2m7s
```

## Quick Reference

| Action                     | Command / Config Snippet                                     |
| -------------------------- | ------------------------------------------------------------ |
| Label generators           | `options.labels.app-config: my-config`                       |
| Apply with pruning         | `kubectl apply -k <overlay> --prune -l app-config=my-config` |
| List ConfigMaps post-prune | `kubectl get configmap`                                      |

## Further Reading

* [Kustomize Documentation](https://kubectl.docs.kubernetes.io/references/kustomize/)
* [Prune Flag Guide](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#apply)

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