> For the complete documentation index, see [llms.txt](https://bagus-cahyono.gitbook.io/programming-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bagus-cahyono.gitbook.io/programming-notes/cka/07_manual_scaling.md).

# Scaling: Manual

The `kubectl scale` command manually adjusts the number of pod replicas for a Deployment, ReplicaSet, StatefulSet, or Job.

This is useful when you want to:

* Increase replicas to handle more traffic.
* Reduce replicas to save resources.
* Perform manual scaling when **Horizontal Pod Autoscaler (HPA)** is not required

## Basic Syntax Usage

```bash
kubectl scale <resource-type> <resource-name> --replicas=<number>
```

* `<resource-type>`: Type of resource (e.g., `deployment`, `replicaset`, `statefulset`, `job`).
* `<resource-name>`: The name of the resource you want to scale.
* `--replicas=<number>`: Desired number of pod replicas.

## Scaling Deployment

Lets create a deployment using `nginx` image.

```bash
➜ kubectl create deployment my-nginx --image=nginx
deployment.apps/my-nginx created
```

It will create a deployment with replicas defaulted to `1`.

```bash
➜ kubectl get deployment my-nginx 
NAME       READY   UP-TO-DATE   AVAILABLE   AGE
my-nginx   1/1     1            1           32s
```

Now lets scale the newly created deployment to `3` replicas using this command below.

```bash
➜ kubectl scale deployment my-nginx --replicas=3
deployment.apps/my-nginx scaled
```

Now if you check teh deployments again, we will have `3` replicas.

```bash
➜ kubectl get deployments my-nginx
NAME       READY   UP-TO-DATE   AVAILABLE   AGE
my-nginx   3/3     3            3  
```

## Others

To scale `replicaset`, `statefulset`, and `job` is similar with scaling deployment, we only need to specify the resource type, resource name, and number of replicas in `kubectl apply` command.

Note that this changes are not persisted. If you have `yaml` file for your deployment definition you need to change the `spec.replicas` value.

## References

* <https://kubernetes.io/docs/reference/kubectl/generated/kubectl_scale/>


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