Scaling
- Docker & Kubernetes course
- Intermediate
- Lesson 34/82
- 4 min
Learn to scale a ReplicaSet with kubectl scale.
Scaling
A ReplicaSet is also scaled with kubectl scale. But if you directly scale a ReplicaSet that belongs to a Deployment, the Deployment immediately undoes it, since the desired state is in the Deployment. Scaling is always done through the top-level owner:
kubectl scale rs/web-7c5b9f6d8 --replicas=10 # the Deployment pulls it back to 3
kubectl scale deploy/web --replicas=10 # the right wayConditional scaling
--current-replicas scales only if the current count is the expected value; it prevents accidental overwrites when two people make changes at the same time. Several deployments can also be scaled with one command:
kubectl scale deploy/web --current-replicas=3 --replicas=5
kubectl scale deploy web api --replicas=2
kubectl scale deploy -l katman=arka --replicas=0Practice Scale at the right level
Write two commands: scale the web deployment to 6 only if its current replica count is 3; scale all deployments labelled katman=arka down to 1 replica.
Starter code
# buraya yazSample solution
kubectl scale deploy/web --current-replicas=3 --replicas=6
kubectl scale deploy -l katman=arka --replicas=1Expected output
deployment.apps/web scaled deployment.apps/api scaled deployment.apps/worker scaled
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What happens if you scale a ReplicaSet owned by a Deployment to 10 replicas?
- The Deployment soon pulls it back to its own replicas value Correct answer
- 10 replicas stay permanently
- The Deployment is deleted
- It errors
Explanation: Controllers continuously enforce the desired state.
2 Scale only if the current count is 3.
kubectl scale deploy/web ____=3 --replicas=5kubectl scale deploy/web --current-replicas=3 --replicas=5Explanation: If the condition doesn't hold, the command errors.
3 Match.
| Term | Meaning |
|---|---|
scale rs/... |
The owner undoes it |
scale deploy/... |
The right level |
--current-replicas |
Conditional scale |
-l katman=arka |
Bulk scale by label |