K
Q

Manage replicas count for deployment using Kubernetes API

1/22/2017

I want to change the number of replications (pods) for a Deployment using the Kubernetes API (v1beta1).

For now I'm able to increase the replicas from CLI using the command:

kubectl scale --replicas=3 deployment my-deployment

In the Kubernetes API documentation it's mention that there is a PUT request to do the same

PUT /apis/extensions/v1beta1/namespaces/{namespace}/deployments/{name}/scale

but there is no example of how to do it.

I'm not sure what to send in the request body in order to perform the update.

-- yuval simhon
kubernetes

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2 Answers

4/24/2020

The previous solution didn't work for me on kubernetes 1.14. I had to use a different API endpoint. Here's the full example:

#!/bin/sh

set -e

NUMBER_OF_REPLICAS="$1"
CURRENT_NAMESPACE="$2"
DEPLOYMENT_NAME="$3"

KUBE_TOKEN=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)
KUBE_CACRT_PATH="/var/run/secrets/kubernetes.io/serviceaccount/ca.crt"

PAYLOAD="{\"spec\":{\"replicas\":$NUMBER_OF_REPLICAS}}"

curl --cacert $KUBE_CACRT_PATH \
     -X PATCH \
     -H "Content-Type: application/strategic-merge-patch+json" \
     -H "Authorization: Bearer $KUBE_TOKEN" \
     --data "$PAYLOAD" \
     https://$KUBERNETES_SERVICE_HOST/apis/apps/v1/namespaces/$CURRENT_NAMESPACE/deployments/$DEPLOYMENT_NAME

Note that the $KUBERNETES_SERVICE_HOST is automatically set by kubernetes inside the pods.

-- Bruno_Ferreira
Source: StackOverflow
1/22/2017

the easiest way is to retrieve the actual data first with:

GET /apis/extensions/v1beta1/namespaces/{namespace}/deployments/{name}/scale

This will give you an yaml or json object which you can modify and send back with the PUT request.

With curl the roundtrip look like this:

API_URL="http://kubernetes:8080/apis/extensions/v1beta1/namespaces/{namespace}/deployments/{name}/scale"
curl  -H 'Accept: application/json' $API_URL > scale.json
# edit scale.json
curl -X PUT -d@scale.json -H 'Content-Type: application/json' $API_URL

Alternatively you could just use a PATCH call:

PAYLOAD='[{"op":"replace","path":"/spec/replicas","value":"3"}]'
curl -X PATCH -d$PAYLOAD -H 'Content-Type: application/json-patch+json' $API_URL
-- pagid
Source: StackOverflow