Use the Kubernetes API - Container Service for Kubernetes

The Kubernetes API is a resource-based (RESTful) programming interface provided by means of HTTP that supports the standard HTTP methods, including POST, PUT, PATCH, DELETE, and GET. You can use these methods to query, create, update, and delete cluster resources. You can call the Kubernetes API by running cURL commands or other programming methods. This topic describes how to manage pods and Deployments using cURL commands with examples.

Obtain cluster credentials in the kubeconfig file

Log on to the ACK console.
Click Go to RAM console to go to the Cloud Resource Access Authorization page, then click Confirm Authorization Policy.
After completing the above authorization, refresh the console to use ACK.
In the left-side navigation pane of the ACK console, click Clusters.
On the Clusters page, find the cluster that you want to manage and click the name of the cluster or click Details in the Actions column. The details page of the cluster appears.
On the cluster details page, click the Connection Information tab. You can find the cluster credential in the kubeconfig file. Copy the content of the kubeconfig file and save it to your on-premises machine.

Run the following commands to retrieve information about the certificate authority (CA), the private key, and the API server:

cat  ./kubeconfig |grep client-certificate-data | awk -F ' ' '{print $2}' |base64 -d > ./client-cert.pem
cat  ./kubeconfig |grep client-key-data | awk -F ' ' '{print $2}' |base64 -d > ./client-key.pem
APISERVER=`cat  ./kubeconfig |grep server | awk -F ' ' '{print $2}'`

Use cURL to call the Kubernetes API

Run the following command to query all namespaces in the cluster:

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/api/v1/namespaces

Common operations to manage pods and Deployments using cURL commands are as follows.

Common operations to manage pods

Run the following command to query all pods in the default namespace:

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/api/v1/namespaces/default/pods

Run the following command to create a pod (JSON format):

cat nginx-pod.json
{
    "apiVersion":"v1",
    "kind":"Pod",
    "metadata":{
        "name":"nginx",
        "namespace": "default"
    },
    "spec":{
        "containers":[
            {
                "name":"nginx",
                "image":"nginx:alpine",
                "ports":[
                    {
                        "containerPort": 80
                    }
                ]
            }
        ]
    }
}

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/api/v1/namespaces/default/pods -X POST --header 'content-type: application/json' -d@nginx-pod.json

Run the following command to create a pod (YAML format):

cat nginx-pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: nginx
  namespace: default
spec:
  containers:
  - name: nginx
    image: nginx:alpine
    ports:
    - containerPort: 80

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/api/v1/namespaces/default/pods -X POST --header 'content-type: application/yaml' --data-binary @nginx-pod.yaml

Run the following command to query the status of a pod:

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/api/v1/namespaces/default/pods/nginx

Run the following command to query the log data of a pod:

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/api/v1/namespaces/default/pods/nginx/log

Run the following command to collect metrics of a pod by using the metric-server API:

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/apis/metrics.k8s.io/v1beta1/namespaces/default/pods/nginx

Run the following command to delete a pod:

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/api/v1/namespaces/default/pods/nginx -X DELETE

Common operations to manage Deployments

The following YAML template is an example of how to create a Deployment:

cat nginx-deploy.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deploy
  labels:
    app: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image:  nginx:alpine
        ports:
        - containerPort: 80
        resources:
          requests:
            cpu: "2"
            memory: "4Gi"

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/apis/apps/v1/namespaces/default/deployments -X POST --header 'content-type: application/yaml' --data-binary @nginx-deploy.yaml

Run the following command to query a Deployment:

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/apis/apps/v1/namespaces/default/deployments

Run the following command to update a Deployment by modifying the number of replicated pods:

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/apis/apps/v1/namespaces/default/deployments/nginx-deploy -X PATCH -H 'Content-Type: application/strategic-merge-patch+json' -d '{"spec": {"replicas": 4}}'

Run the following command to update a Deployment by changing the container image:

curl --cert ./client-cert.pem --key ./client-key.pem -k $APISERVER/apis/apps/v1/namespaces/default/deployments/nginx-deploy -X PATCH -H 'Content-Type: application/strategic-merge-patch+json' -d '{"spec": {"template": {"spec": {"containers": [{"name": "nginx","image": "nginx:1.7.9"}]}}}}'