Using K8S API to access pod [closed] - kubernetes

Question

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 1 year ago.
Improve this question
With kubectl we can run the following command
kubectl exec -ti POD_NAME -- pwd
Can I do that from API level? I checked the POD API and seems it is missing there https://kubernetes.io/docs/reference/kubernetes-api/workload-resources/pod-v1/
What I am looking for, is a UI tool to view the files in POD without extra dependency
UPDATE:
I found the following code to exec command in pod
package main
import (
"bytes"
"context"
"flag"
"fmt"
"path/filepath"
corev1 "k8s.io/api/core/v1"
_ "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/tools/clientcmd"
"k8s.io/client-go/tools/remotecommand"
"k8s.io/client-go/util/homedir"
//
// Uncomment to load all auth plugins
// _ "k8s.io/client-go/plugin/pkg/client/auth"
//
// Or uncomment to load specific auth plugins
// _ "k8s.io/client-go/plugin/pkg/client/auth/azure"
// _ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
// _ "k8s.io/client-go/plugin/pkg/client/auth/oidc"
// _ "k8s.io/client-go/plugin/pkg/client/auth/openstack"
)
func main() {
var kubeconfig *string
if home := homedir.HomeDir(); home != "" {
kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")
} else {
kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
}
flag.Parse()
// use the current context in kubeconfig
config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
if err != nil {
panic(err.Error())
}
// create the clientset
clientset, err := kubernetes.NewForConfig(config)
if err != nil {
panic(err.Error())
}
namespace := "stage"
pods, err := clientset.CoreV1().Pods(namespace).List(context.TODO(), metav1.ListOptions{})
if err != nil {
panic(err.Error())
}
fmt.Printf("There are %d pods in the cluster\n", len(pods.Items))
podName := "ubs-job-qa-0"
containerName := "ubs-job"
// https://github.com/kubernetes/kubernetes/blob/release-1.22/test/e2e/framework/exec_util.go
// https://zhimin-wen.medium.com/programing-exec-into-a-pod-5f2a70bd93bb
req := clientset.CoreV1().
RESTClient().
Post().
Resource("pods").
Name(podName).
Namespace(namespace).
SubResource("exec").
Param("container", containerName)
scheme := runtime.NewScheme()
if err := corev1.AddToScheme(scheme); err != nil {
panic("Cannot add scheme")
}
parameterCodec := runtime.NewParameterCodec(scheme)
req.VersionedParams(&corev1.PodExecOptions{
Stdin: false,
Stdout: true,
Stderr: true,
TTY: true,
Container: podName,
Command: []string{"ls", "-la", "--time-style=iso", "."},
}, parameterCodec)
exec, err := remotecommand.NewSPDYExecutor(config, "POST", req.URL())
if err != nil {
panic(err)
}
var stdout, stderr bytes.Buffer
err = exec.Stream(remotecommand.StreamOptions{
Stdin: nil,
Stdout: &stdout,
Stderr: &stderr,
})
if err != nil {
panic(err)
}
text := string(stdout.Bytes())
fmt.Println(text)
}

Answer 1

In your case, use of kubectl is the same as calling the api-server; which in turn call the kubelet on the node and exec your command in the pod namespace.
You can experiment like this:
kubectl proxy --port=8080 &
curl "localhost:8080/api/v1/namespaces/<namespace>/pods/<pod>/exec?command=pwd&stdin=false"
To copy file you can use: kubectl cp --help

Answer 2

You can leverage tools like Kubernetes Dashboard as UI tool or if you wanna go enterprise level, try Rancher