feat(kubernetes/shell): kubectl web shell and kubeconfig functionality EE-448 (#5229)

* feat(kubernetes/shell): backport kubectl shell backend functionality EE-849 (#5168)

* backported core backend kubectl shell functionality

* - backported kubectl shell unit tests
- backported k8s cli interface update
- backported k8s client library fake patch

* refactored backend to match EE

* fixed test error typo

* GetServiceAccountName -> GetServiceAccount - making the function reusable in multiple contexts

* feat(kubernetes/shell): backport kubeconfig generation backend functionality EE-1004 (#5213)

* backported core backend kubectl shell functionality

* refactored backend to match EE

* - backported kubernetes backend handler implementation
- backported kubernetes config endpoint
- backported kubeconfig file generation
- backported kubeconfig and yaml unit tests
- backported updates to kubeclient interfaces

* feat(app): kubectl shell ui backport EE-927 (#5221)

* Kubectl UI backport to CE

* fix authentication redirect issue

* comment out redirect function

* fix shell full width & change name of shell

* disable button when terminal connected

* fixed whitespace changes for css

* fixed whitespace changes for html

* linting fixes

Co-authored-by: zees-dev <dev.786zshan@gmail.com>

* feat(kubernetes/shell): backport of kubeconfig export functionality EE-926 (#5228)

* EE backport of kubeconfig UI functionality

* using angularjs constant instead of hardcoded URL

* updated portainer kubectl shell image

* fix kubectl button position issue in ce

* fix pod keep running when switching page

* feat(app): Kubectl shell ui EE-833 EE-1099 (#5271)

* fix kubectl shell css

* fix mini css issue

* fix tech issue for ui changes from review

* delete unuse file

* - refactored variable names
- restored content-wrapper scroll
- created object to store wrapper css

Co-authored-by: zees-dev <dev.786zshan@gmail.com>

* addressing PR issues

* fix required changes from tech reviews (#5319)

* fix required changes from tech reviews

* remove unuse css variable

* component refactor accoridng to PR and style guidelines

Co-authored-by: zees-dev <dev.786zshan@gmail.com>

* removed redundant dockerhub api endpoint variable

* - autoHeight -> terminal-window
- removed redundant try-catch
- saving config.yaml file as config

* fix(kube/shell): show error on failure

* fixed default https bug

* resolved merge conflicts

Co-authored-by: Richard Wei <54336863+WaysonWei@users.noreply.github.com>
Co-authored-by: richard <richard@richards-iMac-Pro.local>
Co-authored-by: Chaim Lev-Ari <chiptus@gmail.com>

api/kubernetes/cli/kubeconfig.go

@@ -0,0 +1,66 @@
+package cli
+
+import (
+	"context"
+	"fmt"
+
+	portainer "github.com/portainer/portainer/api"
+	clientV1 "k8s.io/client-go/tools/clientcmd/api/v1"
+)
+
+// GetKubeConfig returns kubeconfig for the current user based on:
+// - portainer server url
+// - portainer user bearer token
+// - portainer token data - which maps to k8s service account
+func (kcl *KubeClient) GetKubeConfig(ctx context.Context, apiServerURL string, bearerToken string, tokenData *portainer.TokenData) (*clientV1.Config, error) {
+	serviceAccount, err := kcl.GetServiceAccount(tokenData)
+	if err != nil {
+		errText := fmt.Sprintf("unable to find serviceaccount associated with user; username=%s", tokenData.Username)
+		return nil, fmt.Errorf("%s; err=%w", errText, err)
+	}
+
+	kubeconfig := generateKubeconfig(apiServerURL, bearerToken, serviceAccount.Name)
+
+	return kubeconfig, nil
+}
+
+// generateKubeconfig will generate and return kubeconfig resource - usable by `kubectl` cli
+// which will allow the client to connect directly to k8s server endpoint via portainer (proxy)
+func generateKubeconfig(apiServerURL, bearerToken, serviceAccountName string) *clientV1.Config {
+	const (
+		KubeConfigPortainerContext = "portainer-ctx"
+		KubeConfigPortainerCluster = "portainer-cluster"
+	)
+
+	return &clientV1.Config{
+		APIVersion:     "v1",
+		Kind:           "Config",
+		CurrentContext: KubeConfigPortainerContext,
+		Contexts: []clientV1.NamedContext{
+			{
+				Name: KubeConfigPortainerContext,
+				Context: clientV1.Context{
+					AuthInfo: serviceAccountName,
+					Cluster:  KubeConfigPortainerCluster,
+				},
+			},
+		},
+		Clusters: []clientV1.NamedCluster{
+			{
+				Name: KubeConfigPortainerCluster,
+				Cluster: clientV1.Cluster{
+					Server:                apiServerURL,
+					InsecureSkipTLSVerify: true,
+				},
+			},
+		},
+		AuthInfos: []clientV1.NamedAuthInfo{
+			{
+				Name: serviceAccountName,
+				AuthInfo: clientV1.AuthInfo{
+					Token: bearerToken,
+				},
+			},
+		},
+	}
+}