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/http/handler/kubernetes/kubernetes_config.go

@@ -0,0 +1,132 @@
+package kubernetes
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	httperror "github.com/portainer/libhttp/error"
+	"github.com/portainer/libhttp/request"
+	"github.com/portainer/libhttp/response"
+	portainer "github.com/portainer/portainer/api"
+	bolterrors "github.com/portainer/portainer/api/bolt/errors"
+	httperrors "github.com/portainer/portainer/api/http/errors"
+	"github.com/portainer/portainer/api/http/security"
+	kcli "github.com/portainer/portainer/api/kubernetes/cli"
+
+	"net/http"
+)
+
+// @id GetKubernetesConfig
+// @summary Generates kubeconfig file enabling client communication with k8s api server
+// @description Generates kubeconfig file enabling client communication with k8s api server
+// @description **Access policy**: authorized
+// @tags kubernetes
+// @security jwt
+// @accept json
+// @produce json
+// @param id path int true "Endpoint identifier"
+// @success 200 "Success"
+// @failure 400 "Invalid request"
+// @failure 401 "Unauthorized"
+// @failure 403 "Permission denied"
+// @failure 404 "Endpoint or ServiceAccount not found"
+// @failure 500 "Server error"
+// @router /kubernetes/{id}/config [get]
+func (handler *Handler) getKubernetesConfig(w http.ResponseWriter, r *http.Request) *httperror.HandlerError {
+	if r.TLS == nil {
+		return &httperror.HandlerError{
+			StatusCode: http.StatusInternalServerError,
+			Message:    "Kubernetes config generation only supported on portainer instances running with TLS",
+			Err:        errors.New("missing request TLS config"),
+		}
+	}
+
+	endpointID, err := request.RetrieveNumericRouteVariableValue(r, "id")
+	if err != nil {
+		return &httperror.HandlerError{http.StatusBadRequest, "Invalid endpoint identifier route variable", err}
+	}
+
+	endpoint, err := handler.DataStore.Endpoint().Endpoint(portainer.EndpointID(endpointID))
+	if err == bolterrors.ErrObjectNotFound {
+		return &httperror.HandlerError{http.StatusNotFound, "Unable to find an endpoint with the specified identifier inside the database", err}
+	} else if err != nil {
+		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to find an endpoint with the specified identifier inside the database", err}
+	}
+
+	bearerToken, err := extractBearerToken(r)
+	if err != nil {
+		return &httperror.HandlerError{http.StatusUnauthorized, "Unauthorized", err}
+	}
+
+	tokenData, err := security.RetrieveTokenData(r)
+	if err != nil {
+		return &httperror.HandlerError{http.StatusForbidden, "Permission denied to access endpoint", err}
+	}
+
+	cli, err := handler.KubernetesClientFactory.GetKubeClient(endpoint)
+	if err != nil {
+		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to create Kubernetes client", err}
+	}
+
+	apiServerURL := getProxyUrl(r, endpointID)
+
+	config, err := cli.GetKubeConfig(r.Context(), apiServerURL, bearerToken, tokenData)
+	if err != nil {
+		return &httperror.HandlerError{http.StatusNotFound, "Unable to generate Kubeconfig", err}
+	}
+
+	contentAcceptHeader := r.Header.Get("Accept")
+	if contentAcceptHeader == "text/yaml" {
+		yaml, err := kcli.GenerateYAML(config)
+		if err != nil {
+			return &httperror.HandlerError{http.StatusInternalServerError, "Failed to generate Kubeconfig", err}
+		}
+		w.Header().Set("Content-Disposition", `attachment; filename=config.yaml`)
+		return YAML(w, yaml)
+	}
+
+	w.Header().Set("Content-Disposition", `attachment; filename="config.json"`)
+	return response.JSON(w, config)
+}
+
+// extractBearerToken extracts user's portainer bearer token from request auth header
+func extractBearerToken(r *http.Request) (string, error) {
+	token := ""
+	tokens := r.Header["Authorization"]
+	if len(tokens) >= 1 {
+		token = tokens[0]
+		token = strings.TrimPrefix(token, "Bearer ")
+	}
+	if token == "" {
+		return "", httperrors.ErrUnauthorized
+	}
+	return token, nil
+}
+
+// getProxyUrl generates portainer proxy url which acts as proxy to k8s api server
+func getProxyUrl(r *http.Request, endpointID int) string {
+	return fmt.Sprintf("https://%s/api/endpoints/%d/kubernetes", r.Host, endpointID)
+}
+
+// YAML writes yaml response as string to writer. Returns a pointer to a HandlerError if encoding fails.
+// This could be moved to a more useful place; but that place is most likely not in this project.
+// It should actually go in https://github.com/portainer/libhttp - since that is from where we use response.JSON.
+// We use `data interface{}` as parameter - since im trying to keep it as close to (or the same as) response.JSON method signature:
+// https://github.com/portainer/libhttp/blob/d20481a3da823c619887c440a22fdf4fa8f318f2/response/response.go#L13
+func YAML(rw http.ResponseWriter, data interface{}) *httperror.HandlerError {
+	rw.Header().Set("Content-Type", "text/yaml")
+
+	strData, ok := data.(string)
+	if !ok {
+		return &httperror.HandlerError{
+			StatusCode: http.StatusInternalServerError,
+			Message:    "Unable to write YAML response",
+			Err:        errors.New("failed to convert input to string"),
+		}
+	}
+
+	fmt.Fprint(rw, strData)
+
+	return nil
+}