k3s/pkg/apiserver/resthandler.go

/*
Copyright 2014 Google Inc. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package apiserver

import (
	"net/http"
	"path"
	"time"

	"github.com/GoogleCloudPlatform/kubernetes/pkg/admission"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/errors"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"

	"github.com/golang/glog"
)

// RESTHandler implements HTTP verbs on a set of RESTful resources identified by name.
type RESTHandler struct {
	storage                map[string]RESTStorage
	codec                  runtime.Codec
	canonicalPrefix        string
	selfLinker             runtime.SelfLinker
	ops                    *Operations
	admissionControl       admission.Interface
	apiRequestInfoResolver *APIRequestInfoResolver
}

// ServeHTTP handles requests to all RESTStorage objects.
func (h *RESTHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	var verb string
	var apiResource string
	var httpCode int
	reqStart := time.Now()
	defer func() { monitor("rest", verb, apiResource, httpCode, reqStart) }()

	requestInfo, err := h.apiRequestInfoResolver.GetAPIRequestInfo(req)
	if err != nil {
		glog.Errorf("Unable to handle request %s %s %v", requestInfo.Namespace, requestInfo.Kind, err)
		notFound(w, req)
		httpCode = http.StatusNotFound
		return
	}
	verb = requestInfo.Verb

	storage, ok := h.storage[requestInfo.Resource]
	if !ok {
		notFound(w, req)
		httpCode = http.StatusNotFound
		return
	}
	apiResource = requestInfo.Resource

	httpCode = h.handleRESTStorage(requestInfo.Parts, req, w, storage, requestInfo.Namespace, requestInfo.Resource)
}

// Sets the SelfLink field of the object.
func (h *RESTHandler) setSelfLink(obj runtime.Object, req *http.Request) error {
	newURL := *req.URL
	newURL.Path = path.Join(h.canonicalPrefix, req.URL.Path)
	newURL.RawQuery = ""
	newURL.Fragment = ""
	namespace, err := h.selfLinker.Namespace(obj)
	if err != nil {
		return err
	}

	// we need to add namespace as a query param, if its not in the resource path
	if len(namespace) > 0 {
		parts := splitPath(req.URL.Path)
		if parts[0] != "ns" {
			query := newURL.Query()
			query.Set("namespace", namespace)
			newURL.RawQuery = query.Encode()
		}
	}

	err = h.selfLinker.SetSelfLink(obj, newURL.String())
	if err != nil {
		return err
	}
	if !runtime.IsListType(obj) {
		return nil
	}

	// Set self-link of objects in the list.
	items, err := runtime.ExtractList(obj)
	if err != nil {
		return err
	}
	for i := range items {
		if err := h.setSelfLinkAddName(items[i], req); err != nil {
			return err
		}
	}
	return runtime.SetList(obj, items)
}

// Like setSelfLink, but appends the object's name.
func (h *RESTHandler) setSelfLinkAddName(obj runtime.Object, req *http.Request) error {
	name, err := h.selfLinker.Name(obj)
	if err != nil {
		return err
	}
	namespace, err := h.selfLinker.Namespace(obj)
	if err != nil {
		return err
	}
	newURL := *req.URL
	newURL.Path = path.Join(h.canonicalPrefix, req.URL.Path, name)
	newURL.RawQuery = ""
	newURL.Fragment = ""
	// we need to add namespace as a query param, if its not in the resource path
	if len(namespace) > 0 {
		parts := splitPath(req.URL.Path)
		if parts[0] != "ns" {
			query := newURL.Query()
			query.Set("namespace", namespace)
			newURL.RawQuery = query.Encode()
		}
	}
	return h.selfLinker.SetSelfLink(obj, newURL.String())
}

// curry adapts either of the self link setting functions into a function appropriate for operation's hook.
func curry(f func(runtime.Object, *http.Request) error, req *http.Request) func(RESTResult) {
	return func(obj RESTResult) {
		if err := f(obj.Object, req); err != nil {
			glog.Errorf("unable to set self link for %#v: %v", obj, err)
		}
	}
}

// handleRESTStorage is the main dispatcher for a storage object.  It switches on the HTTP method, and then
// on path length, according to the following table:
//   Method     Path          Action
//   GET        /foo          list
//   GET        /foo/bar      get 'bar'
//   POST       /foo          create
//   PUT        /foo/bar      update 'bar'
//   DELETE     /foo/bar      delete 'bar'
// Responds with a 404 if the method/pattern doesn't match one of these entries.
// The s accepts several query parameters:
//    timeout=<duration> Timeout for synchronous requests
//    labels=<label-selector> Used for filtering list operations
// Returns the HTTP status code written to the response.
func (h *RESTHandler) handleRESTStorage(parts []string, req *http.Request, w http.ResponseWriter, storage RESTStorage, namespace, kind string) int {
	ctx := api.WithNamespace(api.NewContext(), namespace)
	// TODO: Document the timeout query parameter.
	timeout := parseTimeout(req.URL.Query().Get("timeout"))
	switch req.Method {
	case "GET":
		switch len(parts) {
		case 1:
			label, err := labels.ParseSelector(req.URL.Query().Get("labels"))
			if err != nil {
				return errorJSON(err, h.codec, w)
			}
			field, err := labels.ParseSelector(req.URL.Query().Get("fields"))
			if err != nil {
				return errorJSON(err, h.codec, w)
			}
			lister, ok := storage.(RESTLister)
			if !ok {
				return errorJSON(errors.NewMethodNotSupported(kind, "list"), h.codec, w)
			}
			list, err := lister.List(ctx, label, field)
			if err != nil {
				return errorJSON(err, h.codec, w)
			}
			if err := h.setSelfLink(list, req); err != nil {
				return errorJSON(err, h.codec, w)
			}
			writeJSON(http.StatusOK, h.codec, list, w)
		case 2:
			getter, ok := storage.(RESTGetter)
			if !ok {
				return errorJSON(errors.NewMethodNotSupported(kind, "get"), h.codec, w)
			}
			item, err := getter.Get(ctx, parts[1])
			if err != nil {
				return errorJSON(err, h.codec, w)
			}
			if err := h.setSelfLink(item, req); err != nil {
				return errorJSON(err, h.codec, w)
			}
			writeJSON(http.StatusOK, h.codec, item, w)
		default:
			notFound(w, req)
			return http.StatusNotFound
		}

	case "POST":
		if len(parts) != 1 {
			notFound(w, req)
			return http.StatusNotFound
		}
		creater, ok := storage.(RESTCreater)
		if !ok {
			return errorJSON(errors.NewMethodNotSupported(kind, "create"), h.codec, w)
		}

		body, err := readBody(req)
		if err != nil {
			return errorJSON(err, h.codec, w)
		}
		obj := storage.New()
		err = h.codec.DecodeInto(body, obj)
		if err != nil {
			return errorJSON(err, h.codec, w)
		}

		// invoke admission control
		err = h.admissionControl.Admit(admission.NewAttributesRecord(obj, namespace, parts[0], "CREATE"))
		if err != nil {
			return errorJSON(err, h.codec, w)
		}

		out, err := creater.Create(ctx, obj)
		if err != nil {
			return errorJSON(err, h.codec, w)
		}
		op := h.createOperation(out, timeout, curry(h.setSelfLinkAddName, req))
		return h.finishReq(op, req, w)

	case "DELETE":
		if len(parts) != 2 {
			notFound(w, req)
			return http.StatusNotFound
		}
		deleter, ok := storage.(RESTDeleter)
		if !ok {
			return errorJSON(errors.NewMethodNotSupported(kind, "delete"), h.codec, w)
		}

		// invoke admission control
		err := h.admissionControl.Admit(admission.NewAttributesRecord(nil, namespace, parts[0], "DELETE"))
		if err != nil {
			return errorJSON(err, h.codec, w)
		}

		out, err := deleter.Delete(ctx, parts[1])
		if err != nil {
			return errorJSON(err, h.codec, w)
		}
		op := h.createOperation(out, timeout, nil)
		return h.finishReq(op, req, w)

	case "PUT":
		if len(parts) != 2 {
			notFound(w, req)
			return http.StatusNotFound
		}
		updater, ok := storage.(RESTUpdater)
		if !ok {
			return errorJSON(errors.NewMethodNotSupported(kind, "create"), h.codec, w)
		}

		body, err := readBody(req)
		if err != nil {
			return errorJSON(err, h.codec, w)
		}
		obj := storage.New()
		err = h.codec.DecodeInto(body, obj)
		if err != nil {
			return errorJSON(err, h.codec, w)
		}

		// invoke admission control
		err = h.admissionControl.Admit(admission.NewAttributesRecord(obj, namespace, parts[0], "UPDATE"))
		if err != nil {
			return errorJSON(err, h.codec, w)
		}

		out, err := updater.Update(ctx, obj)
		if err != nil {
			return errorJSON(err, h.codec, w)
		}
		op := h.createOperation(out, timeout, curry(h.setSelfLink, req))
		return h.finishReq(op, req, w)

	default:
		notFound(w, req)
		return http.StatusNotFound
	}
	return http.StatusOK
}

// createOperation creates an operation to process a channel response.
func (h *RESTHandler) createOperation(out <-chan RESTResult, timeout time.Duration, onReceive func(RESTResult)) *Operation {
	op := h.ops.NewOperation(out, onReceive)
	op.WaitFor(timeout)
	return op
}

// finishReq finishes up a request, waiting until the operation finishes or, after a timeout, creating an
// Operation to receive the result and returning its ID down the writer.
// Returns the HTTP status code written to the response.
func (h *RESTHandler) finishReq(op *Operation, req *http.Request, w http.ResponseWriter) int {
	result, complete := op.StatusOrResult()
	obj := result.Object
	var status int
	if complete {
		status = http.StatusOK
		if result.Created {
			status = http.StatusCreated
		}
		switch stat := obj.(type) {
		case *api.Status:
			if stat.Code != 0 {
				status = stat.Code
			}
		}
	} else {
		status = http.StatusAccepted
	}
	writeJSON(status, h.codec, obj, w)
	return status
}