Scheduler extension

plugin/pkg/scheduler/extender.go

@@ -0,0 +1,172 @@
+/*
+Copyright 2015 The Kubernetes Authors 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 scheduler
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"time"
+
+	"k8s.io/kubernetes/pkg/api"
+	client "k8s.io/kubernetes/pkg/client/unversioned"
+	"k8s.io/kubernetes/plugin/pkg/scheduler/algorithm"
+	schedulerapi "k8s.io/kubernetes/plugin/pkg/scheduler/api"
+)
+
+const (
+	DefaultExtenderTimeout = 5 * time.Second
+)
+
+// HTTPExtender implements the algorithm.SchedulerExtender interface.
+type HTTPExtender struct {
+	extenderURL    string
+	filterVerb     string
+	prioritizeVerb string
+	weight         int
+	apiVersion     string
+	client         *http.Client
+}
+
+func makeTransport(config *schedulerapi.ExtenderConfig) (http.RoundTripper, error) {
+	var cfg client.Config
+	if config.TLSConfig != nil {
+		cfg.TLSClientConfig = *config.TLSConfig
+	}
+	if config.EnableHttps {
+		hasCA := len(cfg.CAFile) > 0 || len(cfg.CAData) > 0
+		if !hasCA {
+			cfg.Insecure = true
+		}
+	}
+	tlsConfig, err := client.TLSConfigFor(&cfg)
+	if err != nil {
+		return nil, err
+	}
+	if tlsConfig != nil {
+		return &http.Transport{
+			TLSClientConfig: tlsConfig,
+		}, nil
+	}
+	return http.DefaultTransport, nil
+}
+
+func NewHTTPExtender(config *schedulerapi.ExtenderConfig, apiVersion string) (algorithm.SchedulerExtender, error) {
+	if config.HTTPTimeout.Nanoseconds() == 0 {
+		config.HTTPTimeout = time.Duration(DefaultExtenderTimeout)
+	}
+
+	transport, err := makeTransport(config)
+	if err != nil {
+		return nil, err
+	}
+	client := &http.Client{
+		Transport: transport,
+		Timeout:   config.HTTPTimeout,
+	}
+	return &HTTPExtender{
+		extenderURL:    config.URLPrefix,
+		apiVersion:     apiVersion,
+		filterVerb:     config.FilterVerb,
+		prioritizeVerb: config.PrioritizeVerb,
+		weight:         config.Weight,
+		client:         client,
+	}, nil
+}
+
+// Filter based on extender implemented predicate functions. The filtered list is
+// expected to be a subset of the supplied list.
+func (h *HTTPExtender) Filter(pod *api.Pod, nodes *api.NodeList) (*api.NodeList, error) {
+	var result schedulerapi.ExtenderFilterResult
+
+	if h.filterVerb == "" {
+		return nodes, nil
+	}
+
+	args := schedulerapi.ExtenderArgs{
+		Pod:   *pod,
+		Nodes: *nodes,
+	}
+
+	if err := h.send(h.filterVerb, &args, &result); err != nil {
+		return nil, err
+	}
+	if result.Error != "" {
+		return nil, fmt.Errorf(result.Error)
+	}
+	return &result.Nodes, nil
+}
+
+// Prioritize based on extender implemented priority functions. Weight*priority is added
+// up for each such priority function. The returned score is added to the score computed
+// by Kubernetes scheduler. The total score is used to do the host selection.
+func (h *HTTPExtender) Prioritize(pod *api.Pod, nodes *api.NodeList) (*schedulerapi.HostPriorityList, int, error) {
+	var result schedulerapi.HostPriorityList
+
+	if h.prioritizeVerb == "" {
+		result := schedulerapi.HostPriorityList{}
+		for _, node := range nodes.Items {
+			result = append(result, schedulerapi.HostPriority{Host: node.Name, Score: 0})
+		}
+		return &result, 0, nil
+	}
+
+	args := schedulerapi.ExtenderArgs{
+		Pod:   *pod,
+		Nodes: *nodes,
+	}
+
+	if err := h.send(h.prioritizeVerb, &args, &result); err != nil {
+		return nil, 0, err
+	}
+	return &result, h.weight, nil
+}
+
+// Helper function to send messages to the extender
+func (h *HTTPExtender) send(action string, args interface{}, result interface{}) error {
+	out, err := json.Marshal(args)
+	if err != nil {
+		return err
+	}
+
+	url := h.extenderURL + "/" + h.apiVersion + "/" + action
+
+	req, err := http.NewRequest("POST", url, bytes.NewReader(out))
+	if err != nil {
+		return err
+	}
+
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := h.client.Do(req)
+	if err != nil {
+		return err
+	}
+
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	if err := json.Unmarshal(body, result); err != nil {
+		return err
+	}
+	return nil
+}