kubernetes/pkg/master/publish.go

/*
Copyright 2014 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 master

import (
	"net"
	"time"

	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/endpoints"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/errors"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/rest"

	"github.com/golang/glog"
)

func (m *Master) serviceWriterLoop(stop chan struct{}) {
	t := time.NewTicker(10 * time.Second)
	defer t.Stop()
	for {
		// Update service & endpoint records.
		// TODO: when it becomes possible to change this stuff,
		// stop polling and start watching.
		// TODO: add endpoints of all replicas, not just the elected master.
		if err := m.createMasterNamespaceIfNeeded(api.NamespaceDefault); err != nil {
			glog.Errorf("Can't create master namespace: %v", err)
		}
		if m.serviceReadWriteIP != nil {
			if err := m.createMasterServiceIfNeeded("kubernetes", m.serviceReadWriteIP, m.serviceReadWritePort); err != nil && !errors.IsAlreadyExists(err) {
				glog.Errorf("Can't create rw service: %v", err)
			}
			if err := m.setEndpoints("kubernetes", m.clusterIP, m.publicReadWritePort); err != nil {
				glog.Errorf("Can't create rw endpoints: %v", err)
			}
		}

		select {
		case <-stop:
			return
		case <-t.C:
		}
	}
}

func (m *Master) roServiceWriterLoop(stop chan struct{}) {
	t := time.NewTicker(10 * time.Second)
	defer t.Stop()
	for {
		// Update service & endpoint records.
		// TODO: when it becomes possible to change this stuff,
		// stop polling and start watching.
		if err := m.createMasterNamespaceIfNeeded(api.NamespaceDefault); err != nil {
			glog.Errorf("Can't create master namespace: %v", err)
		}
		if m.serviceReadOnlyIP != nil {
			if err := m.createMasterServiceIfNeeded("kubernetes-ro", m.serviceReadOnlyIP, m.serviceReadOnlyPort); err != nil && !errors.IsAlreadyExists(err) {
				glog.Errorf("Can't create ro service: %v", err)
			}
			if err := m.setEndpoints("kubernetes-ro", m.clusterIP, m.publicReadOnlyPort); err != nil {
				glog.Errorf("Can't create ro endpoints: %v", err)
			}
		}

		select {
		case <-stop:
			return
		case <-t.C:
		}
	}
}

// createMasterNamespaceIfNeeded will create the namespace that contains the master services if it doesn't already exist
func (m *Master) createMasterNamespaceIfNeeded(ns string) error {
	ctx := api.NewContext()
	if _, err := m.namespaceRegistry.GetNamespace(ctx, api.NamespaceDefault); err == nil {
		// the namespace already exists
		return nil
	}
	namespace := &api.Namespace{
		ObjectMeta: api.ObjectMeta{
			Name:      ns,
			Namespace: "",
		},
	}
	_, err := m.storage["namespaces"].(rest.Creater).Create(ctx, namespace)
	if err != nil && errors.IsAlreadyExists(err) {
		err = nil
	}
	return err
}

// createMasterServiceIfNeeded will create the specified service if it
// doesn't already exist.
func (m *Master) createMasterServiceIfNeeded(serviceName string, serviceIP net.IP, servicePort int) error {
	ctx := api.NewDefaultContext()
	if _, err := m.serviceRegistry.GetService(ctx, serviceName); err == nil {
		// The service already exists.
		return nil
	}
	svc := &api.Service{
		ObjectMeta: api.ObjectMeta{
			Name:      serviceName,
			Namespace: api.NamespaceDefault,
			Labels:    map[string]string{"provider": "kubernetes", "component": "apiserver"},
		},
		Spec: api.ServiceSpec{
			Ports: []api.ServicePort{{Port: servicePort, Protocol: api.ProtocolTCP}},
			// maintained by this code, not by the pod selector
			Selector:        nil,
			PortalIP:        serviceIP.String(),
			SessionAffinity: api.AffinityTypeNone,
		},
	}
	_, err := m.storage["services"].(rest.Creater).Create(ctx, svc)
	if err != nil && errors.IsAlreadyExists(err) {
		err = nil
	}
	return err
}

// setEndpoints sets the endpoints for the given apiserver service (ro or rw).
// setEndpoints expects that the endpoints objects it manages will all be
// managed only by setEndpoints; therefore, to understand this, you need only
// understand the requirements and the body of this function.
//
// Requirements:
//  * All apiservers MUST use the same ports for their {rw, ro} services.
//  * All apiservers MUST use setEndpoints and only setEndpoints to manage the
//      endpoints for their {rw, ro} services.
//  * All apiservers MUST know and agree on the number of apiservers expected
//      to be running (m.masterCount).
//  * setEndpoints is called periodically from all apiservers.
//
func (m *Master) setEndpoints(serviceName string, ip net.IP, port int) error {
	ctx := api.NewDefaultContext()
	e, err := m.endpointRegistry.GetEndpoints(ctx, serviceName)
	if err != nil {
		e = &api.Endpoints{
			ObjectMeta: api.ObjectMeta{
				Name:      serviceName,
				Namespace: api.NamespaceDefault,
			},
		}
	}

	// First, determine if the endpoint is in the format we expect (one
	// subset, one port, N IP addresses).
	formatCorrect, ipCorrect := m.checkEndpointSubsetFormat(e, ip.String(), port)
	if !formatCorrect {
		// Something is egregiously wrong, just re-make the endpoints record.
		e.Subsets = []api.EndpointSubset{{
			Addresses: []api.EndpointAddress{{IP: ip.String()}},
			Ports:     []api.EndpointPort{{Port: port, Protocol: api.ProtocolTCP}},
		}}
		glog.Warningf("Resetting endpoints for master service %q to %v", serviceName, e)
		return m.endpointRegistry.UpdateEndpoints(ctx, e)
	} else if !ipCorrect {
		// We *always* add our own IP address; if there are too many IP
		// addresses, we remove the ones lexicographically after our
		// own IP address.  Given the requirements stated at the top of
		// this function, this should cause the list of IP addresses to
		// become eventually correct.
		e.Subsets[0].Addresses = append(e.Subsets[0].Addresses, api.EndpointAddress{IP: ip.String()})
		e.Subsets = endpoints.RepackSubsets(e.Subsets)
		if addrs := &e.Subsets[0].Addresses; len(*addrs) > m.masterCount {
			// addrs is a pointer because we're going to mutate it.
			for i, addr := range *addrs {
				if addr.IP == ip.String() {
					for len(*addrs) > m.masterCount {
						remove := (i + 1) % len(*addrs)
						*addrs = append((*addrs)[:remove], (*addrs)[remove+1:]...)
					}
					break
				}
			}
		}
		return m.endpointRegistry.UpdateEndpoints(ctx, e)
	}
	// We didn't make any changes, no need to actually call update.
	return nil
}

// Determine if the endpoint is in the format setEndpoints expect (one subset,
// one port, N IP addresses); and if the specified IP address is present and
// the correct number of ip addresses are found.
func (m *Master) checkEndpointSubsetFormat(e *api.Endpoints, ip string, port int) (formatCorrect, ipCorrect bool) {
	if len(e.Subsets) != 1 {
		return false, false
	}
	sub := &e.Subsets[0]
	if len(sub.Ports) != 1 {
		return false, false
	}
	p := &sub.Ports[0]
	if p.Port != port || p.Protocol != api.ProtocolTCP {
		return false, false
	}
	for _, addr := range sub.Addresses {
		if addr.IP == ip {
			return true, len(sub.Addresses) == m.masterCount
		}
	}
	return true, false
}