Golang GCEURLMap.GetDefaultBackend方法代碼示例

// UpdateUrlMap translates the given hostname: endpoint->port mapping into a gce url map.
//
// HostRule: Conceptually contains all PathRules for a given host.
// PathMatcher: Associates a path rule with a host rule. Mostly an optimization.
// PathRule: Maps a single path regex to a backend.
//
// The GCE url map allows multiple hosts to share url->backend mappings without duplication, eg:
//   Host: foo(PathMatcher1), bar(PathMatcher1,2)
//   PathMatcher1:
//     /a -> b1
//     /b -> b2
//   PathMatcher2:
//     /c -> b1
// This leads to a lot of complexity in the common case, where all we want is a mapping of
// host->{/path: backend}.
//
// Consider some alternatives:
// 1. Using a single backend per PathMatcher:
//   Host: foo(PathMatcher1,3) bar(PathMatcher1,2,3)
//   PathMatcher1:
//     /a -> b1
//   PathMatcher2:
//     /c -> b1
//   PathMatcher3:
//     /b -> b2
// 2. Using a single host per PathMatcher:
//   Host: foo(PathMatcher1)
//   PathMatcher1:
//     /a -> b1
//     /b -> b2
//   Host: bar(PathMatcher2)
//   PathMatcher2:
//     /a -> b1
//     /b -> b2
//     /c -> b1
// In the context of kubernetes services, 2 makes more sense, because we
// rarely want to lookup backends (service:nodeport). When a service is
// deleted, we need to find all host PathMatchers that have the backend
// and remove the mapping. When a new path is added to a host (happens
// more frequently than service deletion) we just need to lookup the 1
// pathmatcher of the host.
func (l *L7) UpdateUrlMap(ingressRules utils.GCEURLMap) error {
	if l.um == nil {
		return fmt.Errorf("Cannot add url without an urlmap.")
	}
	glog.V(3).Infof("Updating urlmap for l7 %v", l.Name)

	// All UrlMaps must have a default backend. If the Ingress has a default
	// backend, it applies to all host rules as well as to the urlmap itself.
	// If it doesn't the urlmap might have a stale default, so replace it with
	// glbc's default backend.
	defaultBackend := ingressRules.GetDefaultBackend()
	if defaultBackend != nil {
		l.um.DefaultService = defaultBackend.SelfLink
	} else {
		l.um.DefaultService = l.glbcDefaultBackend.SelfLink
	}
	glog.V(3).Infof("Updating url map %+v", ingressRules)

	// Every update replaces the entire urlmap.
	// TODO:  when we have multiple loadbalancers point to a single gce url map
	// this needs modification. For now, there is a 1:1 mapping of urlmaps to
	// Ingresses, so if the given Ingress doesn't have a host rule we should
	// delete the path to that backend.
	l.um.HostRules = []*compute.HostRule{}
	l.um.PathMatchers = []*compute.PathMatcher{}

	for hostname, urlToBackend := range ingressRules {
		// Create a host rule
		// Create a path matcher
		// Add all given endpoint:backends to pathRules in path matcher
		pmName := getNameForPathMatcher(hostname)
		l.um.HostRules = append(l.um.HostRules, &compute.HostRule{
			Hosts:       []string{hostname},
			PathMatcher: pmName,
		})

		pathMatcher := &compute.PathMatcher{
			Name:           pmName,
			DefaultService: l.um.DefaultService,
			PathRules:      []*compute.PathRule{},
		}

		// Longest prefix wins. For equal rules, first hit wins, i.e the second
		// /foo rule when the first is deleted.
		for expr, be := range urlToBackend {
			pathMatcher.PathRules = append(
				pathMatcher.PathRules, &compute.PathRule{Paths: []string{expr}, Service: be.SelfLink})
		}
		l.um.PathMatchers = append(l.um.PathMatchers, pathMatcher)
	}
	um, err := l.cloud.UpdateUrlMap(l.um)
	if err != nil {
		return err
	}
	l.um = um
	return nil
}

// UpdateUrlMap translates the given hostname: endpoint->port mapping into a gce url map.
//
// HostRule: Conceptually contains all PathRules for a given host.
// PathMatcher: Associates a path rule with a host rule. Mostly an optimization.
// PathRule: Maps a single path regex to a backend.
//
// The GCE url map allows multiple hosts to share url->backend mappings without duplication, eg:
//   Host: foo(PathMatcher1), bar(PathMatcher1,2)
//   PathMatcher1:
//     /a -> b1
//     /b -> b2
//   PathMatcher2:
//     /c -> b1
// This leads to a lot of complexity in the common case, where all we want is a mapping of
// host->{/path: backend}.
//
// Consider some alternatives:
// 1. Using a single backend per PathMatcher:
//   Host: foo(PathMatcher1,3) bar(PathMatcher1,2,3)
//   PathMatcher1:
//     /a -> b1
//   PathMatcher2:
//     /c -> b1
//   PathMatcher3:
//     /b -> b2
// 2. Using a single host per PathMatcher:
//   Host: foo(PathMatcher1)
//   PathMatcher1:
//     /a -> b1
//     /b -> b2
//   Host: bar(PathMatcher2)
//   PathMatcher2:
//     /a -> b1
//     /b -> b2
//     /c -> b1
// In the context of kubernetes services, 2 makes more sense, because we
// rarely want to lookup backends (service:nodeport). When a service is
// deleted, we need to find all host PathMatchers that have the backend
// and remove the mapping. When a new path is added to a host (happens
// more frequently than service deletion) we just need to lookup the 1
// pathmatcher of the host.
func (l *L7) UpdateUrlMap(ingressRules utils.GCEURLMap) error {
	if l.um == nil {
		return fmt.Errorf("Cannot add url without an urlmap.")
	}
	glog.V(3).Infof("Updating urlmap for l7 %v", l.Name)

	// All UrlMaps must have a default backend. If the Ingress has a default
	// backend, it applies to all host rules as well as to the urlmap itself.
	// If it doesn't the urlmap might have a stale default, so replace it with
	// glbc's default backend.
	defaultBackend := ingressRules.GetDefaultBackend()
	if defaultBackend != nil {
		l.um.DefaultService = defaultBackend.SelfLink
	} else {
		l.um.DefaultService = l.glbcDefaultBackend.SelfLink
	}
	glog.V(3).Infof("Updating url map %+v", ingressRules)

	for hostname, urlToBackend := range ingressRules {
		// Find the hostrule
		// Find the path matcher
		// Add all given endpoint:backends to pathRules in path matcher
		var hostRule *compute.HostRule
		pmName := getNameForPathMatcher(hostname)
		for _, hr := range l.um.HostRules {
			// TODO: Hostnames must be exact match?
			if hr.Hosts[0] == hostname {
				hostRule = hr
				break
			}
		}
		if hostRule == nil {
			// This is a new host
			hostRule = &compute.HostRule{
				Hosts:       []string{hostname},
				PathMatcher: pmName,
			}
			// Why not just clobber existing host rules?
			// Because we can have multiple loadbalancers point to a single
			// gce url map when we have IngressClaims.
			l.um.HostRules = append(l.um.HostRules, hostRule)
		}
		var pathMatcher *compute.PathMatcher
		for _, pm := range l.um.PathMatchers {
			if pm.Name == hostRule.PathMatcher {
				pathMatcher = pm
				break
			}
		}
		if pathMatcher == nil {
			// This is a dangling or new host
			pathMatcher = &compute.PathMatcher{Name: pmName}
			l.um.PathMatchers = append(l.um.PathMatchers, pathMatcher)
		}
		pathMatcher.DefaultService = l.um.DefaultService

		// TODO: Every update replaces the entire path map. This will need to
		// change when we allow joining. Right now we call a single method
		// to verify current == desired and add new url mappings.
//.........這裏部分代碼省略.........