external-dns/source/ingress.go

/*
Copyright 2017 The Kubernetes Authors.

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 source

import (
	"bytes"
	"fmt"
	"strings"
	"text/template"

	log "github.com/Sirupsen/logrus"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/pkg/apis/extensions/v1beta1"

	"github.com/kubernetes-incubator/external-dns/endpoint"
)

// ingressSource is an implementation of Source for Kubernetes ingress objects.
// Ingress implementation will use the spec.rules.host value for the hostname
// Ingress annotations are ignored
type ingressSource struct {
	client       kubernetes.Interface
	namespace    string
	fqdntemplate *template.Template
}

// NewIngressSource creates a new ingressSource with the given client and namespace scope.
func NewIngressSource(client kubernetes.Interface, namespace string, fqdntemplate string) (Source, error) {
	var tmpl *template.Template
	var err error
	if fqdntemplate != "" {
		tmpl, err = template.New("endpoint").Funcs(template.FuncMap{
			"trimPrefix": strings.TrimPrefix,
		}).Parse(fqdntemplate)
		if err != nil {
			return nil, err
		}
	}

	return &ingressSource{
		client:       client,
		namespace:    namespace,
		fqdntemplate: tmpl,
	}, nil
}

// Endpoints returns endpoint objects for each host-target combination that should be processed.
// Retrieves all ingress resources on all namespaces
func (sc *ingressSource) Endpoints() ([]*endpoint.Endpoint, error) {
	ingresses, err := sc.client.Extensions().Ingresses(sc.namespace).List(metav1.ListOptions{})
	if err != nil {
		return nil, err
	}

	endpoints := []*endpoint.Endpoint{}

	for _, ing := range ingresses.Items {
		// Check controller annotation to see if we are responsible.
		controller, ok := ing.Annotations[controllerAnnotationKey]
		if ok && controller != controllerAnnotationValue {
			log.Debugf("Skipping ingress %s/%s because controller value does not match, found: %s, required: %s",
				ing.Namespace, ing.Name, controller, controllerAnnotationValue)
			continue
		}

		ingEndpoints := endpointsFromIngress(&ing)

		// apply template if host is missing on ingress
		if len(ingEndpoints) == 0 && sc.fqdntemplate != nil {
			ingEndpoints, err = sc.endpointsFromTemplate(&ing)
			if err != nil {
				return nil, err
			}
		}

		if len(ingEndpoints) == 0 {
			log.Debugf("No endpoints could be generated from ingress %s/%s", ing.Namespace, ing.Name)
			continue
		}

		log.Debugf("Endpoints generated from ingress: %s/%s: %v", ing.Namespace, ing.Name, ingEndpoints)
		endpoints = append(endpoints, ingEndpoints...)
	}

	return endpoints, nil
}

func (sc *ingressSource) endpointsFromTemplate(ing *v1beta1.Ingress) ([]*endpoint.Endpoint, error) {
	var endpoints []*endpoint.Endpoint

	var buf bytes.Buffer
	err := sc.fqdntemplate.Execute(&buf, ing)
	if err != nil {
		return nil, fmt.Errorf("failed to apply template on ingress %s: %v", ing.String(), err)
	}

	hostname := buf.String()
	for _, lb := range ing.Status.LoadBalancer.Ingress {
		if lb.IP != "" {
			endpoints = append(endpoints, endpoint.NewEndpoint(hostname, lb.IP, ""))
		}
		if lb.Hostname != "" {
			endpoints = append(endpoints, endpoint.NewEndpoint(hostname, lb.Hostname, ""))
		}
	}

	return endpoints, nil
}

// endpointsFromIngress extracts the endpoints from ingress object
func endpointsFromIngress(ing *v1beta1.Ingress) []*endpoint.Endpoint {
	var endpoints []*endpoint.Endpoint

	for _, rule := range ing.Spec.Rules {
		if rule.Host == "" {
			continue
		}
		for _, lb := range ing.Status.LoadBalancer.Ingress {
			if lb.IP != "" {
				endpoints = append(endpoints, endpoint.NewEndpoint(rule.Host, lb.IP, ""))
			}
			if lb.Hostname != "" {
				endpoints = append(endpoints, endpoint.NewEndpoint(rule.Host, lb.Hostname, ""))
			}
		}
	}

	return endpoints
}