/
nameserverscraper.go
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/
nameserverscraper.go
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package dnsendpoint
import (
"context"
"strings"
"sync"
"time"
"github.com/pkg/errors"
log "github.com/sirupsen/logrus"
"k8s.io/apimachinery/pkg/util/sets"
"k8s.io/client-go/util/workqueue"
"sigs.k8s.io/controller-runtime/pkg/client"
hivev1 "github.com/openshift/hive/apis/hive/v1"
"github.com/openshift/hive/pkg/controller/dnsendpoint/nameserver"
)
const (
defaultScrapePeriod = 2 * time.Hour
)
type endpointState struct {
dnsZone *hivev1.DNSZone
nsValues sets.String
}
type nameServersMap map[string]endpointState
type rootDomainsMap map[string]nameServersMap
type nameServerScraper struct {
logger log.FieldLogger
mux sync.Mutex
scrapePeriod time.Duration
queue workqueue.RateLimitingInterface
nameServers rootDomainsMap
nameServerQuery nameserver.Query
notifyChange func(client.Object)
}
func newNameServerScraper(logger log.FieldLogger, nameServerQuery nameserver.Query, domains []string, notifyChange func(client.Object)) *nameServerScraper {
if len(domains) == 0 {
return nil
}
queue := workqueue.NewNamedRateLimitingQueue(workqueue.NewItemExponentialFailureRateLimiter(10*time.Second, 1*time.Hour), "nameServerScraper")
nameServers := make(rootDomainsMap, len(domains))
for _, domain := range domains {
queue.Add(domain)
nameServers[domain] = nil
}
return &nameServerScraper{
logger: logger.WithField("scraper", "nameServer"),
scrapePeriod: defaultScrapePeriod,
queue: queue,
nameServers: nameServers,
nameServerQuery: nameServerQuery,
notifyChange: notifyChange,
}
}
// GetEndpoint gets the name servers for the specified domain.
func (s *nameServerScraper) GetEndpoint(domain string) (rootDomain string, nameServers sets.String) {
s.mux.Lock()
defer s.mux.Unlock()
rootDomain, nsMap := s.rootDomainNameServers(domain)
return rootDomain, nsMap[domain].nsValues
}
// AddEndpoint adds an endpoint with the specified domain.
func (s *nameServerScraper) AddEndpoint(object *hivev1.DNSZone, domain string, nameServers sets.String) {
s.mux.Lock()
defer s.mux.Unlock()
_, nsMap := s.rootDomainNameServers(domain)
if nsMap == nil {
return
}
nsMap[domain] = endpointState{
dnsZone: object,
nsValues: nameServers,
}
}
// RemoveEndpoint removes the endpoint with the specified domain.
func (s *nameServerScraper) RemoveEndpoint(domain string) {
s.mux.Lock()
defer s.mux.Unlock()
_, nsMap := s.rootDomainNameServers(domain)
delete(nsMap, domain)
}
func (s *nameServerScraper) HasBeenScraped(domain string) bool {
s.mux.Lock()
defer s.mux.Unlock()
_, nsMap := s.rootDomainNameServers(domain)
return nsMap != nil
}
// Start starts the name server scraper.
func (s *nameServerScraper) Start(ctx context.Context) error {
defer s.queue.ShutDown()
go func() {
for {
obj, shutdown := s.queue.Get()
if shutdown {
return
}
func() {
defer s.queue.Done(obj)
domain, ok := obj.(string)
if !ok {
s.logger.WithField("obj", obj).Error("queued object is not a string")
s.queue.Forget(obj)
return
}
if err := s.scrape(domain); err == nil {
s.logger.WithField("domain", domain).Info("scrape name servers for domain")
s.queue.Forget(obj)
s.queue.AddAfter(domain, s.scrapePeriod)
} else {
s.logger.WithField("domain", domain).WithError(err).Error("failed to scrape name servers for domain")
s.queue.AddRateLimited(obj)
}
}()
}
}()
<-ctx.Done()
return nil
}
func (s *nameServerScraper) scrape(rootDomain string) error {
currentNameServers, err := s.nameServerQuery.Get(rootDomain)
if err != nil {
return errors.Wrap(err, "error querying name servers")
}
changedEndpoints := []client.Object{}
func() {
s.mux.Lock()
defer s.mux.Unlock()
oldNameServers, ok := s.nameServers[rootDomain]
if !ok {
s.logger.WithField("domain", rootDomain).Error("domain is not a root domain")
return
}
if oldNameServers == nil {
oldNameServers = nameServersMap{}
s.nameServers[rootDomain] = oldNameServers
}
for domain, oldNameServer := range oldNameServers {
currentNameServer, ok := currentNameServers[domain]
if !ok || !currentNameServer.Equal(oldNameServer.nsValues) {
changedEndpoints = append(changedEndpoints, oldNameServer.dnsZone)
oldNameServer.nsValues = currentNameServer
oldNameServers[domain] = oldNameServer
}
}
}()
for _, e := range changedEndpoints {
s.notifyChange(e)
}
return nil
}
func (s *nameServerScraper) rootDomainNameServers(domain string) (string, nameServersMap) {
for root, nsMap := range s.nameServers {
if strings.HasSuffix(domain, root) {
return root, nsMap
}
}
return "", nil
}