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Commit 4bde13ac authored by Madhusudan.C.S's avatar Madhusudan.C.S
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Remove all the existing records before creating new ones to avoid DNS misconfiguration.

When we fetch the dns records by name, we get a list of records that match the given name. As an optimization we look up to see if the new record we want to create is already in the returned list to avoid performing any updates. However, when the new record we want to create isn't in the returned list, it is hard to say if the returned list contains the list of records that we want to retain. For example, we might get a list of A records and we want to create a CNAME record. Creating a new CNAME record without removing the A records is a DNS misconfiguration. So to play safe we just remove all the existing records in the list and create the new desired record. **Note**: This is the opposite of what I said here - https://reviewable.kubernetes.io/reviews/kubernetes/kubernetes/44626#-Ki9xQOzybryHvsxNrra.
parent 20e55806
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Inline Side-by-side
Showing with 10 additions and 3 deletions
federation/pkg/federation-controller/service/dns.go
View file @ 4bde13ac
...@@ -254,9 +254,11 @@ func (s *ServiceController) ensureDnsRrsets(dnsZone dnsprovider.Zone, dnsName st ...@@ -254,9 +254,11 @@ func (s *ServiceController) ensureDnsRrsets(dnsZone dnsprovider.Zone, dnsName st
// Need to replace the existing one with a better one (or just remove it if we have no healthy endpoints). // Need to replace the existing one with a better one (or just remove it if we have no healthy endpoints).
glog.V(4).Infof("Existing recordset %v not equivalent to needed recordset %v removing existing and adding needed.", rrsetList, newRrset) glog.V(4).Infof("Existing recordset %v not equivalent to needed recordset %v removing existing and adding needed.", rrsetList, newRrset)
changeSet := rrsets.StartChangeset() changeSet := rrsets.StartChangeset()
changeSet.Remove(found) for i := range rrsetList {
changeSet = changeSet.Remove(rrsetList[i])
}
if uplevelCname != "" { if uplevelCname != "" {
changeSet.Add(newRrset) changeSet = changeSet.Add(newRrset)
if err := changeSet.Apply(); err != nil { if err := changeSet.Apply(); err != nil {
return err return err
} }
...@@ -288,7 +290,12 @@ func (s *ServiceController) ensureDnsRrsets(dnsZone dnsprovider.Zone, dnsName st ...@@ -288,7 +290,12 @@ func (s *ServiceController) ensureDnsRrsets(dnsZone dnsprovider.Zone, dnsName st
} else { } else {
// Need to replace the existing one with a better one // Need to replace the existing one with a better one
glog.V(4).Infof("Existing recordset %v is not equivalent to needed recordset %v, removing existing and adding needed.", found, newRrset) glog.V(4).Infof("Existing recordset %v is not equivalent to needed recordset %v, removing existing and adding needed.", found, newRrset)
if err = rrsets.StartChangeset().Remove(found).Add(newRrset).Apply(); err != nil { changeSet := rrsets.StartChangeset()
for i := range rrsetList {
changeSet = changeSet.Remove(rrsetList[i])
}
changeSet = changeSet.Add(newRrset)
if err = changeSet.Apply(); err != nil {
return err return err
} }
glog.V(4).Infof("Successfully replaced recordset %v -> %v", found, newRrset) glog.V(4).Infof("Successfully replaced recordset %v -> %v", found, newRrset)
......
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