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287 lines
7.7 KiB
287 lines
7.7 KiB
/*
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* MinIO Cloud Storage, (C) 2018 MinIO, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package dns
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import (
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"context"
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"encoding/json"
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"errors"
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"fmt"
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"net"
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"sort"
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"strings"
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"time"
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"github.com/minio/minio-go/v6/pkg/set"
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"github.com/coredns/coredns/plugin/etcd/msg"
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"github.com/coreos/etcd/clientv3"
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)
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// ErrNoEntriesFound - Indicates no entries were found for the given key (directory)
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var ErrNoEntriesFound = errors.New("No entries found for this key")
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const etcdPathSeparator = "/"
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// create a new coredns service record for the bucket.
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func newCoreDNSMsg(ip string, port string, ttl uint32) ([]byte, error) {
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return json.Marshal(&SrvRecord{
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Host: ip,
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Port: json.Number(port),
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TTL: ttl,
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CreationDate: time.Now().UTC(),
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})
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}
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// List - Retrieves list of DNS entries for the domain.
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func (c *CoreDNS) List() ([]SrvRecord, error) {
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var srvRecords []SrvRecord
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for _, domainName := range c.domainNames {
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key := msg.Path(fmt.Sprintf("%s.", domainName), c.prefixPath)
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records, err := c.list(key)
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if err != nil {
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return nil, err
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}
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for _, record := range records {
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if record.Key == "" {
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continue
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}
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srvRecords = append(srvRecords, record)
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}
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}
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return srvRecords, nil
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}
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// Get - Retrieves DNS records for a bucket.
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func (c *CoreDNS) Get(bucket string) ([]SrvRecord, error) {
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var srvRecords []SrvRecord
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for _, domainName := range c.domainNames {
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key := msg.Path(fmt.Sprintf("%s.%s.", bucket, domainName), c.prefixPath)
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records, err := c.list(key)
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if err != nil {
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return nil, err
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}
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// Make sure we have record.Key is empty
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// this can only happen when record.Key
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// has bucket entry with exact prefix
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// match any record.Key which do not
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// match the prefixes we skip them.
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for _, record := range records {
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if record.Key != "" {
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continue
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}
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srvRecords = append(srvRecords, record)
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}
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}
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if len(srvRecords) == 0 {
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return nil, ErrNoEntriesFound
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}
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return srvRecords, nil
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}
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// msgUnPath converts a etcd path to domainname.
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func msgUnPath(s string) string {
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ks := strings.Split(strings.Trim(s, etcdPathSeparator), etcdPathSeparator)
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for i, j := 0, len(ks)-1; i < j; i, j = i+1, j-1 {
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ks[i], ks[j] = ks[j], ks[i]
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}
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return strings.Join(ks, ".")
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}
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// Retrieves list of entries under the key passed.
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// Note that this method fetches entries upto only two levels deep.
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func (c *CoreDNS) list(key string) ([]SrvRecord, error) {
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ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
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r, err := c.etcdClient.Get(ctx, key, clientv3.WithPrefix())
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defer cancel()
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if err != nil {
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return nil, err
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}
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if r.Count == 0 {
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key = strings.TrimSuffix(key, etcdPathSeparator)
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r, err = c.etcdClient.Get(ctx, key)
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if err != nil {
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return nil, err
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}
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}
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var srvRecords []SrvRecord
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for _, n := range r.Kvs {
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var srvRecord SrvRecord
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if err = json.Unmarshal([]byte(n.Value), &srvRecord); err != nil {
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return nil, err
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}
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srvRecord.Key = strings.TrimPrefix(string(n.Key), key)
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srvRecord.Key = strings.TrimSuffix(srvRecord.Key, srvRecord.Host)
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// Skip non-bucket entry like for a key
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// /skydns/net/miniocloud/10.0.0.1 that may exist as
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// dns entry for the server (rather than the bucket
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// itself).
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if srvRecord.Key == "" {
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continue
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}
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srvRecord.Key = msgUnPath(srvRecord.Key)
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srvRecords = append(srvRecords, srvRecord)
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}
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sort.Slice(srvRecords, func(i int, j int) bool {
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return srvRecords[i].Key < srvRecords[j].Key
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})
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return srvRecords, nil
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}
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// Put - Adds DNS entries into etcd endpoint in CoreDNS etcd message format.
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func (c *CoreDNS) Put(bucket string) error {
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c.Delete(bucket) // delete any existing entries.
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for ip := range c.domainIPs {
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bucketMsg, err := newCoreDNSMsg(ip, c.domainPort, defaultTTL)
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if err != nil {
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return err
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}
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for _, domainName := range c.domainNames {
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key := msg.Path(fmt.Sprintf("%s.%s", bucket, domainName), c.prefixPath)
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key = key + etcdPathSeparator + ip
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ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
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_, err = c.etcdClient.Put(ctx, key, string(bucketMsg))
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defer cancel()
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if err != nil {
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ctx, cancel = context.WithTimeout(context.Background(), defaultContextTimeout)
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c.etcdClient.Delete(ctx, key)
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defer cancel()
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return err
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}
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}
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}
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return nil
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}
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// Delete - Removes DNS entries added in Put().
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func (c *CoreDNS) Delete(bucket string) error {
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for _, domainName := range c.domainNames {
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key := msg.Path(fmt.Sprintf("%s.%s.", bucket, domainName), c.prefixPath)
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srvRecords, err := c.list(key)
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if err != nil {
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return err
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}
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for _, record := range srvRecords {
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dctx, dcancel := context.WithTimeout(context.Background(), defaultContextTimeout)
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if _, err = c.etcdClient.Delete(dctx, key+etcdPathSeparator+record.Host); err != nil {
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dcancel()
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return err
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}
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dcancel()
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}
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}
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return nil
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}
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// DeleteRecord - Removes a specific DNS entry
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func (c *CoreDNS) DeleteRecord(record SrvRecord) error {
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for _, domainName := range c.domainNames {
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key := msg.Path(fmt.Sprintf("%s.%s.", record.Key, domainName), c.prefixPath)
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dctx, dcancel := context.WithTimeout(context.Background(), defaultContextTimeout)
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if _, err := c.etcdClient.Delete(dctx, key+etcdPathSeparator+record.Host); err != nil {
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dcancel()
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return err
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}
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dcancel()
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}
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return nil
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}
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// CoreDNS - represents dns config for coredns server.
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type CoreDNS struct {
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domainNames []string
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domainIPs set.StringSet
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domainPort string
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prefixPath string
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etcdClient *clientv3.Client
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}
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// Option - functional options pattern style
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type Option func(*CoreDNS)
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// DomainNames set a list of domain names used by this CoreDNS
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// client setting, note this will fail if set to empty when
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// constructor initializes.
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func DomainNames(domainNames []string) Option {
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return func(args *CoreDNS) {
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args.domainNames = domainNames
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}
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}
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// DomainIPs set a list of custom domain IPs, note this will
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// fail if set to empty when constructor initializes.
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func DomainIPs(domainIPs set.StringSet) Option {
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return func(args *CoreDNS) {
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args.domainIPs = domainIPs
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}
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}
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// DomainPort - is a string version of server port
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func DomainPort(domainPort string) Option {
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return func(args *CoreDNS) {
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args.domainPort = domainPort
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}
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}
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// CoreDNSPath - custom prefix on etcd to populate DNS
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// service records, optional and can be empty.
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// if empty then c.prefixPath is used i.e "/skydns"
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func CoreDNSPath(prefix string) Option {
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return func(args *CoreDNS) {
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args.prefixPath = prefix
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}
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}
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// NewCoreDNS - initialize a new coreDNS set/unset values.
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func NewCoreDNS(cfg clientv3.Config, setters ...Option) (*CoreDNS, error) {
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etcdClient, err := clientv3.New(cfg)
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if err != nil {
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return nil, err
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}
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args := &CoreDNS{
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etcdClient: etcdClient,
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}
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for _, setter := range setters {
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setter(args)
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}
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if len(args.domainNames) == 0 || args.domainIPs.IsEmpty() {
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return nil, errors.New("invalid argument")
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}
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// strip ports off of domainIPs
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domainIPsWithoutPorts := args.domainIPs.ApplyFunc(func(ip string) string {
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host, _, err := net.SplitHostPort(ip)
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if err != nil {
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if strings.Contains(err.Error(), "missing port in address") {
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host = ip
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}
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}
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return host
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})
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args.domainIPs = domainIPsWithoutPorts
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return args, nil
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}
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