Add support for CopyObject across regions and multiple Minio IPs

This PR adds CopyObject support for objects residing in buckets in different Minio instances (where Minio instances are part of a federated setup). Also, added support for multiple Minio domain IPs. This is required for distributed deployments, where one deployment may have multiple nodes, each with a different public IP.
2024-12-23 21:55:53 -05:00 · 2018-05-12 00:32:30 +05:30 · 2018-05-12 00:32:30 +05:30 · 6ce7265c8c
commit 6ce7265c8c
parent f30c95a301
12 changed files with 208 additions and 82 deletions
--- a/cmd/bucket-handlers.go
+++ b/cmd/bucket-handlers.go
@ -31,12 +31,17 @@ import (
 	"sync"

 	"github.com/coreos/etcd/client"
+
 	"github.com/gorilla/mux"
+
 	"github.com/minio/minio/cmd/logger"
+	"github.com/minio/minio/pkg/dns"
 	"github.com/minio/minio/pkg/event"
 	"github.com/minio/minio/pkg/hash"
 	"github.com/minio/minio/pkg/policy"
 	"github.com/minio/minio/pkg/sync/errgroup"
+
+	"github.com/minio/minio-go/pkg/set"
 )

 // Check if there are buckets on server without corresponding entry in etcd backend and
@ -47,7 +52,6 @@ import (
 // -- If yes, check if the IP of entry matches local IP. This means entry is for this instance.
 // -- If IP of the entry doesn't match, this means entry is for another instance. Log an error to console.
 func initFederatorBackend(objLayer ObjectLayer) {
-	// List all buckets
 	b, err := objLayer.ListBuckets(context.Background())
 	if err != nil {
 		logger.LogIf(context.Background(), err)
@ -60,15 +64,14 @@ func initFederatorBackend(objLayer ObjectLayer) {
 		g.Go(func() error {
 			r, gerr := globalDNSConfig.Get(b[index].Name)
 			if gerr != nil {
-				if client.IsKeyNotFound(gerr) {
-					// Make a new entry
+				if client.IsKeyNotFound(gerr) || gerr == dns.ErrNoEntriesFound {
 					return globalDNSConfig.Put(b[index].Name)
 				}
 				return gerr
 			}
-			if r.Host != globalDomainIP {
-				// Log error that entry already present for different host
-				return fmt.Errorf("Unable to add bucket DNS entry for bucket %s, an entry exists for the same bucket. Use %s to access the bucket, or rename it to a unique value", b[index].Name, globalDomainIP)
+			if globalDomainIPs.Intersection(set.CreateStringSet(getHostsSlice(r)...)).IsEmpty() {
+				// There is already an entry for this bucket, with all IP addresses different. This indicates a bucket name collision. Log an error and continue.
+				return fmt.Errorf("Unable to add bucket DNS entry for bucket %s, an entry exists for the same bucket. Use one of these IP addresses %v to access the bucket", b[index].Name, globalDomainIPs.ToSlice())
 			}
 			return nil
 		}, index)
@ -418,7 +421,7 @@ func (api objectAPIHandlers) PutBucketHandler(w http.ResponseWriter, r *http.Req

 	if globalDNSConfig != nil {
 		if _, err := globalDNSConfig.Get(bucket); err != nil {
-			if client.IsKeyNotFound(err) {
+			if client.IsKeyNotFound(err) || err == dns.ErrNoEntriesFound {
 				// Proceed to creating a bucket.
 				if err = objectAPI.MakeBucketWithLocation(ctx, bucket, location); err != nil {
 					writeErrorResponse(w, toAPIErrorCode(err), r.URL)
--- a/cmd/common-main.go
+++ b/cmd/common-main.go
@ -28,10 +28,13 @@ import (
 	"time"

 	etcd "github.com/coreos/etcd/client"
+
 	"github.com/minio/cli"
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/auth"
 	"github.com/minio/minio/pkg/dns"
+
+	"github.com/minio/minio-go/pkg/set"
 )

 // Check for updates and print a notification message
@ -59,7 +62,7 @@ func initConfig() {
 		} else {
 			if etcd.IsKeyNotFound(err) {
 				logger.FatalIf(newConfig(), "Unable to initialize minio config for the first time.")
-				logger.Info("Created minio configuration file successfully at", globalEtcdClient.Endpoints())
+				logger.Info("Created minio configuration file successfully at %v", globalEtcdClient.Endpoints())
 			} else {
 				logger.FatalIf(err, "Unable to load config version: '%s'.", serverConfigVersion)
 			}
@ -168,10 +171,20 @@ func handleCommonEnvVars() {
 		logger.FatalIf(err, "Unable to initialize etcd with %s", etcdEndpoints)
 	}

-	globalDomainIP = os.Getenv("MINIO_PUBLIC_IP")
-	if globalDomainName != "" && globalDomainIP != "" && globalEtcdClient != nil {
+	minioEndpointsEnv, ok := os.LookupEnv("MINIO_PUBLIC_IPS")
+	if ok {
+		minioEndpoints := strings.Split(minioEndpointsEnv, ",")
+		globalDomainIPs = set.NewStringSet()
+		for i, ip := range minioEndpoints {
+			if net.ParseIP(ip) == nil {
+				logger.FatalIf(errInvalidArgument, "Unable to initialize Minio server with invalid MINIO_PUBLIC_IPS[%d]: %s", i, ip)
+			}
+			globalDomainIPs.Add(ip)
+		}
+	}
+	if globalDomainName != "" && !globalDomainIPs.IsEmpty() && globalEtcdClient != nil {
 		var err error
-		globalDNSConfig, err = dns.NewCoreDNS(globalDomainName, globalDomainIP, globalMinioPort, globalEtcdClient)
+		globalDNSConfig, err = dns.NewCoreDNS(globalDomainName, globalDomainIPs, globalMinioPort, globalEtcdClient)
 		logger.FatalIf(err, "Unable to initialize DNS config for %s.", globalDomainName)
 	}

--- a/cmd/generic-handlers.go
+++ b/cmd/generic-handlers.go
@ -26,9 +26,12 @@ import (
 	"strings"
 	"time"

+	"github.com/minio/minio-go/pkg/set"
+
 	"github.com/coreos/etcd/client"
 	humanize "github.com/dustin/go-humanize"
 	"github.com/minio/minio/cmd/logger"
+	"github.com/minio/minio/pkg/dns"
 	"github.com/minio/minio/pkg/handlers"
 	"github.com/minio/minio/pkg/sys"
 	"github.com/rs/cors"
@ -629,29 +632,37 @@ func (f bucketForwardingHandler) ServeHTTP(w http.ResponseWriter, r *http.Reques
 		return
 	}
 	bucket, object := urlPath2BucketObjectName(r.URL.Path)
-	// MakeBucket request
+	// MakeBucket requests should be handled at current endpoint
 	if r.Method == http.MethodPut && bucket != "" && object == "" {
 		f.handler.ServeHTTP(w, r)
 		return
 	}
-	// ListBucket request
+	// ListBucket requests should be handled at current endpoint as
+	// all buckets data can be fetched from here.
 	if r.Method == http.MethodGet && bucket == "" && object == "" {
 		f.handler.ServeHTTP(w, r)
 		return
 	}
+	// CopyObject requests should be handled at current endpoint as path style
+	// requests have target bucket and object in URI and source details are in
+	// header fields
+	if r.Method == http.MethodPut && r.Header.Get("X-Amz-Copy-Source") != "" {
+		f.handler.ServeHTTP(w, r)
+		return
+	}
 	sr, err := globalDNSConfig.Get(bucket)
 	if err != nil {
-		if client.IsKeyNotFound(err) {
+		if client.IsKeyNotFound(err) || err == dns.ErrNoEntriesFound {
 			writeErrorResponse(w, ErrNoSuchBucket, r.URL)
 		} else {
 			writeErrorResponse(w, toAPIErrorCode(err), r.URL)
 		}
 		return
 	}
-	if sr.Host != globalDomainIP {
-		backendURL := fmt.Sprintf("http://%s:%d", sr.Host, sr.Port)
+	if globalDomainIPs.Intersection(set.CreateStringSet(getHostsSlice(sr)...)).IsEmpty() {
+		backendURL := fmt.Sprintf("http://%s:%d", sr[0].Host, sr[0].Port)
 		if globalIsSSL {
-			backendURL = fmt.Sprintf("https://%s:%d", sr.Host, sr.Port)
+			backendURL = fmt.Sprintf("https://%s:%d", sr[0].Host, sr[0].Port)
 		}
 		r.URL, err = url.Parse(backendURL)
 		if err != nil {
--- a/cmd/globals.go
+++ b/cmd/globals.go
@ -22,6 +22,8 @@ import (
 	"runtime"
 	"time"

+	"github.com/minio/minio-go/pkg/set"
+
 	etcd "github.com/coreos/etcd/client"
 	humanize "github.com/dustin/go-humanize"
 	"github.com/fatih/color"
@ -161,8 +163,8 @@ var (
 	globalPublicCerts []*x509.Certificate

 	globalIsEnvDomainName bool
-	globalDomainName      string // Root domain for virtual host style requests
-	globalDomainIP        string // Root domain IP address
+	globalDomainName      string        // Root domain for virtual host style requests
+	globalDomainIPs       set.StringSet // Root domain IP address(s) for a distributed Minio deployment

 	globalListingTimeout   = newDynamicTimeout( /*30*/ 600*time.Second /*5*/, 600*time.Second) // timeout for listing related ops
 	globalObjectTimeout    = newDynamicTimeout( /*1*/ 10*time.Minute /*10*/, 600*time.Second)  // timeout for Object API related ops
--- a/cmd/object-api-utils.go
+++ b/cmd/object-api-utils.go
@ -20,12 +20,16 @@ import (
 	"context"
 	"encoding/hex"
 	"fmt"
+	"net"
 	"path"
 	"runtime"
+	"strconv"
 	"strings"
 	"unicode/utf8"

+	miniogo "github.com/minio/minio-go"
 	"github.com/minio/minio/cmd/logger"
+	"github.com/minio/minio/pkg/dns"
 	"github.com/skyrings/skyring-common/tools/uuid"
 )

@ -277,6 +281,40 @@ func isMinioReservedBucket(bucketName string) bool {
 	return bucketName == minioReservedBucket
 }

+// Returns a minio-go Client configured to access remote host described by destDNSRecord
+// Applicable only in a federated deployment
+func getRemoteInstanceClient(destDNSRecord dns.SrvRecord) (*miniogo.Core, error) {
+	// In a federated deployment, all the instances share config files and hence expected to have same
+	// credentials. So, access current instances creds and use it to create client for remote instance
+	client, err := miniogo.NewCore(net.JoinHostPort(destDNSRecord.Host, strconv.Itoa(destDNSRecord.Port)), globalServerConfig.Credential.AccessKey, globalServerConfig.Credential.SecretKey, globalIsSSL)
+	if err != nil {
+		return nil, err
+	}
+	return client, nil
+}
+
+// Checks if a remote putobject call is needed for CopyObject operation
+// 1. If source and destination bucket names are same, it means no call needed to etcd to get destination info
+// 2. If destination bucket doesn't exist locally, only then a etcd call is needed
+func isRemoteCallRequired(ctx context.Context, src, dst string, objAPI ObjectLayer) bool {
+	if src == dst {
+		return false
+	}
+	if _, err := objAPI.GetBucketInfo(ctx, dst); err == toObjectErr(errVolumeNotFound, dst) {
+		return true
+	}
+	return false
+}
+
+// returns a slice of hosts by reading a slice of DNS records
+func getHostsSlice(records []dns.SrvRecord) []string {
+	var hosts []string
+	for _, r := range records {
+		hosts = append(hosts, r.Host)
+	}
+	return hosts
+}
+
 // byBucketName is a collection satisfying sort.Interface.
 type byBucketName []BucketInfo

--- a/cmd/object-handlers.go
+++ b/cmd/object-handlers.go
@ -536,13 +536,51 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 		return
 	}

-	// Copy source object to destination, if source and destination
-	// object is same then only metadata is updated.
-	objInfo, err := objectAPI.CopyObject(ctx, srcBucket, srcObject, dstBucket, dstObject, srcInfo)
-	if err != nil {
-		pipeWriter.CloseWithError(err)
-		writeErrorResponse(w, toAPIErrorCode(err), r.URL)
-		return
+	var objInfo ObjectInfo
+
+	// _, err = objectAPI.GetBucketInfo(ctx, dstBucket)
+	// if err == toObjectErr(errVolumeNotFound, dstBucket) && !cpSrcDstSame
+	if isRemoteCallRequired(ctx, srcBucket, dstBucket, objectAPI) {
+		if globalDNSConfig != nil {
+			if dstRecord, errEtcd := globalDNSConfig.Get(dstBucket); errEtcd == nil {
+				go func() {
+					if gerr := objectAPI.GetObject(ctx, srcBucket, srcObject, 0, srcInfo.Size, srcInfo.Writer, srcInfo.ETag); gerr != nil {
+						pipeWriter.CloseWithError(gerr)
+						writeErrorResponse(w, ErrInternalError, r.URL)
+						return
+					}
+					// Close writer explicitly to indicate data has been written
+					defer srcInfo.Writer.Close()
+				}()
+				// Send PutObject request to appropriate instance (in federated deployment)
+				client, rerr := getRemoteInstanceClient(dstRecord[0])
+				if rerr != nil {
+					pipeWriter.CloseWithError(rerr)
+					writeErrorResponse(w, ErrInternalError, r.URL)
+					return
+				}
+				remoteObjInfo, rerr := client.PutObject(dstBucket, dstObject, srcInfo.Reader, srcInfo.Size, "", "", srcInfo.UserDefined)
+				if rerr != nil {
+					pipeWriter.CloseWithError(rerr)
+					writeErrorResponse(w, ErrInternalError, r.URL)
+					return
+				}
+				objInfo.ETag = remoteObjInfo.ETag
+				objInfo.ModTime = remoteObjInfo.LastModified
+			}
+		} else {
+			writeErrorResponse(w, ErrNoSuchBucket, r.URL)
+			return
+		}
+	} else {
+		// Copy source object to destination, if source and destination
+		// object is same then only metadata is updated.
+		objInfo, err = objectAPI.CopyObject(ctx, srcBucket, srcObject, dstBucket, dstObject, srcInfo)
+		if err != nil {
+			pipeWriter.CloseWithError(err)
+			writeErrorResponse(w, toAPIErrorCode(err), r.URL)
+			return
+		}
 	}

 	pipeReader.Close()
--- a/cmd/server-main.go
+++ b/cmd/server-main.go
@ -91,7 +91,7 @@ ENVIRONMENT VARIABLES:

  BUCKET-DNS:
     MINIO_DOMAIN:    To enable bucket DNS requests, set this value to Minio host domain name.
-     MINIO_PUBLIC_IP: To enable bucket DNS requests, set this value to Minio host public IP.
+     MINIO_PUBLIC_IPS: To enable bucket DNS requests, set this value to list of Minio host public IP(s) delimited by ",".
     MINIO_ETCD_ENDPOINTS: To enable bucket DNS requests, set this value to list of etcd endpoints delimited by ",".

 EXAMPLES:
--- a/cmd/web-handlers.go
+++ b/cmd/web-handlers.go
@ -40,6 +40,7 @@ import (
 	"github.com/minio/minio/browser"
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/auth"
+	"github.com/minio/minio/pkg/dns"
 	"github.com/minio/minio/pkg/event"
 	"github.com/minio/minio/pkg/hash"
 	"github.com/minio/minio/pkg/policy"
@ -138,7 +139,7 @@ func (web *webAPIHandlers) MakeBucket(r *http.Request, args *MakeBucketArgs, rep

 	if globalDNSConfig != nil {
 		if _, err := globalDNSConfig.Get(args.BucketName); err != nil {
-			if etcd.IsKeyNotFound(err) {
+			if etcd.IsKeyNotFound(err) || err == dns.ErrNoEntriesFound {
 				// Proceed to creating a bucket.
 				if err = objectAPI.MakeBucketWithLocation(context.Background(), args.BucketName, globalServerConfig.GetRegion()); err != nil {
 					return toJSONError(err)
--- a/docs/federation/lookup/README.md
+++ b/docs/federation/lookup/README.md
@ -21,21 +21,21 @@ Bucket lookup federation requires two dependencies
 ```
 export MINIO_ETCD_ENDPOINTS="http://remote-etcd1:2379,http://remote-etcd2:4001"
 export MINIO_DOMAIN=domain.com
-export MINIO_PUBLIC_IP=44.35.2.1
+export MINIO_PUBLIC_IPS=44.35.2.1,44.35.2.2,44.35.2.3,44.35.2.4
 minio server http://rack{1...4}.host{1...4}.domain.com/mnt/export{1...32}
 ```
 > cluster2
 ```
 export MINIO_ETCD_ENDPOINTS="http://remote-etcd1:2379,http://remote-etcd2:4001"
 export MINIO_DOMAIN=domain.com
-export MINIO_PUBLIC_IP=44.35.2.2
+export MINIO_PUBLIC_IPS=44.35.1.1,44.35.1.2,44.35.1.3,44.35.1.4
 minio server http://rack{5...8}.host{5...8}.domain.com/mnt/export{1...32}
 ```

 In this configuration you can see `MINIO_ETCD_ENDPOINTS` points to the etcd backend which manages Minio's
 `config.json` and bucket DNS SRV records. `MINIO_DOMAIN` indicates the domain suffix for the bucket which
 will be used to resolve bucket through DNS. For example if you have a bucket such as `mybucket`, the
-client can use now `mybucket.domain.com` to directly resolve itself to the right cluster. `MINIO_PUBLIC_IP`
+client can use now `mybucket.domain.com` to directly resolve itself to the right cluster. `MINIO_PUBLIC_IPS`
 points to the public IP address where each cluster might be accessible, this is unique for each cluster.

 NOTE: `mybucket` only exists on one cluster either `cluster1` or `cluster2` this is random and
--- a/pkg/dns/coredns.go
+++ b/pkg/dns/coredns.go
@ -21,18 +21,22 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"net"
 	"sort"
 	"strconv"
 	"strings"
 	"time"

+	"github.com/minio/minio-go/pkg/set"
+
 	"github.com/coredns/coredns/plugin/etcd/msg"
 	etcd "github.com/coreos/etcd/client"
 )

+// ErrNoEntriesFound - Indicates no entries were found for the given key (directory)
+var ErrNoEntriesFound = errors.New("No entries found for this key")
+
 // create a new coredns service record for the bucket.
-func newCoreDNSMsg(bucket string, ip string, port int, ttl uint32) ([]byte, error) {
+func newCoreDNSMsg(bucket, ip string, port int, ttl uint32) ([]byte, error) {
 	return json.Marshal(&SrvRecord{
 		Host:         ip,
 		Port:         port,
@ -41,12 +45,24 @@ func newCoreDNSMsg(bucket string, ip string, port int, ttl uint32) ([]byte, erro
 	})
 }

-// Retrieves list of DNS entries for a bucket.
+// Retrieves list of DNS entries for the domain.
 func (c *coreDNS) List() ([]SrvRecord, error) {
-	kapi := etcd.NewKeysAPI(c.etcdClient)
 	key := msg.Path(fmt.Sprintf("%s.", c.domainName), defaultPrefixPath)
+	return c.list(key)
+}
+
+// Retrieves DNS records for a bucket.
+func (c *coreDNS) Get(bucket string) ([]SrvRecord, error) {
+	key := msg.Path(fmt.Sprintf("%s.%s.", bucket, c.domainName), defaultPrefixPath)
+	return c.list(key)
+}
+
+// Retrieves list of entries under the key passed.
+// Note that this method fetches entries upto only two levels deep.
+func (c *coreDNS) list(key string) ([]SrvRecord, error) {
+	kapi := etcd.NewKeysAPI(c.etcdClient)
 	ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
-	r, err := kapi.Get(ctx, key, nil)
+	r, err := kapi.Get(ctx, key, &etcd.GetOptions{Recursive: true})
 	cancel()
 	if err != nil {
 		return nil, err
@ -54,48 +70,52 @@ func (c *coreDNS) List() ([]SrvRecord, error) {

 	var srvRecords []SrvRecord
 	for _, n := range r.Node.Nodes {
-		var srvRecord SrvRecord
-		if err = json.Unmarshal([]byte(n.Value), &srvRecord); err != nil {
-			return nil, err
+		if !n.Dir {
+			var srvRecord SrvRecord
+			if err = json.Unmarshal([]byte(n.Value), &srvRecord); err != nil {
+				return nil, err
+			}
+			srvRecord.Key = strings.TrimPrefix(n.Key, key)
+			srvRecords = append(srvRecords, srvRecord)
+		} else {
+			// As this is a directory, loop through all the nodes inside
+			for _, n1 := range n.Nodes {
+				var srvRecord SrvRecord
+				if err = json.Unmarshal([]byte(n1.Value), &srvRecord); err != nil {
+					return nil, err
+				}
+				srvRecord.Key = strings.TrimPrefix(n1.Key, key)
+				srvRecord.Key = strings.TrimSuffix(srvRecord.Key, srvRecord.Host)
+				srvRecords = append(srvRecords, srvRecord)
+			}
 		}
-		srvRecord.Key = strings.TrimPrefix(n.Key, key)
-		srvRecords = append(srvRecords, srvRecord)
 	}
-	sort.Slice(srvRecords, func(i int, j int) bool {
-		return srvRecords[i].Key < srvRecords[j].Key
-	})
+	if srvRecords != nil {
+		sort.Slice(srvRecords, func(i int, j int) bool {
+			return srvRecords[i].Key < srvRecords[j].Key
+		})
+	} else {
+		return nil, ErrNoEntriesFound
+	}
 	return srvRecords, nil
 }

-// Retrieves DNS record for a bucket.
-func (c *coreDNS) Get(bucket string) (SrvRecord, error) {
-	kapi := etcd.NewKeysAPI(c.etcdClient)
-	key := msg.Path(fmt.Sprintf("%s.%s.", bucket, c.domainName), defaultPrefixPath)
-	ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
-	r, err := kapi.Get(ctx, key, nil)
-	cancel()
-	if err != nil {
-		return SrvRecord{}, err
-	}
-	var sr SrvRecord
-	if err = json.Unmarshal([]byte(r.Node.Value), &sr); err != nil {
-		return SrvRecord{}, err
-	}
-	sr.Key = strings.TrimPrefix(r.Node.Key, key)
-	return sr, nil
-}
-
-// Adds DNS entries into etcd endpoint in CoreDNS etcd messae format.
+// Adds DNS entries into etcd endpoint in CoreDNS etcd message format.
 func (c *coreDNS) Put(bucket string) error {
-	bucketMsg, err := newCoreDNSMsg(bucket, c.domainIP, c.domainPort, defaultTTL)
-	if err != nil {
-		return err
+	var err error
+	for ip := range c.domainIPs {
+		var bucketMsg []byte
+		bucketMsg, err = newCoreDNSMsg(bucket, ip, c.domainPort, defaultTTL)
+		if err != nil {
+			return err
+		}
+		kapi := etcd.NewKeysAPI(c.etcdClient)
+		key := msg.Path(fmt.Sprintf("%s.%s", bucket, c.domainName), defaultPrefixPath)
+		key = key + "/" + ip
+		ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
+		_, err = kapi.Set(ctx, key, string(bucketMsg), nil)
+		cancel()
 	}
-	kapi := etcd.NewKeysAPI(c.etcdClient)
-	key := msg.Path(fmt.Sprintf("%s.%s.", bucket, c.domainName), defaultPrefixPath)
-	ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
-	_, err = kapi.Set(ctx, key, string(bucketMsg), nil)
-	cancel()
 	return err
 }

@ -111,18 +131,15 @@ func (c *coreDNS) Delete(bucket string) error {

 // CoreDNS - represents dns config for coredns server.
 type coreDNS struct {
-	domainName, domainIP string
-	domainPort           int
-	etcdClient           etcd.Client
+	domainName string
+	domainIPs  set.StringSet
+	domainPort int
+	etcdClient etcd.Client
 }

 // NewCoreDNS - initialize a new coreDNS set/unset values.
-func NewCoreDNS(domainName, domainIP, domainPort string, etcdClient etcd.Client) (Config, error) {
-	if domainName == "" || domainIP == "" || etcdClient == nil {
-		return nil, errors.New("invalid argument")
-	}
-
-	if net.ParseIP(domainIP) == nil {
+func NewCoreDNS(domainName string, domainIPs set.StringSet, domainPort string, etcdClient etcd.Client) (Config, error) {
+	if domainName == "" || domainIPs.IsEmpty() || etcdClient == nil {
 		return nil, errors.New("invalid argument")
 	}

@ -133,7 +150,7 @@ func NewCoreDNS(domainName, domainIP, domainPort string, etcdClient etcd.Client)

 	return &coreDNS{
 		domainName: domainName,
-		domainIP:   domainIP,
+		domainIPs:  domainIPs,
 		domainPort: port,
 		etcdClient: etcdClient,
 	}, nil
--- a/pkg/dns/dns.go
+++ b/pkg/dns/dns.go
@ -60,6 +60,6 @@ type SrvRecord struct {
 type Config interface {
 	Put(key string) error
 	List() ([]SrvRecord, error)
-	Get(key string) (SrvRecord, error)
+	Get(key string) ([]SrvRecord, error)
 	Delete(key string) error
 }
--- a/pkg/quick/encoding.go
+++ b/pkg/quick/encoding.go
@ -140,6 +140,9 @@ func saveFileConfigEtcd(filename string, clnt etcd.Client, v interface{}) error
 	kapi := etcd.NewKeysAPI(clnt)
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
 	_, err = kapi.Update(ctx, filename, string(dataBytes))
+	if etcd.IsKeyNotFound(err) {
+		_, err = kapi.Create(ctx, filename, string(dataBytes))
+	}
 	cancel()
 	return err
 }