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https://github.com/etcd-io/etcd.git
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Merge pull request #1947 from barakmich/dns_bootstrap
add capability to bootstrap from DNS SRV
This commit is contained in:
Barak Michener
commit
4f2d35679e
@ -59,6 +59,7 @@ var (
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name = fs.String("name", "default", "Unique human-readable name for this node")
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dir = fs.String("data-dir", "", "Path to the data directory")
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durl = fs.String("discovery", "", "Discovery service used to bootstrap the cluster")
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dnsCluster = fs.String("discovery-srv", "", "Bootstrap initial cluster via DNS domain")
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dproxy = fs.String("discovery-proxy", "", "HTTP proxy to use for traffic to discovery service")
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snapCount = fs.Uint64("snapshot-count", etcdserver.DefaultSnapCount, "Number of committed transactions to trigger a snapshot")
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printVersion = fs.Bool("version", false, "Print the version and exit")
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@ -102,6 +103,8 @@ var (
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"v",
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"vv",
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}
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lookupSRV = net.LookupSRV
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)
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func init() {
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@ -403,8 +406,14 @@ func setupCluster(apurls []url.URL) (*etcdserver.Cluster, error) {
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fs.Visit(func(f *flag.Flag) {
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set[f.Name] = true
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})
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if set["discovery"] && set["initial-cluster"] {
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return nil, fmt.Errorf("both discovery and bootstrap-config are set")
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nSet := 0
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for _, v := range []bool{set["discovery"], set["inital-cluster"], set["discovery-srv"]} {
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if v {
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nSet += 1
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}
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}
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if nSet > 1 {
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return nil, fmt.Errorf("multiple discovery or bootstrap flags are set. Choose one of \"discovery\", \"initial-cluster\", or \"discovery-srv\"")
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}
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var cls *etcdserver.Cluster
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var err error
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@ -414,6 +423,12 @@ func setupCluster(apurls []url.URL) (*etcdserver.Cluster, error) {
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// self's advertised peer URLs
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clusterStr := genClusterString(*name, apurls)
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cls, err = etcdserver.NewClusterFromString(*durl, clusterStr)
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case set["discovery-srv"]:
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clusterStr, clusterToken, err := genDNSClusterString(*initialClusterToken, apurls)
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if err != nil {
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return nil, err
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}
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cls, err = etcdserver.NewClusterFromString(clusterToken, clusterStr)
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case set["initial-cluster"]:
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fallthrough
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default:
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@ -430,3 +445,67 @@ func genClusterString(name string, urls types.URLs) string {
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}
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return strings.Join(addrs, ",")
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}
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// TODO(barakmich): Currently ignores priority and weight (as they don't make as much sense for a bootstrap)
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// Also doesn't do any lookups for the token (though it could)
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// Also sees each entry as a separate instance.
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func genDNSClusterString(defaultToken string, apurls types.URLs) (string, string, error) {
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stringParts := make([]string, 0)
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tempName := int(0)
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tcpAPUrls := make([]string, 0)
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// First, resolve the apurls
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for _, url := range apurls {
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tcpAddr, err := net.ResolveTCPAddr("tcp", url.Host)
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if err != nil {
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log.Printf("etcd: Couldn't resolve host %s during SRV discovery", url.Host)
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return "", "", err
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}
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tcpAPUrls = append(tcpAPUrls, tcpAddr.String())
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}
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updateNodeMap := func(service, prefix string) error {
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_, addrs, err := lookupSRV(service, "tcp", *dnsCluster)
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if err != nil {
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return err
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}
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for _, srv := range addrs {
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host := net.JoinHostPort(srv.Target, fmt.Sprintf("%d", srv.Port))
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tcpAddr, err := net.ResolveTCPAddr("tcp", host)
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if err != nil {
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log.Printf("etcd: Couldn't resolve host %s during SRV discovery", host)
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continue
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}
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n := ""
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for _, url := range tcpAPUrls {
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if url == tcpAddr.String() {
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n = *name
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}
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}
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if n == "" {
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n = fmt.Sprintf("%d", tempName)
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tempName += 1
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}
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stringParts = append(stringParts, fmt.Sprintf("%s=%s%s", n, prefix, tcpAddr.String()))
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log.Printf("etcd: Got bootstrap from DNS for %s at host %s to %s%s", service, host, prefix, tcpAddr.String())
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}
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return nil
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}
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failCount := 0
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err := updateNodeMap("etcd-server-ssl", "https://")
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if err != nil {
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log.Printf("etcd: Error querying DNS SRV records for _etcd-server-ssl. Error: %s.", err)
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failCount += 1
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}
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err = updateNodeMap("etcd-server", "http://")
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if err != nil {
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log.Printf("etcd: Error querying DNS SRV records for _etcd-server. Error: %s.", err)
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failCount += 1
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}
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if failCount == 2 {
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log.Printf("etcd: Too many errors querying DNS SRV records. Failing discovery.")
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return "", "", err
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}
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return strings.Join(stringParts, ","), defaultToken, nil
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}
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@ -17,6 +17,8 @@
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package etcdmain
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import (
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"errors"
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"net"
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"net/url"
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"testing"
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@ -24,6 +26,9 @@ import (
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)
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func mustNewURLs(t *testing.T, urls []string) []url.URL {
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if urls == nil {
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return nil
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}
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u, err := types.NewURLs(urls)
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if err != nil {
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t.Fatalf("unexpected new urls error: %v", err)
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@ -54,3 +59,80 @@ func TestGenClusterString(t *testing.T) {
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}
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}
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}
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func TestGenDNSClusterString(t *testing.T) {
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oldname := *name
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*name = "dnsClusterTest"
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defer func() { *name = oldname }()
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tests := []struct {
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withSSL []*net.SRV
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withoutSSL []*net.SRV
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urls []string
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expected string
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}{
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{
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[]*net.SRV{},
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[]*net.SRV{},
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nil,
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"",
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},
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{
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[]*net.SRV{
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&net.SRV{Target: "10.0.0.1", Port: 2480},
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&net.SRV{Target: "10.0.0.2", Port: 2480},
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&net.SRV{Target: "10.0.0.3", Port: 2480},
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},
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[]*net.SRV{},
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nil,
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"0=https://10.0.0.1:2480,1=https://10.0.0.2:2480,2=https://10.0.0.3:2480",
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},
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{
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[]*net.SRV{
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&net.SRV{Target: "10.0.0.1", Port: 2480},
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&net.SRV{Target: "10.0.0.2", Port: 2480},
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&net.SRV{Target: "10.0.0.3", Port: 2480},
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},
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[]*net.SRV{
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&net.SRV{Target: "10.0.0.1", Port: 7001},
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},
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nil,
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"0=https://10.0.0.1:2480,1=https://10.0.0.2:2480,2=https://10.0.0.3:2480,3=http://10.0.0.1:7001",
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},
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{
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[]*net.SRV{
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&net.SRV{Target: "10.0.0.1", Port: 2480},
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&net.SRV{Target: "10.0.0.2", Port: 2480},
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&net.SRV{Target: "10.0.0.3", Port: 2480},
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},
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[]*net.SRV{
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&net.SRV{Target: "10.0.0.1", Port: 7001},
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},
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[]string{"https://10.0.0.1:2480"},
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"dnsClusterTest=https://10.0.0.1:2480,0=https://10.0.0.2:2480,1=https://10.0.0.3:2480,2=http://10.0.0.1:7001",
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},
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}
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for i, tt := range tests {
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lookupSRV = func(service string, proto string, domain string) (string, []*net.SRV, error) {
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if service == "etcd-server-ssl" {
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return "", tt.withSSL, nil
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}
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if service == "etcd-server" {
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return "", tt.withoutSSL, nil
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}
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return "", nil, errors.New("Unkown service in mock")
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}
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defer func() { lookupSRV = net.LookupSRV }()
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urls := mustNewURLs(t, tt.urls)
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str, token, err := genDNSClusterString("token", urls)
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if err != nil {
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t.Fatalf("%d: err: %#v", i, err)
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}
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if token != "token" {
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t.Errorf("%d: token: %s", i, token)
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}
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if str != tt.expected {
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t.Errorf("#%d: cluster = %s, want %s", i, str, tt.expected)
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}
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}
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}
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