105 lines
3.2 KiB
Go
105 lines
3.2 KiB
Go
// Copyright 2015 The etcd Authors
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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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package discovery
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import (
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"fmt"
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"net"
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"net/url"
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"strings"
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"github.com/coreos/etcd/pkg/types"
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)
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var (
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// indirection for testing
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lookupSRV = net.LookupSRV
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resolveTCPAddr = net.ResolveTCPAddr
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)
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// SRVGetCluster gets the cluster information via DNS discovery.
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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 SRVGetCluster(name, dns string, defaultToken string, apurls types.URLs) (string, string, error) {
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tempName := int(0)
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tcp2ap := make(map[string]url.URL)
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// First, resolve the apurls
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for _, url := range apurls {
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tcpAddr, err := resolveTCPAddr("tcp", url.Host)
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if err != nil {
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plog.Errorf("couldn't resolve host %s during SRV discovery", url.Host)
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return "", "", err
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}
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tcp2ap[tcpAddr.String()] = url
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}
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stringParts := []string{}
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updateNodeMap := func(service, scheme string) error {
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_, addrs, err := lookupSRV(service, "tcp", dns)
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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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port := fmt.Sprintf("%d", srv.Port)
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host := net.JoinHostPort(srv.Target, port)
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tcpAddr, err := resolveTCPAddr("tcp", host)
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if err != nil {
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plog.Warningf("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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url, ok := tcp2ap[tcpAddr.String()]
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if ok {
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n = name
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}
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if n == "" {
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n = fmt.Sprintf("%d", tempName)
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tempName++
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}
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// SRV records have a trailing dot but URL shouldn't.
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shortHost := strings.TrimSuffix(srv.Target, ".")
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urlHost := net.JoinHostPort(shortHost, port)
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stringParts = append(stringParts, fmt.Sprintf("%s=%s://%s", n, scheme, urlHost))
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plog.Noticef("got bootstrap from DNS for %s at %s://%s", service, scheme, urlHost)
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if ok && url.Scheme != scheme {
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plog.Errorf("bootstrap at %s from DNS for %s has scheme mismatch with expected peer %s", scheme+"://"+urlHost, service, url.String())
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}
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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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srvErr := make([]string, 2)
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if err != nil {
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srvErr[0] = fmt.Sprintf("error querying DNS SRV records for _etcd-server-ssl %s", err)
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failCount++
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}
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err = updateNodeMap("etcd-server", "http")
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if err != nil {
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srvErr[1] = fmt.Sprintf("error querying DNS SRV records for _etcd-server %s", err)
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failCount++
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}
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if failCount == 2 {
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plog.Warningf(srvErr[0])
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plog.Warningf(srvErr[1])
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plog.Errorf("SRV discovery failed: too many errors querying DNS SRV records")
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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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