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Merge pull request #2625 from bakins/client-srv

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Initial SRV discovery for clients
This commit is contained in:
Xiang Li 2015-04-17 08:07:32 -07:00
commit 61e94ae16c
3 changed files with 188 additions and 0 deletions
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21
client/discover.go Normal file
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// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package client
// Discoverer is an interface that wraps the Discover method.
type Discoverer interface {
// Dicover looks up the etcd servers for the domain.
Discover(domain string) ([]string, error)
}

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client/srv.go Normal file
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// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package client
import (
"fmt"
"net"
"net/url"
)
var (
// indirection for testing
lookupSRV = net.LookupSRV
)
type srvDiscover struct{}
// NewSRVDiscover constructs a new Dicoverer that uses the stdlib to lookup SRV records.
func NewSRVDiscover() Discoverer {
return &srvDiscover{}
}
// Discover looks up the etcd servers for the domain.
func (d *srvDiscover) Discover(domain string) ([]string, error) {
var urls []*url.URL
updateURLs := func(service, scheme string) error {
_, addrs, err := lookupSRV(service, "tcp", domain)
if err != nil {
return err
}
for _, srv := range addrs {
urls = append(urls, &url.URL{
Scheme: scheme,
Host: net.JoinHostPort(srv.Target, fmt.Sprintf("%d", srv.Port)),
})
}
return nil
}
errHTTPS := updateURLs("etcd-server-ssl", "https")
errHTTP := updateURLs("etcd-server", "http")
if errHTTPS != nil && errHTTP != nil {
return nil, fmt.Errorf("dns lookup errors: %s and %s", errHTTPS, errHTTP)
}
endpoints := make([]string, len(urls))
for i := range urls {
endpoints[i] = urls[i].String()
}
return endpoints, nil
}

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client/srv_test.go Normal file
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// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package client
import (
"errors"
"net"
"reflect"
"testing"
)
func TestSRVDiscover(t *testing.T) {
defer func() { lookupSRV = net.LookupSRV }()
tests := []struct {
withSSL []*net.SRV
withoutSSL []*net.SRV
expected []string
}{
{
[]*net.SRV{},
[]*net.SRV{},
[]string{},
},
{
[]*net.SRV{
&net.SRV{Target: "10.0.0.1", Port: 2480},
&net.SRV{Target: "10.0.0.2", Port: 2480},
&net.SRV{Target: "10.0.0.3", Port: 2480},
},
[]*net.SRV{},
[]string{"https://10.0.0.1:2480", "https://10.0.0.2:2480", "https://10.0.0.3:2480"},
},
{
[]*net.SRV{
&net.SRV{Target: "10.0.0.1", Port: 2480},
&net.SRV{Target: "10.0.0.2", Port: 2480},
&net.SRV{Target: "10.0.0.3", Port: 2480},
},
[]*net.SRV{
&net.SRV{Target: "10.0.0.1", Port: 7001},
},
[]string{"https://10.0.0.1:2480", "https://10.0.0.2:2480", "https://10.0.0.3:2480", "http://10.0.0.1:7001"},
},
{
[]*net.SRV{
&net.SRV{Target: "10.0.0.1", Port: 2480},
&net.SRV{Target: "10.0.0.2", Port: 2480},
&net.SRV{Target: "10.0.0.3", Port: 2480},
},
[]*net.SRV{
&net.SRV{Target: "10.0.0.1", Port: 7001},
},
[]string{"https://10.0.0.1:2480", "https://10.0.0.2:2480", "https://10.0.0.3:2480", "http://10.0.0.1:7001"},
},
{
[]*net.SRV{
&net.SRV{Target: "a.example.com", Port: 2480},
&net.SRV{Target: "b.example.com", Port: 2480},
&net.SRV{Target: "c.example.com", Port: 2480},
},
[]*net.SRV{},
[]string{"https://a.example.com:2480", "https://b.example.com:2480", "https://c.example.com:2480"},
},
}
for i, tt := range tests {
lookupSRV = func(service string, proto string, domain string) (string, []*net.SRV, error) {
if service == "etcd-server-ssl" {
return "", tt.withSSL, nil
}
if service == "etcd-server" {
return "", tt.withoutSSL, nil
}
return "", nil, errors.New("Unkown service in mock")
}
d := NewSRVDiscover()
endpoints, err := d.Discover("example.com")
if err != nil {
t.Fatalf("%d: err: %#v", i, err)
}
if !reflect.DeepEqual(endpoints, tt.expected) {
t.Errorf("#%d: endpoints = %v, want %v", i, endpoints, tt.expected)
}
}
}