Add pkg/discovery for nodes discovery

Absorb Swarm's discovery package in order to provide a common node
discovery mechanism to be used by both Swarm and networking code.

Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>
This commit is contained in:
Arnaud Porterie 2015-08-31 13:23:17 -07:00
parent fdd5ab2fc3
commit 35c086fa6b
13 changed files with 1015 additions and 0 deletions

109
discovery/file/file.go Normal file
View file

@ -0,0 +1,109 @@
package file
import (
"fmt"
"io/ioutil"
"strings"
"time"
"github.com/docker/docker/pkg/discovery"
)
// Discovery is exported
type Discovery struct {
heartbeat time.Duration
path string
}
func init() {
Init()
}
// Init is exported
func Init() {
discovery.Register("file", &Discovery{})
}
// Initialize is exported
func (s *Discovery) Initialize(path string, heartbeat time.Duration, ttl time.Duration) error {
s.path = path
s.heartbeat = heartbeat
return nil
}
func parseFileContent(content []byte) []string {
var result []string
for _, line := range strings.Split(strings.TrimSpace(string(content)), "\n") {
line = strings.TrimSpace(line)
// Ignoring line starts with #
if strings.HasPrefix(line, "#") {
continue
}
// Inlined # comment also ignored.
if strings.Contains(line, "#") {
line = line[0:strings.Index(line, "#")]
// Trim additional spaces caused by above stripping.
line = strings.TrimSpace(line)
}
for _, ip := range discovery.Generate(line) {
result = append(result, ip)
}
}
return result
}
func (s *Discovery) fetch() (discovery.Entries, error) {
fileContent, err := ioutil.ReadFile(s.path)
if err != nil {
return nil, fmt.Errorf("failed to read '%s': %v", s.path, err)
}
return discovery.CreateEntries(parseFileContent(fileContent))
}
// Watch is exported
func (s *Discovery) Watch(stopCh <-chan struct{}) (<-chan discovery.Entries, <-chan error) {
ch := make(chan discovery.Entries)
errCh := make(chan error)
ticker := time.NewTicker(s.heartbeat)
go func() {
defer close(errCh)
defer close(ch)
// Send the initial entries if available.
currentEntries, err := s.fetch()
if err != nil {
errCh <- err
} else {
ch <- currentEntries
}
// Periodically send updates.
for {
select {
case <-ticker.C:
newEntries, err := s.fetch()
if err != nil {
errCh <- err
continue
}
// Check if the file has really changed.
if !newEntries.Equals(currentEntries) {
ch <- newEntries
}
currentEntries = newEntries
case <-stopCh:
ticker.Stop()
return
}
}
}()
return ch, errCh
}
// Register is exported
func (s *Discovery) Register(addr string) error {
return discovery.ErrNotImplemented
}

106
discovery/file/file_test.go Normal file
View file

@ -0,0 +1,106 @@
package file
import (
"io/ioutil"
"os"
"testing"
"github.com/docker/docker/pkg/discovery"
"github.com/stretchr/testify/assert"
)
func TestInitialize(t *testing.T) {
d := &Discovery{}
d.Initialize("/path/to/file", 1000, 0)
assert.Equal(t, d.path, "/path/to/file")
}
func TestNew(t *testing.T) {
d, err := discovery.New("file:///path/to/file", 0, 0)
assert.NoError(t, err)
assert.Equal(t, d.(*Discovery).path, "/path/to/file")
}
func TestContent(t *testing.T) {
data := `
1.1.1.[1:2]:1111
2.2.2.[2:4]:2222
`
ips := parseFileContent([]byte(data))
assert.Len(t, ips, 5)
assert.Equal(t, ips[0], "1.1.1.1:1111")
assert.Equal(t, ips[1], "1.1.1.2:1111")
assert.Equal(t, ips[2], "2.2.2.2:2222")
assert.Equal(t, ips[3], "2.2.2.3:2222")
assert.Equal(t, ips[4], "2.2.2.4:2222")
}
func TestRegister(t *testing.T) {
discovery := &Discovery{path: "/path/to/file"}
assert.Error(t, discovery.Register("0.0.0.0"))
}
func TestParsingContentsWithComments(t *testing.T) {
data := `
### test ###
1.1.1.1:1111 # inline comment
# 2.2.2.2:2222
### empty line with comment
3.3.3.3:3333
### test ###
`
ips := parseFileContent([]byte(data))
assert.Len(t, ips, 2)
assert.Equal(t, "1.1.1.1:1111", ips[0])
assert.Equal(t, "3.3.3.3:3333", ips[1])
}
func TestWatch(t *testing.T) {
data := `
1.1.1.1:1111
2.2.2.2:2222
`
expected := discovery.Entries{
&discovery.Entry{Host: "1.1.1.1", Port: "1111"},
&discovery.Entry{Host: "2.2.2.2", Port: "2222"},
}
// Create a temporary file and remove it.
tmp, err := ioutil.TempFile(os.TempDir(), "discovery-file-test")
assert.NoError(t, err)
assert.NoError(t, tmp.Close())
assert.NoError(t, os.Remove(tmp.Name()))
// Set up file discovery.
d := &Discovery{}
d.Initialize(tmp.Name(), 1000, 0)
stopCh := make(chan struct{})
ch, errCh := d.Watch(stopCh)
// Make sure it fires errors since the file doesn't exist.
assert.Error(t, <-errCh)
// We have to drain the error channel otherwise Watch will get stuck.
go func() {
for range errCh {
}
}()
// Write the file and make sure we get the expected value back.
assert.NoError(t, ioutil.WriteFile(tmp.Name(), []byte(data), 0600))
assert.Equal(t, expected, <-ch)
// Add a new entry and look it up.
expected = append(expected, &discovery.Entry{Host: "3.3.3.3", Port: "3333"})
f, err := os.OpenFile(tmp.Name(), os.O_APPEND|os.O_WRONLY, 0600)
assert.NoError(t, err)
assert.NotNil(t, f)
_, err = f.WriteString("\n3.3.3.3:3333\n")
assert.NoError(t, err)
f.Close()
assert.Equal(t, expected, <-ch)
// Stop and make sure it closes all channels.
close(stopCh)
assert.Nil(t, <-ch)
assert.Nil(t, <-errCh)
}