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config.go
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config.go
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// Copyright 2018 Authors of Cilium
//
// 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 clustermesh
import (
"io/ioutil"
"path"
"path/filepath"
"strings"
fsnotify "gopkg.in/fsnotify.v1"
)
// clusterLifecycle is the interface to implement in order to receive cluster
// configuration lifecycle events. This is implemented by the ClusterMesh.
type clusterLifecycle interface {
add(clusterName, clusterConfigPath string)
remove(clusterName string)
}
type configDirectoryWatcher struct {
watcher *fsnotify.Watcher
lifecycle clusterLifecycle
path string
stop chan struct{}
}
func createConfigDirectoryWatcher(path string, lifecycle clusterLifecycle) (*configDirectoryWatcher, error) {
watcher, err := fsnotify.NewWatcher()
if err != nil {
return nil, err
}
if err := watcher.Add(path); err != nil {
watcher.Close()
return nil, err
}
return &configDirectoryWatcher{
watcher: watcher,
path: path,
lifecycle: lifecycle,
stop: make(chan struct{}),
}, nil
}
func isEtcdConfigFile(path string) bool {
b, err := ioutil.ReadFile(path)
if err != nil {
return false
}
// search for the "endpoints:" string
return strings.Contains(string(b), "endpoints:")
}
func (cdw *configDirectoryWatcher) watch() error {
log.WithField(fieldConfig, cdw.path).Debug("Starting config directory watcher")
files, err := ioutil.ReadDir(cdw.path)
if err != nil {
return err
}
for _, f := range files {
// A typical directory will look like this:
// lrwxrwxrwx. 1 root root 12 Jul 21 16:32 test5 -> ..data/test5
// lrwxrwxrwx. 1 root root 12 Jul 21 16:32 test7 -> ..data/test7
//
// Ignore all backing files and only read the symlinks
if strings.HasPrefix(f.Name(), "..") {
continue
}
absolutePath := path.Join(cdw.path, f.Name())
if !isEtcdConfigFile(absolutePath) {
continue
}
log.WithField(fieldClusterName, f.Name()).WithField("mode", f.Mode()).Debugf("Found configuration in initial scan")
cdw.lifecycle.add(f.Name(), absolutePath)
}
go func() {
for {
select {
case event := <-cdw.watcher.Events:
name := filepath.Base(event.Name)
log.WithField(fieldClusterName, name).Debugf("Received fsnotify event: %+v", event)
switch event.Op {
case fsnotify.Create, fsnotify.Write, fsnotify.Chmod:
cdw.lifecycle.add(name, event.Name)
case fsnotify.Remove, fsnotify.Rename:
cdw.lifecycle.remove(name)
}
case err := <-cdw.watcher.Errors:
log.WithError(err).WithField("path", cdw.path).Warning("error encountered while watching directory with fsnotify")
case <-cdw.stop:
return
}
}
}()
return nil
}
func (cdw *configDirectoryWatcher) close() {
close(cdw.stop)
cdw.watcher.Close()
}