prometheus/retrieval/discovery/nerve.go

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// Copyright 2015 The Prometheus Authors
// 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 discovery
import (
"encoding/json"
"fmt"
"sync"
"time"
"github.com/prometheus/common/model"
"github.com/samuel/go-zookeeper/zk"
"golang.org/x/net/context"
"github.com/prometheus/prometheus/config"
"github.com/prometheus/prometheus/util/treecache"
)
const (
nerveLabelPrefix = model.MetaLabelPrefix + "nerve_"
nervePathLabel = nerveLabelPrefix + "path"
nerveEndpointLabelPrefix = nerveLabelPrefix + "endpoint"
)
type nerveMember struct {
Host string `json:"host"`
Port int `json:"port"`
Name string `json:"name"`
}
// NerveDiscovery retrieves target information from a Nerve server
// and updates them via watches.
type NerveDiscovery struct {
conf *config.NerveSDConfig
conn *zk.Conn
mu sync.RWMutex
sources map[string]*config.TargetGroup
sdUpdates *chan<- []*config.TargetGroup
updates chan treecache.ZookeeperTreeCacheEvent
treeCaches []*treecache.ZookeeperTreeCache
}
// NewNerveDiscovery returns a new NerveDiscovery for the given config.
func NewNerveDiscovery(conf *config.NerveSDConfig) *NerveDiscovery {
conn, _, err := zk.Connect(conf.Servers, time.Duration(conf.Timeout))
conn.SetLogger(treecache.ZookeeperLogger{})
if err != nil {
return nil
}
updates := make(chan treecache.ZookeeperTreeCacheEvent)
sd := &NerveDiscovery{
conf: conf,
conn: conn,
updates: updates,
sources: map[string]*config.TargetGroup{},
}
go sd.processUpdates()
for _, path := range conf.Paths {
sd.treeCaches = append(sd.treeCaches, treecache.NewZookeeperTreeCache(conn, path, updates))
}
return sd
}
func (sd *NerveDiscovery) processUpdates() {
defer sd.conn.Close()
for event := range sd.updates {
tg := &config.TargetGroup{
Source: event.Path,
}
sd.mu.Lock()
if event.Data != nil {
labelSet, err := parseNerveMember(*event.Data, event.Path)
if err == nil {
tg.Targets = []model.LabelSet{*labelSet}
sd.sources[event.Path] = tg
} else {
delete(sd.sources, event.Path)
}
} else {
delete(sd.sources, event.Path)
}
sd.mu.Unlock()
if sd.sdUpdates != nil {
*sd.sdUpdates <- []*config.TargetGroup{tg}
}
}
if sd.sdUpdates != nil {
close(*sd.sdUpdates)
}
}
// Run implements the TargetProvider interface.
func (sd *NerveDiscovery) Run(ctx context.Context, ch chan<- []*config.TargetGroup) {
// Send on everything we have seen so far.
sd.mu.Lock()
all := make([]*config.TargetGroup, 0, len(sd.sources))
for _, tg := range sd.sources {
all = append(all, tg)
}
ch <- all
// Tell processUpdates to send future updates.
sd.sdUpdates = &ch
sd.mu.Unlock()
<-ctx.Done()
for _, tc := range sd.treeCaches {
tc.Stop()
}
}
func parseNerveMember(data []byte, path string) (*model.LabelSet, error) {
member := nerveMember{}
err := json.Unmarshal(data, &member)
if err != nil {
return nil, fmt.Errorf("error unmarshaling nerve member %q: %s", path, err)
}
labels := model.LabelSet{}
labels[nervePathLabel] = model.LabelValue(path)
labels[model.AddressLabel] = model.LabelValue(
fmt.Sprintf("%s:%d", member.Host, member.Port))
labels[nerveEndpointLabelPrefix+"_host"] = model.LabelValue(member.Host)
labels[nerveEndpointLabelPrefix+"_port"] = model.LabelValue(fmt.Sprintf("%d", member.Port))
labels[nerveEndpointLabelPrefix+"_name"] = model.LabelValue(member.Name)
return &labels, nil
}