forked from prometheus/prometheus
/
consul.go
529 lines (471 loc) · 16.2 KB
/
consul.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 consul
import (
"context"
"fmt"
"net"
"net/http"
"strconv"
"strings"
"time"
"github.com/go-kit/kit/log"
"github.com/go-kit/kit/log/level"
consul "github.com/hashicorp/consul/api"
"github.com/mwitkow/go-conntrack"
"github.com/prometheus/client_golang/prometheus"
config_util "github.com/prometheus/common/config"
"github.com/prometheus/common/model"
"github.com/prometheus/prometheus/discovery/targetgroup"
"github.com/prometheus/prometheus/util/strutil"
)
const (
watchTimeout = 30 * time.Second
retryInterval = 15 * time.Second
// addressLabel is the name for the label containing a target's address.
addressLabel = model.MetaLabelPrefix + "consul_address"
// nodeLabel is the name for the label containing a target's node name.
nodeLabel = model.MetaLabelPrefix + "consul_node"
// metaDataLabel is the prefix for the labels mapping to a target's metadata.
metaDataLabel = model.MetaLabelPrefix + "consul_metadata_"
// serviceMetaDataLabel is the prefix for the labels mapping to a target's service metadata.
serviceMetaDataLabel = model.MetaLabelPrefix + "consul_service_metadata_"
// tagsLabel is the name of the label containing the tags assigned to the target.
tagsLabel = model.MetaLabelPrefix + "consul_tags"
// serviceLabel is the name of the label containing the service name.
serviceLabel = model.MetaLabelPrefix + "consul_service"
// serviceAddressLabel is the name of the label containing the (optional) service address.
serviceAddressLabel = model.MetaLabelPrefix + "consul_service_address"
//servicePortLabel is the name of the label containing the service port.
servicePortLabel = model.MetaLabelPrefix + "consul_service_port"
// datacenterLabel is the name of the label containing the datacenter ID.
datacenterLabel = model.MetaLabelPrefix + "consul_dc"
// serviceIDLabel is the name of the label containing the service ID.
serviceIDLabel = model.MetaLabelPrefix + "consul_service_id"
// Constants for instrumentation.
namespace = "prometheus"
)
var (
rpcFailuresCount = prometheus.NewCounter(
prometheus.CounterOpts{
Namespace: namespace,
Name: "sd_consul_rpc_failures_total",
Help: "The number of Consul RPC call failures.",
})
rpcDuration = prometheus.NewSummaryVec(
prometheus.SummaryOpts{
Namespace: namespace,
Name: "sd_consul_rpc_duration_seconds",
Help: "The duration of a Consul RPC call in seconds.",
},
[]string{"endpoint", "call"},
)
// DefaultSDConfig is the default Consul SD configuration.
DefaultSDConfig = SDConfig{
TagSeparator: ",",
Scheme: "http",
Server: "localhost:8500",
AllowStale: true,
RefreshInterval: model.Duration(watchTimeout),
}
)
// SDConfig is the configuration for Consul service discovery.
type SDConfig struct {
Server string `yaml:"server,omitempty"`
Token config_util.Secret `yaml:"token,omitempty"`
Datacenter string `yaml:"datacenter,omitempty"`
TagSeparator string `yaml:"tag_separator,omitempty"`
Scheme string `yaml:"scheme,omitempty"`
Username string `yaml:"username,omitempty"`
Password config_util.Secret `yaml:"password,omitempty"`
// See https://www.consul.io/docs/internals/consensus.html#consistency-modes,
// stale reads are a lot cheaper and are a necessity if you have >5k targets.
AllowStale bool `yaml:"allow_stale"`
// By default use blocking queries (https://www.consul.io/api/index.html#blocking-queries)
// but allow users to throttle updates if necessary. This can be useful because of "bugs" like
// https://github.com/hashicorp/consul/issues/3712 which cause an un-necessary
// amount of requests on consul.
RefreshInterval model.Duration `yaml:"refresh_interval,omitempty"`
// See https://www.consul.io/api/catalog.html#list-services
// The list of services for which targets are discovered.
// Defaults to all services if empty.
Services []string `yaml:"services,omitempty"`
// An optional tag used to filter instances inside a service. A single tag is supported
// here to match the Consul API.
ServiceTag string `yaml:"tag,omitempty"`
// Desired node metadata.
NodeMeta map[string]string `yaml:"node_meta,omitempty"`
TLSConfig config_util.TLSConfig `yaml:"tls_config,omitempty"`
}
// UnmarshalYAML implements the yaml.Unmarshaler interface.
func (c *SDConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
*c = DefaultSDConfig
type plain SDConfig
err := unmarshal((*plain)(c))
if err != nil {
return err
}
if strings.TrimSpace(c.Server) == "" {
return fmt.Errorf("Consul SD configuration requires a server address")
}
return nil
}
func init() {
prometheus.MustRegister(rpcFailuresCount)
prometheus.MustRegister(rpcDuration)
// Initialize metric vectors.
rpcDuration.WithLabelValues("catalog", "service")
rpcDuration.WithLabelValues("catalog", "services")
}
// Discovery retrieves target information from a Consul server
// and updates them via watches.
type Discovery struct {
client *consul.Client
clientDatacenter string
tagSeparator string
watchedServices []string // Set of services which will be discovered.
watchedTag string // A tag used to filter instances of a service.
watchedNodeMeta map[string]string
allowStale bool
refreshInterval time.Duration
finalizer func()
logger log.Logger
}
// NewDiscovery returns a new Discovery for the given config.
func NewDiscovery(conf *SDConfig, logger log.Logger) (*Discovery, error) {
if logger == nil {
logger = log.NewNopLogger()
}
tls, err := config_util.NewTLSConfig(&conf.TLSConfig)
if err != nil {
return nil, err
}
transport := &http.Transport{
IdleConnTimeout: 5 * time.Duration(conf.RefreshInterval),
TLSClientConfig: tls,
DialContext: conntrack.NewDialContextFunc(
conntrack.DialWithTracing(),
conntrack.DialWithName("consul_sd"),
),
}
wrapper := &http.Client{
Transport: transport,
Timeout: 35 * time.Second,
}
clientConf := &consul.Config{
Address: conf.Server,
Scheme: conf.Scheme,
Datacenter: conf.Datacenter,
Token: string(conf.Token),
HttpAuth: &consul.HttpBasicAuth{
Username: conf.Username,
Password: string(conf.Password),
},
HttpClient: wrapper,
}
client, err := consul.NewClient(clientConf)
if err != nil {
return nil, err
}
cd := &Discovery{
client: client,
tagSeparator: conf.TagSeparator,
watchedServices: conf.Services,
watchedTag: conf.ServiceTag,
watchedNodeMeta: conf.NodeMeta,
allowStale: conf.AllowStale,
refreshInterval: time.Duration(conf.RefreshInterval),
clientDatacenter: conf.Datacenter,
finalizer: transport.CloseIdleConnections,
logger: logger,
}
return cd, nil
}
// shouldWatch returns whether the service of the given name should be watched.
func (d *Discovery) shouldWatch(name string, tags []string) bool {
return d.shouldWatchFromName(name) && d.shouldWatchFromTags(tags)
}
// shouldWatch returns whether the service of the given name should be watched based on its name.
func (d *Discovery) shouldWatchFromName(name string) bool {
// If there's no fixed set of watched services, we watch everything.
if len(d.watchedServices) == 0 {
return true
}
for _, sn := range d.watchedServices {
if sn == name {
return true
}
}
return false
}
// shouldWatch returns whether the service of the given name should be watched based on its tags.
// This gets called when the user doesn't specify a list of services in order to avoid watching
// *all* services. Details in https://github.com/prometheus/prometheus/pull/3814
func (d *Discovery) shouldWatchFromTags(tags []string) bool {
// If there's no fixed set of watched tags, we watch everything.
if d.watchedTag == "" {
return true
}
for _, tag := range tags {
if d.watchedTag == tag {
return true
}
}
return false
}
// Get the local datacenter if not specified.
func (d *Discovery) getDatacenter() error {
// If the datacenter was not set from clientConf, let's get it from the local Consul agent
// (Consul default is to use local node's datacenter if one isn't given for a query).
if d.clientDatacenter != "" {
return nil
}
info, err := d.client.Agent().Self()
if err != nil {
level.Error(d.logger).Log("msg", "Error retrieving datacenter name", "err", err)
rpcFailuresCount.Inc()
return err
}
dc, ok := info["Config"]["Datacenter"].(string)
if !ok {
err := fmt.Errorf("Invalid value '%v' for Config.Datacenter", info["Config"]["Datacenter"])
level.Error(d.logger).Log("msg", "Error retrieving datacenter name", "err", err)
return err
}
d.clientDatacenter = dc
return nil
}
// Initialize the Discoverer run.
func (d *Discovery) initialize(ctx context.Context) {
// Loop until we manage to get the local datacenter.
for {
// We have to check the context at least once. The checks during channel sends
// do not guarantee that.
select {
case <-ctx.Done():
return
default:
}
// Get the local datacenter first, if necessary.
err := d.getDatacenter()
if err != nil {
time.Sleep(retryInterval)
continue
}
// We are good to go.
return
}
}
// Run implements the Discoverer interface.
func (d *Discovery) Run(ctx context.Context, ch chan<- []*targetgroup.Group) {
if d.finalizer != nil {
defer d.finalizer()
}
d.initialize(ctx)
if len(d.watchedServices) == 0 || d.watchedTag != "" {
// We need to watch the catalog.
ticker := time.NewTicker(d.refreshInterval)
// Watched services and their cancellation functions.
services := make(map[string]func())
var lastIndex uint64
for {
select {
case <-ctx.Done():
ticker.Stop()
return
default:
d.watchServices(ctx, ch, &lastIndex, services)
<-ticker.C
}
}
} else {
// We only have fully defined services.
for _, name := range d.watchedServices {
d.watchService(ctx, ch, name)
}
<-ctx.Done()
}
}
// Watch the catalog for new services we would like to watch. This is called only
// when we don't know yet the names of the services and need to ask Consul the
// entire list of services.
func (d *Discovery) watchServices(ctx context.Context, ch chan<- []*targetgroup.Group, lastIndex *uint64, services map[string]func()) error {
catalog := d.client.Catalog()
level.Debug(d.logger).Log("msg", "Watching services", "tag", d.watchedTag)
t0 := time.Now()
srvs, meta, err := catalog.Services(&consul.QueryOptions{
WaitIndex: *lastIndex,
WaitTime: watchTimeout,
AllowStale: d.allowStale,
NodeMeta: d.watchedNodeMeta,
})
elapsed := time.Since(t0)
rpcDuration.WithLabelValues("catalog", "services").Observe(elapsed.Seconds())
if err != nil {
level.Error(d.logger).Log("msg", "Error refreshing service list", "err", err)
rpcFailuresCount.Inc()
time.Sleep(retryInterval)
return err
}
// If the index equals the previous one, the watch timed out with no update.
if meta.LastIndex == *lastIndex {
return nil
}
*lastIndex = meta.LastIndex
// Check for new services.
for name := range srvs {
// catalog.Service() returns a map of service name to tags, we can use that to watch
// only the services that have the tag we are looking for (if specified).
// In the future consul will also support server side for service metadata.
// https://github.com/hashicorp/consul/issues/1107
if !d.shouldWatch(name, srvs[name]) {
continue
}
if _, ok := services[name]; ok {
continue // We are already watching the service.
}
wctx, cancel := context.WithCancel(ctx)
d.watchService(wctx, ch, name)
services[name] = cancel
}
// Check for removed services.
for name, cancel := range services {
if _, ok := srvs[name]; !ok {
// Call the watch cancellation function.
cancel()
delete(services, name)
// Send clearing target group.
select {
case <-ctx.Done():
return ctx.Err()
case ch <- []*targetgroup.Group{{Source: name}}:
}
}
}
return nil
}
// consulService contains data belonging to the same service.
type consulService struct {
name string
tag string
labels model.LabelSet
discovery *Discovery
client *consul.Client
tagSeparator string
logger log.Logger
}
// Start watching a service.
func (d *Discovery) watchService(ctx context.Context, ch chan<- []*targetgroup.Group, name string) {
srv := &consulService{
discovery: d,
client: d.client,
name: name,
tag: d.watchedTag,
labels: model.LabelSet{
serviceLabel: model.LabelValue(name),
datacenterLabel: model.LabelValue(d.clientDatacenter),
},
tagSeparator: d.tagSeparator,
logger: d.logger,
}
go func() {
ticker := time.NewTicker(d.refreshInterval)
var lastIndex uint64
catalog := srv.client.Catalog()
for {
select {
case <-ctx.Done():
ticker.Stop()
return
default:
srv.watch(ctx, ch, catalog, &lastIndex)
<-ticker.C
}
}
}()
}
// Get updates for a service.
func (srv *consulService) watch(ctx context.Context, ch chan<- []*targetgroup.Group, catalog *consul.Catalog, lastIndex *uint64) error {
level.Debug(srv.logger).Log("msg", "Watching service", "service", srv.name, "tag", srv.tag)
t0 := time.Now()
nodes, meta, err := catalog.Service(srv.name, srv.tag, &consul.QueryOptions{
WaitIndex: *lastIndex,
WaitTime: watchTimeout,
AllowStale: srv.discovery.allowStale,
NodeMeta: srv.discovery.watchedNodeMeta,
})
elapsed := time.Since(t0)
rpcDuration.WithLabelValues("catalog", "service").Observe(elapsed.Seconds())
// Check the context before in order to exit early.
select {
case <-ctx.Done():
return ctx.Err()
default:
// Continue.
}
if err != nil {
level.Error(srv.logger).Log("msg", "Error refreshing service", "service", srv.name, "tag", srv.tag, "err", err)
rpcFailuresCount.Inc()
time.Sleep(retryInterval)
return err
}
// If the index equals the previous one, the watch timed out with no update.
if meta.LastIndex == *lastIndex {
return nil
}
*lastIndex = meta.LastIndex
tgroup := targetgroup.Group{
Source: srv.name,
Labels: srv.labels,
Targets: make([]model.LabelSet, 0, len(nodes)),
}
for _, node := range nodes {
// We surround the separated list with the separator as well. This way regular expressions
// in relabeling rules don't have to consider tag positions.
var tags = srv.tagSeparator + strings.Join(node.ServiceTags, srv.tagSeparator) + srv.tagSeparator
// If the service address is not empty it should be used instead of the node address
// since the service may be registered remotely through a different node
var addr string
if node.ServiceAddress != "" {
addr = net.JoinHostPort(node.ServiceAddress, fmt.Sprintf("%d", node.ServicePort))
} else {
addr = net.JoinHostPort(node.Address, fmt.Sprintf("%d", node.ServicePort))
}
labels := model.LabelSet{
model.AddressLabel: model.LabelValue(addr),
addressLabel: model.LabelValue(node.Address),
nodeLabel: model.LabelValue(node.Node),
tagsLabel: model.LabelValue(tags),
serviceAddressLabel: model.LabelValue(node.ServiceAddress),
servicePortLabel: model.LabelValue(strconv.Itoa(node.ServicePort)),
serviceIDLabel: model.LabelValue(node.ServiceID),
}
// Add all key/value pairs from the node's metadata as their own labels
for k, v := range node.NodeMeta {
name := strutil.SanitizeLabelName(k)
labels[metaDataLabel+model.LabelName(name)] = model.LabelValue(v)
}
// Add all key/value pairs from the service's metadata as their own labels
for k, v := range node.ServiceMeta {
name := strutil.SanitizeLabelName(k)
labels[serviceMetaDataLabel+model.LabelName(name)] = model.LabelValue(v)
}
tgroup.Targets = append(tgroup.Targets, labels)
}
select {
case <-ctx.Done():
return ctx.Err()
case ch <- []*targetgroup.Group{&tgroup}:
}
return nil
}