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discovery.go
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discovery.go
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// Copyright 2017 Istio 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 envoy
import (
"encoding/json"
"fmt"
"net/http"
"net/http/pprof"
"sort"
"strconv"
"sync"
"sync/atomic"
restful "github.com/emicklei/go-restful"
"github.com/golang/glog"
multierror "github.com/hashicorp/go-multierror"
"istio.io/pilot/model"
"istio.io/pilot/proxy"
)
// DiscoveryService publishes services, clusters, and routes for all proxies
type DiscoveryService struct {
proxy.Environment
server *http.Server
// TODO Profile and optimize cache eviction policy to avoid
// flushing the entire cache when any route, service, or endpoint
// changes. An explicit cache expiration policy should be
// considered with this change to avoid memory exhaustion as the
// entire cache will no longer be periodically flushed and stale
// entries can linger in the cache indefinitely.
sdsCache *discoveryCache
cdsCache *discoveryCache
rdsCache *discoveryCache
ldsCache *discoveryCache
}
type discoveryCacheStatEntry struct {
Hit uint64 `json:"hit"`
Miss uint64 `json:"miss"`
}
type discoveryCacheStats struct {
Stats map[string]*discoveryCacheStatEntry `json:"cache_stats"`
}
type discoveryCacheEntry struct {
data []byte
hit uint64 // atomic
miss uint64 // atomic
}
type discoveryCache struct {
disabled bool
mu sync.RWMutex
cache map[string]*discoveryCacheEntry
}
func newDiscoveryCache(enabled bool) *discoveryCache {
return &discoveryCache{
disabled: !enabled,
cache: make(map[string]*discoveryCacheEntry),
}
}
func (c *discoveryCache) cachedDiscoveryResponse(key string) ([]byte, bool) {
if c.disabled {
return nil, false
}
c.mu.RLock()
defer c.mu.RUnlock()
// Miss - entry.miss is updated in updateCachedDiscoveryResponse
entry, ok := c.cache[key]
if !ok || entry.data == nil {
return nil, false
}
// Hit
atomic.AddUint64(&entry.hit, 1)
return entry.data, true
}
func (c *discoveryCache) updateCachedDiscoveryResponse(key string, data []byte) {
if c.disabled {
return
}
c.mu.Lock()
defer c.mu.Unlock()
entry, ok := c.cache[key]
if !ok {
entry = &discoveryCacheEntry{}
c.cache[key] = entry
} else if entry.data != nil {
glog.Warningf("Overriding cached data for entry %v", key)
}
entry.data = data
atomic.AddUint64(&entry.miss, 1)
}
func (c *discoveryCache) clear() {
c.mu.Lock()
defer c.mu.Unlock()
for _, v := range c.cache {
v.data = nil
}
}
func (c *discoveryCache) resetStats() {
c.mu.RLock()
defer c.mu.RUnlock()
for _, v := range c.cache {
atomic.StoreUint64(&v.hit, 0)
atomic.StoreUint64(&v.miss, 0)
}
}
func (c *discoveryCache) stats() map[string]*discoveryCacheStatEntry {
c.mu.RLock()
defer c.mu.RUnlock()
stats := make(map[string]*discoveryCacheStatEntry, len(c.cache))
for k, v := range c.cache {
stats[k] = &discoveryCacheStatEntry{
Hit: atomic.LoadUint64(&v.hit),
Miss: atomic.LoadUint64(&v.miss),
}
}
return stats
}
type hosts struct {
Hosts []*host `json:"hosts"`
}
type host struct {
Address string `json:"ip_address"`
Port int `json:"port"`
Tags *tags `json:"tags,omitempty"`
}
type tags struct {
AZ string `json:"az,omitempty"`
Canary bool `json:"canary,omitempty"`
// Weight is an integer in the range [1, 100] or empty
Weight int `json:"load_balancing_weight,omitempty"`
}
type ldsResponse struct {
Listeners Listeners `json:"listeners"`
}
type keyAndService struct {
Key string `json:"service-key"`
Hosts []*host `json:"hosts"`
}
// Request parameters for discovery services
const (
ServiceKey = "service-key"
ServiceCluster = "service-cluster"
ServiceNode = "service-node"
RouteConfigName = "route-config-name"
)
// DiscoveryServiceOptions contains options for create a new discovery
// service instance.
type DiscoveryServiceOptions struct {
Port int
EnableProfiling bool
EnableCaching bool
}
// NewDiscoveryService creates an Envoy discovery service on a given port
func NewDiscoveryService(ctl model.Controller, configCache model.ConfigStoreCache,
environment proxy.Environment, o DiscoveryServiceOptions) (*DiscoveryService, error) {
out := &DiscoveryService{
Environment: environment,
sdsCache: newDiscoveryCache(o.EnableCaching),
cdsCache: newDiscoveryCache(o.EnableCaching),
rdsCache: newDiscoveryCache(o.EnableCaching),
ldsCache: newDiscoveryCache(o.EnableCaching),
}
container := restful.NewContainer()
if o.EnableProfiling {
container.ServeMux.HandleFunc("/debug/pprof/", pprof.Index)
container.ServeMux.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
container.ServeMux.HandleFunc("/debug/pprof/profile", pprof.Profile)
container.ServeMux.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
container.ServeMux.HandleFunc("/debug/pprof/trace", pprof.Trace)
}
out.Register(container)
out.server = &http.Server{Addr: ":" + strconv.Itoa(o.Port), Handler: container}
// Flush cached discovery responses whenever services, service
// instances, or routing configuration changes.
serviceHandler := func(s *model.Service, e model.Event) { out.clearCache() }
if err := ctl.AppendServiceHandler(serviceHandler); err != nil {
return nil, err
}
instanceHandler := func(s *model.ServiceInstance, e model.Event) { out.clearCache() }
if err := ctl.AppendInstanceHandler(instanceHandler); err != nil {
return nil, err
}
if configCache != nil {
configHandler := func(model.Config, model.Event) { out.clearCache() }
configCache.RegisterEventHandler(model.RouteRule.Type, configHandler)
configCache.RegisterEventHandler(model.IngressRule.Type, configHandler)
configCache.RegisterEventHandler(model.EgressRule.Type, configHandler)
configCache.RegisterEventHandler(model.DestinationPolicy.Type, configHandler)
}
return out, nil
}
// Register adds routes a web service container
func (ds *DiscoveryService) Register(container *restful.Container) {
ws := &restful.WebService{}
ws.Produces(restful.MIME_JSON)
// List all known services (informational, not invoked by Envoy)
ws.Route(ws.
GET("/v1/registration").
To(ds.ListAllEndpoints).
Doc("Services in SDS"))
// This route makes discovery act as an Envoy Service discovery service (SDS).
// See https://envoyproxy.github.io/envoy/intro/arch_overview/service_discovery.html#service-discovery-service-sds
ws.Route(ws.
GET(fmt.Sprintf("/v1/registration/{%s}", ServiceKey)).
To(ds.ListEndpoints).
Doc("SDS registration").
Param(ws.PathParameter(ServiceKey, "tuple of service name and tag name").DataType("string")))
// This route makes discovery act as an Envoy Cluster discovery service (CDS).
// See https://envoyproxy.github.io/envoy/configuration/cluster_manager/cds.html#config-cluster-manager-cds
ws.Route(ws.
GET(fmt.Sprintf("/v1/clusters/{%s}/{%s}", ServiceCluster, ServiceNode)).
To(ds.ListClusters).
Doc("CDS registration").
Param(ws.PathParameter(ServiceCluster, "client proxy service cluster").DataType("string")).
Param(ws.PathParameter(ServiceNode, "client proxy service node").DataType("string")))
// This route makes discovery act as an Envoy Route discovery service (RDS).
// See https://lyft.github.io/envoy/docs/configuration/http_conn_man/rds.html
ws.Route(ws.
GET(fmt.Sprintf("/v1/routes/{%s}/{%s}/{%s}", RouteConfigName, ServiceCluster, ServiceNode)).
To(ds.ListRoutes).
Doc("RDS registration").
Param(ws.PathParameter(RouteConfigName, "route configuration name").DataType("string")).
Param(ws.PathParameter(ServiceCluster, "client proxy service cluster").DataType("string")).
Param(ws.PathParameter(ServiceNode, "client proxy service node").DataType("string")))
// This route responds to LDS requests
// See https://lyft.github.io/envoy/docs/configuration/listeners/lds.html
ws.Route(ws.
GET(fmt.Sprintf("/v1/listeners/{%s}/{%s}", ServiceCluster, ServiceNode)).
To(ds.ListListeners).
Doc("LDS registration").
Param(ws.PathParameter(ServiceCluster, "client proxy service cluster").DataType("string")).
Param(ws.PathParameter(ServiceNode, "client proxy service node").DataType("string")))
ws.Route(ws.
GET("/cache_stats").
To(ds.GetCacheStats).
Doc("Get discovery service cache stats").
Writes(discoveryCacheStats{}))
ws.Route(ws.
POST("/cache_stats_delete").
To(ds.ClearCacheStats).
Doc("Clear discovery service cache stats"))
container.Add(ws)
}
// Run starts the server and blocks
func (ds *DiscoveryService) Run() {
glog.Infof("Starting discovery service at %v", ds.server.Addr)
if err := ds.server.ListenAndServe(); err != nil {
glog.Warning(err)
}
}
// GetCacheStats returns the statistics for cached discovery responses.
func (ds *DiscoveryService) GetCacheStats(_ *restful.Request, response *restful.Response) {
stats := make(map[string]*discoveryCacheStatEntry)
for k, v := range ds.sdsCache.stats() {
stats[k] = v
}
for k, v := range ds.cdsCache.stats() {
stats[k] = v
}
for k, v := range ds.rdsCache.stats() {
stats[k] = v
}
for k, v := range ds.ldsCache.stats() {
stats[k] = v
}
if err := response.WriteEntity(discoveryCacheStats{stats}); err != nil {
glog.Warning(err)
}
}
// ClearCacheStats clear the statistics for cached discovery responses.
func (ds *DiscoveryService) ClearCacheStats(_ *restful.Request, _ *restful.Response) {
ds.sdsCache.resetStats()
ds.cdsCache.resetStats()
ds.rdsCache.resetStats()
ds.ldsCache.resetStats()
}
func (ds *DiscoveryService) clearCache() {
glog.Infof("Cleared discovery service cache")
ds.sdsCache.clear()
ds.cdsCache.clear()
ds.rdsCache.clear()
ds.ldsCache.clear()
}
// ListAllEndpoints responds with all Services and is not restricted to a single service-key
func (ds *DiscoveryService) ListAllEndpoints(request *restful.Request, response *restful.Response) {
services := make([]*keyAndService, 0)
svcs, err := ds.Services()
if err != nil {
// If client experiences an error, 503 error will tell envoy to keep its current
// cache and try again later
errorResponse(response, http.StatusServiceUnavailable, "EDS "+err.Error())
return
}
for _, service := range svcs {
if !service.External() {
for _, port := range service.Ports {
hosts := make([]*host, 0)
instances, err := ds.Instances(service.Hostname, []string{port.Name}, nil)
if err != nil {
// If client experiences an error, 503 error will tell envoy to keep its current
// cache and try again later
errorResponse(response, http.StatusInternalServerError, "EDS "+err.Error())
return
}
for _, instance := range instances {
// Only set tags if theres an AZ to set, ensures nil tags when there isnt
var t *tags
if instance.AvailabilityZone != "" {
t = &tags{AZ: instance.AvailabilityZone}
}
hosts = append(hosts, &host{
Address: instance.Endpoint.Address,
Port: instance.Endpoint.Port,
Tags: t,
})
}
services = append(services, &keyAndService{
Key: service.Key(port, nil),
Hosts: hosts,
})
}
}
}
// Sort servicesArray. This is not strictly necessary, but discovery_test.go will
// be comparing against a golden example using test/util/diff.go which does a textual comparison
sort.Slice(services, func(i, j int) bool { return services[i].Key < services[j].Key })
if err := response.WriteEntity(services); err != nil {
glog.Warning(err)
}
}
// ListEndpoints responds to EDS requests
func (ds *DiscoveryService) ListEndpoints(request *restful.Request, response *restful.Response) {
key := request.Request.URL.String()
out, cached := ds.sdsCache.cachedDiscoveryResponse(key)
if !cached {
hostname, ports, tags := model.ParseServiceKey(request.PathParameter(ServiceKey))
// envoy expects an empty array if no hosts are available
hostArray := make([]*host, 0)
endpoints, err := ds.Instances(hostname, ports.GetNames(), tags)
if err != nil {
// If client experiences an error, 503 error will tell envoy to keep its current
// cache and try again later
errorResponse(response, http.StatusServiceUnavailable, "EDS "+err.Error())
return
}
for _, ep := range endpoints {
hostArray = append(hostArray, &host{
Address: ep.Endpoint.Address,
Port: ep.Endpoint.Port,
})
}
if out, err = json.MarshalIndent(hosts{Hosts: hostArray}, " ", " "); err != nil {
errorResponse(response, http.StatusInternalServerError, "EDS "+err.Error())
return
}
ds.sdsCache.updateCachedDiscoveryResponse(key, out)
}
writeResponse(response, out)
}
func (ds *DiscoveryService) parseDiscoveryRequest(request *restful.Request) (proxy.Node, error) {
node := request.PathParameter(ServiceNode)
role, err := proxy.ParseServiceNode(node)
if err != nil {
return role, multierror.Prefix(err, fmt.Sprintf("unexpected %s: ", ServiceNode))
}
return role, nil
}
// ListClusters responds to CDS requests for all outbound clusters
func (ds *DiscoveryService) ListClusters(request *restful.Request, response *restful.Response) {
key := request.Request.URL.String()
out, cached := ds.cdsCache.cachedDiscoveryResponse(key)
if !cached {
role, err := ds.parseDiscoveryRequest(request)
if err != nil {
errorResponse(response, http.StatusNotFound, "CDS "+err.Error())
return
}
clusters, err := buildClusters(ds.Environment, role)
if err != nil {
// If client experiences an error, 503 error will tell envoy to keep its current
// cache and try again later
errorResponse(response, http.StatusServiceUnavailable, "CDS "+err.Error())
return
}
if out, err = json.MarshalIndent(ClusterManager{Clusters: clusters}, " ", " "); err != nil {
errorResponse(response, http.StatusInternalServerError, "CDS "+err.Error())
return
}
ds.cdsCache.updateCachedDiscoveryResponse(key, out)
}
writeResponse(response, out)
}
// ListListeners responds to LDS requests
func (ds *DiscoveryService) ListListeners(request *restful.Request, response *restful.Response) {
key := request.Request.URL.String()
out, cached := ds.ldsCache.cachedDiscoveryResponse(key)
if !cached {
role, err := ds.parseDiscoveryRequest(request)
if err != nil {
errorResponse(response, http.StatusNotFound, "LDS "+err.Error())
return
}
listeners, err := buildListeners(ds.Environment, role)
if err != nil {
// If client experiences an error, 503 error will tell envoy to keep its current
// cache and try again later
errorResponse(response, http.StatusServiceUnavailable, "LDS "+err.Error())
return
}
out, err = json.MarshalIndent(ldsResponse{Listeners: listeners}, " ", " ")
if err != nil {
errorResponse(response, http.StatusInternalServerError, "LDS "+err.Error())
return
}
ds.ldsCache.updateCachedDiscoveryResponse(key, out)
}
writeResponse(response, out)
}
// ListRoutes responds to RDS requests, used by HTTP routes
// Routes correspond to HTTP routes and use the listener port as the route name
// to identify HTTP filters in the config. Service node value holds the local proxy identity.
func (ds *DiscoveryService) ListRoutes(request *restful.Request, response *restful.Response) {
key := request.Request.URL.String()
out, cached := ds.rdsCache.cachedDiscoveryResponse(key)
if !cached {
role, err := ds.parseDiscoveryRequest(request)
if err != nil {
errorResponse(response, http.StatusNotFound, "RDS "+err.Error())
return
}
routeConfigName := request.PathParameter(RouteConfigName)
routeConfig, err := buildRDSRoute(ds.Mesh, role, routeConfigName,
ds.ServiceDiscovery, ds.IstioConfigStore)
if err != nil {
// If client experiences an error, 503 error will tell envoy to keep its current
// cache and try again later
errorResponse(response, http.StatusServiceUnavailable, "RDS "+err.Error())
return
}
if out, err = json.MarshalIndent(routeConfig, " ", " "); err != nil {
errorResponse(response, http.StatusInternalServerError, "RDS "+err.Error())
return
}
ds.rdsCache.updateCachedDiscoveryResponse(key, out)
}
writeResponse(response, out)
}
func errorResponse(r *restful.Response, status int, msg string) {
glog.Warning(msg)
if err := r.WriteErrorString(status, msg); err != nil {
glog.Warning(err)
}
}
func writeResponse(r *restful.Response, data []byte) {
r.WriteHeader(http.StatusOK)
if _, err := r.Write(data); err != nil {
glog.Warning(err)
}
}