[v2] add RUM event rate limit per ip per sec(elastic#1367)

* Enabled for RUM endpoints with default value 300, burst multiplier 3
* Throttle read if rate limit is hit while reading the request, deny request if limit is already hit when the request is started.
* Check rate limit in batches of 10.
* Use eviction handling for LRU cache holding the rate limiters. 
* Keep rate limiting for v1 unchanged.

partly implements elastic#1299

CHANGELOG.asciidoc

@@ -28,6 +28,7 @@ https://github.com/elastic/apm-server/compare/6.4\...master[View commits]
 - Require either `message` or `type` for `error.exception` {pull}1354[1354].
 - Require `span.parent_id`, forbid `null` for `span.trace_id`, `transaction.trace_id` {pull}1391[1391]
 - Require `error.id` and changed description to 128 random bits ID {pull}1384[1384]
+- Add rate limit handling per event {pull}1367[1367]
 
 [[release-notes-6.4]]
 == APM Server version 6.4

_meta/beat.yml

@@ -42,9 +42,26 @@ apm-server:
     # To enable real user monitoring (RUM) support set this to true.
     #enabled: false
 
+    #-- v1 RUM endpoint
+
     # Rate limit per second and IP address for requests sent to the RUM endpoint.
     #rate_limit: 10
 
+    #-- v2 RUM endpoint
+
+    #event_rate:
+
+      # Defines the maximum amount of events allowed to be sent to the APM Server v2 RUM
+      # endpoint per ip per second. Defaults to 300.
+      #limit: 300
+
+      # An LRU cache is used to keep a rate limit per IP for the most recently seen IPs.
+      # This setting defines the number of unique IPs that can be tracked in the cache.
+      # Sites with many concurrent clients should consider increasing this limit. Defaults to 1000.
+      #lru_size: 1000
+
+    #-- General RUM settings
+
     # Comma separated list of permitted origins for real user monitoring. 
     # User-agents will send an origin header that will be validated against this list.
     # An origin is made of a protocol scheme, host and port, without the url path.
@@ -90,6 +107,7 @@ apm-server:
       # is changed, a matching index pattern needs to be specified here.
       #index_pattern: "apm-*-sourcemap*"
 
+
   # If set to true, APM Server augments data received by the agent with the original IP of the backend server,
   # or the IP and User Agent of the real user (RUM requests). It defaults to true.
   #capture_personal_data: true

apm-server.yml

@@ -42,9 +42,26 @@ apm-server:
     # To enable real user monitoring (RUM) support set this to true.
     #enabled: false
 
+    #-- v1 RUM endpoint
+
     # Rate limit per second and IP address for requests sent to the RUM endpoint.
     #rate_limit: 10
 
+    #-- v2 RUM endpoint
+
+    #event_rate:
+
+      # Defines the maximum amount of events allowed to be sent to the APM Server v2 RUM
+      # endpoint per ip per second. Defaults to 300.
+      #limit: 300
+
+      # An LRU cache is used to keep a rate limit per IP for the most recently seen IPs.
+      # This setting defines the number of unique IPs that can be tracked in the cache.
+      # Sites with many concurrent clients should consider increasing this limit. Defaults to 1000.
+      #lru_size: 1000
+
+    #-- General RUM settings
+
     # Comma separated list of permitted origins for real user monitoring. 
     # User-agents will send an origin header that will be validated against this list.
     # An origin is made of a protocol scheme, host and port, without the url path.
@@ -90,6 +107,7 @@ apm-server:
       # is changed, a matching index pattern needs to be specified here.
       #index_pattern: "apm-*-sourcemap*"
 
+
   # If set to true, APM Server augments data received by the agent with the original IP of the backend server,
   # or the IP and User Agent of the real user (RUM requests). It defaults to true.
   #capture_personal_data: true

beater/approved-stream-result/TestRequestIntegrationRumRateLimit.approved.json

@@ -0,0 +1,8 @@
+{
+    "accepted": 30,
+    "errors": [
+        {
+            "message": "rate limit exceeded"
+        }
+    ]
+}

beater/beater.go

@@ -18,16 +18,13 @@
 package beater
 
 import (
-	"fmt"
 	"net"
 	"net/http"
 	"net/url"
 	"os"
-	"regexp"
 	"sync"
 	"time"
 
-	"github.com/pkg/errors"
 	"golang.org/x/sync/errgroup"
 
 	"github.com/elastic/apm-agent-go"
@@ -52,18 +49,11 @@ type beater struct {
 // Creates beater
 func New(b *beat.Beat, ucfg *common.Config) (beat.Beater, error) {
 	logger := logp.NewLogger("beater")
-	beaterConfig := defaultConfig(b.Info.Version)
-	if err := ucfg.Unpack(beaterConfig); err != nil {
-		return nil, errors.Wrap(err, "Error processing configuration")
+	beaterConfig, err := NewConfig(b.Info.Version, ucfg)
+	if err != nil {
+		return nil, err
 	}
-	beaterConfig.SetRumConfig()
 	if beaterConfig.RumConfig.isEnabled() {
-		if _, err := regexp.Compile(beaterConfig.RumConfig.LibraryPattern); err != nil {
-			return nil, errors.New(fmt.Sprintf("Invalid regex for `library_pattern`: %v", err.Error()))
-		}
-		if _, err := regexp.Compile(beaterConfig.RumConfig.ExcludeFromGrouping); err != nil {
-			return nil, errors.New(fmt.Sprintf("Invalid regex for `exclude_from_grouping`: %v", err.Error()))
-		}
 		if b.Config != nil && beaterConfig.RumConfig.SourceMapping.EsConfig == nil {
 			// fall back to elasticsearch output configuration for sourcemap storage if possible
 			if isElasticsearchOutput(b) {

beater/beater_test.go

@@ -86,8 +86,12 @@ func TestBeatConfig(t *testing.T) {
 					"url":     "/debug/vars",
 				},
 				"frontend": map[string]interface{}{
-					"enabled":       true,
-					"rate_limit":    1000,
+					"enabled":    true,
+					"rate_limit": 1000,
+					"event_rate": map[string]interface{}{
+						"limit":    7200,
+						"lru_size": 2000,
+					},
 					"allow_origins": []string{"example*"},
 					"source_mapping": map[string]interface{}{
 						"cache": map[string]interface{}{
@@ -128,8 +132,12 @@ func TestBeatConfig(t *testing.T) {
 					Url:     "/debug/vars",
 				},
 				FrontendConfig: &rumConfig{
-					Enabled:      &truthy,
-					RateLimit:    1000,
+					Enabled:   &truthy,
+					RateLimit: 1000,
+					EventRate: &eventRate{
+						Limit:   7200,
+						LruSize: 2000,
+					},
 					AllowOrigins: []string{"example*"},
 					SourceMapping: &SourceMapping{
 						Cache:        &Cache{Expiration: 8 * time.Minute},
@@ -140,8 +148,12 @@ func TestBeatConfig(t *testing.T) {
 					beatVersion:         "6.2.0",
 				},
 				RumConfig: &rumConfig{
-					Enabled:      &truthy,
-					RateLimit:    1000,
+					Enabled:   &truthy,
+					RateLimit: 1000,
+					EventRate: &eventRate{
+						Limit:   7200,
+						LruSize: 2000,
+					},
 					AllowOrigins: []string{"example*"},
 					SourceMapping: &SourceMapping{
 						Cache:        &Cache{Expiration: 8 * time.Minute},
@@ -182,6 +194,9 @@ func TestBeatConfig(t *testing.T) {
 				"frontend": map[string]interface{}{
 					"enabled":    true,
 					"rate_limit": 890,
+					"event_rate": map[string]interface{}{
+						"lru_size": 200,
+					},
 					"source_mapping": map[string]interface{}{
 						"cache": map[string]interface{}{
 							"expiration": 4,
@@ -224,6 +239,10 @@ func TestBeatConfig(t *testing.T) {
 				FrontendConfig: &rumConfig{
 					Enabled:   &truthy,
 					RateLimit: 890,
+					EventRate: &eventRate{
+						Limit:   300,
+						LruSize: 200,
+					},
 					SourceMapping: &SourceMapping{
 						Cache: &Cache{
 							Expiration: 4 * time.Second,
@@ -236,8 +255,12 @@ func TestBeatConfig(t *testing.T) {
 					beatVersion:         "6.2.0",
 				},
 				RumConfig: &rumConfig{
-					Enabled:      &truthy,
-					RateLimit:    10,
+					Enabled:   &truthy,
+					RateLimit: 10,
+					EventRate: &eventRate{
+						Limit:   300,
+						LruSize: 1000,
+					},
 					AllowOrigins: []string{"*"},
 					SourceMapping: &SourceMapping{
 						Cache: &Cache{

beater/common_handlers.go

@@ -27,12 +27,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/gofrs/uuid"
-	"github.com/hashicorp/golang-lru"
-	"github.com/pkg/errors"
-	"github.com/ryanuber/go-glob"
-	"golang.org/x/time/rate"
-
 	"github.com/elastic/apm-server/decoder"
 	"github.com/elastic/apm-server/processor"
 	"github.com/elastic/apm-server/publish"
@@ -42,12 +36,14 @@ import (
 	"github.com/elastic/beats/libbeat/logp"
 	"github.com/elastic/beats/libbeat/monitoring"
 	"github.com/elastic/beats/libbeat/version"
+	"github.com/gofrs/uuid"
+	lru "github.com/hashicorp/golang-lru"
+	"github.com/pkg/errors"
+	"github.com/ryanuber/go-glob"
+	"golang.org/x/time/rate"
 )
 
 const (
-	rateLimitCacheSize       = 1000
-	rateLimitBurstMultiplier = 2
-
 	supportedHeaders = "Content-Type, Content-Encoding, Accept"
 	supportedMethods = "POST, OPTIONS"
 )
@@ -126,10 +122,11 @@ var (
 			counter: validateCounter,
 		}
 	}
+	rateLimitCounter    = counter("response.errors.ratelimit")
 	rateLimitedResponse = serverResponse{
 		err:     errors.New("too many requests"),
 		code:    http.StatusTooManyRequests,
-		counter: counter("response.errors.ratelimit"),
+		counter: rateLimitCounter,
 	}
 	methodNotAllowedCounter  = counter("response.errors.method")
 	methodNotAllowedResponse = serverResponse{
@@ -172,7 +169,7 @@ func newMuxer(beaterConfig *Config, report publish.Reporter) *http.ServeMux {
 	for path, route := range V2Routes {
 		logger.Infof("Path %s added to request handler", path)
 
-		mux.Handle(path, route.Handler(beaterConfig, report))
+		mux.Handle(path, route.Handler(path, beaterConfig, report))
 	}
 
 	mux.Handle(rootURL, rootHandler(beaterConfig.SecretToken))
@@ -244,9 +241,11 @@ func rootHandler(secretToken string) http.Handler {
 	return logHandler(handler)
 }
 
-type contextKey string
+type reqLoggerKey struct{}
 
-const reqLoggerContextKey = contextKey("requestLogger")
+func ContextWithReqLogger(ctx context.Context, rl *logp.Logger) context.Context {
+	return context.WithValue(ctx, reqLoggerKey{}, rl)
+}
 
 func logHandler(h http.Handler) http.Handler {
 	logger := logp.NewLogger("request")
@@ -266,13 +265,8 @@ func logHandler(h http.Handler) http.Handler {
 			"remote_address", utility.RemoteAddr(r),
 			"user-agent", r.Header.Get("User-Agent"))
 
-		lr := r.WithContext(
-			context.WithValue(r.Context(), reqLoggerContextKey, reqLogger),
-		)
-
 		lw := utility.NewRecordingResponseWriter(w)
-
-		h.ServeHTTP(lw, lr)
+		h.ServeHTTP(lw, r.WithContext(ContextWithReqLogger(r.Context(), reqLogger)))
 
 		if lw.Code <= 399 {
 			reqLogger.Infow("handled request", []interface{}{"response_code", lw.Code}...)
@@ -290,7 +284,7 @@ func requestTimeHandler(h http.Handler) http.Handler {
 // requestLogger is a convenience function to retrieve the logger that was
 // added to the request context by handler `logHandler``
 func requestLogger(r *http.Request) *logp.Logger {
-	logger, ok := r.Context().Value(reqLoggerContextKey).(*logp.Logger)
+	logger, ok := r.Context().Value(reqLoggerKey{}).(*logp.Logger)
 	if !ok {
 		logger = logp.NewLogger("request")
 	}
@@ -307,6 +301,11 @@ func killSwitchHandler(killSwitch bool, h http.Handler) http.Handler {
 	})
 }
 
+const (
+	rateLimitCacheSize       = 1000
+	rateLimitBurstMultiplier = 2
+)
+
 func ipRateLimitHandler(rateLimit int, h http.Handler) http.Handler {
 	cache, _ := lru.New(rateLimitCacheSize)
 

beater/config.go

@@ -30,6 +30,7 @@ import (
 	"github.com/elastic/beats/libbeat/common"
 	"github.com/elastic/beats/libbeat/outputs"
 	"github.com/elastic/go-ucfg"
+	"github.com/pkg/errors"
 )
 
 const defaultPort = "8200"
@@ -64,6 +65,7 @@ type ExpvarConfig struct {
 type rumConfig struct {
 	Enabled             *bool          `config:"enabled"`
 	RateLimit           int            `config:"rate_limit"`
+	EventRate           *eventRate     `config:"event_rate"`
 	AllowOrigins        []string       `config:"allow_origins"`
 	LibraryPattern      string         `config:"library_pattern"`
 	ExcludeFromGrouping string         `config:"exclude_from_grouping"`
@@ -72,6 +74,11 @@ type rumConfig struct {
 	beatVersion string
 }
 
+type eventRate struct {
+	Limit   int `config:"limit"`
+	LruSize int `config:"lru_size"`
+}
+
 type metricsConfig struct {
 	Enabled *bool `config:"enabled"`
 }
@@ -136,6 +143,24 @@ type InstrumentationConfig struct {
 	SecretToken string   `config:"secret_token"`
 }
 
+func NewConfig(version string, ucfg *common.Config) (*Config, error) {
+	c := defaultConfig(version)
+	if err := ucfg.Unpack(c); err != nil {
+		return nil, errors.Wrap(err, "Error processing configuration")
+	}
+
+	c.setRumConfig()
+	if c.RumConfig.isEnabled() {
+		if _, err := regexp.Compile(c.RumConfig.LibraryPattern); err != nil {
+			return nil, errors.New(fmt.Sprintf("Invalid regex for `library_pattern`: %v", err.Error()))
+		}
+		if _, err := regexp.Compile(c.RumConfig.ExcludeFromGrouping); err != nil {
+			return nil, errors.New(fmt.Sprintf("Invalid regex for `exclude_from_grouping`: %v", err.Error()))
+		}
+	}
+	return c, nil
+}
+
 func (c *Config) setSmapElasticsearch(esConfig *common.Config) {
 	if c != nil && c.RumConfig.isEnabled() && c.RumConfig.SourceMapping != nil {
 		c.RumConfig.SourceMapping.EsConfig = esConfig
@@ -170,7 +195,7 @@ func (c *pipelineConfig) shouldOverwrite() bool {
 	return c != nil && (c.Overwrite != nil && *c.Overwrite)
 }
 
-func (c *Config) SetRumConfig() {
+func (c *Config) setRumConfig() {
 	if c.RumConfig != nil && c.RumConfig.Enabled != nil {
 		return
 	}
@@ -210,7 +235,11 @@ func replaceVersion(pattern, version string) string {
 
 func defaultRum(beatVersion string) *rumConfig {
 	return &rumConfig{
-		RateLimit:    10,
+		RateLimit: 10,
+		EventRate: &eventRate{
+			Limit:   300,
+			LruSize: 1000,
+		},
 		AllowOrigins: []string{"*"},
 		SourceMapping: &SourceMapping{
 			Cache: &Cache{