feat(router): optimize playground delivery, add concurrency_limit to config

router-tests/testenv/testenv.go

@@ -828,6 +828,7 @@ func configureRouter(listenerAddr string, testConfig *Config, routerConfig *node
 		core.WithGraphApiToken(graphApiToken),
 		core.WithDevelopmentMode(true),
 		core.WithPlayground(true),
+		core.WithPlaygroundConfig(config.PlaygroundConfig{Enabled: true}),
 		core.WithEngineExecutionConfig(engineExecutionConfig),
 		core.WithSecurityConfig(cfg.SecurityConfiguration),
 		core.WithCacheControlPolicy(cfg.CacheControl),

router/cmd/instance.go

@@ -114,6 +114,7 @@ func NewRouter(ctx context.Context, params Params, additionalOptions ...core.Opt
 		core.WithGraphQLPath(cfg.GraphQLPath),
 		core.WithModulesConfig(cfg.Modules),
 		core.WithGracePeriod(cfg.GracePeriod),
+		core.WithPlaygroundConfig(cfg.PlaygroundConfig),
 		core.WithPlaygroundPath(cfg.PlaygroundPath),
 		core.WithHealthCheckPath(cfg.HealthCheckPath),
 		core.WithLivenessCheckPath(cfg.LivenessCheckPath),

router/core/graph_server.go

@@ -235,8 +235,8 @@ func newGraphServer(ctx context.Context, r *Router, routerConfig *nodev1.RouterC
 
 	// We mount the playground once here when we don't have a conflict with the websocket handler
 	// If we have a conflict, we mount the playground during building the individual muxes
-	if s.playgroundHandler != nil && s.graphqlPath != s.playgroundPath {
-		httpRouter.Get(r.playgroundPath, s.playgroundHandler(nil).ServeHTTP)
+	if s.playgroundHandler != nil && s.graphqlPath != s.playgroundConfig.Path {
+		httpRouter.Get(r.playgroundConfig.Path, s.playgroundHandler(nil).ServeHTTP)
 	}
 
 	httpRouter.Get(s.healthCheckPath, r.healthcheck.Liveness())
@@ -1049,7 +1049,7 @@ func (s *graphServer) buildGraphMux(ctx context.Context,
 
 		// When the playground path is equal to the graphql path, we need to handle
 		// ws upgrades and html requests on the same route.
-		if s.playground && s.graphqlPath == s.playgroundPath {
+		if s.playgroundConfig.Enabled && s.graphqlPath == s.playgroundConfig.Path {
 			httpRouter.Use(s.playgroundHandler, wsMiddleware)
 		} else {
 			httpRouter.Use(wsMiddleware)

router/core/router.go

@@ -177,6 +177,7 @@ type (
 		healthCheckPath                 string
 		readinessCheckPath              string
 		livenessCheckPath               string
+		playgroundConfig                config.PlaygroundConfig
 		cacheControlPolicy              config.CacheControlPolicy
 		routerConfigPollerConfig        *RouterConfigPollerConfig
 		cdnConfig                       config.CDNConfiguration
@@ -258,8 +259,18 @@ func NewRouter(opts ...Option) (*Router, error) {
 		r.graphqlWebURL = r.graphqlPath
 	}
 
-	if r.playgroundPath == "" {
-		r.playgroundPath = "/"
+	// this is set via the deprecated method
+	if !r.playground {
+		r.playgroundConfig.Enabled = r.playground
+		r.logger.Warn("The playground_enabled option is deprecated. Use the playground.enabled option in the config instead.")
+	}
+	if r.playgroundPath != "" && r.playgroundPath != "/" {
+		r.playgroundConfig.Path = r.playgroundPath
+		r.logger.Warn("The playground_path option is deprecated. Use the playground.path option in the config instead.")
+	}
+
+	if r.playgroundConfig.Path == "" {
+		r.playgroundConfig.Path = "/"
 	}
 
 	if r.instanceID == "" {
@@ -598,7 +609,7 @@ func (r *Router) newServer(ctx context.Context, cfg *nodev1.RouterConfig) error
 func (r *Router) listenAndServe(cfg *nodev1.RouterConfig) error {
 	r.logger.Info("Server listening and serving",
 		zap.String("listen_addr", r.listenAddr),
-		zap.Bool("playground", r.playground),
+		zap.Bool("playground", r.playgroundConfig.Enabled),
 		zap.Bool("introspection", r.introspection),
 		zap.String("config_version", cfg.GetVersion()),
 	)
@@ -854,15 +865,16 @@ func (r *Router) bootstrap(ctx context.Context) error {
 		debug.ReportMemoryUsage(ctx, r.logger)
 	}
 
-	if r.playground {
-		playgroundUrl, err := url.JoinPath(r.baseURL, r.playgroundPath)
+	if r.playgroundConfig.Enabled {
+		playgroundUrl, err := url.JoinPath(r.baseURL, r.playgroundConfig.Path)
 		if err != nil {
 			return fmt.Errorf("failed to join playground url: %w", err)
 		}
 		r.logger.Info("Serving GraphQL playground", zap.String("url", playgroundUrl))
 		r.playgroundHandler = graphiql.NewPlayground(&graphiql.PlaygroundOptions{
-			Html:       graphiql.PlaygroundHTML(),
-			GraphqlURL: r.graphqlWebURL,
+			Html:             graphiql.PlaygroundHTML(),
+			GraphqlURL:       r.graphqlWebURL,
+			ConcurrencyLimit: int64(r.playgroundConfig.ConcurrencyLimit),
 		})
 	}
 
@@ -1128,7 +1140,7 @@ func (r *Router) Start(ctx context.Context) error {
 		return err
 	}
 
-	if r.playground {
+	if r.playgroundConfig.Enabled {
 		graphqlEndpointURL, err := url.JoinPath(r.baseURL, r.graphqlPath)
 		if err != nil {
 			return fmt.Errorf("failed to join graphql endpoint url: %w", err)
@@ -1381,6 +1393,13 @@ func WithPlaygroundPath(p string) Option {
 	}
 }
 
+// WithPlaygroundPath sets the path where the GraphQL Playground is served.
+func WithPlaygroundConfig(c config.PlaygroundConfig) Option {
+	return func(r *Router) {
+		r.playgroundConfig = c
+	}
+}
+
 // WithConfigPoller sets the poller client to fetch the router config. If not set, WithConfigPollerConfig should be set.
 func WithConfigPoller(cf configpoller.ConfigPoller) Option {
 	return func(r *Router) {

router/internal/graphiql/playgroundhandler.go

@@ -1,30 +1,52 @@
 package graphiql
 
 import (
+	"bytes"
+	"golang.org/x/sync/semaphore"
 	"net/http"
 	"strconv"
 	"strings"
 )
 
 type PlaygroundOptions struct {
-	Html       string
-	GraphqlURL string
+	Html             string
+	GraphqlURL       string
+	ConcurrencyLimit int64
 }
 
 type Playground struct {
-	next http.Handler
-	opts *PlaygroundOptions
+	next          http.Handler
+	opts          *PlaygroundOptions
+	templateBytes []byte
+	sem           *semaphore.Weighted
 }
 
+var (
+	defaultLimitUsage = int64(10)
+)
+
 func NewPlayground(opts *PlaygroundOptions) func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
-		return &Playground{
+		limit := opts.ConcurrencyLimit
+		if limit == 0 {
+			limit = defaultLimitUsage
+		}
+		p := &Playground{
 			next: next,
 			opts: opts,
+			sem:  semaphore.NewWeighted(limit),
 		}
+		p.initPlayground()
+		return p
 	}
 }
 
+func (p *Playground) initPlayground() {
+	tpl := strings.Replace(p.opts.Html, "{{graphqlURL}}", p.opts.GraphqlURL, -1)
+	play := []byte(tpl)
+	p.templateBytes = play
+}
+
 func (p *Playground) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// Only serve the playground if the request is for text/html
 	// if not, just pass through to the next handler
@@ -35,12 +57,14 @@ func (p *Playground) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	tpl := strings.Replace(p.opts.Html, "{{graphqlURL}}", p.opts.GraphqlURL, -1)
-	resp := []byte(tpl)
-
+	if err := p.sem.Acquire(r.Context(), 1); err != nil {
+		http.Error(w, "Too many requests", http.StatusTooManyRequests)
+		return
+	}
+	defer p.sem.Release(1) // Ensure the semaphore slot is released
 	w.Header().Set("Content-Type", "text/html; charset=utf-8")
-	w.Header().Set("Content-Length", strconv.Itoa(len(resp)))
+	w.Header().Set("Content-Length", strconv.Itoa(len(p.templateBytes)))
 
 	w.WriteHeader(http.StatusOK)
-	_, _ = w.Write(resp)
+	_, _ = bytes.NewBuffer(p.templateBytes).WriteTo(w)
 }

router/pkg/config/config.go

@@ -805,6 +805,7 @@ type Config struct {
 
 	ListenAddr                    string                      `yaml:"listen_addr" envDefault:"localhost:3002" env:"LISTEN_ADDR"`
 	ControlplaneURL               string                      `yaml:"controlplane_url" envDefault:"https://cosmo-cp.wundergraph.com" env:"CONTROLPLANE_URL"`
+	PlaygroundConfig              PlaygroundConfig            `yaml:"playground,omitempty"`
 	PlaygroundEnabled             bool                        `yaml:"playground_enabled" envDefault:"true" env:"PLAYGROUND_ENABLED"`
 	IntrospectionEnabled          bool                        `yaml:"introspection_enabled" envDefault:"true" env:"INTROSPECTION_ENABLED"`
 	QueryPlansEnabled             bool                        `yaml:"query_plans_enabled" envDefault:"true" env:"QUERY_PLANS_ENABLED"`
@@ -851,6 +852,12 @@ type Config struct {
 	ClientHeader              ClientHeader                    `yaml:"client_header"`
 }
 
+type PlaygroundConfig struct {
+	Enabled          bool   `yaml:"enabled" envDefault:"true" env:"PLAYGROUND_ENABLED"`
+	Path             string `yaml:"path" envDefault:"/" env:"PLAYGROUND_PATH"`
+	ConcurrencyLimit int    `yaml:"concurrency_limit,omitempty" envDefault:"10" env:"PLAYGROUND_CONCURRENCY_LIMIT"`
+}
+
 type LoadResult struct {
 	Config        Config
 	DefaultLoaded bool

router/pkg/config/config.schema.json

@@ -1075,10 +1075,36 @@
       "default": "https://cosmo-cp.wundergraph.com",
       "format": "http-url"
     },
+    "playground": {
+      "type": "object",
+      "description": "The configuration for the playground. The playground is a web-based GraphQL IDE that allows you to interact with the GraphQL API.",
+      "additionalProperties": false,
+      "properties": {
+        "enabled": {
+          "type": "boolean",
+          "description": "Enable the GraphQL Playground. The GraphQL Playground is a web-based GraphQL IDE that allows you to interact with the GraphQL API. The default value is true. If the value is false, the GraphQL Playground is disabled.",
+          "default": true
+        },
+        "path": {
+          "type": "string",
+          "format": "x-uri",
+          "default": "/",
+          "description": "The path of the GraphQL Playground. The GraphQL Playground is a web-based GraphQL IDE that allows you to interact with the GraphQL API. The default value is '/'."
+        },
+        "concurrency_limit": {
+          "type": "integer",
+          "description": "The concurrency limit for loading the playground. This shouldn't impact normal usage.",
+          "default": 10,
+          "minimum": 1
+        }
+      }
+    },
     "playground_enabled": {
       "type": "boolean",
       "description": "Enable the GraphQL Playground. The GraphQL Playground is a web-based GraphQL IDE that allows you to interact with the GraphQL API. The default value is true. If the value is false, the GraphQL Playground is disabled.",
-      "default": true
+      "default": true,
+      "deprecated": true,
+      "deprecationMessage": "playground_enabled is deprecated. Please use the playground.enabled configuration instead."
     },
     "introspection_enabled": {
       "type": "boolean",
@@ -1159,7 +1185,9 @@
       "type": "string",
       "format": "x-uri",
       "default": "/",
-      "description": "The path of the GraphQL Playground. The GraphQL Playground is a web-based GraphQL IDE that allows you to interact with the GraphQL API. The default value is '/'."
+      "description": "The path of the GraphQL Playground. The GraphQL Playground is a web-based GraphQL IDE that allows you to interact with the GraphQL API. The default value is '/'.",
+      "deprecated": true,
+      "deprecationMessage": "playground_path is deprecated. Please use the playground.path configuration instead."
     },
     "file_upload": {
       "type": "object",

router/pkg/config/fixtures/full.yaml

@@ -11,6 +11,10 @@ listen_addr: "localhost:3002"
 controlplane_url: "https://cosmo-cp.wundergraph.com"
 playground_enabled: true
 playground_path: "/"
+playground:
+  enabled: false
+  path: "/my-playground"
+  concurrency_limit: 1500
 introspection_enabled: true
 json_log: true
 shutdown_delay: 15s

router/pkg/config/testdata/config_defaults.json

@@ -160,6 +160,11 @@
   },
   "ListenAddr": "localhost:3002",
   "ControlplaneURL": "https://cosmo-cp.wundergraph.com",
+  "PlaygroundConfig": {
+    "Enabled": true,
+    "Path": "/",
+    "ConcurrencyLimit": 10
+  },
   "PlaygroundEnabled": true,
   "IntrospectionEnabled": true,
   "QueryPlansEnabled": true,

router/pkg/config/testdata/config_full.json

@@ -321,6 +321,11 @@
   },
   "ListenAddr": "localhost:3002",
   "ControlplaneURL": "https://cosmo-cp.wundergraph.com",
+  "PlaygroundConfig": {
+    "Enabled": false,
+    "Path": "/my-playground",
+    "ConcurrencyLimit": 1500
+  },
   "PlaygroundEnabled": true,
   "IntrospectionEnabled": true,
   "QueryPlansEnabled": true,