feat: ability to configure the min size for response compression

router-tests/response_compression_test.go

@@ -13,6 +13,8 @@ import (
 
 	"github.com/stretchr/testify/require"
 	"github.com/wundergraph/cosmo/router-tests/testenv"
+	"github.com/wundergraph/cosmo/router/core"
+	"github.com/wundergraph/cosmo/router/pkg/config"
 )
 
 const employeesIdData = `{"data":{"employees":[{"id":1},{"id":2},{"id":3},{"id":4},{"id":5},{"id":7},{"id":8},{"id":10},{"id":11},{"id":12}]}}`
@@ -100,3 +102,82 @@ func TestResponseCompression(t *testing.T) {
 		})
 	}
 }
+
+func TestResponseCompressionWithCustomMinSize(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name         string
+		minSize      config.BytesString
+		encoding     string
+		responseData string
+	}{
+		{"compression enabled when response is greater than custom min size", config.BytesString(len(employeesIdData) - 1), "gzip", employeesIdData},
+		{"compression enabled when response is equal to custom min size", config.BytesString(len(employeesIdData)), "gzip", employeesIdData},
+		{"compression disabled when response is less than custom min size", config.BytesString(len(employeesIdData) + 1), "", employeesIdData},
+	}
+
+	for _, tc := range testCases {
+		tc := tc // capture range variable
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel() // mark the subtest as parallel
+			testenv.Run(t, &testenv.Config{
+				RouterOptions: []core.Option{
+					core.WithRouterTrafficConfig(&config.RouterTrafficConfiguration{
+						ResponseCompressionMinSize: tc.minSize,
+						MaxRequestBodyBytes:        5 << 20, // 5MB
+					}),
+				},
+				Subgraphs: testenv.SubgraphsConfig{
+					Employees: testenv.SubgraphConfig{
+						Middleware: func(handler http.Handler) http.Handler {
+							return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+								w.Header().Set("Content-Type", "application/json")
+								data, err := io.ReadAll(r.Body)
+								require.NoError(t, err)
+								_, dt, _, _ := jsonparser.Get(data, "extensions", "persistedQuery")
+								require.Equal(t, jsonparser.NotExist, dt)
+								_, _ = w.Write([]byte(tc.responseData))
+							})
+						},
+					},
+				},
+			}, func(t *testing.T, xEnv *testenv.Environment) {
+				headers := http.Header{
+					"Content-Type":    []string{"application/json"},
+					"Accept-Encoding": []string{"gzip"},
+				}
+
+				data := map[string]interface{}{
+					"query": `query { employees { id } }`,
+				}
+				body, err := json.Marshal(data)
+				require.NoError(t, err)
+
+				res, err := xEnv.MakeRequest(http.MethodPost, "/graphql", headers, bytes.NewReader(body))
+				require.NoError(t, err)
+				defer res.Body.Close()
+
+				if tc.encoding != "" {
+					require.Equal(t, tc.encoding, res.Header.Get("Content-Encoding"))
+				} else {
+					require.Empty(t, res.Header.Get("Content-Encoding"))
+				}
+
+				// Read and decompress the response
+				responseBody, err := io.ReadAll(res.Body)
+				require.NoError(t, err)
+
+				var decompressedBody []byte
+				if tc.encoding != "" {
+					decompressedBody = decompressGzip(t, bytes.NewReader(responseBody))
+				} else {
+					decompressedBody = responseBody
+				}
+
+				require.Contains(t, res.Header.Get("Content-Type"), "application/json")
+				require.JSONEq(t, tc.responseData, string(decompressedBody))
+			})
+		})
+	}
+}

router/core/graph_server.go

@@ -284,7 +284,7 @@ func newGraphServer(ctx context.Context, r *Router, routerConfig *nodev1.RouterC
 	}
 
 	wrapper, err := gzhttp.NewWrapper(
-		gzhttp.MinSize(1024*4), // 4KB
+		gzhttp.MinSize(int(s.routerTrafficConfig.ResponseCompressionMinSize)),
 		gzhttp.CompressionLevel(gzip.DefaultCompression),
 		gzhttp.ContentTypes(CompressibleContentTypes),
 	)

router/core/router.go

@@ -1802,7 +1802,8 @@ func WithDisableUsageTracking() Option {
 
 func DefaultRouterTrafficConfig() *config.RouterTrafficConfiguration {
 	return &config.RouterTrafficConfiguration{
-		MaxRequestBodyBytes: 1000 * 1000 * 5, // 5 MB
+		MaxRequestBodyBytes:        1000 * 1000 * 5, // 5 MB
+		ResponseCompressionMinSize: 1024 * 4,        // 4 KiB
 	}
 }
 

router/pkg/config/config.go

@@ -181,6 +181,8 @@ type RouterTrafficConfiguration struct {
 	MaxHeaderBytes BytesString `yaml:"max_header_bytes" envDefault:"0MiB" env:"MAX_HEADER_BYTES"`
 	// DecompressionEnabled is the configuration for request compression
 	DecompressionEnabled bool `yaml:"decompression_enabled" envDefault:"true"`
+	// ResponseCompressionMinSize is the minimum size of the response body in bytes to enable response compression
+	ResponseCompressionMinSize BytesString `yaml:"response_compression_min_size" envDefault:"4KiB" env:"RESPONSE_COMPRESSION_MIN_SIZE"`
 }
 
 type GlobalSubgraphRequestRule struct {

router/pkg/config/config.schema.json

@@ -1474,6 +1474,15 @@
               "type": "boolean",
               "description": "When enabled, the router will check incoming requests for a 'Content-Encoding' header and decompress the body accordingly. Currently only gzip is supported",
               "default": true
+            },
+            "response_compression_min_size": {
+              "type": "string",
+              "format": "bytes-string",
+              "description": "The minimum size of the response body in bytes to enable response compression. The size is specified as a string with a number and a unit, e.g. 4KiB, 10KB, 1MB",
+              "default": "4KiB",
+              "bytes": {
+                "minimum": "1B"
+              }
             }
           }
         },

router/pkg/config/fixtures/full.yaml

@@ -198,6 +198,7 @@ traffic_shaping:
     max_request_body_size: 5MB
     max_header_bytes: 4MiB
     decompression_enabled: false
+    response_compression_min_size: 4KiB
   all: # Rules are applied to all subgraph requests.
     # Subgraphs transport options
     request_timeout: 60s

router/pkg/config/testdata/config_defaults.json

@@ -169,7 +169,8 @@
     "Router": {
       "MaxRequestBodyBytes": 5000000,
       "MaxHeaderBytes": 0,
-      "DecompressionEnabled": true
+      "DecompressionEnabled": true,
+      "ResponseCompressionMinSize": 4096
     },
     "Subgraphs": null
   },

router/pkg/config/testdata/config_full.json

@@ -334,7 +334,8 @@
     "Router": {
       "MaxRequestBodyBytes": 5000000,
       "MaxHeaderBytes": 4194304,
-      "DecompressionEnabled": false
+      "DecompressionEnabled": false,
+      "ResponseCompressionMinSize": 4096
     },
     "Subgraphs": {
       "products": {