Set default compression algos specifically

Author: mterhar

receiver/libhoneyreceiver/README.md

@@ -28,7 +28,7 @@ The following settings are required:
 
 - `http`
   - `endpoint` must set an endpoint. Defaults to `127.0.0.1:8080`
-  - `compression_algorithms` (optional): List of supported compression algorithms. Defaults to `["", "gzip", "zstd", "zlib", "snappy", "deflate"]`. Set to `[]` to disable automatic decompression.
+  - `compression_algorithms` (optional): List of supported compression algorithms. Defaults to `["", "gzip", "zstd", "zlib", "deflate"]`. Set to `[]` to disable automatic decompression.
 - `resources`: if the `service.name` field is different, map it here.
 - `scopes`: to get the `library.name` and `library.version` set in the scope section, set them here.
 - `attributes`: if the other trace-related data have different keys, map them here, defaults are otlp-like field names.

receiver/libhoneyreceiver/factory.go

@@ -42,7 +42,7 @@ func createDefaultConfig() component.Config {
 		HTTP: configoptional.Default(HTTPConfig{
 			ServerConfig: confighttp.ServerConfig{
 				Endpoint:              endpointStr,
-				CompressionAlgorithms: []string{},
+				CompressionAlgorithms: []string{"", "zstd", "gzip", "deflate"},
 			},
 			TracesURLPaths: defaultTracesURLPaths,
 		}),

receiver/libhoneyreceiver/receiver_test.go

@@ -588,6 +588,18 @@ func TestLibhoneyReceiver_ZstdDecompressionPanic(t *testing.T) {
 			expectErrorCode: 200,
 			description:     "JSON processing handles nil MsgPackTimestamp correctly after fix",
 		},
+		{
+			name: "real_libhoney_json_format",
+			createPayload: func() []byte {
+				// Real JSON format as sent by libhoney clients (S3 handler, etc)
+				// Note: time is at root level, all fields under "data"
+				// This format bypasses custom UnmarshalJSON, leaving MsgPackTimestamp nil
+				return []byte(`[{"data":{"message":"test event from S3","aws.s3.bucket":"test-bucket"},"samplerate":1,"time":"2025-09-24T15:03:49.883965174Z"}]`)
+			},
+			expectPanic:     false,
+			expectErrorCode: 200,
+			description:     "Real libhoney JSON format should be handled without panic",
+		},
 		{
 			name: "valid_msgpack_data",
 			createPayload: func() []byte {
@@ -627,7 +639,7 @@ func TestLibhoneyReceiver_ZstdDecompressionPanic(t *testing.T) {
 			var contentType string
 
 			switch tt.name {
-			case "valid_json_data_nil_pointer_bug":
+			case "valid_json_data_nil_pointer_bug", "real_libhoney_json_format":
 				reqBody = bytes.NewReader(payload)
 				contentType = "application/json"
 			case "valid_msgpack_data":
@@ -647,7 +659,7 @@ func TestLibhoneyReceiver_ZstdDecompressionPanic(t *testing.T) {
 			req.Header.Set("Content-Type", contentType)
 
 			// Only set compression headers for zstd tests
-			if tt.name != "valid_json_data_nil_pointer_bug" && tt.name != "valid_msgpack_data" {
+			if tt.name != "valid_json_data_nil_pointer_bug" && tt.name != "valid_msgpack_data" && tt.name != "real_libhoney_json_format" {
 				req.Header.Set("Content-Encoding", "zstd")
 			}