fix : #404 : trace level shows the first kb of the payload before being decoded

Author: sebsto

Sources/AWSLambdaRuntime/Lambda.swift

@@ -44,6 +44,21 @@ public enum Lambda {
                 let (invocation, writer) = try await runtimeClient.nextInvocation()
                 logger[metadataKey: "aws-request-id"] = "\(invocation.metadata.requestID)"
 
+                // when log level is trace or lower, print the first Kb of the payload
+                let bytes = invocation.event
+                var metadata: Logger.Metadata? = nil
+                if logger.logLevel <= .trace,
+                    let buffer = bytes.getSlice(at: 0, length: min(bytes.readableBytes, 1024))
+                {
+                        metadata = [
+                        "Event's first bytes": .string(String(buffer: buffer) + (bytes.readableBytes > 1024 ? "..." : ""))
+                    ]
+                }
+                logger.trace(
+                    "Sending invocation event to lambda handler",
+                    metadata: metadata
+                )
+
                 do {
                     try await handler.handle(
                         invocation.event,