feat: allow for user-defined client context

Author: mcieno

cmd/aws-lambda-rie/handlers.go

@@ -5,6 +5,7 @@ package main
 
 import (
 	"bytes"
+	"encoding/base64"
 	"fmt"
 	"io/ioutil"
 	"math"
@@ -81,6 +82,13 @@ func InvokeHandler(w http.ResponseWriter, r *http.Request, sandbox Sandbox, bs i
 		return
 	}
 
+	rawClientContext, err := base64.StdEncoding.DecodeString(r.Header.Get("X-Amz-Client-Context"))
+	if err != nil {
+		log.Errorf("Failed to decode X-Amz-Client-Context: %s", err)
+		w.WriteHeader(500)
+		return
+	}
+
 	initDuration := ""
 	inv := GetenvWithDefault("AWS_LAMBDA_FUNCTION_TIMEOUT", "300")
 	timeoutDuration, _ := time.ParseDuration(inv + "s")
@@ -114,6 +122,7 @@ func InvokeHandler(w http.ResponseWriter, r *http.Request, sandbox Sandbox, bs i
 		TraceID:            r.Header.Get("X-Amzn-Trace-Id"),
 		LambdaSegmentID:    r.Header.Get("X-Amzn-Segment-Id"),
 		Payload:            bytes.NewReader(bodyBytes),
+		ClientContext:      string(rawClientContext),
 	}
 	fmt.Println("START RequestId: " + invokePayload.ID + " Version: " + functionVersion)
 

test/integration/local_lambda/test_end_to_end.py

@@ -4,6 +4,8 @@
 from subprocess import Popen, PIPE
 from unittest import TestCase, main
 from pathlib import Path
+import base64
+import json
 import time
 import os
 import requests
@@ -62,12 +64,14 @@ def run_command(self, cmd):
 
     def sleep_1s(self):
         time.sleep(SLEEP_TIME)
-        
-    def invoke_function(self):
+
+    def invoke_function(self, json={}, headers={}):
         return requests.post(
-            f"http://localhost:{self.PORT}/2015-03-31/functions/function/invocations", json={}
+            f"http://localhost:{self.PORT}/2015-03-31/functions/function/invocations",
+            json=json,
+            headers=headers,
         )
-        
+
     @contextmanager
     def create_container(self, param, image):
         try:
@@ -234,6 +238,24 @@ def test_port_override(self):
             self.assertEqual(b'"My lambda ran succesfully"', r.content)
 
 
+    def test_custom_client_context(self):
+        image, rie, image_name = self.tagged_name("custom_client_context")
+
+        params = f"--name {image} -d -v {self.path_to_binary}:/local-lambda-runtime-server -p {self.PORT}:8080 --entrypoint /local-lambda-runtime-server/{rie} {image_name} {DEFAULT_1P_ENTRYPOINT} main.custom_client_context_handler"
+
+        with self.create_container(params, image):
+            r = self.invoke_function(headers={
+                "X-Amz-Client-Context": base64.b64encode(json.dumps({
+                    "custom": {
+                        "foo": "bar",
+                        "baz": 123,
+                    }
+                }).encode('utf8')).decode('utf8'),
+            })
+            content = json.loads(r.content)
+            self.assertEqual("bar", content["foo"])
+            self.assertEqual(123, content["baz"])
+
 
 if __name__ == "__main__":
     main()

test/integration/testdata/main.py

@@ -41,3 +41,7 @@ def check_remaining_time_handler(event, context):
     # Wait 1s to see if the remaining time changes
     time.sleep(1)
     return context.get_remaining_time_in_millis()
+
+
+def custom_client_context_handler(event, context):
+    return context.client_context.custom