fix(handler) ensure multivalueheaders are handled

Ensure the `multiValueHeaders` field is handled in AWS Lambda proxy
integration responses.

Fix #53.

kong/plugins/aws-lambda/handler.lua

@@ -101,6 +101,13 @@ local function extract_proxy_response(content)
     body = ngx_decode_base64(body)
   end
 
+  local multiValueHeaders = serialized_content.multiValueHeaders
+  if multiValueHeaders then
+    for header, values in pairs(multiValueHeaders) do
+      headers[header] = values
+    end
+  end
+
   headers["Content-Length"] = #body
 
   return {

spec/fixtures/aws-lambda.lua

@@ -41,6 +41,8 @@ local fixtures = {
 
                     elseif string.match(ngx.var.uri, "functionWithBase64EncodedResponse") then
                       ngx.say("{\"statusCode\": 200, \"body\": \"dGVzdA==\", \"isBase64Encoded\": true}")
+                    elseif string.match(ngx.var.uri, "functionWithMultiValueHeadersResponse") then
+                      ngx.say("{\"statusCode\": 200, \"headers\": { \"Age\": \"3600\"}, \"multiValueHeaders\": {\"Access-Control-Allow-Origin\": [\"site1.com\", \"site2.com\"]}}")
 
                     elseif type(res) == 'string' then
                       ngx.header["Content-Length"] = #res + 1

spec/plugins/aws-lambda/99-access_spec.lua

@@ -111,6 +111,12 @@ for _, strategy in helpers.each_strategy() do
         service     = null,
       }
 
+      local route17 = bp.routes:insert {
+        hosts       = { "lambda17.com" },
+        protocols   = { "http", "https" },
+        service     = null,
+      }
+
       bp.plugins:insert {
         name     = "aws-lambda",
         route    = { id = route1.id },
@@ -333,6 +339,19 @@ for _, strategy in helpers.each_strategy() do
         }
       }
 
+      bp.plugins:insert {
+        name     = "aws-lambda",
+        route    = { id = route17.id },
+        config                 = {
+          port                 = 10001,
+          aws_key              = "mock-key",
+          aws_secret           = "mock-secret",
+          aws_region           = "us-east-1",
+          function_name        = "functionWithMultiValueHeadersResponse",
+          is_proxy_integration = true,
+        }
+      }
+
       assert(helpers.start_kong({
         database   = strategy,
         plugins = "aws-lambda",
@@ -898,6 +917,18 @@ for _, strategy in helpers.each_strategy() do
         assert.res_status(200, res)
         assert.equal("test", res:read_body())
       end)
+      it("returns multivalueheaders response from a Lambda function #o", function()
+        local res = assert(proxy_client:send {
+          method  = "GET",
+          path    = "/get?key1=some_value1&key2=some_value2&key3=some_value3",
+          headers = {
+            ["Host"] = "lambda17.com"
+          }
+        })
+        assert.res_status(200, res)
+        assert.is_string(res.headers.age)
+        assert.is_array(res.headers["Access-Control-Allow-Origin"])
+      end)
     end)
   end)
 end