How do I debug AWS Api Gateway & Lambda's "AWS/ApiGateway 5XXError"
<p>I have an API Gateway resource that runs a lambda function.  I'm calling the API Gateway resource using the AWS Generated SDK from my Api Gateway.</p>

<p>Here's the portion of the stacktrace from my client that seems relevant:</p>

<pre><code>Caused by: com.amazonaws.mobileconnectors.apigateway.ApiClientException: {"message": "Internal server error"} (Service: DevnetcountableClient; Status Code: 500; Error Code: null; Request ID: 348e8f98-6f55-11e6-97f6-098c2caf220f)
at com.amazonaws.mobileconnectors.apigateway.ApiClientHandler.handleResponse(ApiClientHandler.java:255) at com.amazonaws.mobileconnectors.apigateway.ApiClientHandler.invoke(ApiClientHandler.java:88)
    at java.lang.reflect.Proxy.invoke(Proxy.java:393)
    at $Proxy1.accountCreatePost(Unknown Source)
</code></pre>

<p>Now looking at the AWS console, within my Api Gateway Dashboard I see the requests coming in and resulting in "AWS/ApiGateway 5XXError".  However there are 0 logs (that I can find).  My lambda function does NOT appear to be called, and no lambda logs are shown.</p>

<p>Right now this is what my lambda looks like:</p>

<pre><code>module.exports.createAccount = function(event, context, cb) {
    console.log('createAccount');
    console.log(event);
    console.log(context);
    console.log(cb);
    cb(null, {status: 'SUCCESS', message: 'I ran!'});
};
</code></pre>

<p>What can I do to debug this?</p>

<p>Edit:  Okay here is the cloudformation script that's throwing everything together.</p>

<pre><code>{
   "AWSTemplateFormatVersion":"2010-09-09",
   "Description":"The AWS CloudFormation template for this Serverless application",
   "Resources":{
      "ServerlessDeploymentBucket":{
         "Type":"AWS::S3::Bucket"
      },
      "IamRoleLambda":{
         "Type":"AWS::IAM::Role",
         "Properties":{
            "AssumeRolePolicyDocument":{
               "Version":"2012-10-17",
               "Statement":[
                  {
                     "Effect":"Allow",
                     "Principal":{
                        "Service":[
                           "lambda.amazonaws.com"
                        ]
                     },
                     "Action":[
                        "sts:AssumeRole"
                     ]
                  }
               ]
            },
            "Path":"/"
         }
      },
      "IamPolicyLambda":{
         "Type":"AWS::IAM::Policy",
         "Properties":{
            "PolicyName":"dev-coolsoftware-lambda",
            "PolicyDocument":{
               "Version":"2012-10-17",
               "Statement":[
                  {
                     "Effect":"Allow",
                     "Action":[
                        "logs:CreateLogGroup",
                        "logs:CreateLogStream",
                        "logs:PutLogEvents"
                     ],
                     "Resource":"arn:aws:logs:us-west-2:*:*"
                  }
               ]
            },
            "Roles":[
               {
                  "Ref":"IamRoleLambda"
               }
            ]
         }
      },
      "createAccount":{
         "Type":"AWS::Lambda::Function",
         "Properties":{
            "Code":{
               "S3Bucket":{
                  "Ref":"ServerlessDeploymentBucket"
               },
               "S3Key":"coolsoftware-1472853507538.zip"
            },
            "FunctionName":"coolsoftware-dev-createAccount",
            "Handler":"handler.createAccount",
            "MemorySize":128,
            "Role":{
               "Fn::GetAtt":[
                  "IamRoleLambda",
                  "Arn"
               ]
            },
            "Runtime":"nodejs4.3",
            "Timeout":30
         }
      },
      "RestApiApigEvent":{
         "Type":"AWS::ApiGateway::RestApi",
         "Properties":{
            "Name":"dev-coolsoftware"
         }
      },
      "ResourceApigEventCreateaccountAccount":{
         "Type":"AWS::ApiGateway::Resource",
         "Properties":{
            "ParentId":{
               "Fn::GetAtt":[
                  "RestApiApigEvent",
                  "RootResourceId"
               ]
            },
            "PathPart":"account",
            "RestApiId":{
               "Ref":"RestApiApigEvent"
            }
         }
      },
      "PutMethodApigEventCreateaccountAccount":{
         "Type":"AWS::ApiGateway::Method",
         "Properties":{
            "AuthorizationType":"AWS_IAM",
            "HttpMethod":"PUT",
            "MethodResponses":[
               {
                  "ResponseModels":{
                     "application/json":"AccountCreationResponseModel"
                  },
                  "ResponseParameters":{

                  },
                  "StatusCode":"200"
               }
            ],
            "RequestParameters":{

            },
            "Integration":{
               "IntegrationHttpMethod":"POST",
               "Type":"AWS",
               "Uri":{
                  "Fn::Join":[
                     "",
                     [
                        "arn:aws:apigateway:",
                        {
                           "Ref":"AWS::Region"
                        },
                        ":lambda:path/2015-03-31/functions/",
                        {
                           "Fn::GetAtt":[
                              "createAccount",
                              "Arn"
                           ]
                        },
                        "/invocations"
                     ]
                  ]
               },
               "RequestTemplates":{
                  "application/json":"\n            #define( $loop )\n              {\n              #foreach($key in $map.keySet())\n                  \"$util.escapeJavaScript($key)\":\n                    \"$util.escapeJavaScript($map.get($key))\"\n                    #if( $foreach.hasNext ) , #end\n              #end\n              }\n            #end\n            {\n              \"body\": $input.json(\"$\"),\n              \"method\": \"$context.httpMethod\",\n              \"principalId\": \"$context.authorizer.principalId\",\n              \"stage\": \"$context.stage\",\n\n              #set( $map = $input.params().header )\n              \"headers\": $loop,\n\n              #set( $map = $input.params().querystring )\n              \"query\": $loop,\n\n              #set( $map = $input.params().path )\n              \"path\": $loop,\n\n              #set( $map = $context.identity )\n              \"identity\": $loop,\n\n              #set( $map = $stageVariables )\n              \"stageVariables\": $loop\n            }\n          "
               },
               "IntegrationResponses":[
                  {
                     "StatusCode":"200",
                     "ResponseParameters":{

                     },
                     "ResponseTemplates":{
                        "application/json":""
                     }
                  }
               ]
            },
            "ResourceId":{
               "Ref":"ResourceApigEventCreateaccountAccount"
            },
            "RestApiId":{
               "Ref":"RestApiApigEvent"
            },
            "RequestModels":{
               "application/json":"AccountCreationRequestModel"
            }
         }
      },
      "DeploymentApigEvent1472853508283":{
         "Type":"AWS::ApiGateway::Deployment",
         "Properties":{
            "RestApiId":{
               "Ref":"RestApiApigEvent"
            },
            "StageName":"dev"
         },
         "DependsOn":[
            "PutMethodApigEventCreateaccountAccount"
         ]
      },
      "createAccountApigPermission":{
         "Type":"AWS::Lambda::Permission",
         "Properties":{
            "FunctionName":{
               "Fn::GetAtt":[
                  "createAccount",
                  "Arn"
               ]
            },
            "Action":"lambda:InvokeFunction",
            "Principal":"apigateway.amazonaws.com"
         }
      },
      "DynamoDBTableAccounts":{
         "Type":"AWS::DynamoDB::Table",
         "DeletionPolicy":"Retain",
         "Properties":{
            "TableName":"dev-coolsoftware-accounts",
            "ProvisionedThroughput":{
               "ReadCapacityUnits":1,
               "WriteCapacityUnits":1
            },
            "AttributeDefinitions":[
               {
                  "AttributeName":"accountid",
                  "AttributeType":"S"
               }
            ],
            "KeySchema":[
               {
                  "AttributeName":"accountid",
                  "KeyType":"HASH"
               }
            ]
         }
      },
      "AccountCreationRequestModel":{
         "Type":"AWS::ApiGateway::Model",
         "Properties":{
            "RestApiId":{
               "Ref":"RestApiApigEvent"
            },
            "ContentType":"application/json",
            "Description":"Schema for AccountCreationRequestModel",
            "Name":"AccountCreationRequestModel",
            "Schema":{
               "$schema":"http://json-schema.org/draft-04/schema#",
               "title":"AccountCreationRequestModel",
               "type":"object",
               "properties":{
                  "publickey":{
                     "type":"string"
                  },
                  "deviceid":{
                     "type":"string"
                  }
               }
            }
         }
      },
      "AccountCreationResponseModel":{
         "Type":"AWS::ApiGateway::Model",
         "Properties":{
            "RestApiId":{
               "Ref":"RestApiApigEvent"
            },
            "ContentType":"application/json",
            "Description":"Schema for AccountCreationResponseModel",
            "Name":"AccountCreationResponseModel",
            "Schema":{
               "$schema":"http://json-schema.org/draft-04/schema#",
               "title":"AccountCreationResponseModel",
               "type":"object",
               "properties":{
                  "status":{
                     "type":"string"
                  },
                  "message":{
                     "type":"string"
                  }
               }
            }
         }
      },
      "FailureResponseModel":{
         "Type":"AWS::ApiGateway::Model",
         "Properties":{
            "RestApiId":{
               "Ref":"RestApiApigEvent"
            },
            "ContentType":"application/json",
            "Description":"Schema for FailureResponseModel",
            "Name":"FailureResponseModel",
            "Schema":{
               "$schema":"http://json-schema.org/draft-04/schema#",
               "title":"FailureResponseModel",
               "type":"object",
               "properties":{
                  "status":{
                     "type":"string"
                  },
                  "message":{
                     "type":"string"
                  }
               }
            }
         }
      }
   },
   "Outputs":{
      "ServerlessDeploymentBucketName":{
         "Value":{
            "Ref":"ServerlessDeploymentBucket"
         }
      },
      "Function1Arn":{
         "Description":"Lambda function info",
         "Value":{
            "Fn::GetAtt":[
               "createAccount",
               "Arn"
            ]
         }
      },
      "ServiceEndpoint":{
         "Description":"URL of the service endpoint",
         "Value":{
            "Fn::Join":[
               "",
               [
                  "https://",
                  {
                     "Ref":"RestApiApigEvent"
                  },
                  ".execute-api.us-west-2.amazonaws.com/dev"
               ]
            ]
         }
      }
   }
}
</code></pre>

<p>Edit 2:  When I test the endpoint using API Gateway's test feature in the AWS Console everything works great :/</p>

<p>Edit 3: Updated the cloudformation script again--still not working.</p>