Curl on AWS Lambda

Question

I have written a simple aws lambda function with Java:

My handler looks like this

public class HelloAWS implements RequestHandler<Map<String,String>, Object>{

@Override
public Object handleRequest(Map<String,String> i, Context cntxt) {
        String input = i.values().toString();
        return "Hello World via Lambda and Java!" + input;
}

The output of the AWS dashboard test looks like I expect it to look like: "Hello World via Lambda and Java![value1, value2, value3]"

I'm trying to reproduce this test result with Ubuntu curl:

curl "https://myUrl.lambda-url.us-east-1.on.aws/" -X POST -H "Content-type: application/json" -d '{"key1": "value1"}'

This yields an error:

An error occurred during JSON parsing: java.lang.RuntimeException
java.lang.RuntimeException: An error occurred during JSON parsing
Caused by: java.io.UncheckedIOException: com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.lang.String` out of START_OBJECT token
 at [Source: (ByteArrayInputStream); line: 1, column: 84] (through reference chain: java.util.LinkedHashMap["headers"])
    at com.amazonaws.services.lambda.runtime.serialization.factories.JacksonFactory$InternalSerializer.fromJson(JacksonFactory.java:184)
Caused by: com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.lang.String` out of START_OBJECT token
 at [Source: (ByteArrayInputStream); line: 1, column: 84] (through reference chain: java.util.LinkedHashMap["headers"])
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59)
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1445)
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1219)
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1129)
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:63)
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:10)
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.MapDeserializer._readAndBindStringKeyMap(MapDeserializer.java:527)
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:364)
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:29)
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.ObjectReader._bindAndClose(ObjectReader.java:1719)
    at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.ObjectReader.readValue(ObjectReader.java:1228)
    at com.amazonaws.services.lambda.runtime.serialization.factories.JacksonFactory$InternalSerializer.fromJson(JacksonFactory.java:182)

An error occurred during JSON parsing: java.lang.RuntimeException java.lang.RuntimeException: An error occurred during JSON parsing Caused by: java.io.UncheckedIOException: com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.lang.String` out of START_OBJECT token at [Source: (ByteArrayInputStream); line: 1, column: 84] (through reference chain: java.util.LinkedHashMap["headers"]) at com.amazonaws.services.lambda.runtime.serialization.factories.JacksonFactory$InternalSerializer.fromJson(JacksonFactory.java:184) Caused by: com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.lang.String` out of START_OBJECT token at [Source: (ByteArrayInputStream); line: 1, column: 84] (through reference chain: java.util.LinkedHashMap["headers"]) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1445) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1219) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1129) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:63) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:10) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.MapDeserializer._readAndBindStringKeyMap(MapDeserializer.java:527) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:364) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:29) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.ObjectReader._bindAndClose(ObjectReader.java:1719) at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.ObjectReader.readValue(ObjectReader.java:1228) at com.amazonaws.services.lambda.runtime.serialization.factories.JacksonFactory$InternalSerializer.fromJson(JacksonFactory.java:182)

I found multiple sources indicating that I should be able to curl my service like this:

https://aws.amazon.com/blogs/aws/announcing-aws-lambda-function-urls-built-in-https-endpoints-for-single-function-microservices/

https://docs.aws.amazon.com/lambda/latest/dg/urls-invocation.html

Why is Java treating my dashboard tests and my curl requests differently?

Answer 1

You can use API gateway to configure your Lambda function so you can invoke it via CURL. Once you configure API Gateway, you can invoke a Lambda function built by using the Java Lambda run-time API with a command like:

curl -XGET "https://xxxxqjko1o3.execute-api.us-east-1.amazonaws.com/cronstage/employee" 

Here is a Java example that walks you through this process. The Lambda function created in this example also invokes AWS Services -- such as Amazon DynamoDB.

Using Amazon API Gateway to invoke Lambda functions

Update

I just tested that and it worked fine. My Lambda function was invoked using this Curl command.

With respect to invoking a standalone Lambda function without using API Gateway, see this new article that may help here:

Announcing AWS Lambda Function URLs: Built-in HTTPS Endpoints for Single-Function Microservices

Confirmed - i followed that new article and it gives you an URL you can use to invoke via CURL without API Gateway....

When deploying your JAR (Lambda function) - make sure you choose this option: