Call aws Lambda function without using API Gateway and EC2 Instance

Question

Can we call lambda function from outside aws without using API Gateway? I want to call lambda function directly from outside aws services is it possible?

Answer 1

AWS Lambda functions can be triggered by:

• Events happening on other AWS services (eg Object uploaded to an Amazon S3 bucket)
• A message being sent to AWS API Gateway (eg a REST call)
• A schedule in Amazon CloudWatch Events
• A direct API call

From Supported Event Sources documentation:

In addition to invoking Lambda functions using event sources, you can also invoke your Lambda function on demand. You don't need to preconfigure any event source mapping in this case. However, make sure that the custom application has the necessary permissions to invoke your Lambda function.

For example, user applications can also generate events (build your own custom event sources). User applications such as client, mobile, or web applications can publish events and invoke Lambda functions using the AWS SDKs or AWS Mobile SDKs such as the AWS Mobile SDK for Android.

So, anything on the Internet can invoke a Lambda function, but it will need to use AWS credentials to authenticate.