How do you invoke a Lambda function manually?

Difficulty: 2/10

invocation-types, cli-sdk-console, payload-handling

You can manually invoke a Lambda function for testing or operational purposes using the AWS Management Console, AWS CLI, SDKs, or tools like Postman (if the function is exposed via API Gateway). This is especially useful during development and debugging.

Ways to Manually Invoke a Lambda Function

1
Using the AWS Console: Navigate to the Lambda function, use the 'Test' tab, configure a test event, and invoke.
2
Using AWS CLI: Run the aws lambda invoke command with a payload.
3
Using AWS SDKs: Programmatically invoke using SDKs in languages like Python, Node.js, or Java.
4
Via API Gateway: If connected, send an HTTP request to the endpoint.
5
Using CloudShell: Execute CLI commands directly from the AWS Console.

Manually Invoke via AWS CLI

Scenario Questions

0-2 years experience

1You just deployed a Lambda function and want to test it quickly in the AWS Console — walk me through the steps you'd take and what you'd look for in the result.
2A teammate asks you to invoke a Lambda from your laptop using the AWS CLI with a JSON payload — what command would you run, and how do you verify it executed successfully?
3What happens if you try to invoke a Lambda function that doesn't exist, or one you don't have permission to invoke? What error would you see?

Follow-up Questions

What's the difference between synchronous and asynchronous invocation, and when would you choose each?
How would you handle a situation where the Lambda function returns an error during manual invocation?
What limits should you be aware of when invoking Lambda functions manually at scale?