Step 5 - Calling through the API Gateway with Postman

It's Postman time again. We use the same settings as we did in the first part of the tutorial but slightly changed to incorporate the following:

1. The new HTTP endpoint
2. Authorization should now be AWS Signature
3. User Access Key
4. User Secret Key
5. AWS Region
6. Service name of 'execute-api'

Leaving the body/payload of the call as it is:



Postman generates special headers that include an AWS Signature calculated by the combination of the user's Access and Secret Keys.


 
Submitting the payload {"key1:"value1"} results in the by now familiar {"received":"value1"} response:


A quick look at the log entry of our API-Gateway-Execution point confirms that everything runs just fine:





This takes us to the end of Part 2.

Recap

So what have achieved in this part? 

• Created a new Lambda function, HTTP endpoint and Trigger
  
  
• Created a Role and a User
  
  
• Bound the Role to the User and vice versa and granted  permissions on both the Lambda function and API Gateway
  
  
• Installed and configured the AWS CLI
  
  
• Assumed the role and called the function through the CLI with the 'aws lambda invoke' command
  
  
• Called the function through the HTTP endpoint by using Postman, passing the user's Access and Secret key in to create a unique signature for authenticating

In the next and final part we're going to call our lambda programmatically through the help of Perl and its awesome Paws module.

Related Articles

AWS Lambda For The Impatient Part 1

AWS Lambda For The Impatient Part 3 

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