AWS Billing Report API:

1. Setup billing integration with Athena:
   a. https://aws.amazon.com/blogs/aws-cost-management/querying-your-aws-cost-and-usage-report-using-amazon-athena/
2. Define, if required, previous month adjustments:
   a.
3. Configure how we will send data to Athena:
   a.
   b. Reference https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/athena.html.
4. Create a lambda fuction using the sample code: https://github.com/mpcloud/code/aws-billing-api/blob/master/athena_billing.py
   a. Example on hot to create lambda: https://docs.aws.amazon.com/es_es/toolkit-for-eclipse/v1/user-guide/lambda-tutorial.html.
5. Assign the required values:
   a.
6. You need to have a role previously created with access to S3 ans to query Athena.
7. Create a ner API in API Gateway and associate the lambda you currently created mapping the parameters to the lambda input:
   a.
8. Create a resource and a Methos in API Gateway:
   a.
9. Setup the example parameters wou will use in the GET Request to the URL:
   a.
   b. Method Request
   
   c. Integration Request
   i.
   ii.
   d. Integration Response
   
   e. Method Response
   
   The parameters we defined will be used like this: AccountID=Your-Account-ID&Month=12&Year=2018, we can go to test to validate before deploying, this is an example of how your URL would look like with this example: https://your-url.execute-api.us-east-1.amazonaws.com/Prod/test?AccountID=360616938971&Month=12&Year=2018