Add details about how to use IRSA in Astro

[manmeetkaur]

Issue Type

Missing content for an existing feature

Links to Affected Docs

may be : https://docs.astronomer.io/astro/authorize-deployments-to-your-cloud?tab=aws#cloud-provider ? or in Learn tab

The Issue or Context

missing info about using web identity token

Fix or Proposed Change

we leverage IRSA, so you'll have to use boto3's assume_role_with_web_identity to get your container to assume the initial Astro role. you'd get the RoleArn from os.environ['AWS_ROLE_ARN'] and the file containing the WebIdentityToken from os.environ['AWS_WEB_IDENTITY_TOKEN_FILE'] once you've assumed the Astro role, you can leverage those credentials to again use assume_role to assume their target role

Older doc: https://www.notion.so/astronomerio/How-to-Setup-Astro-AWS-Cross-Account-Access-ee7089c4c1ad474f9646e3f360462fcb?pvs=4

slack thread

Additional Notes

No response

Required Reviewers

No response