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Organisations

Links: 101 AWS SAA Index


Introduction

  • It is a Global service.
  • It allows us to manage multiple AWS accounts in the organisation.
  • The main account is called the master account and cannot be changed and other accounts are known as member accounts.
  • Member accounts can only be part of one AWS organisation but they can be moved from one AWS organisation to another.
How to move an AWS member account from Organisation A to B

To move an account from organisation A to B Remove the member account from the old organisation. Send an invite to the member account from the new Organisation. Accept the invite to the new organisation from the member account

Remove -> Invite -> Accept

How to make master account join the new organisation.

Remove all the members from the current organisation. Delete the organisation. Invite the master to the new account.

  • You can invite other accounts to join your organisation.
  • Consolidated billing across all the accounts. All the AWS accounts should fall under a single consolidated billing for the monthly fee to be charged only once.
  • Pricing benefits from aggregated usage
  • We can create member accounts using API.
  • We can group accounts into Organisation Units (OUs).
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How to identify questions related to organisations

There will be words like sharing, centrally manage, consolidated billing.

Multi Account Strategies

  • Create accounts per department, per cost centre, per dev / test prod, based on regulatory restrictions (using SCP), for better resource isolation (ex: VPC), to have separate per-account service limits, isolated account for logging
  • Enable CloudTrail on all accounts, send logs to central S3 account.
  • Send CloudWatch Logs to central logging account.

SCP (Service Control Policies)

  • Used for managing permissions easily from a central location.
  • We can whitelist or blacklist IAM actions applied at the OU or account level but does not apply to Master account.
SCPs have no effect on master account
  • SCP is applied to all the Users and Roles of the Account, including Root. So if you are not able to use EC2 then the admin of that account will also not be able to use EC2
  • A user can access a service if both SCP and IAM policies allow it. If denied by either of them then user won't be access the service.
  • SCP doesn't apply to service linked roles. Service-linked roles enable other AWS services to integrate with AWS Organisations and can't be restricted by SCPs.
SCPs must have an explicit allow. By default everything is denied.
  • Only service control policies (SCPs) in organisations can restrict the permissions that are granted to the root user of an account.

  • SCP hierarchy

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Last updated: 2022-04-18