This post was contributed by James Devine, Sr. Outposts SA

AWS Outposts enables customers to run AWS services in their on-premises environments. With the release of Outposts and local gateway (LGW) sharing, customers can now configure multi-account access and sharing within an AWS Organization.

Prior to this release, an Outpost was only viable within a single AWS account. VPC sharing was the main way to enable multiple accounts to use Outposts capacity. With the release of Outposts and LGW sharing support, there is now additional functionality to enable multi-account access Outpost capacity within an AWS Organization.

Outposts and LGW sharing is facilitated through AWS Resource Access Manager (RAM). It enables Outposts and LGWs to be shared with AWS accounts within the same AWS Organization. The account that orders Outposts is the owner account that can create resource shares. The accounts that have access to the share are called consumer accounts. Each consumer account can create its own VPCs with subnets that reside on the shared Outpost.

This post will discuss how to start using this new functionality and considerations to take into account.

Use cases

Per AWS best practices, customers typically deploy a number of AWS accounts. Utilizing multiple accounts allows for reduced blast radius and the ability to provide infrastructure isolation by line of business, environment type, and even down to individual workloads. Outposts sharing enables customers to extend their existing AWS account structures to seamlessly integrate with Outposts.

Getting started – creating a resource share

Before any resources can be shared, the first step is to configure an AWS Organization (if one does not already exist). Outposts resources can only be shared with accounts under the same AWS Organization. The Outposts can reside in any account under an organization. For centralized management of Outposts, it is recommend to create a dedicated account, or set of accounts, to host Outposts.

Once an organization is created with member AWS accounts, resources shares can then be created. It’s possible to place multiple resources into a resource share. To facilitate Outposts, LGW, and customer-owned IP (CoIP) sharing, a single resource share can be created that includes all three resources. Principals can then be added to the resource share. The principals can be both organizational units (OUs) and individual AWS account IDs within the AWS Organization. In this case, I’ve shared all three resources with a consumer account ID as a principal, as demonstrated in the following screenshot.

Screen shot of resource sharing.

Sharing an Outpost

After an Outposts is provisioned, the logical Outpost ID can be shared with any account under the AWS Organization. The consumer account then has access to provision resources on the Outposts, such as Amazon EBS volumes and Outposts subnets, as well as launching instances on the shared Outpost.

From the AWS Management Console in the consumer account, I can see the shared Outposts ID, its associated Availability Zone, and the owner account ID.

From the AWS Management Console in the consumer account, I can see the shared Outposts ID, its associated Availability Zone, and the owner account ID.

Once the Outposts ID is selected, I can use the Actions drop down menu to create Outposts subnets and EBS volumes. I can also select Launch instance to provision instances on the Outpost.

Once the Outposts ID is selected, I can use the Actions drop down menu to create Outposts subnets and EBS volumes. I can also select Launch instance to provision instances on the Outpost.

Sharing an LGW

Each consumer account can create their own Outposts subnets within their own VPCs. LGW sharing enables the consumer account to create routes an Outposts subnet route table that has a shared LGW as the destination. This enables Outposts subnets in the consumer account to have communication with the on-premises network through the shared LGW.

The consumer account view shared LGWs, as shown in the following screenshot.

The consumer account view shared LGWs, as shown in the following screenshot.

The consumer account can then select VPCs within the account to associate with the LGW route table. This enables routing to on-premises if a CoIP is assigned to an instance.

This enables routing to on-premises if a CoIP is assigned to an instance.

Considerations

LGW and Outposts sharing is meant to enable sharing of resources between various accounts within a larger organizational structure. It is not suitable for multi-tenancy outside of an AWS Organization. Additional considerations around capacity planning, access, and local network connectivity should be taken into account.

Resources created in the consumer account are only visible from within the consumer account. The AWS account that owns the Outpost does not have the ability to view instances, EBS volumes, VPCs, subnets, or any other resource created within the consumer account. Since the consumer account is part of an AWS Organization, it is possible to use the default OrganizationAccountAccessRole role that is created by AWS Organizations. This allows for visibility and management of Outpost resources across the AWS Organization.

Capacity information is not shared with the consumer account. However, it is possible to use cross-account CloudWatch metric sharing. Outposts utilization metrics from the account that owns the Outpost can be shared with the consumer account. This allows the consumer account to see what capacity is available on the shared Outposts. I’ve configured the cross-account sharing, and from my consumer account I can see that there is ample c5.xlarge capacity on the shared Outposts.

I’ve configured the cross-account sharing, and from my consumer account I can see that there is ample c5.xlarge capacity on the shared Outposts.

If a principal (consumer account or organizational unit) no longer requires access to Outposts capacity, the resource share can be deleted through RAM in the primary Outposts account. It is important to note that this does not delete subnets, EBS volumes, instances, or other resources running on the shared Outposts. Proper cleanup of Outposts resources within the consumer account (EBS volumes, instances, subnets, etc.) should be planned for whenever removing principals from a resource share to ensure that the capacity is released.

Conclusion 

In the blog post, I described the Outposts and LGW sharing capabilities and demonstrated how they can be used to enable multi-account sharing of an Outpost within an AWS Organization. These new capabilities unlock even more customer use cases and allow for stronger blast-radius and account isolation. It’s exciting to see continued functionality come to Outposts! You can start using LGW and Outposts sharing today. There’s no need to upgrade or modify your Outposts in any way to take advantage of this new and exciting functionality.