Add support for federated querying capability to query multiple workspaces

[maulikpandey]

Context We plan to shard metrics from a group of services into a predefined workspace. This approach allows us to streamline cost attribution/chargeback to appropriate service team owners. Additionally, this strategy helps us isolate noisy services into individual workspaces for scalability.

Problem We anticipate that metrics for large platform teams (like Service Networking, and Compute Infra) would be spread across different workspaces. It's difficult to setup alerts and build accurate dashboards because AMP doesn't have support for federated queries that span more than one workspace.

Feature Request Providing a federated query support allows large customers to seamlessly shard metrics across workspaces while maintaining a consistent user experience.

[maulikpandey]

Here are additional details from my chat with Abhi -

Primary reason for requesting this feature is that we don’t think a single workspace will be able to contain all metrics for large Platform teams. The cost attribution story is clean(er) with routing all metrics for a given team into a single workspace. However, this is a side effect of the primary reason.

[ampabhi-aws]

While we are working on developing this feature, there is an open source project, promxy that you can use to federate queries across multiple AMP workspaces. It does require you to utilize the sigv4 proxy as well to do the authentication.