feat: Custom Resource to Perform Manual Merge of a Source API And Signal Cl…

[ndejaco2]

This feature allows the source API owner to ensure that when merge conflicts are introduced, the Cloudformation stack update would fail and cause a rollback. Otherwise, if the merge is successful, the team knows that the updates were successfully applied to the merged API.

The SourceApiAssociationMergeOperationProvider construct creates the Lambda handlers for submitting the merge operation and ensuring that it succeeded or failed.
The SourceApiAssociationMergeOperation construct provides the ability to merge a source api to a Merged Api, invoking a merge within a Cloudformation custom
resource. If the merge operation fails with a conflict, the Cloudformation update will fail and rollback the changes to the source API in the stack. This constructs accepts a merge operation provider which allows the customer to customize the default SourceApiAssociationMergeOperationProvider class if they desire and ensures that we only require a single provider that can be used across multiple merge operations.

Closes aws/aws-cdk#27170, we decided to implement the functionality here instead of in cdk package itself for now.

[MrArnoldPalmer]

This is pretty close, just a question on the provider instantiation. I don't really have additional feedback beyond that we should in the future migrate away from NodeJSFunction usage and package the lambda handlers ourselves as part of publishing this library. That way a user won't have to wait for esbuild to build our handler when using this construct.

That isn't a hard requirement for merging but definitely something we should add.

[ndejaco2]

This is pretty close, just a question on the provider instantiation. I don't really have additional feedback beyond that we should in the future migrate away from NodeJSFunction usage and package the lambda handlers ourselves as part of publishing this library. That way a user won't have to wait for esbuild to build our handler when using this construct. That isn't a hard requirement for merging but definitely something we should add.

Sounds good. I plan on removing it as soon as the latest version of sdk gets into the lambda runtime. Today its on an older version that does not include these new apis in appsync client.