AWS CDK Service Specification

Source of truth for CDK code generation.

Packages

• @cdklabs/tskb - a typed database; contains build tools, query tools, validation mechanism

• @cdklabs/typewriter - a code generator with support for types

• @aws-cdk/service-spec-importers - import spec from data sources, transform into the db format

• @aws-cdk/service-spec-types - loading, saving, querying and diffing a db

• @aws-cdk/aws-service-spec - the actual db file

Data Sources

The data is read iteratively from various sources. Information from later sources adds on to, or replaces, information from older sources.

• Properties are added: new properties are added into existing resources and type definitions. Existing properties (and attributes) will never be removed.
• Property type information is added: when a new type is found, the old type is moved to the previousTypes array. However, for backwards compatibility reasons, CDK will currently (only) render the oldest type it can find. Newer types can be also rendered in the future, but are not right now. In a model diff, type history is rendered with a ⇐ between them, in order from new to old. If you see type1 ⇐ type2 ⇐ type3, then type3 is the oldest and is the one that will be used by CDK.
• Other property attributes are overwritten: things like documentation, optionality, etc. are overwritten, so newer specifications fully overwrite the information from older specifications.

Sources are read in this order:

What	Description	Updates
Resource Spec	This is the original CloudFormation Resource Specification, which is being replaced by the Registry Schema. Imported in order from us-east-1, us-west-2.	Frozen at version 144.0.0 (Oct 13, 2023).
SAM Resource Spec	This is the unofficial SAM resource spec as voluntarily maintained by the GoFormation project	Daily
Patches	Handwritten patches are applied to these data sources to correct historical data quality issues with the vended specification	Manual
Registry Schema	This is the new CloudFormation Resource Provider Schema, replacing the old Resource Spec. It is more expressive than the old spec. Imported in order: us-east-1, us-east-2, us-west-2.	Daily
SAM JSON Schema	This is the newer version of the unofficial GoFormation SAM specification, expressed in JSON Schema.	Daily
Patches	Coded patches are applied to the JSON Schemas to correct for schema inconsistencies	Manual
GetAtt AllowList	A static list of attributes with the same name as properties	Manual
CloudFormation Docs	A JSON rendering of the AWS CloudFormation Resource Reference.	Weekly
Stateful Resources	An import of a single configuration file of cfn-lint, containing resources that should be considered stateful	Weekly
Canned Metrics	An import of an inventory of metrics for various resource types, built by the AWS CloudWatch team for their console	Manual
Scrutinies	A classification of a number of resources and resource properties, indicating whether they contain IAM Policies or not	Manual
Augmentations	A manual declaration of a set of resource-related metrics, used in CDK code generation	Manual

Contributing

This repository uses Git LFS. Before you clone this repository, run the following commands once:

brew install git-lfs   # Or equivalent, see the website above
git lfs install        # Need to run this once per repo

If you end up with the files not being downloaded from LFS (these are called LFS pointer files), the following command will download them for you:

git lfs pull