SAM JSON schema

[jlhood]

Description:

Today, SAM's spec is a document meant for human consumption only. SAM should also have an authoritative, machine-readable spec (schema). This would be beneficial in multiple ways:

1. This would allow cfn-lint to remove its dependency on the SAM translator code, which can cause dependency conflicts with other modules if they depend on a different version of SAM translator. cfn-lint could keep a copy the SAM schema similar to what it does for CloudFormation schemas. Then there would no longer be a dependency conflict.
   1. Somewhat tangential: I'd prefer for SAM CLI's sam validate command to just run cfn-lint against the template. I think this would be far more valuable than what the current sam validate command offers. Removing cfn-lint's dependency on SAM translator would unblock this.
2. If we could embed the documentation of the current spec into the schema, this could lead to the human-readable version of the spec being auto-generated. This would allow us to auto-generate the SAM spec in the official SAM documentation after each SAM release.

[kddejong]

From a cfn lint perspective I like this idea. sam translator is currently essential to us being able to lint serverless templates. Having a shema could remove us from that requirement and allow us to directly lint the original file.

[nija-at]

+1 to this.

AWS CDK is currently using the spec for awslabs/goformation to auto-generate CDK L1 resources (i.e. language bindings) and we're seeing a couple of cases where the handcrafted spec deviates from SAM's spec, specifically in terms of required and optional attributes, that blocks our customers from doing the right thing.

Referencing aws/aws-cdk#3841 and awslabs/goformation#87.

[stilvoid]

Another +1. I'd like to add SAM resource types to https://github.com/aws-cloudformation/rain :)

[tj]

There's https://github.com/aws/serverless-application-model/blob/develop/samtranslator/validator/sam_schema/schema.json , but it doesn't seem up-to-date, it's missing HttpApi, I'd like to have something as well though!

[jfuss]

Pining to clear the maintainer/need-response label. The team is looking at a better validation experience through jsonschema but none of that work is in progress or fully designed.

We did some work on this already: #2195 and #2032

[hoffa]

Relevant: #2645

[hoffa]

Resolving; done in PRs above.

See https://github.com/aws/serverless-application-model/blob/develop/samtranslator/schema/schema.json and #2645.