Added FromCustomAuthorizerAttribute and tests.

[kabaluk]

Description of changes:
Added FromCustomAuthorizerAttribute and tests.
This will allow to retrieve values from CustomAuthorizer context without having to receive the full APIGatewayProxyRequest or APIGatewayHttpApiV2ProxyRequest..

Both REST and HttpApi supported

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[normj]

Cool PR!

Can you fix the whitespaces changes to the LambdaFunctionTemplate.tt file? The whole file is looks different.

Who should we handle the other type of authorizer properties. For example on the APIGatewayHttpApiV2ProxyRequest besides the Lambda property there is also Jwt and IAM properties. Should we make the string accessing the authorizer field have the prefix of the property.

[kabaluk]

Wiil do my best with the withspace.
The other types of authorizer are not custom authorizers as far as i am aware.
I would not create string prefixes.
We could create an iam authorizer attribute and a jwt authorizer attribute and those wold look on the respective locations...

[kabaluk]

don't seem to be able to fix the whitespace issue to save my life :(
Please review ignoring whitespace ?? Maybe?

Tried setting EOL to LF and CR, both cause problems with the generated file. The correct one seems to be CRLF .
but obviously git doens't like it :(

Please feel free to edit.

[kabaluk]

Would be really nice to get this avail;able. I will gladly fix the conflicts if this can be looked at again.

[kabaluk]

I can see you did a major refactoring in the dev branch will push again once released.

If i might be so bold, I looked at what you did.
why not take it one step further and separate each attribute into it's own file?
Talking about the APIGatewaySetupParameters.tt
Breaking that file down, using the technique you used before, would make it much easier to add new attributes in the future

Just a thought.

[normj]

@kabaluk I suspect adding new attributes would be done in separate files. For example if we added SQS or S3 I would put them in separate TT. One of my goals with the refactor was to make it easier to add new attributes as the previous monolithic tt file was really hard to reconcile with. HttpApi and RestApi attributes are 9X percent the same code so I didn't really want to make 2 separate tt files for each one of those. Plus I thought the parameter setup was getting pretty long so I was looking for some separation which is why I divided the parameter setup and the invoke. I suspect in SQS or S3 use cases the parameter setup wouldn't be so complicated.

Another goal I had was I wanted to generate the exact same code including whitespaces to make the PR review easier and then later I could do more specific refactoring. Otherwise the PR review would have been every line is different and that is hard to review. But going forward I could see putting each of the FromXXX in a separate tt file as well.

[kabaluk]

@kabaluk I suspect adding new attributes would be done in separate files. For example if we added SQS or S3 I would put them in separate TT. One of my goals with the refactor was to make it easier to add new attributes as the previous monolithic tt file was really hard to reconcile with. HttpApi and RestApi attributes are 9X percent the same code so I didn't really want to make 2 separate tt files for each one of those. Plus I thought the parameter setup was getting pretty long so I was looking for some separation which is why I divided the parameter setup and the invoke. I suspect in SQS or S3 use cases the parameter setup wouldn't be so complicated.

Another goal I had was I wanted to generate the exact same code including whitespaces to make the PR review easier and then later I could do more specific refactoring. Otherwise the PR review would have been every line is different and that is hard to review. But going forward I could see putting each of the FromXXX in a separate tt file as well.

I was talking specifically of the FromXXX attributes. Apologies, I should have been more explicit. Sounds like a great change and it would make it a lot easier to add and test more FromXXX attributes. Looking forward to have that in main so i can re add the FromCustomAuthorizer attribute.
Even started looking on how to do the FromJwt. 😄

[kabaluk]

Readded CustomAuthorizerAttribute..

Hope you like it :)

[kabaluk]

Any possibility of having this looked at again, please?

[normj]

I did an initial scan and it looks good. I had one comment so far. I need to test the experience end to end next. I'll try and find time to do that soon.

[ashishdhingra]

@kabaluk Please review the last review comment from @normj and see if you are able to address it.

[kabaluk]

@kabaluk Please review the last review comment from @normj and see if you are able to address it.

Please have a look.

[GarrettBeatty]

im working on rebasing this

[GarrettBeatty]

Why We Need .ToString() for Custom Authorizer Values

The Data Flow

1. Authorizer Lambda returns context: When your custom authorizer runs, it returns a context dictionary:

   Context = new Dictionary<string, object>
   {
       { "userId", "12345" },
       { "permissions", "admin" }
   }

2. API Gateway passes this to the protected Lambda in the request payload as JSON:

   {
     "requestContext": {
       "authorizer": {
         "userId": "12345",
         "permissions": "admin"
       }
     }
   }

3. Lambda deserializes the request using the configured serializer (System.Text.Json or Newtonsoft.Json).

The Problem: Dictionary<string, object> Deserialization

The Authorizer property is typed as Dictionary<string, object>:

public class APIGatewayCustomAuthorizerContext : Dictionary<string, object>

When the serializer encounters a JSON value like "12345" and needs to deserialize it into object, it doesn't know what concrete type to use. So:

• System.Text.Json wraps it in a JsonElement struct
• Newtonsoft.Json wraps it in a JToken (like JValue)

so rather than having statements like

if (__authValue__ is System.Text.Json.JsonElement jsonElement)
{
    userId = Convert.ChangeType(jsonElement.ToString(), typeof(string));
}

i just call toString which both of these serializers have.

not sure if there is a better way

[GarrettBeatty]

@normj not sure if you have any better ideas here of it ToString is good enough

[Copilot]

Pull request overview

Adds a new [FromCustomAuthorizer] parameter-binding attribute to AWS Lambda Annotations so Lambda handlers can directly receive values from API Gateway custom authorizer context (REST API + HTTP API), along with generator/template updates and accompanying tests/examples.

Changes:

• Introduce FromCustomAuthorizerAttribute and wire it into the source generator attribute modeling and parameter setup templates.
• Add source-generator snapshot tests and update test templates/examples to validate generated output.
• Add a new test application (TestCustomAuthorizerApp) and update docs to demonstrate usage.

Reviewed changes

Copilot reviewed 22 out of 22 changed files in this pull request and generated 13 comments.

Show a summary per file

File	Description
Libraries/test/TestServerlessApp/serverless.template	Adds new test function resources for custom authorizer examples.
Libraries/test/TestServerlessApp/CustomAuthorizerRestExample.cs	REST API example using [FromCustomAuthorizer].
Libraries/test/TestServerlessApp/CustomAuthorizerHttpApiExample.cs	HTTP API example using [FromCustomAuthorizer].
Libraries/test/TestCustomAuthorizerApp/serverless.template	New demo stack showing HTTP API + REST API Lambda authorizers and protected endpoints.
Libraries/test/TestCustomAuthorizerApp/aws-lambda-tools-defaults.json	Deployment defaults for the new demo app.
Libraries/test/TestCustomAuthorizerApp/TestCustomAuthorizerApp.csproj	New demo project configuration and references.
Libraries/test/TestCustomAuthorizerApp/README.md	Demo documentation and usage instructions.
Libraries/test/TestCustomAuthorizerApp/ProtectedFunction.cs	Demo functions showing authorizer-context usage.
Libraries/test/TestCustomAuthorizerApp/AuthorizerFunction.cs	Demo authorizer implementations for HTTP API and REST API.
Libraries/test/Amazon.Lambda.Annotations.SourceGenerators.Tests/SourceGeneratorTests.cs	Adds generator tests for REST + HTTP API (v2) custom authorizer extraction.
Libraries/test/Amazon.Lambda.Annotations.SourceGenerators.Tests/Snapshots/ServerlessTemplates/authorizerRest.template	Snapshot of expected SAM template output for REST authorizer test.
Libraries/test/Amazon.Lambda.Annotations.SourceGenerators.Tests/Snapshots/ServerlessTemplates/authorizerHttpApi.template	Snapshot of expected SAM template output for HTTP API authorizer test.
Libraries/test/Amazon.Lambda.Annotations.SourceGenerators.Tests/Snapshots/CustomAuthorizerRestExample_RestAuthorizer_Generated.g.cs	Snapshot of expected generated handler for REST authorizer extraction.
Libraries/test/Amazon.Lambda.Annotations.SourceGenerators.Tests/Snapshots/CustomAuthorizerHttpApiExample_HttpApiAuthorizer_Generated.g.cs	Snapshot of expected generated handler for HTTP API authorizer extraction.
Libraries/test/Amazon.Lambda.Annotations.SourceGenerators.Tests/Amazon.Lambda.Annotations.SourceGenerators.Tests.csproj	Updates snapshot item handling for the new templates.
Libraries/src/Amazon.Lambda.Annotations/README.md	Documents [FromCustomAuthorizer] usage and behavior.
Libraries/src/Amazon.Lambda.Annotations/APIGateway/FromCustomAuthorizerAttribute.cs	Adds the new public attribute.
Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/TypeFullNames.cs	Registers the new attribute type name for generator recognition.
Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Templates/APIGatewaySetupParameters.tt	Adds template logic to extract values from authorizer context.
Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Templates/APIGatewaySetupParameters.cs	Regenerated T4 output reflecting the new parameter extraction logic.
Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Models/Attributes/FromCustomAuthorizerAttributeBuilder.cs	Adds attribute data builder for the generator model.
Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Models/Attributes/AttributeModelBuilder.cs	Wires the new attribute builder into attribute model creation.

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