Lambda could not load resource bundle

[johnmorrell]

I have a swift target including static resources referenced in the package target. This target is included in the Lambda executable. The static resources are available when running locally via a CLI executable. When deployed to Lambda via the archive plugin using 1.0.0-alpha.3 these resources don't seem to be available. The error from CloudWatch is:

App/resource_bundle_accessor.swift:12: Fatal error: could not load resource bundle: from /var/task/Sandbox_App.resources or /workspace/.build/x86_64-unknown-linux-gnu/release/Sandbox_App.resources

[sebsto]

Thank you for having reported this.
Can you update to the v2 of the project ? Currently, you can get it from the main branch and we will tag a 2.0.0-alpha.1 shortly

This issue is fixed in the main branch and there is an example project you can use as a reference.

https://github.com/swift-server/swift-aws-lambda-runtime/tree/main/Examples/ResourcesPackaging

[johnmorrell]

Thanks for the quick response. We are using this in conjunction with:

https://github.com/hummingbird-project/hummingbird-lambda

It looks like their v2 development branch has fallen behind main, but thank you for confirming the issue and fix.

[sebsto]

I will ask @adam-fowler to check - thanks for having reported this.

[adam-fowler]

The issue being reported is unrelated to the version of Hummingbird. Although I should release a new beta, with 1.0.0 of swift-aws-lambda-events. This is probably related to the archive plugin not packaging the resources.

[adam-fowler]

There is the start of an implementation of hummingbird-lambda with the new v2 runtime in the lambda-runtime-v2 branch of hummingbird-lambda. It involves a few changes. Unfortunately undocumented at the moment, but it moves the lambda API closer to the server API. Application is replaced with LambdaFunction. It requires a release of the v2 runtime though (@sebsto is there going to be an alpha soon) before it can get a proper release.

[johnmorrell]

Thank you @adam-fowler I have been looking at lambda-runtime-v2. Are you able to upload the example in the README?

[sebsto]

@adam-fowler @johnmorrell
Yes, there will be a Swift lambda Runtime 2.0.0-alpha.1 soon. We've made significant progress last week with @fabianfett
Still a few things to iron out before a release though

[johnmorrell]

@sebsto @adam-fowler thanks for all the work on theses projects, I'll look out for the new releases.

[adam-fowler]

@johnmorrell I've updated the lambda-runtime-v2 branch so it compiles again and updated the README with a simple example

[sebsto]

@johnmorrell if the Lambda packager plugin continues to fail including resources in the zip, please let us know.
Include the directory layout, the output of of zip -r <your zip file>, relevant portions of the Package.swift file, and any relevant error messages or steps to reproduce.

[johnmorrell]

@johnmorrell I've updated the lambda-runtime-v2 branch so it compiles again and updated the README with a simple example

Thank you. Are you able to include the equivalent of:

@main
struct Lambda: APIGatewayLambdaFunction {

}

[adam-fowler]

You could add your own wrapper for that

@main
struct MyApp {
    static func run() async throws {
         let router = Router()
         ...etc
    }
}

[johnmorrell]

I was able to get up and running with APIGW v2 using the two projects, however I still hit the original issue. Using the same hello.txt package reference as the example project above I am able to access the file running the server locally and calling with a JSON body via /invoke. But it does not make it in to the .zip file buillt with the archive plugin:

% zipinfo Lambda.zip
Archive:  Lambda.zip
Zip file size: 34568915 bytes, number of entries: 1
-rwxr-xr-x  3.0 unx 108939824 bx defN 25-Mar-13 12:15 bootstrap
1 file, 108939824 bytes uncompressed, 34568747 bytes compressed:  68.3%

The CloudWatch error on trying to access the resource is:

App/resource_bundle_accessor.swift:12: Fatal **error**: could not load resource bundle: from /var/task/Sandbox_App.resources or /workspace/.build/x86_64-unknown-linux-gnu/release/Sandbox_App.resources

So *.resources is not deployed. The closest to getting something working is to manually add the hello.txt file to the .zip before deployment and access via:

URL(fileURLWithPath: "/var/task/hello.txt")

Which did allow we to access the file via APIGW/Lambda.

[sebsto]

Thank you @johnmorrell for the extra checks.
Can you share your Package.swift file ? It must contain a resource section to trigger the copy of your resources to the zip file.
You can see an example here

swift-aws-lambda-runtime/Examples/ResourcesPackaging/Package.swift

Line 25 in eb634fa

resources: [

targets: [
        .executableTarget(
            name: "MyLambda",
            dependencies: [
                .product(name: "AWSLambdaRuntime", package: "swift-aws-lambda-runtime")
            ],
            path: ".",
            resources: [
                .process("hello.txt")
            ]
        )
    ]

[sebsto]

I don't access the resource file with URL(fileUrlWithPath:) as you wrote.
I use Bundle.module.url(forResource: "hello", withExtension: "txt") instead.

You can see the code example here.

swift-aws-lambda-runtime/Examples/ResourcesPackaging/Sources/main.swift

Line 18 in eb634fa

let runtime = LambdaRuntime {

let runtime = LambdaRuntime {
    (event: String, context: LambdaContext) in
    guard let fileURL = Bundle.module.url(forResource: "hello", withExtension: "txt") else {
        fatalError("no file url")
    }
    return try String(contentsOf: fileURL, encoding: .utf8)
}

I just build and deployed the ZIP file, and it returned the content of the file.

 » cd Examples/ResourcesPackaging 
 » swift package archive --allow-network-connection docker 
...

  Build of product 'MyLambda' complete! (40.63s)
-------------------------------------------------------------------------
archiving "MyLambda"
-------------------------------------------------------------------------
1 archive created
  * MyLambda at /Users/stormacq/Documents/amazon/code/swift/lambda/swift-aws-lambda-runtime/Examples/ResourcesPackaging/.build/plugins/AWSLambdaPackager/outputs/AWSLambdaPackager/MyLambda/MyLambda.zip
  * 

 » unzip -l .build/plugins/AWSLambdaPackager/outputs/AWSLambdaPackager/MyLambda/MyLambda.zip 
Archive:  .build/plugins/AWSLambdaPackager/outputs/AWSLambdaPackager/MyLambda/MyLambda.zip
  Length      Date    Time    Name
---------  ---------- -----   ----
 80804136  03-13-2025 14:27   bootstrap
        0  03-13-2025 14:27   ResourcesPackaging_MyLambda.resources/
       12  03-13-2025 14:27   ResourcesPackaging_MyLambda.resources/hello.txt
---------                     -------
 80804148                     3 files

[johnmorrell]

Thanks @sebsto I can confirm package file contains the resource reference as your example. It would not compile or work locally without it when using the Bundle.module accessor - this is the crash I am seeing under Lambda.

I have just tried running the swift package archive locally on macos and I do get a .zip with the resources included. The issue now looks to be on building on GitHub action ubuntu-latest

[sebsto]

I'm glad we identified the issue. To summarize the above discussion : it looks like the resources are not bundled when running the archive plugin on Linux.
I will try to reproduce that and check what happens.

[johnmorrell]

That's right. I have just added a step to add the static resource *.resources/hello.txt to the zip before deployment and works as expected.

[sebsto]

Yes, this is just a workaround. I'll try to fix the root cause.

[sebsto]

Thank you for having reported this problem. I can reproduce the issue with main branch on Ubuntu 24.04, with Swift 6.0.3
I opened this issue #505 to track the search for root cause and resolution