Lambda ASP.NET Core Minimal API complains about missing 'libhostpolicy.so' library when deployed

[baynezy]

Describe the bug

I have created a vanilla project from the Lambda ASP.NET Core Minimal API template. I have called it ProfileAPI. I have deployed it via Terraform to AWS. The function will not execute successfully.

Expected Behavior

The function should allow me to execute the / route and the Calculator routes in the template.

Current Behavior

Via API GW I get a 500 Internal Server Error. If I trigger it via the AWS console using the apigateway-api-proxy template I get the following error:-

{
  "errorType": "Runtime.ExitError",
  "errorMessage": "RequestId: 899a669f-cbd3-43cb-b06a-24398aea22df Error: Runtime exited with error: exit status 131"
}

A fatal error was encountered. The library 'libhostpolicy.so' required to execute the application was not found in '/var/task/'.
Failed to run as a self-contained app.
- The application was run as a self-contained app because '/var/task/ProfileAPI.runtimeconfig.json' did not specify a framework.
- If this should be a framework-dependent app, specify the appropriate framework in '/var/task/ProfileAPI.runtimeconfig.json'.
START RequestId: 899a669f-cbd3-43cb-b06a-24398aea22df Version: $LATEST
RequestId: 899a669f-cbd3-43cb-b06a-24398aea22df Error: Runtime exited with error: exit status 131
Runtime.ExitError
END RequestId: 899a669f-cbd3-43cb-b06a-24398aea22df
REPORT RequestId: 899a669f-cbd3-43cb-b06a-24398aea22df	Duration: 162.41 ms	Billed Duration: 163 ms	Memory Size: 128 MB	Max Memory Used: 3 MB	

Reproduction Steps

1. Create a new project from Lambda ASP.NET Core Minimal API template.
2. Publish to AWS with relevant roles and API GW integration
3. Test function

Possible Solution

No response

Additional Information/Context

No response

AWS .NET SDK and/or Package version used

Amazon.Lambda.AspNetCoreServer.Hosting 1.5.1

Targeted .NET Platform

net6.0

Operating System and version

Amazon Lambda

[ashishdhingra]

Hi @baynezy,

Good afternoon.

Thanks for reporting the issue. Although I didn't try reproducing it using Terraform, I was unable to reproduce it using Publish to AWS Lambda option in Visual Studio, which uses .NET Deploy Tool behind the scenes. Kindly note that my project was using Amazon.Lambda.AspNetCoreServer.Hosting version 1.6.0. Could you please check the following:

• Does your .csproj file has the element <GenerateRuntimeConfigurationFiles>true</GenerateRuntimeConfigurationFiles>? If not, could you please try adding it and test again?
• For your use case, what is the Acchitecture in Runtime settings for the underlying Lambda function? In my case, it was x86_64.
• If possible, please share the sample code solution and deployment steps to reproduce the issue.

Thanks,
Ashish

[baynezy]

@ashishdhingra thank you so much for taking the time to look into this. I will answer your questions as best I can.

Does your .csproj file has the element <GenerateRuntimeConfigurationFiles>true</GenerateRuntimeConfigurationFiles>? If not, could you please try adding it and test again?

It does.

<Project Sdk="Microsoft.NET.Sdk.Web">
    <PropertyGroup>
        <TargetFramework>net6.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
        <Nullable>enable</Nullable>
        <GenerateRuntimeConfigurationFiles>true</GenerateRuntimeConfigurationFiles>
        <AWSProjectType>Lambda</AWSProjectType>
        <!-- This property makes the build directory similar to a publish directory and helps the AWS .NET Lambda Mock Test Tool find project dependencies. -->
        <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
        <!-- Generate ready to run images during publishing to improvement cold starts. -->
        <PublishReadyToRun>true</PublishReadyToRun>
    </PropertyGroup>
    <ItemGroup>
        <PackageReference Include="Amazon.Lambda.AspNetCoreServer.Hosting" Version="1.5.1" />
    </ItemGroup>
</Project>

For your use case, what is the architecture in Runtime settings for the underlying Lambda function? In my case, it was x86_64.

The same.

If possible, please share the sample code solution and deployment steps to reproduce the issue.

If you follow the steps in this repository you can replicate the problem.

Much appreciated.

[normj]

@baynezy I'm not well versed in the Cake build system but it looks like your Cake config is triggering a self contained publish for win-x64 instead of linux-x64. Or possibly it is win-x64 because that is what my laptop is. That is of course not going to work packaging for windows and deploying to Linux. Also since you are targeting .NET 6 and using the Lambda .NET 6 managed runtime you probably don't even want to do a self contained publish.

Bare with my Cake ignorance but are there things we could do to make the Amazon.Lambda.Tools and its dotnet lambda package work for your use case with Cake? That tool does more to make sure the settings being used to build the .NET project is correct for Lambda.

[baynezy]

Thanks, @normj - that makes sense. In this instance, I had been using my Win10 laptop to build the project.

That explains why using the same Cake script I have successfully built and deployed a similar project from an Ubuntu-based GitHub Action.

I had avoided the dotnet lambda tooling because as far as I can tell, it relies on the CDK/serverless framework and I want to standardise on Terraform.

Can I use dotnet lambda publish to generate the needed files? Or am I also going to need those other tools?

[baynezy]

@normj - based on your help I have made a change to the Cake script and that is now working perfectly.

Thanks very much for your patients and help.

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