An Amazon Elastic Beanstalk .ebextensions config to get .NET Core 2.0 working on existing AMIs (http://xm.x-infinity.com/2017/08/net-core-20-in-aws-elasticbeanstalk.html)

netcore2.config

files:
  "C:\\Users\\Administrator\\Documents\\installnetcore2.ps1":
    content: |
      if (!(Test-Path -path 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\2.0.0\')) {
        $url = "https://download.microsoft.com/download/B/1/D/B1D7D5BF-3920-47AA-94BD-7A6E48822F18/DotNetCore.2.0.0-WindowsHosting.exe"
        $path = "C:\Users\Administrator\Downloads\DotNetCore.2.0.0-WindowsHosting.exe"
        (New-Object System.Net.WebClient).DownloadFile($url, $path)
        &$path /quiet
        Start-Sleep -s 5
        Remove-Item $path
      }

commands:
  install_netcore2:
    command: powershell.exe -ExecutionPolicy ByPass -File C:\Users\Administrator\Documents\installnetcore2.ps1

project.csproj

  <ItemGroup>
    <None Include=".ebextensions\netcore2.config" CopyToPublishDirectory="preserveNewest" />
  </ItemGroup>

When using AWS Toolikt for Visual Studio 2017 you can publish your ASP.NET Core apps to AWS using Elastic Beanstalk.
Unfortunately, at this time the AMIs do not support .NET Core 2.0.
Fortunately, you do not have to wait, just add netcore2.config to .ebextensions/netcore2.config in your project, and modify the .csproj as shown above.