Add support for app settings

[noahhai]

Would this be possible?

[normj]

Can you give more details about what you mean by support for app settings?

[noahhai]

This may be instead a request for the AWS Lambda team, regarding this issue:
https://stackoverflow.com/questions/46879797/app-config-in-an-aws-lambda-function
(App.config is not respected by Lambda).

I noticied the issue when using System.Configuration.ConfigurationManager nuget package in a .net core 2.0 Lambda; the ConfigurationManager loads the app settings when running locally, but it errors when being run by Lambda. I don't know enough about the Lambda .net core 2.0 runtime to know if it would be possible to modify the deploy/package utilities to support either an app.config file getting deployed to the proper location so as to be picked up by the Lambda .net core runtime, or to add some type of custom app settings parameter (to allow separating out credentials, etc to a separate file from source code).

[jrstill]

Any reason you can't use environment variables for your deployed lambdas? Dotnet core has good support for merging all the places it can get config from, so we set ours up to pull in environment variables last. Devs can use app config locally during development, but then the deployed ones skip that and we set everything in environment variables. As a bonus, if you find you need to tweak a config setting on a deployed lambda (for instance, to turn up your logging level temporarily), you can do it via the console (or terraform, or whatever you use to manage infrastructure) instead of having to redeploy the whole package.

[PaulDMendoza]

@noahhai My solution ended up being to just move away from ConfigurationManager references in my app and put everything in environment variables. It took a few days but in the end it was worth it. Environment variables are the way to go for configuration instead of App.Config. It makes it easier to run your app in a Docker Container or to stick it in Lambda. I'd suggest just biting the bullet and moving your configuration to environment variables if possible.

[tobyhei]

Does this issue also affect AppSettings.json and AppSettings{environment}.json etc? I don't think only supporting environment variables is a robust enough solution. dotnet core with docker and ECS etc has excellent support using appsettings for configuration as well as environment variables, and forcing people to move to environment variables only for lambda specifically makes it a lot less desirable.

Bit confusing why the ASP.NET Core 2.0 blue prints have explicit support for appsettings, but not the plain old dot net core ones as far as I can tell.

[raban33]

When .NET core 2.0 is deployed on to lambda, it doesn't honor the environment variables as far as appSettings.{env.EnvironmentName}.json is concerned and always picks appSettings.json. However the environment variable for ASPNETCORE_ENVIRONMENT is correctly read in rest of the program, is this the known issue?

[andycmaj]

Can you give more details about what you mean by support for app settings?

I think this refers to the fact that dotnet lambda package doesn't include appsettings.json by default when it publishes your app before zipping...

@noahhai you can probably add the following to your .csproj to enable this:

  <ItemGroup>
    <None Update="appsettings.json">
      <CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
    </None>
  </ItemGroup>

[cgaughan22]

Has anyone ever found a solution to either use the ConfigurationManager class that uses the app.config file, like in traditional .Net applications, or a workaround without having to change the references to the ConfigurationManager class, with .Net Core 2 and Lambda?

The reason why it would be helpful to us in Lambda, instead of moving away from using the ConfigurationManager class to use environmental variables, is because we have multiple EC2 instances that do use app.config and we want to be able to use the same library as it changes - it's our main CRUD library used for our users.

[Nodios]

@raban33 Did you find the solution? I am experiencing the same issue.

[petarrepac]

Make your library .NetStandard2.0 + do not read settings directly, but instead always go through some "settings class".
Settings class only has properties, but underneath it uses some sort of helper class that will read the setting value given setting name and also convert to bool, string, int, ...

Now this helper class can access setting values from env variables, IConfiguration interface (look here https://www.nuget.org/packages/Microsoft.Extensions.Configuration/2.1.1) or System.Configuration.ConfigurationManager depending how you configure it.

Not ideal, but the same NetStandard2.0 code works on both .NetFx and .Netcore runtimes.

P.S. @Nodios: nice surname you have there :)

[justinhelgerson]

This issue should be renamed. The OP was asking about an app.config file specifically, not the appsettings.json file from .NET Core.

As for the appsettings.json issue some people are having (@Nodios & @raban33) I was running into an issue as well. My environment specific file wasn't being picked up. After some digging I realized AWS is running .NET Core on Linux and the file system is case sensitive. Changing my environment variable ASPNETCORE_ENVIRONMENT to have the same case as the settings file appsettings.<EnvironmentName>.json fixed the issue.

[genifycom]

Here is what I have found. My appsettings.json is set to Always Copy. I can see that both files:

... zipping: appsettings.Development.json
... zipping: appsettings.json

are included in the AWS Lambda ZipFile. However, when I write out the appsettings.json I get this one (Is this a default appsettings.json?)

{
"Logging": {
"IncludeScopes": false,
"LogLevel": {
"Default": "Information"
}
}
}

So it looks like the copied appsettings.json is not getting into the Lambda app execution directory.