Inject settings thru environment variables

[sorbonad]

Hi! Should be possible to load the reverse proxy configuration from a environment variable instead of relying on the appsettings.json?

I understand that I can override some parts by using config layering but I am trying to keep the whole config structure out in a env var.

Thanks!

[Tratcher]

Yes, any config value can be represented as an environment variable, but you would need a lot of them.
https://learn.microsoft.com/aspnet/core/fundamentals/configuration/#naming-of-environment-variables

[sorbonad]

Sure, in my case I need to deploy instances of YARP which will run in isolated from each other in different clusters. The settings of those instances will be different and can independently vary as time goes by. The current deployment strategy assumes that you can set settings thru environment variables. I need to have only one central 'vanilla' image. Currently the deployment pipeline injects the proper configuration by using environment variables.

[Tratcher]

Env vars can't be changed without restarting the app. What about an env var that pointed to a scenario specific config file? Or having the deployment pipeline inject a specific config file? It already seems to know the entire config.

[sorbonad]

Those were some options I was about to try, I will do some test and I will let you know. Thanks again!

[sorbonad]

Ater browsing the code a little bit, I believe this would work:

var builder = WebApplication.CreateBuilder(args);
builder.Configuration.AddJsonStream(new MemoryStream(Encoding.UTF8.GetBytes(GetJsonConfigFromEnvironmentVariables())));
...

GetJsonConfigFromEnvironmentVariables is just reading the env variable which contains a valid json config payload.

I believe this won't play nicely with the auto config hot reloads, but in my case that scenario is not going to happen since every configuration/code change requires a deployment.

What do you think?

[Tratcher]

Seems workable. It's a shame not to support hot reloads though.

[sorbonad]

I agree, I will revisit that approach when possible.