Configuring ASPNETCORE_ENVIRONMENT In TFS for .Net Core 2

Question

We're having an issue right now where we're unable to debug our Dev server environment:

Now, I've spent literal hours searching for how to set ASPNETCORE_ENVIRONMENT and I've only found two (practical) ways:

1. Create a web.[MYCONFIGURATION].config file and add in the following, where [MYCONFIGURATION] would be something like Development or Release:

web.[MYCONFIGURATION].config:

<environmentVariables>
  <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Development" />
</environmentVariables>

2. Set IIS variables on the deployed server to enable ASPCORE_ENVIRONMENT

Here are the problems with each:

1. Since .NET Core uses appsettings.json files for its configuration (a web.config is generated from it, so far as I understand), things like our database connection strings and other settings get lost if we create a web.config ourselves.
2. We are running in an enterprise-level, multi-application environment with a combination of .NET Core and non-Core ASP.NET applications (which I do not have access to), so changing IIS's settings for our application only is not an option.

It should be noted that we are using TFS's Build/Release to publish to our Dev server. I had hoped that adding a BuildConfiguration variable of "development" would also work to set ASPNETCORE_ENVIRONMENT, but unfortunately it does not.

What can I do to set ASPNETCORE_ENVIRONMENT for our application only without needing a web.config or IIS settings? Or, if that is presently impossible, how can I make one of the two options work, given the constraints I have described?

Answer 1

I don't think I'm following correctly, seems to me you're almost there. We have a similar setup and here's what my deploy looks like.

Essentially, you don't create web.config from appsettings.json. You tell your app (running on Kestrel behind IIS) which appsettings.[Env].json to use, depending on ASPNETCORE_ENVIRONMENT value set in web.config. Not really sure what you mean by

things like our database connection strings and other settings get lost if we create a web.config ourselves

All my deployment scripts are using PS and PS remoting via our build server (as a TFS user, you should be familiar with this), so in a nutshell, this is what happens:

// Where Env.Name is the runtime configuration - i.e. "Production"
$environmentVariable = [PSCustomObject]@{Name='ASPNETCORE_ENVIRONMENT'; Value=$using:Env.Name}

// This is how I add the actual value for ASPNETCORE_ENVIRONMENT in web.config
Add-WebConfigurationProperty $IISSite -Filter "system.webServer/aspNetCore" -Name environmentVariables -Value $environmentVariable

The last line adds

<aspNetCore processPath=".\PathToMyApp.exe" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout">
    <environmentVariables>
        <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Production" />
    </environmentVariables>
</aspNetCore>

to web.config, and you're all set.

Answer 2

You can also use the "IIS Web App Manage" task to set the variables using the section Advanced and Additional appcmd.exe commands:

set config "APPNAME" -section:system.webServer/aspNetCore /+"environmentVariables.[name='ASPNETCORE_ENVIRONMENT',value='Staging']" /commit:site

However, multiple executions of this script are not working. Maybe anyone has an idea?

See also: How to set environment variables per site on IIS using appcmd.exe?

Answer 3

Since I didn't have access to the server, the server admins refused to set a global environment variable across a multi-app server, and I couldn't pre-modify a web.config file in Visual Studio pre-release, the admins found an alternate solution.

Since I'm building/releasing using TFS, they added a Patch XML File task to TFS and instructed me to configure the task as seen below:

+ /configuration/system.webServer/aspNetCore/- => "environmentVariables"
+ /configuration/system.webServer/aspNetCore/environmentVariables/- => "environmentVariable"
= /configuration/system.webServer/aspNetCore/environmentVariables/environmentVariable/@name => "ASPNETCORE_ENVIRONMENT"
= /configuration/system.webServer/aspNetCore/environmentVariables/environmentVariable/@value=> "Development"

It seems to have worked just fine:

I must say it is irritating that this was my only recourse in .Net Core 2.0. Apparently being a server admin or having access to one who is very willing to update server configurations is a requirement to properly using .Net Core 2. Not impressed.