How to deploy asp.net core application on multiple environments using Octopus?

Question

I am developing an ASP.NET Core API (.NET Core 3.1). Everything works as expected. When I deploy the application on the consumer environment using Octopus, it reads the appsettings.Production.json, not the appsettings.Uat.json even if I have set the ASPNETCORE_ENVIRONMENT to Consumer.

web.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <location path="." inheritInChildApplications="false">
    <system.webServer>
      <handlers>
        <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
      </handlers>
      <aspNetCore processPath="dotnet" arguments=".\Mydll.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" hostingModel="inprocess" />
    </system.webServer>
  </location>
</configuration>

launchsettings.json

{
  "iisSettings": {
    "windowsAuthentication": false,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:50900",
      "sslPort": 0
    }
  },
  "$schema": "http://json.schemastore.org/launchsettings.json",
  "profiles": {
    "IIS Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "launchUrl": "default",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    },
    "IIS_UAT Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "launchUrl": "default",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Consumer"
      }
    },
    "IIS_PRODUCTION Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "launchUrl": "default",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Production"
      }
    },
    "ISOXMLValidationApi": {
      "commandName": "Project",
      "launchBrowser": true,
      "launchUrl": "default",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      },
      "applicationUrl": "https://localhost:5001;http://localhost:5000"
    }
  }
}

Octopus variables:

Answer 1

Are you using the ASPNETCORE_ENVIRONMENT Octopus variable anywhere? Octopus won't automatically set the ENV variable with that name so you might need to add a script to do that during your deployment.

If you haven't done this yet, you can use a separate Run a Script step on the target or the custom deployment scripts feature on your Deploy a Package step.

Information on custom scripts and scripts in packages:

• https://octopus.com/docs/deployment-examples/custom-scripts
• https://octopus.com/docs/deployment-examples/custom-scripts/scripts-in-packages

There's also a chance that you don't need the environmental JSON configuration files as Octopus can inject variable values directly into JSON configuration files.

• https://octopus.com/docs/deployment-process/configuration-features[/structured-configuration-variables-feature

To set an environment variable with PowerShell, it would look something like

$aspEnvironment = $OctopusParameters["ASPNETCORE_ENVIRONMENT"]
[System.Environment]::SetEnvironmentVariable('ASPNETCORE_ENVIRONMENT', $aspEnvironment, [System.EnvironmentVariableTarget]::User)

See https://www.tachytelic.net/2019/03/powershell-environment-variables/ as a reference.