Managing Code for Different Environments

This document will go through how to maintain different versions of code for different environments. For example, having a test login endpoint on DEV and UAT, but disabling the endpoint for PROD. We will go through how to set things up so that there won’t be a need to modify code when building/deploying for different environments.

There are 2 different methods:

• Preprocessor Directives
• IHostEnvironment Extensions

Prerequisites#

Before reading this document, make sure you understand the following:

• Build configurations
• Preprocessor directives
• Dotnet build command
• Dotnet publish command
• Dependency Injection
• IHostEnvironment

Sample Project#

Refer to this sample project to see things in action.

Preprocessor Directives#

Build Configurations#

Firstly, create build configurations for every environment:

• DEV
• UAT/QA
• PROD (can use the default Release)
• and any other environments as required

Assuming that you’ve added Dev and UAT build configurations, you should see the following in your csproj file:

<Configurations>Debug;Release;UAT;Dev</Configurations>

Defining Preprocessor Directive Constants#

Next, define the constants that you want to use for the different environments in the csproj file.

For example:

    <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
        <DefineConstants>IS_PROD</DefineConstants>
    </PropertyGroup>
    <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='UAT|AnyCPU'">
        <DefineConstants>IS_UAT</DefineConstants>
    </PropertyGroup>
    <!-- Set IS_DEV for local and DEV environments -->
	<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
		<DefineConstants>IS_DEV</DefineConstants>
	</PropertyGroup>
	<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Dev|AnyCPU'">
		<DefineConstants>IS_DEV</DefineConstants>
	</PropertyGroup>

Using Preprocessor Directives#

After the setup, you can start using the preprocessor directives to write code that will be compiled for different platforms.

For example:

#if IS_PROD
  RunProdLoginCode();
#elif IS_UAT
  RunUatLoginCode();
#else
  RunDevLoginCode();
#endif

Building and Publishing#

For building and publishing, use the build or publish commands with the appropriate build configuration that is required.

For example to build for UAT:

dotnet build -c UAT

IHostEnvironment#

Using IHostEnvironment#

IHostEnvironment extensions are available in .NET by default. Use dependency injection to add IHostEnvironment to the class as required.

Once done, you can use the extensions to manage environment-specific behaviours as required.

For example:

if (HostEnvironmentEnvExtensions.IsDevelopment(_hostEnvironment))
{
    // run dev code
}
else {
    // run non-dev code
}

Changing the host environment#

We can change the host environment at runtime by adding the environment flag when using dotnet run.

For example to set the environment as Staging:

dotnet run --environment Staging