How Do I Set an Environment Variable in C#?

Introduction

In this guide, we will explore how to set an environment variable in C# using Pulumi, specifically focusing on AWS Lambda functions. Setting environment variables is a crucial step in configuring cloud resources, as it allows you to pass configuration data to your application without hardcoding values. This tutorial will walk you through the process of defining and deploying an AWS Lambda function with environment variables using Pulumi in C#.

Step-by-Step Guide

1. Install the necessary Pulumi packages: Ensure that you have the Pulumi CLI and the AWS Pulumi package installed on your system.

2. Create a Pulumi C# project: Initialize a new Pulumi project for AWS in C# by running the command:

   pulumi new aws-csharp
   

3. Define the Lambda function and set an environment variable: Open the Program.cs file in your Pulumi project and configure your AWS Lambda function, including setting an environment variable.

Below is the complete code example:

using Pulumi;
using Lambda = Pulumi.Aws.Lambda;
using Pulumi.Aws.Iam;
using System.Collections.Generic;

return await Deployment.RunAsync(() =>
{
    // Create a role for the lambda function
    var role = new Role("lambdaRole", new RoleArgs
    {
        AssumeRolePolicy = @"{
  ""Version"": ""2012-10-17"",
  ""Statement"": [
    {
      ""Action"": ""sts:AssumeRole"",
      ""Principal"": {
        ""Service"": ""lambda.amazonaws.com""
      },
      ""Effect"": ""Allow"",
      ""Sid"": """"
    }
  ]
}"
    });

    // Attach the AWSLambdaBasicExecutionRole policy to the role
    var rolePolicyAttachment = new RolePolicyAttachment("lambdaRolePolicyAttachment", new RolePolicyAttachmentArgs
    {
        Role = role.Name,
        PolicyArn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
    });

    // Define the Lambda function
    var lambda = new Lambda.Function("myLambdaFunction", new Lambda.FunctionArgs
    {
        Runtime = "dotnetcore3.1",  // Specifies the runtime environment for the Lambda function
        Role = role.Arn,  // Associates the role created above
        Handler = "MyLambdaNamespace.MyLambdaClass::MyLambdaNamespace.MyLambdaClass::FunctionHandler",
        Code = new FileArchive("./code.zip"),  // Upload the Lambda function code, replace with your file path.

        // Setting environment variables for Lambda function
        Environment = new Lambda.Inputs.FunctionEnvironmentArgs
        {
            Variables = 
            {
                { "MyEnvironmentVariable", "ValueOfMyEnvironmentVariable" }
            }
        }
    });

    // Export the name of the Lambda function
    return new Dictionary<string, object?>
    {
        ["lambdaName"] = lambda.Name
    };
});

Explanation

1. Role Creation: An IAM role is created for the Lambda function, which includes the necessary permissions for execution.
2. Policy Attachment: The role is linked to the AWS Lambda Basic Execution Role policy, granting essential permissions.
3. Lambda Function: The function is defined with a specified runtime, handler, and source code. Environment variables are set within the FunctionEnvironmentArgs.

Running the Program

Before deploying, ensure your AWS CLI is configured and authenticated. In your project directory, execute:

pulumi up

This command will deploy the Lambda function to your AWS account, including the environment variable. The function name will be displayed in the console upon successful deployment.

Key Points

• Pulumi CLI and AWS Pulumi package are prerequisites.
• Environment variables are set using FunctionEnvironmentArgs.
• IAM roles and policies are crucial for Lambda permissions.

Conclusion

By following this guide, you have learned how to set environment variables in a Pulumi C# project for an AWS Lambda function. This approach can be extended to other cloud resources and providers, allowing for flexible and dynamic application configurations.