Get a value from an environment variable - AWS Cloud Development Kit (AWS CDK) v2

This is the AWS CDK v2 Developer Guide. The older CDK v1 entered maintenance on June 1, 2022 and ended support on June 1, 2023.

Get a value from an environment variable

To get the value of an environment variable, use code like the following. This code gets the value of the environment variable amzn-s3-demo-bucket.

TypeScript

// Sets bucket_name to undefined if environment variable not set
var bucket_name = process.env.amzn-s3-demo-bucket;

// Sets bucket_name to a default if env var doesn't exist
var bucket_name = process.env.amzn-s3-demo-bucket || "DefaultName";
JavaScript

// Sets bucket_name to undefined if environment variable not set
var bucket_name = process.env.amzn-s3-demo-bucket;

// Sets bucket_name to a default if env var doesn't exist
var bucket_name = process.env.amzn-s3-demo-bucket || "DefaultName";
Python
import os

# Raises KeyError if environment variable doesn't exist
bucket_name = os.environ["amzn-s3-demo-bucket"]
        
# Sets bucket_name to None if environment variable doesn't exist
bucket_name = os.getenv("amzn-s3-demo-bucket")

# Sets bucket_name to a default if env var doesn't exist
bucket_name = os.getenv("amzn-s3-demo-bucket", "DefaultName")
Java
// Sets bucketName to null if environment variable doesn't exist
String bucketName = System.getenv("amzn-s3-demo-bucket");

// Sets bucketName to a default if env var doesn't exist
String bucketName = System.getenv("amzn-s3-demo-bucket");
if (bucketName == null) bucketName = "DefaultName";
C#
using System;

// Sets bucket name to null if environment variable doesn't exist
string bucketName = Environment.GetEnvironmentVariable("amzn-s3-demo-bucket");

// Sets bucket_name to a default if env var doesn't exist
string bucketName = Environment.GetEnvironmentVariable("amzn-s3-demo-bucket") ?? "DefaultName";