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Build environment variables

Netlify environment variables are accessible during your build. This allows you to change behaviors based on deploy parameters or to include information you don’t want to save in your repository, such as API keys.

This page describes how to create environment variables, the specific configuration and read-only variables that are available in the Netlify build environment, and how to use environment variables during the build process.

# Declare variables

You can declare and set environment variables using the Netlify UI, CLI, API, or a Netlify configuration file. If you have the option to set specific scopes for your environment variables, the scope must include Builds to be available to the build system.

Visit the environment variables overview to learn more about environment variables at Netlify.

# Netlify configuration variables

By setting custom values for certain reserved environment variables, you can change some aspects of your build, such as language and dependency versions. Links in the variable descriptions below provide more information about requirements, defaults, and accepted values.

The following variables should be set in the Netlify UI rather than in netlify.toml. This is because the Netlify configuration file is read after your repository has been cloned.

  • GIT_LFS_ENABLED: value that is undefined by default. If set, we’ll use git lfs clone to check out your repository — otherwise we use git clone.
  • GIT_LFS_FETCH_INCLUDE: if GIT_LFS_ENABLED is set, this specifies by file extension which Git LFS files will be downloaded when cloning your repository. Any other file extensions will have only text pointer files downloaded instead of the original media files.
  • NETLIFY_BUILD_DEBUG: set this to true to print additional debugging information in the build logs. The output does not contain sensitive information. To disable debugging, delete the variable. Alternatively, delete everything in the variable’s Value field.

# Read-only variables

In addition to the variables you choose to declare, Netlify has a number of pre-defined variables built in. The following variables are automatically set for your builds, and their values are not changeable.

# Build metadata

  • NETLIFY: always true. Can be used to check if the build is running on Netlify.
  • BUILD_ID: unique ID for the build; for example: 5d4aeac2ccabf517d2f219b8.
  • CONTEXT: name of the build’s deploy context. It can be production, deploy-preview, branch-deploy, or dev.

# Git metadata

  • REPOSITORY_URL: URL for the linked Git repository.
  • BRANCH: reference to check out after fetching changes from the Git repository. Can be useful for split testing.
  • HEAD: name of the head branch received from a Git provider.
  • COMMIT_REF: reference ID (also known as “SHA” or “hash”) of the commit we’re building.
  • CACHED_COMMIT_REF: reference ID (also known as “SHA” or “hash”) of the last commit that we built before the current build. When a build runs without cache, CACHED_COMMIT_REF will be the same as the COMMIT_REF.
  • PULL_REQUEST: whether the build is from a pull/merge request (true) or not (false).
  • REVIEW_ID: ID of the request and the Deploy Preview it generated (for example, 1211) if from a pull/merge request. These two numbers will always match. (For example, deploy-preview-12 is for PR #12 in your repository.)

# Deploy URLs and metadata

  • URL: URL representing the main address to your site. It can be either a Netlify subdomain or your own custom domain if you set one; for example, https://petsof.netlify.app or https://www.petsofnetlify.com.
  • DEPLOY_URL: URL representing the unique URL for an individual deploy. It starts with a unique ID that identifies the deploy; for example, https://5b243e66dd6a547b4fee73ae--petsof.netlify.app.
  • DEPLOY_PRIME_URL: URL representing the primary URL for an individual deploy, or a group of them, like branch deploys and Deploy Previews; for example, https://feature-branch--petsof.netlify.app or https://deploy-preview-1--petsof.netlify.app. If you set up an automatic deploy subdomain, this URL will update.
  • DEPLOY_ID: unique ID for the deploy; for example, 578ab634d6865d5cf960d620. Matches the beginning of DEPLOY_URL.
  • SITE_NAME: name of the site, its Netlify subdomain; for example, petsof.
  • SITE_ID: unique ID for the site; for example, 1d01c0c0-4554-4747-93b8-34ce3448ab95.

# Build hook metadata and payload

If your build is triggered from a custom build hook, Netlify also has three build-hook-specific variables:

  • INCOMING_HOOK_TITLE: title of the build hook.
  • INCOMING_HOOK_URL: URL of the build hook.
  • INCOMING_HOOK_BODY: payload of the request sent to the build hook URL.

# Access variables

Build environment variables are available in the build system they’re set in and are available for use by build plugins and scripts run during the build step for a site. This section outlines how to access these variables during the build process.

Note that, as these are build variables specifically, you will need to take extra steps if you want your site to have access to these values after the build is complete.

Check your variable scope

If you have the option to set specific scopes for your environment variables, the scope must include Builds to be available to the Netlify build system.

# Prepare your build environment

To use these environment variables, you need to ensure they’re set in the environment where the build will run - on Netlify through continuous deployment or in your local development environment.

# Build on Netlify

If you have continuous deployment set up, Netlify will automatically start a build and deploy whenever you push code to your Git repo. While the build runs on Netlify, the build system already has access to all of the variables set in the Netlify build environment and can use them during the build process.

Note that when you build on Netlify, the build system doesn’t read .env files. To use variables declared in a .env file, we recommend you import the variables into Netlify before you build. This way the variables in your .env file remain secure and out of your shared repository.

# Build locally

When you build in your local development environment, you need to ensure these environment variables are set in the local environment before you run the build command.

The best way to build locally is to use the Netlify CLI. Building locally with the CLI mimics the behavior of running a build on Netlify and will give you access to the environment variables you’ve already set there.

netlify build

You can also use Netlify Dev with --context production to run a local development environment that mimics the Netlify production environment. Netlify Dev will automatically pull down environment variables stored on Netlify and read any variables stored in a .env file on your machine.

If you don’t want to use the Netlify CLI or Netlify Dev, you need to set the variables in your local development environment yourself.

There are a few different ways to do this, including declaring variables directly in the command line or using a .env file and dotenv. Just remember not to commit any sensitive values to your repository.

Visit our Forums for a verified Support Guide on how to access environment variables during your site build for more tips.

# Use variables during the build

Once the variables are set correctly in the environment you want to build in, you can access them in a few different ways depending on the context.

# Use variables in the netlify.toml or Netlify UI

Netlify commands use the Bash shell, so you can use Bash syntax to select the environment variable: $VARIABLE_NAME.

You can use this format in the Netlify UI and in the netlify.toml with the build.command and ignore.command.

For example, to print a not-sensitive variable (GREETING = "hi there") to the deploy log at the end of the build step, set the build command in the Netlify UI to npm run build && echo $GREETING.

The next time you build and deploy the site, the build process will print the variable to the deploy log at the end of the build step.

Note that if you would like to use environment variable values in the [[headers]] and [[redirects]] sections of the netlify.toml, you need to inject the values as part of your build command.

# Use variables to install private npm modules

To use an environment variable for private npm module installs, you can set an NPM_TOKEN value in your build environment. Whenever Netlify runs an install and build, npm will automatically check the environment for an NPM_TOKEN to use for authentication. This way, you can avoid declaring or accessing this sensitive variable value directly in your package.json. If you use Yarn to manage dependencies, set YARN_NPM_AUTH_TOKEN instead of NPM_TOKEN.

# Use variables in Node.js script files

To access environment variables in script files that Node.js runs during the build process, you need to use the format process.env.VARIABLE_NAME.

For example, create a file sayHello in TypeScript or JavaScript that will log your non-sensitive variable (GREETING = "hi there") to the console when run:

  const greetPerson: string = process.env.GREETING;
  console.log(`Say hello: ${greetPerson}`);

  const greetPerson = process.env.GREETING;
  console.log(`Say hello: ${greetPerson}`);

Then, update the build command in the package.json or in the netlify.toml to include the instruction to run the script file:

# Replace ts-node with the appropriate command 
# for your TypeScript compiler for node.js
[build]
  command = "npm run build && ts-node ./sayHello.ts"

[build]
  command = "npm run build && node ./sayHello.js"

The next time you build and deploy the site, the build process will print the variable to the deploy log at the end of the build step.

# Use variables in build plugins

There are two ways to access environment variables in build plugins: using process.env.VARIABLE_NAME or using netlifyConfig.

# Use variables in a site after it’s built

If you want to use environment variable values in a site after it’s built, you need to take further action to provide access. Here are a few options:

If you inject values into the site using a build script or snippet injection, make sure to only include non-sensitive values.

More details are available in our verified Support Guide on how to access environment variables.

# More environment variables resources

Environment variables overview: Sensitive variable policy

← File-based configuration →