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WordPress Constants

Autoscale generates wp-config.php per environment. It is not part of your repository and cannot be edited. Set your own constants in config/config.php in your repository, or, for sensitive values, as secrets in the User Portal.

Load order

Section titled “Load order”
wp-config.php
require_once '/config/platform.php';


if ( file_exists( __DIR__ . '/wp-content/config/config.php' ) ) {
  require_once __DIR__ . '/wp-content/config/config.php';
}

platform.php holds the platform-managed constants, followed by your secrets. config/config.php loads last.

The first define() of a constant wins, so precedence is platform constants, then secrets, then config/config.php. Redefining an earlier name has no effect and emits a PHP warning.

Platform-managed constants

Section titled “Platform-managed constants”

These are set for every environment and cannot be overridden.

Constant Value Notes
PWP_NAME Your environment name, as in the User Portal Fixed when the environment is created. Unique across WP Engine.
WPE_PLATFORM_NAME autoscale Always this value on Autoscale. Use it to detect that your code is running on the platform.

Defining your own constants

Section titled “Defining your own constants”

Add config/config.php to the root of your repository. It is built into your image, so changes require a deployment.

Guard every define() call:

config/config.php
<?php


if ( ! defined( 'WP_MEMORY_LIMIT' ) ) {
  define( 'WP_MEMORY_LIMIT', '512M' );
}


if ( ! defined( 'MY_APP_API_BASE' ) ) {
  define(
    'MY_APP_API_BASE',
    'my-site-prod' === PWP_NAME ? 'https://api.example.com' : 'https://sandbox.api.example.com'
  );
}

Because config/config.php is the same file in every environment, branch on PWP_NAME when a value needs to differ between them. For values that should not be in your repository at all, use secrets, which are set per environment.

For the constants WordPress itself recognizes, see the wp-config.php reference.

Secrets

Section titled “Secrets”

A secret is a constant whose value is stored by WP Engine rather than in your repository. Values are set per environment and never appear in Git or in your built image.

Manage them in the User Portal under Environment Secrets:

https://my.wpengine.com/installs/<environment-name>/environment_secrets

Environment Secrets in the User Portal

The name you enter becomes the constant. A secret named EXAMPLE_SECRET is defined for you at startup:

platform.php
define( 'EXAMPLE_SECRET', 'the value you entered' );
Field Rule
Name Letters, numbers, and underscores only, starting with a letter or an underscore.
Name Unique within the environment, ignoring case.
Value Required, and cannot be empty.
Value A single line of printable text. Single quotes, double quotes, and backslashes are not accepted.

Reading a constant in your code

Section titled “Reading a constant in your code”

Constants behave the same whatever defined them. A platform constant, one from config/config.php, and a secret are all read by name from any theme, plugin, or must-use plugin:

$response = wp_remote_get(
  'https://api.example.com/v1/orders',
  array(
    'headers' => array( 'Authorization' => 'Bearer ' . EXAMPLE_SECRET ),
  )
);

All three sources load before WordPress loads plugins and themes, so a constant is available everywhere your code runs. Use defined() first for anything optional, such as a secret that exists in production but not in every environment:

$api_key = defined( 'EXAMPLE_SECRET' ) ? EXAMPLE_SECRET : '';

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