Environment variables allow you to separate configuration data from your application code, making it more maintainable and portable.

RoadRunner supports the expansion of environment variables using the ${VARIABLE} or $VARIABLE syntax in a configuration file and CLI commands. You can use this feature to dynamically set values based on the current environment, such as database connection strings, API keys, and other sensitive information.

You can specify a default value for an environment variable using the ${VARIABLE:-DEFAULT_VALUE} syntax. For example, if you want to use a default value of 8080 for the HTTP_PORT environment variable if it is not defined or is empty, you can use the following configuration:


You can find more information on Bash Environment Variable Defaults in the Bash Reference Manual.

This allows you to easily customize the configuration based on your specific environment without changing the configuration file itself.

Here's an example of a docker-compose.yaml file that redefines the HTTP_PORT for an RR service:

version: '3.8'

    image: xxx
      - HTTP_PORT=8081

Setting Env Variables

You can set environment variables for PHP workers by defining them in the server.env section of the RoadRunner configuration file. These variables will be applied to all workers when they are started by the server.

Here's an example:

  command: "php worker.php"
     APP_RUNTIME: prod

In this example, when RoadRunner starts a PHP worker, it will set the APP_RUNTIME environment variable to prod.

All environment variable keys will be automatically converted to uppercase.


RoadRunner supports reading environment variables from .env files, which are typically used to store sensitive or environment-specific variables outside your codebase.

To read environment variables from an .env file, you can use the --dotenv CLI option when starting RoadRunner.

./rr serve --dotenv /var/www/config/.env

Default Env variables in PHP Workers

RoadRunner comes with a set of default environment (ENV) values that facilitate proper communication between the PHP process and the server. These values are automatically available to workers and can be used to configure and manage various aspects of the worker's operation.

Here's a list of the default ENV values provided by RoadRunner:



Identifies what mode worker should work with (http, temporal, grpc, jobs, tcp, centrifuge, etc.)


Contains RPC connection address when enabled.


pipes or tcp://..., depends on server relay configuration.


RoadRunner version started the PHP worker (minimum 2023.1.0)

These default environment values can be used within your PHP worker to configure various settings and adapt the worker's behavior according to the specific requirements of your application.

See how these variables are used in the spiral/roadrunner-worker to determine the Environment.

What's Next?

  1. Environment variables - Learn how to use environment variables in your RoadRunner configuration.

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