Add environment variables¶

Environment variables are name/value pairs that are dynamically loaded into your containers at runtime. They are often used to pass configuration details to your application. Using environment variables instead of hard-coded values lets you keep environment-specific details out of your source code.

When you define your application stack with a Uffizzi Compose file, you have two options for adding environment variables to your containers: environment or env_file.

Use environment if you have a small number of environment variables to add. You can list your variables in an environment block within the service definition. For example, the following docker-compose.uffizzi.yml snippet adds two environment variables, FOO and BAR, to the myservice container:
```
services:
    mysevice:
      image: example/myservice:latest
      environment:
        FOO: bar
        BAR: baz
```
Use env_file if you have a large number of enviroment variables that would otherwise clutter up your compose file. You can store your variables in a file within your repository and use the env_file component to specify the path to this file. For example, the following docker-compose.uffizzi.yml snippet tells Uffizzi to read the contents of envs/myconfigs.env and add them to the container myservice:
```
services:
    mysevice:
      image: example/myservice:latest
      env_file: ./envs/myconfigs.env
```