# Environment variables

You can configure the agent with any of the supported properties through environment variables.

The environment variables need to be set before the agent starts up, and in a location where the agent has access to it. Environment variables can be set within the same process or system-wide.

### Important

If you set system-wide environment variables, this may impact other Contrast agents running on the same server.

You can convert any Contrast property between command line, YAML and an environment variable.

To convert a command line formatted variable to an environment variable, replace the path segment delimiters (.) with double underscores (__).

To convert a YAML formatted variable to an environment variable, start with the top-level property and separate every nested property with a double underscore (__).

Then, prepend the "contrast" namespace (either contrast. or CONTRAST__).

Environment variables should be in all caps and have no spaces.

For example:

Command line

YAML property

Environment variable

contrast.server.name

server:
name: 

CONTRAST__SERVER__NAME

contrast.api.api_key

api:
api_key:

CONTRAST__API__API_KEY

You can see a list of all supported properties for each agent  in their respective YAML templates: