# CapturedEnvironmentVariable

- Module: [Aspire.Hosting.Docker](/reference/api/typescript/aspire.hosting.docker.md)
- Version: `13.4.0`
- Kind: `handle`
- Source: [GitHub](https://github.com/microsoft/aspire)

Represents a captured environment variable that will be written to the .env file adjacent to the Docker Compose file.

## Definition

```typescript
interface CapturedEnvironmentVariable {
  defaultValue: string;
  description: string;
  source: ContainerPortReference;
}
```

## Properties

- `defaultValue`: `string` `get - set` -- Gets or sets the default value for the environment variable.
- `description`: `string` `get - set` -- Gets or sets the description for the environment variable.
- `source`: `ContainerPortReference` `get - set` -- Gets or sets the source object that originated this environment variable. This could be a `ParameterResource`, `ContainerMountAnnotation`, `ContainerImageReference`, or `ContainerPortReference`.