Environmental variables

Wrapper developers can declare a map of environmental variables for application developers to provide.

If you're an application developer, check out ClientConfig. If you're a wrapper developer, keep reading!

Schema declaration

To use environmental variables, wrapper developers must first declare an Env type and add the @env directive to methods in the Wrapper Schema. You can learn more about the schema declarations in the Environmental Variables section of the Wrapper Schema documentation.

type Env {
  str: String!
}

type Module {
  foo(
    arg: String!
  ): String! @env(required: true)
}

Access Env in the module

Environmental variables can be used in both plugin wrappers and Wasm wrappers.

Env in plugin wrappers

Plugin wrapper developers can access the Env instance as a class property.

const env: Env = this.env;

Env in wasm wrappers

Wasm wrapper developers can access the Env instance by accepting the Env as a second argument in their module's methods. When an application developer invokes the method, the environmental variables they set in their ClientConfig will be provided.

AssemblyScript

export class Module extends ModuleBase {
  // App developers are required to provide Env to invoke this method
  methodRequireEnv(_: Args_methodRequireEnv, env: Env): Env {
    return env;
  }

  // Env is optional when invoking this method
  methodOptionalEnv(_: Args_methodOptionalEnv, env: Env | null): Env | null {
    return env ? (env as Env) : null;
  }
}

Rust

impl ModuleTrait for Module {
  // App developers are required to provide Env to invoke this method
  fn method_require_env(_: ArgsMethodRequireEnv, env: Env) -> Env {
    env
  }

  // Env is optional when invoking this method
  fn method_optional_env(args: ArgsMethodOptionalEnv, env: Option<Env>) -> Option<Env> {
    env
  }
}