Configuration

The configuration system is designed to provide a managed experience for applications. Definitions are built into modules, and the system sources values from both files and environment sources.

Defining Configurations

Definitions are provided as part of the library/application creation

const MY_LIB = CreateLibrary({
  configuration: {
    STRING_CONFIG: {
      type: "string",
      description: "An example string configuration",
      default: "foo"
    },
    ENUM_CONFIG: {
      type: "string",
      description: "Another example string configuration",
      default: "foo",
      enum: ["foo","bar"]
    } as StringConfig<"foo" | "bar">,
    NUMBER_CONFIG: {
      type: "number",
      description: "A numeric configuration",
      default: 8080
    },
    BOOLEAN_CONFIG: {
      type: "boolean",
      description: "A boolean configuration",
      default: false
    }
  },
  name: "my_lib"
});

This creates the following configuration variables:

• config.my_lib.STRING_CONFIG (generic string)
• config.my_lib.ENUM_CONFIG (string union)
• config.my_lib.NUMBER_CONFIG (number)
• config.my_lib.BOOLEAN_CONFIG (boolean)

Supported Types

Type	Notes	Extras
string	Strings and things that extend them	enum: string[] property may also be supplied
string[]	An array of strings
boolean	Simple boolean configurations	Using CLI switches, just passing --CONFIG_NAME can be used for passing true
number	Simple number configurations
record	Record<string, string> for defining key/value pairs of strings

For more details on configuration sourcing and advanced usage, see Configuration Sourcing.

Using configs

Values are provided via service params and are accessible in .project.value format.

export function MyService({ logger, config, lifecycle }: TServiceParams) {
  lifecycle.onPostConfig(() => {
    // Properly cast to the string union
    logger.info(`value for ENUM_CONFIG is`, config.my_lib.ENUM_CONFIG);
  });
}