Usage of Layer and Config from Effect for DI and configuration.

Config.ts

import { Effect as IO, Config, Context, Layer, pipe } from "effect";

export type ServerConfig = Readonly<{
	port: number;
	mode: "development" | "production" | "test";
}>;

export class ServerConfigCtx extends Context.Tag("ServerConfigCtx")<ServerConfigCtx, ServerConfig>() {}

const getNodeEnv = Config.literal("development", "production", "test")("NODE_ENV");

export const ServerConfigCtxLive = Layer.effect(ServerConfigCtx)(
	pipe(
		Config.all([Config.number("PORT"), getNodeEnv]),
		Config.map(([port, mode]) => ({ port, mode })),
	),
);

export const ServerConfigCtxTest = Layer.effect(ServerConfigCtx)(
	pipe(
		Config.all([Config.number("TEST_PORT"), getNodeEnv]),
		Config.map(([port, mode]) => ({ port, mode })),
	),
);

export type JwtConfig = Readonly<{
	secret: string;
	issuer: string;
	expiresIn: string;
	cookieExpiresIn: string;
}>;

export class JwtConfigCtx extends Context.Tag("JwtConfigCtx")<JwtConfigCtx, JwtConfig>() {}

export const getJwtConfig = Config.all([
	Config.string("SECRET"),
	Config.string("ISSUER"),
	Config.string("EXPIRES_IN"),
	Config.string("COOKIE_EXPIRES_IN"),
]).pipe(Config.nested("JWT"));

export const JwtConfigCtxLive = Layer.effect(JwtConfigCtx)(
	pipe(
		getJwtConfig,
		Config.map(([secret, issuer, expiresIn, cookieExpiresIn]) => ({ secret, issuer, expiresIn, cookieExpiresIn })),
	),
);

export const JwtConfigCtxTest = Layer.effect(JwtConfigCtx)(
	pipe(
		getJwtConfig,
		Config.nested("TEST"),
		Config.map(([secret, issuer, expiresIn, cookieExpiresIn]) => ({ secret, issuer, expiresIn, cookieExpiresIn })),
	),
);

export type MasterConfig = Readonly<{
	server: ServerConfig;
	jwt: JwtConfig;
}>;

export class MasterConfigCtx extends Context.Tag("MasterConfigCtx")<MasterConfigCtx, MasterConfig>() {}

const getMasterConfig = pipe(
	IO.all([ServerConfigCtx, JwtConfigCtx]),
	IO.map(([server, jwt]) => ({ server, jwt })),
);

export const MasterConfigCtxLive = Layer.effect(MasterConfigCtx)(getMasterConfig).pipe(
	Layer.provide(ServerConfigCtxLive),
	Layer.provide(JwtConfigCtxLive),
);

export const MasterConfigCtxTest = Layer.effect(MasterConfigCtx)(getMasterConfig).pipe(
	Layer.provide(ServerConfigCtxTest),
	Layer.provide(JwtConfigCtxTest),
);