Examples

Real-world configuration examples using popular schema libraries:

ArkType

Demonstrates envictus with ArkType for schema validation.

/**
 * ArkType example - uses string-based type expressions for concise schema definitions.
 * - Inline defaults: `= 'value'` syntax (e.g., `"'dev' | 'prod' = 'dev'"`)
 * - Optional fields: `"key?"` syntax (e.g., `"DEBUG?"`)
 * - Built-in validators: `string.url`, `string.numeric`, etc.
 */

import { type } from "arktype";
import { defineConfig } from "envictus";

export default defineConfig({
  schema: type({
    NODE_ENV: "'development' | 'production' | 'test' = 'development'",
    DATABASE_URL: "string.url",
    PORT: "string.numeric",
    "DEBUG?": "string",
    LOG_LEVEL: "'debug' | 'info' | 'warn' | 'error' = 'info'",
  }),
  discriminator: "NODE_ENV",
  defaults: {
    development: {
      DATABASE_URL: "postgres://localhost:5432/dev",
      PORT: "3000",
      DEBUG: "true",
      LOG_LEVEL: "debug",
    },

    production: {
      DATABASE_URL: "postgres://prod.example.com:5432/prod",
      PORT: "8080",
      DEBUG: "false",
      LOG_LEVEL: "warn",
    },

    test: {
      DATABASE_URL: "postgres://localhost:5432/test",
      PORT: "3001",
      DEBUG: "false",
      LOG_LEVEL: "error",
    },
  },
});

Composition

Demonstrates splitting environment configuration into separate client and server configs, where the client schema serves as the shared base that the server extends via mergeDefaults.

client.env.config.ts

import { defineConfig } from "envictus";
import { z } from "zod";

// Client schema is the base — only browser-safe, prefixed variables.
// Frameworks like Next.js and Vite strip unprefixed vars from the client bundle,
// so this schema doubles as the shared foundation that the server config extends.

export const clientSchema = z.object({
  NEXT_PUBLIC_APP_ENV: z.enum(["local", "staging", "production"]).default("local"),
  NEXT_PUBLIC_API_URL: z.string().url(),
  NEXT_PUBLIC_SENTRY_DSN: z.string().optional(),
});

export const clientDefaults = {
  local: {
    NEXT_PUBLIC_API_URL: "http://localhost:3000/api",
  },
  staging: {
    NEXT_PUBLIC_API_URL: "https://staging.api.example.com",
    NEXT_PUBLIC_SENTRY_DSN: "https://abc@sentry.io/123",
  },
  production: {
    NEXT_PUBLIC_API_URL: "https://api.example.com",
    NEXT_PUBLIC_SENTRY_DSN: "https://abc@sentry.io/456",
  },
};

export default defineConfig({
  schema: clientSchema,
  discriminator: "NEXT_PUBLIC_APP_ENV",
  defaults: clientDefaults,
});

server.env.config.ts

import { defineConfig, mergeDefaults } from "envictus";
import { z } from "zod";
import { clientDefaults, clientSchema } from "./client.env.config.js";

// Server config extends the client schema with secrets and internal config.
// The server needs public vars too (e.g. API_URL for SSR, Sentry DSN for error reporting).

const serverSchema = z.object({
  LOG_LEVEL: z.enum(["debug", "info", "warn", "error"]).default("info"),
  DATABASE_URL: z.string().url(),
  REDIS_URL: z.string().url(),
  SESSION_SECRET: z.string().min(32),
  PORT: z.coerce.number().min(1).max(65535),
});

const serverDefaults = {
  local: {
    LOG_LEVEL: "debug" as const,
    DATABASE_URL: "postgres://localhost:5432/myapp_dev",
    REDIS_URL: "redis://localhost:6379",
    SESSION_SECRET: "local-secret-that-is-at-least-32-characters",
    PORT: 3000,
  },
  staging: {
    LOG_LEVEL: "info" as const,
    PORT: 8080,
  },
  production: {
    LOG_LEVEL: "warn" as const,
    PORT: 8080,
  },
};

export default defineConfig({
  schema: clientSchema.merge(serverSchema),
  discriminator: "NEXT_PUBLIC_APP_ENV",
  defaults: mergeDefaults(clientDefaults, serverDefaults),
});

Custom Discriminator

Demonstrates envictus with a custom discriminator variable instead of the default NODE_ENV.

import { defineConfig } from "envictus";
import { z } from "zod";

// Example with a custom discriminator (not NODE_ENV)
export default defineConfig({
  schema: z.object({
    APP_ENV: z.enum(["local", "staging", "prod"]).default("local"),
    API_URL: z.string().url(),
    API_KEY: z.string().min(1),
    TIMEOUT_MS: z.coerce.number().positive().default(5000),
  }),
  discriminator: "APP_ENV",
  defaults: {
    local: {
      API_URL: "http://localhost:4000",
      API_KEY: "local-dev-key",
      TIMEOUT_MS: 10000,
    },

    staging: {
      API_URL: "https://staging.api.example.com",
      API_KEY: "staging-key",
      TIMEOUT_MS: 5000,
    },

    prod: {
      API_URL: "https://api.example.com",
      API_KEY: "prod-key",
      TIMEOUT_MS: 3000,
    },
  },
});

Env Files

Demonstrates envictus loading defaults from .env files using parseEnv().

import { defineConfig, parseEnv } from "envictus";
import { z } from "zod";

// Example loading defaults from .env files
export default defineConfig({
  schema: z.object({
    NODE_ENV: z.enum(["development", "production", "test"]).default("development"),
    API_URL: z.string().url(),
    API_KEY: z.string().min(1),
    TIMEOUT_MS: z.coerce.number().positive().default(5000),
  }),
  discriminator: "NODE_ENV",
  defaults: {
    development: {
      ...parseEnv(".env.local", { onMissing: "ignore" }),
      API_URL: "https://localhost:3000/api",
    },
    test: {
      API_URL: "https://localhost:3000/api",
      API_KEY: "test-key",
    },
    production: {
      API_URL: "https://api.example.com",
      // API_KEY required with no default in prod
    },
  },
});

Joi

Demonstrates envictus with Joi for schema validation.

/**
 * Joi example - strict by default, requires explicit allowances for extra fields.
 * - `.unknown()` on object allows extra env vars to pass through without errors
 * - `.valid()` constrains to specific values (enum-like behavior)
 * - Built-in validators: `.port()` (1-65535), `.uri()`, etc.
 */

import { defineConfig } from "envictus";
import Joi from "joi";

export default defineConfig({
  schema: Joi.object({
    NODE_ENV: Joi.string().valid("development", "production", "test").default("development"),
    DATABASE_URL: Joi.string().uri().required(),
    PORT: Joi.number().port().required(),
    DEBUG: Joi.boolean().optional(),
    LOG_LEVEL: Joi.string().valid("debug", "info", "warn", "error").default("info"),
  }).unknown(),
  discriminator: "NODE_ENV",
  defaults: {
    development: {
      DATABASE_URL: "postgres://localhost:5432/dev",
      PORT: 3000,
      DEBUG: true,
      LOG_LEVEL: "debug",
    },

    production: {
      DATABASE_URL: "postgres://prod.example.com:5432/prod",
      PORT: 8080,
      DEBUG: false,
      LOG_LEVEL: "warn",
    },

    test: {
      DATABASE_URL: "postgres://localhost:5432/test",
      PORT: 3001,
      DEBUG: false,
      LOG_LEVEL: "error",
    },
  },
});

Valibot

Demonstrates envictus with Valibot for schema validation.

/**
 * Valibot example - requires explicit transformation pipelines for type coercion.
 * - `v.pipe()` chains validators/transformers (e.g., unknown -> transform -> validate)
 * - `v.unknown()` accepts any input, allowing subsequent transform/validation
 * - Boolean transform needed because env vars are strings ("true"/"1" -> boolean)
 */

import { defineConfig } from "envictus";
import * as v from "valibot";

export default defineConfig({
  schema: v.object({
    NODE_ENV: v.optional(v.picklist(["development", "production", "test"]), "development"),
    DATABASE_URL: v.pipe(v.string(), v.url()),
    PORT: v.pipe(v.unknown(), v.transform(Number), v.number(), v.minValue(1), v.maxValue(65535)),
    DEBUG: v.optional(
      v.pipe(
        v.unknown(),
        v.transform((val) => val === "true" || val === "1"),
      ),
    ),
    LOG_LEVEL: v.optional(v.picklist(["debug", "info", "warn", "error"]), "info"),
  }),
  discriminator: "NODE_ENV",
  defaults: {
    development: {
      DATABASE_URL: "postgres://localhost:5432/dev",
      PORT: 3000,
      DEBUG: true,
      LOG_LEVEL: "debug",
    },

    production: {
      DATABASE_URL: "postgres://prod.example.com:5432/prod",
      PORT: 8080,
      DEBUG: false,
      LOG_LEVEL: "warn",
    },

    test: {
      DATABASE_URL: "postgres://localhost:5432/test",
      PORT: 3001,
      DEBUG: false,
      LOG_LEVEL: "error",
    },
  },
});

Yup

Demonstrates envictus with Yup for schema validation.

/**
 * Yup example - has built-in coercion for common types (string -> number, string -> boolean).
 * - `.required()` marks field as mandatory; `.optional()` allows undefined
 * - `.oneOf()` constrains to specific values (enum-like behavior)
 * - `.default()` provides fallback value if field is undefined
 */

import { defineConfig } from "envictus";
import * as yup from "yup";

export default defineConfig({
  schema: yup.object({
    NODE_ENV: yup.string().oneOf(["development", "production", "test"]).default("development"),
    DATABASE_URL: yup.string().url().required(),
    PORT: yup.number().min(1).max(65535).required(),
    DEBUG: yup.boolean().optional(),
    LOG_LEVEL: yup.string().oneOf(["debug", "info", "warn", "error"]).default("info"),
  }),
  discriminator: "NODE_ENV",
  defaults: {
    development: {
      DATABASE_URL: "https://db.example.com/dev",
      PORT: 3000,
      DEBUG: true,
      LOG_LEVEL: "debug",
    },

    production: {
      DATABASE_URL: "https://db.example.com/prod",
      PORT: 8080,
      DEBUG: false,
      LOG_LEVEL: "warn",
    },

    test: {
      DATABASE_URL: "https://db.example.com/test",
      PORT: 3001,
      DEBUG: false,
      LOG_LEVEL: "error",
    },
  },
});

Zod

Demonstrates envictus with Zod for schema validation.

import { defineConfig } from "envictus";
import { z } from "zod";

export default defineConfig({
  schema: z.object({
    NODE_ENV: z.enum(["development", "production", "test"]).default("development"),
    DATABASE_URL: z.string().url(),
    PORT: z.coerce.number().min(1).max(65535),
    DEBUG: z.coerce.boolean().optional(),
    LOG_LEVEL: z.enum(["debug", "info", "warn", "error"]).default("info"),
  }),
  discriminator: "NODE_ENV",
  defaults: {
    // Defaults when NODE_ENV=development
    development: {
      DATABASE_URL: "postgres://localhost:5432/dev",
      PORT: 3000,
      DEBUG: true,
      LOG_LEVEL: "debug",
    },

    // Defaults when NODE_ENV=production
    production: {
      DATABASE_URL: "postgres://prod.example.com:5432/prod",
      PORT: 8080,
      DEBUG: false,
      LOG_LEVEL: "warn",
    },

    // Defaults when NODE_ENV=test
    test: {
      DATABASE_URL: "postgres://localhost:5432/test",
      PORT: 3001,
      DEBUG: false,
      LOG_LEVEL: "error",
    },
  },
});