Read configuration from environment variables Core

EnvVarBind maps environment variables to config elements. It translates element paths to uppercase environment variable names: section.element becomes SECTION_ELEMENT. With a prefix, section.element becomes PREFIX_SECTION_ELEMENT.

Steps

1. Create the bind and pass it to ConfigBound.createConfig:

import { ConfigBound, configItem, configSection } from "@config-bound/config-bound";
import { EnvVarBind } from "@config-bound/config-bound";
import { z } from "zod";

const config = await ConfigBound.createConfig(
  {
    port: configItem<number>({
      default: 3000,
      validator: z.number().int().min(1).max(65535)
    }),
    database: configSection({
      host: configItem<string>({
        default: "localhost",
        validator: z.hostname()
      })
    })
  },
  {
    binds: [new EnvVarBind()]
  }
);

With this config, PORT sets port and DATABASE_HOST sets database.host.

2. To avoid collisions with other applications' environment variables, use a prefix:

const binds = [new EnvVarBind({ prefix: "MYAPP" })];

With the prefix MYAPP, MYAPP_PORT sets port and MYAPP_DATABASE_HOST sets database.host. The prefix is stripped before lookup - your code still calls config.get("app", "port").

Variable naming

Element path	No prefix	Prefix MYAPP
port	PORT	MYAPP_PORT
database.host	DATABASE_HOST	MYAPP_DATABASE_HOST
server.api.url	SERVER_API_URL	MYAPP_SERVER_API_URL

Related

• EnvVarBind API reference
• Use FileBind - read config from a file instead