#Environment Variables

srvkit supports deferred environment variables — values that are resolved at runtime instead of being hardcoded at build time. This lets you configure different options from environment variables without embedding them in the output bundle.

#How It Works

srvkit uses Envkist under the hood. In development, env references resolve immediately by reading process.env etc. In production, they are injected as runtime-appropriate code that reads the environment variable when the server starts.

#Usage

Import env from the plugin entry:

import { defineConfig } from "vite";
import { srvkit, env } from "@srvkit/vite/plugin";

export default defineConfig({
    plugins: [
        srvkit({
            build: {
                host: env.string("HOST"),
                port: env.number("PORT"),
            },
        }),
    ],
});

import { defineConfig } from "@rsbuild/core";
import { pluginSrvkit, env } from "@srvkit/rsbuild/plugin";

export default defineConfig({
    plugins: [
        pluginSrvkit({
            build: {
                host: env.string("HOST"),
                port: env.number("PORT"),
            },
        }),
    ],
});

#env.string

Creates a resolvable string value that reads from an environment variable:

env.string("HOST");

#env.number

Creates a resolvable number value that reads from an environment variable:

env.number("PORT");

#With Fallback Values

Pass a second argument to set a default when the environment variable is not set:

env.string("HOST", "0.0.0.0");
env.number("PORT", 8080);

#Static Values

You can still use plain strings and numbers — they are fully supported alongside env references:

srvkit({
    build: {
        host: env.string("HOST", "0.0.0.0"),
        port: 4000,
    },
});

#Supported Options

The following options accept either a static value or an env reference:

#Runtime Behavior

In production builds, srvkit injects runtime-specific code for reading environment variables based on the runtime option:

When targeting workerd (Cloudflare Workers), srvkit automatically injects import { env } from "cloudflare:workers" into the output entry.