Setup a .env file in the root of your project.

# .env
GREETING=hello world

Then import the configuration using the config function.

// app.ts
import { config } from "https://deno.land/std@$STD_VERSION/dotenv/mod.ts";

console.log(await config());

Then run your app.

> deno run --allow-read app.ts
{ GREETING: "hello world" }

• path?: string: Optional path to .env file. Defaults to ./.env.
• export?: boolean: Set to true to export all .env variables to the current processes environment. Variables are then accessable via Deno.env.get(<key>). Defaults to false.
• safe?: boolean: Set to true to ensure that all necessary environment variables are defined after reading from .env. It will read .env.example to get the list of needed variables.
• example?: string: Optional path to .env.example file. Defaults to ./.env.example.
• allowEmptyValues?: boolean: Set to true to allow required env variables to be empty. Otherwise it will throw an error if any variable is empty. Defaults to false.
• defaults?: string: Optional path to .env.defaults file which defaults to ./.env.defaults.

load.ts automatically loads the local .env file on import and exports it to the process environment:

# .env
GREETING=hello world

// app.ts
import "https://deno.land/std@$STD_VERSION/dotenv/load.ts";

console.log(Deno.env.get("GREETING"));

> deno run --allow-env --allow-read app.ts
hello world

To enable safe mode, create a .env.example file in the root of the project.

# .env.example
GREETING=

Then import the configuration with safe option set to true.

// app.ts
import { config } from "https://deno.land/std@$STD_VERSION/dotenv/mod.ts";

console.log(await config({ safe: true }));

If any of the defined variables is not in .env, an error will occur. This method is preferred because it prevents runtime errors in a production application due to improper configuration.

Another way to supply required variables is externally, like so:

GREETING="hello world" deno run --allow-env app.ts

Default values can be easily added via creating a .env.defaults file and using the same format as an.env file.

# .env.defaults
# Will not be set if GREETING is set in base .env file
GREETING="a secret to everybody"

The parsing engine currently supports the following rules:

• Variables that already exist in the environment are not overridden with export: true
• BASIC=basic becomes { BASIC: "basic" }
• empty lines are skipped
• lines beginning with # are treated as comments
• empty values become empty strings (EMPTY= becomes { EMPTY: "" })
• single and double quoted values are escaped (SINGLE_QUOTE='quoted' becomes { SINGLE_QUOTE: "quoted" })
• new lines are expanded in double quoted values (MULTILINE="new\nline" becomes

{ MULTILINE: "new
line" }

• inner quotes are maintained (think JSON) (JSON={"foo": "bar"} becomes { JSON: "{\"foo\": \"bar\"}" })
• whitespace is removed from both ends of unquoted values (see more on trim) (FOO= some value becomes { FOO: "some value" })
• whitespace is preserved on both ends of quoted values (FOO=" some value " becomes { FOO: " some value " })

• Inspired by the node module dotenv.