Use environment variables

You can use environment variables to compile your Snap. This is useful if you want to use different variables for testing your Snap locally and publishing your Snap. You can use environment variables on the command line or in a .env file.

note

In addition to the environment variables you set, the following environment variables are set by the Snaps CLI:

• NODE_ENV="production"
• NODE_DEBUG=false
• DEBUG=false

Use environment variables on the command line

1. Specify environment variables on the command line. For example:

   PUBLIC_KEY=abc123 SNAP_ENV=dev

2. Build your Snap using the Snaps CLI:

   yarn mm-snap build

Use environment variables in a .env file

1. Specify environment variables in a .env file. For example:

   .env

   PUBLIC_KEY=abc123
   SNAP_ENV=dev

2. Specify the environment variables in your Snap's configuration file using the environment option. For example:

   JavaScript

   snap.config.js

   require("dotenv").config();
   
   module.exports = {
     environment: {
       SNAP_ENV: process.env.SNAP_ENV,
       PUBLIC_KEY: process.env.PUBLIC_KEY,
     },
     // Other options.
   };

   TypeScript

   snap.config.ts

   import type { SnapConfig } from "@metamask/snaps-cli";
   import * as dotenv from "dotenv";
   dotenv.config();
   
   const config: SnapConfig = {
     environment: {
       SNAP_ENV: process.env.SNAP_ENV,
       PUBLIC_KEY: process.env.PUBLIC_KEY,
     },
     // Other options.
   };
   
   export default config;

3. You can also use environment variables directly in your Snap. For example:

   index.ts

   import { panel, text, heading } from "@metamask/snaps-sdk";
   
   await snap.request({
     method: "snap_dialog",
     params: {
       type: "alert",
       content: panel([
         heading("This custom alert is just for display purposes."),
         text(`SNAP_ENV is ${process.env.SNAP_ENV}, PUBLIC_KEY is ${process.env.PUBLIC_KEY}`),
       ]),
     },
   });