Using Environment Variables in a Frontity project
Environment variables are a very useful way of managing custom data that shouldn't be in the code. A prime example would be API KEYs or other authentication credentials for external APIs.
Since a Frontity app is an Isomorphic React app we need to consider whether these environment variables should be accessible only to the code running server-side, or whether they should also be accessible to the code running client-side.
Adding environment variables to a Frontity Project
If you use
cross-env, you will not have to do anything special in Frontity. You just need to add it to your package.json scripts thus:1
{
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"scripts": {
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"dev": "cross-env MY_VARIABLE=xxx frontity dev",
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"serve": "cross-env MY_VARIABLE=xxx frontity serve",
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"build": "cross-env MY_VARIABLE=xxx frontity build"
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}
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}
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dotenv only runs in Node, so rather than using an index.js file you should instead divide the content of your index.js file across two files, namely client.js and server.js.If
client.js and server.js exist, the index.js file can also still exist but it will be ignored by both the server and the client.So for
dotenv we must create a .env file:1
MY_VARIABLE=xxx
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Accessing the environment variables
Private access to the environment variables 
As we can create different entry points for our Frontity theme package by creating separate
server.js and client.js files (that will each only be executed in the appropriate environment), we are therefore able to privately access the content of the environment variable on the server (for example to perform a request to an external API and storing this data in the state so it can be accessed from your React components).The content of the
server.js file could be something like this:1
import { config } from "dotenv";
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import { fetch } from "frontity";
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import packageClient from "./client";
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// Launch dotenv.
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config();
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export default {
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...packageClient,
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actions: {
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theme: {
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...packageClient.actions.theme,
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beforeSSR: async ({ state }) => {
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const {API_TMDB} = process.env
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const URL = `https://api.themoviedb.org/3/movie/550?api_key=${API_TMDB}`
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const detailsMovie = await fetch(URL)
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.then( response => response.json() )
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state.tmdb = { detailsMovie }
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}
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}
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},
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};
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In this example a
API_TMDB environment variable is defined in a .env file included in that projectThis method (
beforeSSR defined in the server.js) will ensure that your API credentials are secure (i.e. they will not be part of the client bundle) and are only visible to the code running server-side. However, remember to take into account that this logic will be executed in the initialization (or bootstrapping) of the Frontity app (i.e. for any page loaded the first time).Generic access to the environment variables 
If you need to use the ENV variable also in the client, the best way is to add it to the
state.You can use
frontity.settings.js or your package state for that, whichever is more appropriate for your situation.frontity.settings.js:1
import { config } from "dotenv";
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// Launch dot-env.
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config();
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const settings = {
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name: "my-project",
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state: {
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env: {
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myVariable: process.env.MY_VARIABLE
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}
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},
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packages: [
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// ...
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];
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}
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packages/my-package/src/server.js:1
import { config } from "dotenv";
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// Launch dot-env.
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config();
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export default {
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state: {
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theme: {
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myVariable: process.env.MY_VARIABLE,
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},
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},
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};
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Either way, the ENV variable will be serialized with the rest of the
state and it will be sent to the client for the React hydration.Please note that any ENV variable exposed in
state will end up in the client. Do not expose any secret API KEY or password.