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Using Environment Variables with Platformatic

Applications built with Platformatic loosely follows the twelve factor app methodology. This guide will show how to make your application configurable, while keeping your deployment environments as close as possible.

Environment Variables replacement

In any Platformatic configuration file, you can always interpolate an environment variable inside a value:

{
...
"db": {
"connectionString": "{DATABASE_URL}"
}
...
}

The replacement is done via pupa, before the JSON file is parsed.

All Platformatic configuration files support Environment Variables replacement, i.e. env variables are supported in Platformatic Service, Platformatic DB, Platformatic Composer, Platformatic Runtime.

dotenv support

dotenv is built in inside Platformatic, allowing you to create an envfile with all your environment variables, that is loaded automatically by Platformatic at startup. If a .env file exists it will automatically be loaded by Platformatic using dotenv. For example:

.env
DATABASE_URL=sqlite://./db.sqlite

The .env file must be located in the same folder as the Platformatic configuration file or in the current working directory.

Environment variables can also be set directly on the command line, for example:

PLT_SERVER_LOGGER_LEVEL=debug npx platformatic start

Allowed Environment Variables

All placeholders in a configuration must be available as an environment variable and must meet the allowed placeholder name rules.

Allowed placeholder names

Only placeholder names prefixed with PLT_, or that are in this allow list, will be dynamically replaced in the configuration file:

  • PORT
  • DATABASE_URL

This restriction is to avoid accidentally exposing system environment variables. An error will be raised by Platformatic if it finds a configuration placeholder that isn't allowed.

The default allow list can be extended by passing a --allow-env CLI option with a comma separated list of strings, for example:

npx platformatic start --allow-env=HOST,SERVER_LOGGER_LEVEL

If --allow-env is passed as an option to the CLI, it will be merged with the default allow list.

Placeholder wildcard

You're also able to define a placeholder wildcard, with your own prefix, for example:

npx platformatic service start --allow-env=MY_NS_*
# OR
npx platformatic start --allow-env=MY_NS_*

This will allow you to use placeholders like {MY_NS_MY_VAR}.

Adding a custom environment variable to a project

Create a Platformatic DB App

Run this command in your terminal to start the Platformatic creator wizard:

npm create platformatic@latest

This interactive command-line tool will ask you some questions about how you'd like to set up your new Platformatic project. For this guide, select these options:

- What kind of project do you want to create?   => Application
- Where would you like to create your project? => quick-start
- Which kind of project do you want to create? => DB
- What is the name of the service? => (generated-randomly), e.g. legal-soup
- What is the connection string? => sqlite://./db.sqlite
- Do you want to create default migrations? => Yes
- Do you want to create another service? => No
- Do you want to use TypeScript? => No
- What port do you want to use? => 3042
- Do you want to init the git repository? => No

Once the wizard is complete, you'll have a Platformatic app project in the folder quick-start, with example migration files, plugin script, routes, and tests inside your service directory under services/

info

Make sure you run the npm/yarn/pnpm command install command manually if you don't ask the wizard to do it for you.

This same tutorial applies to all other Platformatic tools.

Modify platformatic.db.json

Add a greeting option inside your plugins configuration:

{
...
"plugins": {
"paths": [
{
"path": "./plugins",
"encapsulate": false,
"options": {
"greeting": "{PLT_GREETING}"
}
},
{
"path": "./routes"
}
]
},
...
}

This new options will be available inside all the options passed to all plugins in the plugins/ folder.

Decorate the Fastify instance

Create a new plugins/greeting.js file, calling fastify.decorate() to expose some functionality to other plugins:

/// <reference path="../global.d.ts" />
'use strict'
/** @param {import('fastify').FastifyInstance} fastify */
module.exports = async function (fastify, opts) {
fastify.decorate('sayHello', sayHello)

function sayHello (name) {
return `${opts.greeting} ${name}`
}
}

Use it inside a route

Create a new routes/hello.js file that uses the newly added functionality, like so:

/// <reference path="../global.d.ts" />
'use strict'
/** @param {import('fastify').FastifyInstance} fastify */
module.exports = async function (fastify, opts) {
fastify.get('/hello', {
schema: {
querystring: {
type: 'object',
properties: {
name: { type: 'string' }
}
},
required: ['name']
}
}, async (request, reply) => {
return fastify.sayHello(request.query.name)
})
}

Add an environemnt variable

Edit your .env file and add:

PLT_GREETING=Hello

Don't forget to add a default value to your .env.sample, as the .env file is not committed to the repository.

Run your application and test the new route

Run your application with npm start, and then test the new route with:

curl 'http://localhost:3042/hello?name=matteo'