Environment variables and secrets in Supabase

Introduction

Environment variables and secrets help keep important information safe and separate from your code. They make it easy to change settings without changing the code.

When you need to store API keys safely without putting them in your code.

When you want to change database connection details without editing your app.

When you deploy the same app to different places with different settings.

When you want to keep passwords or tokens hidden from public view.

When you want to update secrets without restarting or changing your app code.

Syntax

Supabase

SUPABASE_URL=your-supabase-url
SUPABASE_ANON_KEY=your-anon-key

# In Supabase dashboard, find these in Project Settings > API

Environment variables are key-value pairs stored outside your code.

Secrets like API keys should never be hardcoded or shared publicly.

Examples

Example of setting environment variables for Supabase URL and anonymous key.

Supabase

SUPABASE_URL=https://xyzcompany.supabase.co
SUPABASE_ANON_KEY=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...

Accessing environment variables in a Node.js app to connect to Supabase.

Supabase

// Using environment variables in JavaScript
const supabaseUrl = process.env.SUPABASE_URL;
const supabaseAnonKey = process.env.SUPABASE_ANON_KEY;

How to find your Supabase URL and anon key in the dashboard.

Supabase

# In Supabase dashboard
# Go to Project Settings > API
# Find your Project URL (SUPABASE_URL) and anon key (SUPABASE_ANON_KEY)

Sample Program

This example shows how to store Supabase URL and anon key in environment variables and use them in a JavaScript app to connect securely. The getUser function fetches the current user info.

Supabase

# .env file content
SUPABASE_URL=https://xyzcompany.supabase.co
SUPABASE_ANON_KEY=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...

// JavaScript example to initialize Supabase client
import { createClient } from '@supabase/supabase-js';

const supabaseUrl = process.env.SUPABASE_URL;
const supabaseAnonKey = process.env.SUPABASE_ANON_KEY;

const supabase = createClient(supabaseUrl, supabaseAnonKey);

async function getUser() {
  const { data, error } = await supabase.auth.getUser();
  if (error) {
    console.error('Error fetching user:', error.message);
  } else {
    console.log('User data:', data.user);
  }
}

getUser();

Important Notes

Never commit your environment files (.env) to public repositories.

Use Supabase dashboard to manage secrets safely for production.

Environment variables help keep your app flexible and secure.

Summary

Environment variables store important info outside your code.

Secrets like API keys should be kept private and secure.

Supabase dashboard lets you manage these variables easily.

Practice

1. What is the main purpose of environment variables in Supabase?

easy

A. To display data on the website

B. To write SQL queries directly in the dashboard

C. To store important information like API keys outside the code

D. To create user accounts automatically

Solution

1. Step 1: Understand environment variables

   Environment variables hold data like API keys or URLs outside the code to keep it safe and flexible.

2. Step 2: Identify their use in Supabase

   Supabase uses environment variables to keep secrets safe and avoid hardcoding sensitive info.

3. Final Answer:

   To store important information like API keys outside the code -> Option C

4. Quick Check:

   Environment variables = store secrets safely [OK]

Hint: Environment variables keep secrets outside code [OK]

Common Mistakes:

• Thinking environment variables are for writing SQL
• Confusing environment variables with user data
• Assuming environment variables display data

2. Which is the correct way to reference an environment variable named SUPABASE_URL in a Supabase project?

easy

A. env.SUPABASE_URL()

B. process.env.SUPABASE_URL

C. getEnv('SUPABASE_URL')

D. SUPABASE_URL.value

Solution

1. Step 1: Recall environment variable syntax in JavaScript

   In JavaScript, environment variables are accessed using process.env.VARIABLE_NAME.

2. Step 2: Match with Supabase usage

   Supabase projects use this standard way to access environment variables like SUPABASE_URL.

3. Final Answer:

   process.env.SUPABASE_URL -> Option B

4. Quick Check:

   Access env vars with process.env.VAR [OK]

Hint: Use process.env.VAR to access environment variables [OK]

Common Mistakes:

• Using function calls like getEnv() which don't exist
• Trying to access variables as object properties incorrectly
• Forgetting the process.env prefix

3. Given this code snippet in a Supabase project:

const supabaseUrl = process.env.SUPABASE_URL;
const supabaseKey = process.env.SUPABASE_ANON_KEY;
console.log(supabaseUrl, supabaseKey);

What will be the output if SUPABASE_URL is set to https://xyz.supabase.co and SUPABASE_ANON_KEY is not set?

medium

A. https://xyz.supabase.co undefined

B. undefined undefined

C. https://xyz.supabase.co null

D. Error: SUPABASE_ANON_KEY not found

Solution

1. Step 1: Check environment variable values

   SUPABASE_URL is set to a URL string, but SUPABASE_ANON_KEY is missing, so it is undefined.

2. Step 2: Understand console.log output

   Logging both variables prints the URL string and undefined for the missing key.

3. Final Answer:

   https://xyz.supabase.co undefined -> Option A

4. Quick Check:

   Missing env vars print undefined [OK]

Hint: Missing env vars show as undefined in logs [OK]

Common Mistakes:

• Expecting an error when env var is missing
• Assuming missing vars print null
• Confusing undefined with empty string

4. You added a secret API_SECRET in the Supabase dashboard but your app still logs undefined when accessing process.env.API_SECRET. What is the most likely cause?

medium

A. You must include the secret in your code manually

B. The secret name is case-insensitive and should be lowercase

C. Supabase does not support environment variables

D. You forgot to restart the app after adding the secret

Solution

1. Step 1: Understand environment variable loading

   Environment variables are loaded when the app starts, so changes require a restart to take effect.

2. Step 2: Identify the cause of undefined

   If the app logs undefined, it likely did not reload the updated environment variables after adding the secret.

3. Final Answer:

   You forgot to restart the app after adding the secret -> Option D

4. Quick Check:

   Restart app to load new env vars [OK]

Hint: Restart app after adding secrets to load them [OK]

Common Mistakes:

• Thinking secret names are case-insensitive
• Believing Supabase doesn't support env vars
• Trying to hardcode secrets in code

5. You want to securely use a third-party API key in your Supabase Edge Function without exposing it in client code. Which approach is best?

hard

A. Store the API key as a secret in Supabase dashboard and access it via process.env inside the Edge Function

B. Hardcode the API key directly in the Edge Function code

C. Send the API key from the client app to the Edge Function on every request

D. Publish the API key in a public GitHub repo for easy access

Solution

1. Step 1: Understand secure storage of secrets

   Secrets like API keys should never be hardcoded or exposed publicly to avoid leaks.

2. Step 2: Use Supabase secrets in Edge Functions

   Storing the API key as a secret in the dashboard and accessing it via process.env inside the Edge Function keeps it secure and hidden from clients.

3. Final Answer:

   Store the API key as a secret in Supabase dashboard and access it via process.env inside the Edge Function -> Option A

4. Quick Check:

   Use secrets in server code, not client [OK]

Hint: Keep API keys in secrets, access only server-side [OK]

Common Mistakes:

• Hardcoding keys in code risking exposure
• Sending keys from client risking interception
• Publishing keys publicly causing leaks