Environment configuration in Firebase - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

Firebase environment variable usage in functions

You have set an environment variable in Firebase Functions using firebase functions:config:set api.key="12345". What will be the output of the following code snippet when deployed and called?

exports.getApiKey = functions.https.onRequest((req, res) => {  res.send(process.env.api.key || 'No key');});

Firebase

exports.getApiKey = functions.https.onRequest((req, res) => {  res.send(process.env.api.key || 'No key');});

A It will respond with 'undefined'

B It will respond with '12345'

C It will throw a runtime error because process.env.api.key is undefined

D It will respond with 'No key'

💡 Hint

Firebase environment variables are accessed differently than process.env.

Firebase Functions environment variables set via 'firebase functions:config:set' are accessed using 'functions.config()', not 'process.env'. So 'process.env.api.key' is undefined, resulting in the fallback 'No key'.

❓ Configuration

intermediate

Correct Firebase environment variable access

Given you set an environment variable with firebase functions:config:set service.id="abc123", which code snippet correctly retrieves this value inside a Firebase Function?

A const serviceId = process.env.service.id;

B const serviceId = functions.config().service.id;

C const serviceId = functions.config.service.id;

D const serviceId = process.env.SERVICE_ID;

💡 Hint

Firebase environment config is accessed via a function call.

The correct way is to call 'functions.config()' which returns the config object. Accessing 'service.id' is done with 'functions.config().service.id'.

❓ Architecture

advanced

Managing multiple Firebase environments

You want to deploy your Firebase project to both staging and production environments with different environment variables. Which approach best supports this?

A Use separate Firebase projects for staging and production, each with its own environment config.

B Store all environment variables in one project and select them at runtime based on request headers.

C Use the same Firebase project and switch environment variables manually before each deploy.

D Use Firebase Emulator Suite to simulate different environments in production.

💡 Hint

Consider isolation and safety of production data.

Using separate Firebase projects for staging and production ensures isolation of data and environment variables, reducing risk of accidental changes.

❓ security

advanced

Protecting sensitive environment variables in Firebase

Which practice best protects sensitive environment variables like API keys in Firebase Functions?

A Store sensitive keys in Firebase Functions config and never commit them to source code.

B Store sensitive keys in Firestore database and read them at runtime.

C Hardcode sensitive keys in your function code but restrict access to the repository.

D Include sensitive keys in client-side code but obfuscate them.

💡 Hint

Think about where environment variables should live and visibility.

Firebase Functions config is encrypted and not exposed to clients. Hardcoding or storing in Firestore risks exposure.

✅ Best Practice

expert

Automating environment config deployment in CI/CD

You want to automate deployment of Firebase Functions with environment variables in a CI/CD pipeline. Which method ensures environment variables are correctly set during deployment?

A Store environment variables in a .env file committed to the repository and load them during deploy.

B Manually run 'firebase functions:config:set' on your local machine before pipeline runs.

C Include 'firebase functions:config:set' commands in the pipeline before 'firebase deploy'.

D Use Firebase Hosting rewrites to inject environment variables at runtime.

💡 Hint

Think about how to keep environment variables in sync with deployment automatically.

Running 'firebase functions:config:set' in the pipeline ensures environment variables are set in the correct project before deploying functions.