Preview channels in Firebase - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Preview Channel in Firebase Hosting?

A Preview Channel is a temporary URL where you can test your website changes before making them live. It helps you see how your site looks and works without affecting the main site.

beginner

How long does a Firebase Preview Channel stay active by default?

By default, a Firebase Preview Channel stays active for 7 days before it expires and is deleted automatically.

beginner

Why use Preview Channels instead of deploying directly to production?

Preview Channels let you test changes safely without affecting your live website. This helps catch errors and get feedback before users see the updates.

beginner

How do you create a Preview Channel using Firebase CLI?

You run the command firebase hosting:channel:deploy CHANNEL_ID where CHANNEL_ID is a name you choose for your preview.

intermediate

Can multiple Preview Channels exist at the same time?

Yes, you can create multiple Preview Channels to test different versions or features of your site independently.

What is the main purpose of a Firebase Preview Channel?

A To backup your website data

B To permanently host your website

C To speed up website loading

D To test website changes before going live

Preview Channels provide a temporary URL to test changes safely before publishing them to the live site.

How do you deploy to a Preview Channel using Firebase CLI?

A firebase hosting:channel:deploy CHANNEL_ID

B firebase hosting:disable

C firebase init hosting

D firebase deploy --only hosting

The command 'firebase hosting:channel:deploy CHANNEL_ID' creates or updates a preview channel with your site changes.

How long does a Firebase Preview Channel last by default?

A 30 days

B 1 day

C 7 days

D Indefinitely

Preview Channels expire automatically after 7 days unless extended or deleted earlier.

Can you have multiple Preview Channels active at the same time?

A Yes, multiple preview channels can exist

B No, only one preview channel is allowed

C Only if you pay for a premium plan

D Only for Firebase projects with less than 5 users

Firebase allows multiple preview channels so you can test different versions or features independently.

What happens if you deploy directly to production without using a Preview Channel?

A Your changes are tested automatically

B Your live site updates immediately

C Your site is backed up first

D Your site is put into maintenance mode

Deploying directly to production updates your live website immediately, which can cause issues if there are errors.

Explain what a Firebase Preview Channel is and why it is useful.

Think about how you test changes before sharing with others.

Describe the steps to create and use a Preview Channel with Firebase CLI.

Focus on the command and what happens after deployment.

Practice

1. What is the main purpose of Firebase preview channels?

easy

A. To create temporary, shareable versions of your app for testing

B. To permanently host your live app

C. To backup your Firebase database

D. To monitor app usage statistics

Solution

1. Step 1: Understand preview channels concept

   Preview channels allow you to create temporary versions of your app that you can share for testing.

2. Step 2: Compare with other options

   Permanent hosting, backups, and monitoring are different Firebase features unrelated to preview channels.

3. Final Answer:

   To create temporary, shareable versions of your app for testing -> Option A

4. Quick Check:

   Preview channels = temporary test versions [OK]

Hint: Preview channels = temporary test app versions [OK]

Common Mistakes:

• Confusing preview channels with permanent hosting
• Thinking preview channels backup data
• Assuming preview channels track usage

2. Which command correctly creates a Firebase preview channel named test123?

easy

A. firebase hosting:channel:deploy test123

B. firebase deploy --channel test123

C. firebase hosting:deploy test123

D. firebase channel:create test123

Solution

1. Step 1: Recall the correct Firebase CLI command

   The command to create a preview channel is firebase hosting:channel:deploy CHANNEL_ID.

2. Step 2: Match the command with the channel name

   Replacing CHANNEL_ID with test123 gives firebase hosting:channel:deploy test123.

3. Final Answer:

   firebase hosting:channel:deploy test123 -> Option A

4. Quick Check:

   Correct CLI command = firebase hosting:channel:deploy test123 [OK]

Hint: Use hosting:channel:deploy with your channel name [OK]

Common Mistakes:

• Using deploy without hosting:channel
• Using channel:create which is invalid
• Mixing command order or flags

3. What happens when you deploy to a Firebase preview channel with the command firebase hosting:channel:deploy preview1?

medium

A. The live app is overwritten immediately

B. The app is published to the app stores

C. The Firebase database is reset

D. A temporary URL is created to share the app version

Solution

1. Step 1: Understand the effect of deploying to a preview channel

   Deploying to a preview channel creates a temporary, shareable URL for testing.

2. Step 2: Eliminate incorrect options

   It does not overwrite the live app, reset databases, or publish to app stores.

3. Final Answer:

   A temporary URL is created to share the app version -> Option D

4. Quick Check:

   Deploy to preview channel = temporary URL [OK]

Hint: Deploying preview channel creates temporary share URL [OK]

Common Mistakes:

• Thinking it overwrites live app immediately
• Confusing preview deploy with database reset
• Assuming it publishes app to stores

4. You ran firebase hosting:channel:deploy MyTest but got an error saying the channel name is invalid. What is a likely cause?

medium

A. You need to be logged out of Firebase CLI

B. You must include the --force flag

C. Channel names cannot contain uppercase letters

D. Channel names must be numeric only

Solution

1. Step 1: Check Firebase preview channel naming rules

   Channel names must be lowercase alphanumeric and can include dashes, but no uppercase letters.

2. Step 2: Evaluate other options

   --force flag is not required for naming; numeric-only names are not required; being logged out causes authentication errors, not naming errors.

3. Final Answer:

   Channel names cannot contain uppercase letters -> Option C

4. Quick Check:

   Invalid channel name = uppercase letters [OK]

Hint: Use only lowercase letters in channel names [OK]

Common Mistakes:

• Trying uppercase letters in channel names
• Assuming --force fixes naming errors
• Confusing auth errors with naming errors

5. You want to share a new feature with your team without affecting the live app. Which steps correctly use Firebase preview channels to do this?

hard

A. Run firebase deploy to update live app, then email the team

B. Run firebase hosting:channel:deploy featureX and share the generated URL

C. Create a new Firebase project and deploy the app there

D. Use firebase hosting:disable to stop live hosting temporarily

Solution

1. Step 1: Identify the correct way to create a preview version

   Using firebase hosting:channel:deploy featureX creates a temporary preview channel for sharing.

2. Step 2: Understand why other options are incorrect

   Deploy updates live app; creating new project is unnecessary; disabling hosting stops live app, not preview.

3. Final Answer:

   Run firebase hosting:channel:deploy featureX and share the generated URL -> Option B

4. Quick Check:

   Preview channel deploy + share URL = safe testing [OK]

Hint: Deploy preview channel and share URL, not live deploy [OK]

Common Mistakes:

• Deploying directly to live app by mistake
• Creating new projects unnecessarily
• Disabling hosting instead of previewing