Preview channels in Firebase - Step-by-Step Execution

Process Flow - Preview channels

Create Preview Channel

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Deploy Preview Build

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Generate Preview URL

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Share URL for Testing

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Receive Feedback

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Decide to Promote or Discard

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Promote to Live

This flow shows how a preview channel is created, deployed, shared for testing, and then either promoted to live or deleted.

Execution Sample

Firebase

firebase hosting:channel:create preview-123
firebase deploy --only hosting:preview-123
firebase hosting:channel:open preview-123

Commands to create a preview channel, deploy to it, and open the preview URL.

Process Table

Step	Action	Input/Command	Result	Notes
1	Create preview channel	firebase hosting:channel:create preview-123	Preview channel 'preview-123' created	Channel ready to receive deploys
2	Deploy to preview channel	firebase deploy --only hosting:preview-123	Build deployed to 'preview-123'	Preview site updated with new build
3	Open preview URL	firebase hosting:channel:open preview-123	URL generated: https://preview-123--project.web.app	URL can be shared for testing
4	Share URL	Share URL with testers	Testers access preview site	Feedback collected
5	Decide promotion	Promote or delete preview	If promote: promote to live If delete: remove preview channel	Final step based on feedback
6	Exit	N/A	Process ends	Preview channel either promoted or deleted

💡 Process ends after promotion or deletion of preview channel

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 5	Final
previewChannelName	null	preview-123	preview-123	preview-123	preview-123	null or live
previewURL	null	null	https://preview-123--project.web.app	https://preview-123--project.web.app	null or live URL	null or live URL
deploymentStatus	none	created	deployed	deployed	promoted or deleted	promoted or deleted

Key Moments - 3 Insights

Why do we need to create a preview channel before deploying?

Creating a preview channel sets up an isolated environment for your build. As shown in step 1 of the execution_table, without this, you cannot deploy a preview build separately from live.

What happens if I delete a preview channel after deployment?

Deleting a preview channel removes the preview site and URL, as indicated in step 5. This means testers can no longer access that preview.

Can I promote a preview channel directly to live?

Yes, after collecting feedback, you can promote the preview build to live, replacing the live site. This is shown in step 5 where promotion is a decision point.

Visual Quiz - 3 Questions

Look at the execution_table, what is the previewURL after step 3?

A null

B https://preview-123--project.web.app

C https://live-project.web.app

D preview-123

💡 Hint

Check the 'Result' column in row for step 3 in execution_table

At which step does the deploymentStatus change to 'deployed'?

A Step 3

B Step 1

C Step 2

D Step 5

💡 Hint

Look at deploymentStatus changes in variable_tracker after Step 2

If you skip creating a preview channel, what will happen when deploying?

A Deployment fails because no preview channel exists

B Preview URL is generated automatically

C Deployment succeeds to live site

D Preview channel is created automatically

💡 Hint

Refer to key_moments about the importance of creating preview channel before deploy

Concept Snapshot

Preview channels let you deploy a test version of your site.
Create a channel with 'firebase hosting:channel:create <name>'.
Deploy to it with 'firebase deploy --only hosting:<name>'.
Open the preview URL to share and test.
After feedback, promote to live or delete the preview.
This keeps live site safe while testing changes.

Full Transcript

Preview channels in Firebase Hosting allow you to create isolated environments to test your site before making changes live. The process starts by creating a preview channel with a unique name. Then you deploy your build to this channel. Firebase generates a special URL for this preview, which you can share with testers. They can access the preview site and provide feedback. Based on this feedback, you decide to either promote the preview build to your live site or delete the preview channel to discard changes. This workflow helps keep your live site stable while safely testing updates.