Print hosting default URL (or channel URL) with Firebase CLI - firebase-cli

Question

The Firebase CLI tool can show me the default URLs of the hosting site(s) of a project in a human-readable format:
$ firebase hosting:sites:list
Sites for project <my-app>
┌──────────────────┬──────────────────────────────────┬─────────────────┐
│ Site ID │ Default URL │ App ID (if set) │
├──────────────────┼──────────────────────────────────┼─────────────────┤
│ my-app │ https://<my-app>.web.app │ -- │
└──────────────────┴──────────────────────────────────┴─────────────────┘
If I have multiple channels, it can also show me the URLs for each channel on a given site:
$ firebase hosting:channel:list
Channels for site <my-app>
┌────────────┬─────────────────────┬──────────────────────────────────┬─────────────┐
│ Channel ID │ Last Release Time │ URL │ Expire Time │
├────────────┼─────────────────────┼──────────────────────────────────┼─────────────┤
│ live │ 2022-10-27 15:06:54 │ https://<my-app>.web.app │ never │
└────────────┴─────────────────────┴──────────────────────────────────┴─────────────┘
But how do I print only the URL of a channel, for use in a shell script? (Without resorting to regexes.)

Answer 1

You can use a --json argument.
Combined with jq, you can retrieve a specific URL.
Example with live channel:
$ firebase hosting:channel:list --json |\
jq '.result.channels[]|select(.name|contains("live")) | .url'

Answer 2

There isn't any command that prints just the default URLs. The CLI uses a package cli-table and prints all the data together.
You can however use the Firebase Hosting REST API to list all the sites of a project and their channels and create a script or even better fork the Firebase CLI and add a new function alongside listSites() function of the CLI to print the URLs without the table.
The REST APIs response is just an array of sites so it should be pretty straightforward:
{
"sites": [
{
"name": "projects/<project_id>/sites/<site_id>",
"defaultUrl": "https://<project_id>.web.app",
"type": "DEFAULT_SITE"
}
]
}