Listing files in Cloud Storage for Firebase using firebase-admin

I wanted to use firebase-admin to get a list of files existing in an arbitrary directory of Cloud Storage for Firebase. However, even after reading the Official Admin Cloud Storage API Overview, I was at a loss regarding how to use it beyond admin.storage().bucket(). I am recording the results of my research here.

Use getFiles

For example, in a case where you want a list of images in gs://xxxxx.appspot.com/users/${uid}/photos/*.png, you can retrieve them by specifying xxxxx.appspot.com in the storageBucket of initializeApp and using bucket#getFiles with the directory specified as directory: users/${uid}/photos/.

From there, if you want the file URLs, use bucket#getSignedUrl.

const admin = require('firebase-admin');

admin.initializeApp({
  credential: admin.credential.cert(require(certFilePath)),
  storageBucket: "xxxxx.appspot.com"
});

const bucket = admin.storage().bucket();

const files = await bucket.getFiles({
  directory: `users/${uid}/photos/`
});

for (const item of files[0]) {
  const url = await item.getSignedUrl({
    action: 'read',
    expires: '01-01-2021'
  });

  console.log(url);
}