Storage

"firebase/storage"
"firebase-admin/storage"

Google's infrastructure

Firebase Storage is a wrapper around Google's Cloud Storage service: https://cloud.google.com/storage/?hl=en, which is similar to Amazon S3.

As other storage providers, it uses the concepts of objects living in a bucket.

objects in a bucket

we use the term object instead of file to emphasize some differences:

• objects are immutable. If we want to save a modified version, we must create a new, distinct object. We may keep or delete the former object. This is distinct from files that are writable and may change over time.
• objects live in a single, flat container, which is different from most file systems where a file lives somewhere in a vertical hierarchy made of nested directories. The flat layout is simpler and makes it easier for providers to scale.
• bucket is the name given to such flat container. Within a bucket, we may emulate a hierarchy by adding subpaths in the file name such as public/ in public/abc.png

bucket globally unique identifier

The name of the bucket uses the form of an URL. The project ID, which is unique, makes the URL unique.

projectname.appspot.com
PROJECT_ID.firebasestorage.app

We may not use the URL as-is to access the content. Instead, the access HTTP requests typically embed this URL within a bigger one.

the extended ID may use the gs:// prefix

"gs://projectname.appspot.com"

client SDK: specify a bucket

A firebase project is given a default bucket. The storage service picks the default bucket by default.

const storage = getStorage(app)

If we are to use a distinct bucket, we must provide its ID.

const storage = getStorage(app, bucketID)
const storage = getStorage(app, "gs://my-custom-bucket")