Copy a file on firebase storage?

There is no method in the Firebase Storage API to make a copy of a file that you've already uploaded.

But Firebase Storage is built on top of Google Cloud Storage, which means that you can use the latter's API too. It looks like gsutil cp is what you're looking for. From the docs:

The gsutil cp command allows you to copy data between your local file system and the cloud, copy data within the cloud, and copy data between cloud storage providers.

Keep in mind that gsutil has full access to your storage bucket. So it is meant to be run on devices you fully trust (such as a server or your own development machine).

Here is an approach I ended up with for my project.

While it covers a broader case and copies all files under folder fromFolder to toFolder, it can be easily adopted to the case from the question (to copy only files one can pass delimiter = "/" - refer to the docs for more details)

const {Storage} = require('@google-cloud/storage');


module.exports = class StorageManager{

    constructor() {
        this.storage = new Storage();
        this.bucket = this.storage.bucket(<bucket-name-here>)
    }

    listFiles(prefix, delimiter){
        return this.bucket.getFiles({prefix, delimiter});
    }
    deleteFiles(prefix, delimiter){
        return this.bucket.deleteFiles({prefix, delimiter, force: true});
    }

    copyFilesInFolder(fromFolder, toFolder){
        return this.listFiles(fromFolder)
            .then(([files]) => {
                let promiseArray = files.map(file => {
                    let fileName = file.name
                    let destination = fileName.replace(fromFolder, toFolder)
                    console.log("fileName = ", fileName, ", destination = ", destination)
                    return file.copy(destination)
                })
                return Promise.all(promiseArray)
            })
    }
}