Upload image from URL to Firebase Storage

There's no need to use Firebase Storage if all you're doing is saving a url path. Firebase Storage is for physical files, while the Firebase Realtime Database could be used for structured data.

Example . once you get the image url from the external site this is all you will need :

var externalImageUrl = 'https://foo.com/images/image.png';

then you would store this in your json structured database:

databaseReference.child('whatever').set(externalImageUrl);

OR

If you want to actually download the physical images straight from external site to storage then this will require making an http request and receiving a blob response or probably may require a server side language ..

Javascript Solution : How to save a file from a url with javascript

PHP Solution : Saving image from PHP URL

Javascript solution to this using fetch command.

var remoteimageurl = "https://example.com/images/photo.jpg"
var filename = "images/photo.jpg"

fetch(remoteimageurl).then(res => {
  return res.blob();
}).then(blob => {
    //uploading blob to firebase storage
  firebase.storage().ref().child(filename).put(blob).then(function(snapshot) {
    return snapshot.ref.getDownloadURL()
 }).then(url => {
   console.log("Firebase storage image uploaded : ", url); 
  }) 
}).catch(error => {
  console.error(error);
});

This answer is similar to @HalesEnchanted's answer but with less code. In this case it's done with a Cloud Function but I assume the same can be done from the front end. Notice too how createWriteStream() has an options parameter similar to bucket.upload().

const fetch = require("node-fetch");

const bucket = admin.storage().bucket('my-bucket');
const file = bucket.file('path/to/image.jpg');

fetch('https://example.com/image.jpg').then((res: any) => {
  const contentType = res.headers.get('content-type');
  const writeStream = file.createWriteStream({
    metadata: {
      contentType,
      metadata: {
        myValue: 123
      }
    }
  });
  res.body.pipe(writeStream);
});