We are planning to implement a feature to let customers browse their images in their own google drive or dropbox accounts (within our app), and select ones they wanna use in our app. Then, we will save these images into our Google cloud storage (GCS) place.
A simple approach is to use OAuth to download the customers' images from dropbox/drive to our local disk, then upload them to our GCS.
I am wondering if it is possible to make a direct transfer between dropbox/drive and GCS? GCS does provide transfer service for S3. You can also create a list of URL list, but each URL needs to be publicly accessible, which in our case does not seem possible.
Is there any better suggestion on how to implement this feature? Thanks
Well you could stream the files so at least you wouldn't have to save them to local disk, but other than that I think your solution is the way to go.
It depends on your language how streaming works exactly, but basically you download the file and upload it to GCS right away without ever writing any bytes to local disk.
I ran into your question during my search of finding a way to transfer data from G-drive to Google Cloud Storage. Since they are both under Google umbrella, so I guess they should be able to seamlessly upload/download. So far in my search, without programming, the answer is NO.
I don't have a exactly solution for your question, because it really depend on how much data you have and how often of the uploading/downloading. Unfortunately, there is not straight shot (even for the Gdrive!). But maybe thinking of trying the RESTful API calling to Google and make the connection with Dropbox API. Hoping this could help.
来源：https://stackoverflow.com/questions/41754935/transfer-files-from-dropbox-drive-to-google-cloud-storage