Convenience function to make private files public

[ajhool]

Is your feature request related to a problem? Please describe.
A common use-case is to have private files that are "published" and made to be public.

Describe the solution you'd like
I think the simplest way to do this with the aws-sdk is a client-side call to s3.copyObject where (altough, this would not gracefully handle interruptions). If these functions were added to Storage, the methods might be:

// pseudocode
makePublic(keys: string | string[]) {
   // convert single keys to an array
   const toMakePublic = [].concat(keys);
   const reqs = toMakePublic.map(item => ({
        Bucket: Storage.Bucket, 
        CopySource: path(Storage.Bucket, 'private', userId, prefix, key), 
        Key: path('public', userId, prefix, key)
   })

   for(r in reqs) {
     await s3.copyObject(r)
   }

   // Maybe add a delete flag that would delete the files from the private paths if the copy is a success.
}
```

**Describe alternatives you've considered**
Relying on secretive key names and disabling "list" to implement a private access pattern within the public bucket.

**Additional context**

[sammartinez]

@ajhool Do you have an example of this working out in the world? It seems like if an image/file is set to private, there would be a reason for this correct? Just want a little more context for this is all. Thanks ahead of time!

[ajhool]

Oftentimes in applications a file will go through a "Draft" stage before a "Publish" phase.

For instance, a text document might be stored as a text file before it is finally published (see, medium.com). That would be a private -> public transition.

Or a photo sharing website might have private photos that you can choose to share with friends or choose to make public.

In my specific application, users have photo albums that are almost always private; but there is a feature that allows the user to "publish" their photo album so that the general public can rate the photos in the album. That would be a transition from private to public.

[undefobj]

This sounds like a valid use case, there are two ways to accomplish this:

1. Have the administrator move the files on the backend, this can be done via Lambda functions orchestrated with the Amplify CLI. In some ways this is similar to the new Cognito Admin functionality recently added
2. Do it from the client, in which case there is still a "copy" action behind the scenes where the client fetches it's content and puts it in the new location, at which point it then deletes the old item to ensure data integrity. There's a similar moveTo command in .Net SDK: https://docs.aws.amazon.com/sdkfornet1/latest/apidocs/html/M_Amazon_S3_IO_S3FileInfo_MoveTo_2.htm

If we did this, I would imagine that it should be a generic Storage.move(source, destination|fileLevel) which would allow private->public, public->private, private->protected, etc.

For the time being this is possible using the existing Storage APIs but lets leave this issue open to get some feedback for future work.

[arelaxend]

Up!

[renebrandel]

hi folks! You can now accomplish this via the Storage.copy(...) command. More details here: https://twitter.com/renebrandel/status/1405915684781977604

[github-actions]

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