[WIP] All Backends: add --backend-token flag - fixes #2849

[jake-stripe]

Note: The scope of this PR now includes adding a similar token flag to each backend in Rclone. (In addition to the original Dropbox request.)

What is the purpose of this change?

Add a --dropbox-token flag so that a user is able to supply an Access Token (as a JSON blob) outside of the default rclone.conf file. Use of this option (in conjunction with --dropbox-client-id
and --dropbox-client-secret) would allow users to to keep all plaintext credentials off-disk.

Was the change discussed in an issue or in the forum before?

No, just in the Github issue section. Please see #2849.

Checklist

• I have read the contribution guidelines.
• I have added tests for all changes in this PR if appropriate.
• I have added documentation for the changes if appropriate.
• All commit messages are in house style.
• I'm done, this Pull Request is ready for review :-)

[ncw]

Sorry for the delay in replying to this! Christmas plus Norovirus has taken its toll!

What you've written will work fine. I'm just wondering if it can or should be generalised.

All the oauth based remotes could potentially do with this.

$ git grep -l oauth2 backend/
backend/amazonclouddrive/amazonclouddrive.go
backend/box/box.go
backend/drive/drive.go
backend/dropbox/dropbox.go
backend/googlecloudstorage/googlecloudstorage.go
backend/hubic/hubic.go
backend/onedrive/onedrive.go
backend/pcloud/pcloud.go
backend/yandex/yandex.go

So we could extend your patch do do all of the backends like that? Or possibly be a bit more clever and reduce the code duplication a bit.... Maybe making an oauthutil.AddOptions() which would take a fs.Option and return another fs.Option with the oauthutil options in.

Likewise we should be able to do actually setting the token entirely in the oauthutil module I think.

What do you think?

[jake-stripe]

Hey Nick,

Happy New Year! No worries about the delay, I've been on holiday as well. I hope you are feeling better post-Norovirus 🤒.

I agree with you that it would be nice to have this feature available regardless of the backend being utilized. I would be happy to take a crack at implementing; though i'm not 100% sure if I'd be able to test all the backends (I only currently have Dropbox + Google Drive creds).

With regard to the current PR and failed Travis CI build, I'm having trouble understanding what the exact error is during the make check run (I understand its breaking on file backend/dropbox/dropbox.go, line 262, char 18, but little else). If you have the time (no rush), would you mind helping me understand the output? Or pointing me at a resource that you maybe would recommend?

Thanks again,

-Jake

[ncw]

Happy New Year! No worries about the delay, I've been on holiday as well. I hope you are feeling better post-Norovirus .

Thanks :-)

I agree with you that it would be nice to have this feature available regardless of the backend being utilized. I would be happy to take a crack at implementing; though i'm not 100% sure if I'd be able to test all the backends (I only currently have Dropbox + Google Drive creds).

Great!

The daily integration tests will run the backends against all the different providers so that will test that basic functionality isn't broken at least!

With regard to the current PR and failed Travis CI build, I'm having trouble understanding what the exact error is during the make check run (I understand its breaking on file backend/dropbox/dropbox.go, line 262, char 18, but little else). If you have the time (no rush), would you mind helping me understand the output? Or pointing me at a resource that you maybe would recommend?

This is the relevant part of the log. What it means is that errcheck is complaining that config.SetValue returns an error but it didn't get checked.

I'd like to make these code quality checks more obvious - I have a branch with gometalinter doing it which produces better error messages, but I couldn't get it to work with build tags.

errcheck -tags "cmount" ./...
backend/dropbox/dropbox.go:262:18:	config.SetValue(name, config.ConfigToken, opt.Token)
make: *** [check] Error 1

[ncw]

Sorry for the loooong delay responding. Do you still want to work on this? I think the feature is a useful one, but only if we can make it for all backends that need it.

[jake-stripe]

@ncw I agree that this is an important feature, but unfortunately I won't be able to dedicate time to work on it in the near future. I think it would be best to hand this off to someone else. I'll go ahead and close the request.

[ncw]

Thanks for your work on this - I'll pull it into a branch and have a think about how to continue it.