Multiple devices as "master folder"?

General
1

This doubt arose out of following use case, which I think is not possible at the moment with syncthing:

I have a folder shared between 2 devices, A and B. None of A or B has “Folder master” checked, so all changes propagate bi-directionally on A and B. So far so good. Now, I want to share this folder with my friend but in a ‘read-only’ mode (lets call my friend’s device C). This means that I still want to sync the folder bidirectionally for any changes on A and B. However, C should only be able to receive those changes but not make any new changes (or ignore/override any change made by C).

Can this be done?

I initially though that if I mark the folder to be “Folder master” on both A and B, it can be achieved. But, I read on forum that it is not like that - both A and B will be sitting with their own changes. If that is correct, does it mean that for a meaningful share exactly one of the devices in a cluster can be set to “Folder master”? It will be good to understand the sync behavior when more than one devices have “Folder master” checked. Eg: In a cluster of 4 devices, (A,B,C,D), A & B has “Folder master” checked. Then what files does C & D get? Does changes between C and D propagate bidirectionally?

I was able to do “Read-only” share using bittorrent sync. This is the only thing I miss in syncthing. I wish there is a way to do it…

2 Likes
2

This is not currently possible. You want https://github.com/syncthing/syncthing/issues/62 (and you’re not alone…).

3

Ah, I see. Somehow I could not find that issue when I was searching.

4

What happens in above scenario?

5

Changes propagate

  • A → C & D
  • B → C & D
  • C ⇄ D

Neither A nor B will accept any changes from the outside. That’s what Master does and all that it does.

I wouldn’t recommend this setup. Change something on A and it syncs to C and D. Change the same thing on B and you have a conflict on both C and D.

6

Would it make sense to set up syncthing like this:

  • A → C & D (FolderName: MasterA)
  • B → C & D (FolderName: MasterB)
  • A ⇄ B (FolderName: ShareAB)
  • C ⇄ D (FolderName: ShareCD)

A is Master for C&D B is Master for C&D, too but a separate folderID. A shared the same Data in a different folderID with B C shared the same Data in a different folderID with D

Legend:

  • → indicates Master
  • ⇄ indicates normal share

It would involve nested folders…

7

This seems to be complicated. Are you implying to share same folder-path multiple times with different FolderID? Is it a recommended thing to do?

8

It is complicated. It’s not exactly recommended. It may have surprising effects on conflict handling. It may also work around the issue you’re trying to solve, though.

9

Even if it would be working… It surely doesn´t scale…

10

Maybe the only problem is that not exist a “receive only” share, or the share can’t configured in “Send only” or “send receive” in a per devices way.

I solve similar problem in a “dirty way”.

I create share a folder between 3 PC A,B,C in Send&Recive mode. No problem.

Then I need to share the same folder in my phone but the phone only “receive” the files I dont care the changes in the phone.

So I created another share in 3 PC A,B,C but in “Send Only” mode. but in the same location that the first share (Send&Recive) and the share in “send only” is send to the phone.

The send only share complain “out of sync” between 3 PC but i dont care because the folder in sync but the send-receive.

so to send the “changes” to the phone I need press button overrrides changes in any PC.

1 Like