# How to use git-annex on a Synology NAS

This is known to work with DSM 4.3-3810 Update 1 and git-annex standalone version 5.20131224-g6ca5271.

## Installation Steps

(1) In the DSM Package Center, install Git, which is available from Synology (no third-party repository needed).

(2) Download the latest [[standalone|install/Linux_standalone]] git-annex build for Linux on armel.

(3) Extract it somewhere sensible (eg: a bin/ directory your users home directory)

(4) Go into the git-annex.linux directory and ./runshell. You can now run git-annex as you normally would.

## How to sync with the Synology NAS

### On the Synology
(1) Setup port forwarding and associated dynamic dns, if applicable. Many good guides online for this.

(2) Setup ssh key based authentication with the Synology for each computer you want to sync with it. You want a specific key that is used only by git-annex, for each computer. Again, many good guides online.

(3) In the Synology .ssh/authorized_keys file for your account, add (substituing your username)
[[!format sh """
command="/home/$yourusername/.ssh/git-annex-shell"
"""]]
to the beginning of the line. Eg, it would look like this:
[[!format sh """
command="/home/greg/.ssh/git-annex-shell" ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDT1yE96E/JQNPt0ziiNYJRvndCvLK4uG5h/SNYoAIBF1uH6L7VYAt3HWVqSyi3BcV70WDZ/yWgtNzbrcir46JpvEHMcvYaXLbANwoDGNjG/gsz7kP/8VUxZ6hG3P3ICuwnqVum5+rYXm6oj3xzWPfTRhhRoDZLOQdevSNpdGNaa/lSg8Vuq2suHwjQlQb8AIUuCZmS5cm6XwoUq/jJtN4LTuTPqMjzA6NkdhWM2Kigi9jPQBFborkYBPMphmZwBZiVnhsH1XpaOff+mP03D2gF/huC+b1vbWQstjuehUbY59rvJ4ijb3810Uq2ep7dwLagmILtX5GbL+GS64pAn9sIP annex-othercomputer
"""]]

(4) the git-annex-shell script in your .ssh should be created for you aftering your initial ./runshell

(5) Double check that the script points to the correct directory of where your extracted git-annex.linux lives.

### On the other computers - the manual way
(1) See step 2 above about creating the specific git-annex ssh keys.

(2) In your .ssh/config, create an alias for your Synology that includes specifying the right sshkey. For example, mine looks like:
[[!format sh """
Host synologyhost
    HostName mydynamicdomain.no-ip.org
    IdentityFile /home/greg/.ssh/annex_rsa
"""]]

(3) Now when you clone the git repo from the Synology, or add it as a remote, do the following:
[[!format sh """
git clone greg@synologyhost:/absolute/path/to/annexname annexname
"""]]
or

[[!format sh """
git remote add synology greg@synologyhost:/absolute/path/to/annexname
"""]]

(4) Run git-annex sync

### On the other computers - Using the assistant

(1) Use the webapp to add the remote. I'm not sure if there are any gotchas here as I have not done it this way yet.