Not today...

Sometimes I just can’t work on a local environment (particular architecture, particular services, local configuration too complex, etc…). So, I have to synchronize my local directory with a remote one and test the web interface on my local machine.

ssh

First, ssh! For this I need a ssh connection to the remote server, here I use a particular ssh key.

ssh -i ~/.ssh/my_ssh.key mylogin@192.168.0.1

# urls also work
ssh -i ~/.ssh/my_ssh.key mylogin@my.url.com

Okay, at this moment we can use a config file for ssh: $HOME/.ssh/config :)

Host 192.168.0.1 my.url.com
   user mylogin
   IdentityFile ~/.ssh/my_ssh.key

The CLI is now:

# with IP
ssh 192.168.0.1

# with url
ssh my.url.com

I have a connection but now I want to share my dev server on the remote host to my local web browser. For that I will use the -L of ssh, this will forward the local port with the remote one.

ssh -L 5000:localhost:9999 192.168.0.1 # same as before it works with url

This command will connect my local port 5000 to the port 9999 of the remote host local interface (so I do not have to open another port on the remote except the ssh one)

rsync

Then, we will use rsync to send files to our server

rsync -avz -e "ssh" local/folder my.url.com:/home/username/remote_folder

• -a the archive option (recursive, preserve links, times, permissions, group, owner, devices files
• -v the verbose option
• -z the compress option
• -e remote shell to use (basically we specify here all the ssh configuration needed. If we didn’t had the .ssh/config file the command line should have been rsync -avz -e "ssh -i ~/.ssh/my_ssh.key" local/folder mylogin@my.url.com:/home/username/remote_folder

It is possible to not want to synchronize all files (.git folder, generated files, etc…), so we will use the --exclude-from option. In the folder we want to synchronize, we create a file exclude.txt (the name is not important), then we fill it with the needed files or folder:

.git
/static
*.pyc

Take care that the / apply at the point where the rsync command is launched. So it will not have the same effect if we change the working directory.

The command will look like:

# move to working dir
cd local/folder

remote_loc="my.url.com:/home/username/remote_folder"

rsync -avz -e "ssh" . $(remote_loc) --exclude-from 'exclude.txt'

fswatch (or inotify)

I also want my folder to synchronize automatically with the remote one when a file change. For this purpose I will use fswatch because I use MacOS (shame on me), inotify can be use on linux platforms.

First, check the changes on my working directory:

fswatch -e .git/ -e .pyc -e $(pwd)/static .

Here I use $(pwd) in order to not catch the /static folder at the root of the folder, but keep the nested one included. This catch the same files as the exclude file from rsync. At this point I haven’t found any solution to unify those two commands.

xargs

The last piece needed is xargs, this will read stdin and execute a command on each entry.

All together

Here is my final command:

cd local/folder

remote_loc="my.url.com:/home/username/remote_folder"

fswatch -0 -o -e .git/ -e .pyc -e $(pwd)/static . | \
xargs -0 -I {} rsync -avz -e "ssh" . $remote_loc --exclude-from 'exclude.txt'

• The option -0 indicates that fswatch will use \0 as a line separator.

• The option -o will only indicates how many files have been modified, has long has I do not need the filename to perform the command.

• The command xargs take the same option -0 so it will accept \0 as the separator between each command.

• The -I {} option will tell xargs that the caught at first will be injected in the command at the place of {} (this is the same as the -exec command in find). We do not use it because rsync will take care to check which file has changed, this is a trick to avoid xargs to complain.