Mount an sshfs via macfuse at boot

Question

I want to mount an sshfs folder at boot under Mac OSX: I'm using Macfusion right now, that is a GUI for MacFUSE, but I have to mount the folder manually.

How can I achieve that?

Answer 1

If you maintain a remote machine, it can be really useful to mount that machine's filesystem locally to move files around. MacFuse and sshfs make this really easy, although getting it set up and mounted automatically at login can be a bit tricky.

First, make sure you can ssh to your remote machine without entering a password. Do the setup in Leopard finally supporting ssh-agent at login and verify that it works:

ssh USER@HOSTNAME:

If it logged you in without prompting for a password or passkey, you're ready to proceed.

Next, install sshfs and MacFuse as per Installing sshfs 1.9 with MacFuse 1.7 on OS X Leopard 10.5.5.

Figure out where you want to mount your remote volume. I wouldn't recommend using /Volumes since it appears that OS X automatically deletes directories in there when you unmount things. So instead I used /mnt/HOSTNAME

mkdir -p /mnt/HOSTNAME

(Obviously, you'll replace HOSTNAME with your remote server's name.)

Then make sure you can mount your remote site as a volume without specifying a password using sshfs:

sshfs USER@HOSTNAME:PATH /mnt/HOSTNAME -oreconnect,allow_other,volname=VOLUME_NAME

Set VOLUME_NAME to whatever you want your volume to be named in the Finder. I used HOSTNAME. PATH is optional; set it to whichever directory you want to mount on the remote host. If it's not set, it'll use your home directory.

If you get no error messages, and when you do an ls /mnt/HOSTNAME the remote files show up, then you're ready to proceed to the next step.

Unmount the volume you just mounted:

umount /mnt/HOSTNAME

Now comes the tricky party. You'll need to create a LaunchAgent item to mount your volume at login. This in itself is pretty easy. However, if your system is anything like mine, this item won't have its SSH_AUTH_SOCK set properly, so it won't be able to login to the remote host without using a password. You'll have to manually set the SSH_AUTH_SOCK yourself.

First, create a wrapper around sshfs that will set the SSH_AUTH_SOCK for you. Put this in a file wherever you want.  I suggest /opt/local/bin/sshfs-authsock.

#!/bin/bash
export SSH_AUTH_SOCK=$(ls -t /tmp/launch-*/Listeners | head -1)
/opt/local/bin/sshfs $*

Basically, this file sets SSH_AUTH_SOCK to the most recent socket in your tmp directory.  In most cases, this should be the proper one. It's unlikely to fail, and there's no security issue if it does.

Now you can finally create the launchd plist file. Put this in

~/Library/LaunchAgents/BACKWARDS_HOST_DNS.PATH.sshfs.plist

(If your host's path is, say, foo.niskala.org and your PATH was /tmp, then your resulting filename would be org.niskala.foo.tmp.sshfs.plist.  This is just a convention, feel free to name the file whatever you want, really; but it does need to end in .plist.)

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>Label</key>
        <string>BACKWARDS_HOST_DNS.PATH.sshfs</string>
        <key>ProgramArguments</key>
        <array>
                <string>/opt/local/bin/sshfs-authsock</string>
                <string>USER@HOSTNAME:</string>
                <string>/mnt/HOSTNAME</string>
                <string>-oreconnect,allow_other,volname=VOLUME_NAME</string>
        </array>
        <key>RunAtLoad</key>
        <true/>
</dict>
</plist>

Now load the plist file and run it to see if it works.

launchctl load ~/Library/LaunchAgents/BACKWARDS_HOST_DNS.PATH.sshfs
launchctl start BACKWARDS_HOST_DNS.PATH.sshfs

If you see no error messages, see if the volume was mounted properly:

ls /mnt/HOSTNAME

If your remote files show up, then great! You're done!

If not, use

launchctl unload ~/Library/LaunchAgents/BACKWARDS_HOST_DNS.PATH.sshfs

to unload the file before making edits to it, then use ps auxwww | grep sshfs and kill to find and kill any sshfs processes before trying again.

References:

• http://discussions.apple.com/thread.jspa?threadID=1674891&tstart=22
• http://ccraig.org/sshfs-mac.html
• http://code.google.com/p/macfuse/wiki/MACFUSE_FS_SSHFS

Answer 2

I'd like to update the great answer from dag729. On El Captain OS X with the OS X Fuse 2.8.3 the things are slightly different:

1. Some paths are changed
2. osxfuse must be forced to run in foreground mode with -f option
3. SSH_AUTH_SOCK is already defined so there is no more reason to create the sshfs-authsock script

Also I would advice to don't use allow_other option (for security reasons) and use auto_cache option just because it sounds useful. Please check OS X Fuse mount options for details.

Here is ~/Library/LaunchAgents/NAME.sshfs.plist file that I use:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>NAME.sshfs</string>
    <key>ProgramArguments</key>
    <array>
            <string>/usr/local/bin/sshfs</string>
            <string>[USER@]HOST:REMOTE_DIR</string>
            <string>MOUNT_DIR</string>
            <string>-oreconnect,auto_cache,volname=FINDER_VOLUME_NAME</string>
            <string>-f</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
</dict>
</plist>

Where NAME is any name you like and the rest variables are quite self descriptive.

---

If for some reason you don't have SSH_AUTH_SOCK defined (run command launchctl getenv SSH_AUTH_SOCK to check it) then create a helper script, for example /usr/local/bin/sshfs-authsock with the following content:

#!/bin/bash
export SSH_AUTH_SOCK=$(ls -t /tmp/com.apple.launchd.*/Listeners | head -1)
/usr/local/bin/sshfs $*

And run this script instead of sshfs from plist file. So your ~/Library/LaunchAgents/NAME.sshfs.plist should be:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>NAME.sshfs</string>
    <key>ProgramArguments</key>
    <array>
            <string>/usr/local/bin/sshfs-authsock</string>
            <string>[USER@]HOST:REMOTE_DIR</string>
            <string>MOUNT_DIR</string>
            <string>-oreconnect,auto_cache,volname=FINDER_VOLUME_NAME</string>
            <string>-f</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
</dict>
</plist>

Answer 3

I'd like to add something to dag729's very complete answer.

If you have Lion and have now OS X Fuse instead of the old MacFuse, then the procedure above won't work out of the box because the path of sshfs is different.

If that's the case for you, look where sshfs is in your installation using

which sshfs

and put that path in the /opt/local/bin/sshfs-authsock script.

In my installation, that path is /usr/local/bin/sshfs and therefore my script is:

#!/bin/bash
export SSH_AUTH_SOCK=$( ls -t /tmp/launch-*/Listeners | head -1)
/usr/local/bin/sshfs $*

I can confirm that the rest is still valid.