[SOLVED] Automount fs over ssh using autofs and sshfs (with fuse)

AnsemEco · 08-12-2016, 01:27 PM

I've just found out how effective autofs is, especially with mounting and unmounting network file systems.

I am attempting to have autofs automount a directory from a server configured to use openssh. I do not have any power over the server other than reading and writing my files.

I have setup auto.master to include the following line:

Code:

/netfs/ssh /etc/autofs/auto.ssh --timeout=60,--ghost

and auto.ssh to include the following:

Code:

myServer    fstype=fuse,rw,uid=1000,gid=1000,allow_other :sshfs\#user@host\:

I can use sshfs just fine on the command line and it mounts for both my $user and root. The issue is when accessing myServer under netfs/ssh/, the system hangs then cd prints out

Code:

cd: no such file or directory: myServer

I believe 'cd' reacts like so since the dirctory is a ghost (just a trigger to autofs); only succeeding when mounting is done.

How am I able to automount this directory via autofs without this issue?

jpollard · 08-13-2016, 07:13 AM

The usual problem is getting proper access to the keys for ssh. Root is the one doing the mount, not the user; So I would expect some issues with identifying the correct keys for use.

AnsemEco · 08-13-2016, 07:24 AM

I thought that was the problem since, as you just mentioned, root was the one actually doing the mount.
However, I have authorised both my username and root for passwordless authentication.
Root also has the server on the list of known hosts.
I attempted to mount my directory using sshfs as root and it mounted without issues.
I just wished to automate this with autofs.

jpollard · 08-13-2016, 08:37 AM

Quote:

Originally Posted by AnsemEco

I thought that was the problem since, as you just mentioned, root was the one actually doing the mount.
However, I have authorised both my username and root for passwordless authentication.
Root also has the server on the list of known hosts.
I attempted to mount my directory using sshfs as root and it mounted without issues.
I just wished to automate this with autofs.

Depending on distribution, the credentials used are identified by the login identity - not the uid. The root process doing the autofs has / for a home directory (sometimes it may be /etc or even /tmp), not /root, thus trying to access the credentials could fail.

AnsemEco · 08-13-2016, 08:44 AM

So is there a way to direct the root process to the credentials to use?
Something I would probably include in the list of options for autofs or the underlying sshfs.

Better yet is there a log file where I can look into the connection process and get a better look on what's really going on?

jpollard · 08-13-2016, 09:08 AM

Not that I know of.

The other problem with autofs is that it will try to dismount the filesystem using umount... which isn't a "fusermount -u"

There may actually be a way - but most of the references I find for using autofs and sshfs are old (2012 was the most recent, but https://wiki.archlinux.org/index.php/autofs for Arch has a posting only a couple of months old.

AnsemEco · 08-13-2016, 10:40 AM

I tried adding the option 'IdentityFile=/home/username/.ssh/id_rsa' ofcourse applying it to my case (username).
Though it still hangs for about 10 sec then fails.

keefaz · 08-13-2016, 10:56 AM

For convenience, you can always set an alias and skip autofs

Code:

alias cdnetfs="sshfs user@host:/remote/dir /netfs/ssh && cd /netfs/ssh"

jpollard · 08-13-2016, 01:08 PM

Quote:

Originally Posted by keefaz

For convenience, you can always set an alias and skip autofs

Code:

alias cdnetfs="sshfs user@host:/remote/dir /netfs/ssh && cd /netfs/ssh"

Or make script for an auto start login that does the mount. Might have to experiment with getting it dismounted though.

AnsemEco · 08-13-2016, 02:39 PM

These are both valid options.
Though I wish the original issue to be solved.
For the mean time, I will keep this thread open to give opportunity for other suggestions.

michaelk · 08-13-2016, 04:28 PM

May not make a difference but you might have two syntax errors i.e.
fstype=fuse... should be -fstype=fuse...

And you did not specify a directory on the server i.e.
:sshfs\#user@host\: should be :sshfs\#user@host\:/path/to/directory

You can debug autofs by using the automount command. Shutdown autofs then run the command in another terminal
automount -f --debug (once started ctrl-c is required to shutdown automount)

Now go back and try to cd to your myserver directory. Look at the debug messages to see where autofs errors. ssh is particular on the id_rsa permissions. When you ssh via the command line as root are you using your user or roots id_rsa key? Are you using the standard (22) or non standard port?

AnsemEco · 08-13-2016, 06:09 PM

Thanks to michaelk, I think I have a lead.

Code:

add_host_addrs: hostname lookup failed: Name or service not known
mount(nfs): no hosts available
dev_ioctl_send_fail: token = 3
failed to mount /netfs/ssh/myServer

PS.
When mounting as root I used the root's id_rsa key under /root.
I tried using

Code:

IdentityFile=/root/.ssh/id_rsa

though the outcome did not change.
and yes I use the standard port 22.

michaelk · 08-13-2016, 07:05 PM

Are you using ip address in the auto.ssh file?

jpollard · 08-13-2016, 09:41 PM

If you happen to be using a NetworkManager for initialization you likely have to enable "NetworkManager-wait-online" to force systemd to wait until the network is actually up.

michaelk · 08-13-2016, 09:59 PM

Not necessarily, since autofs is "on demand" the network should already be up.