[StarCluster] working with EBS volumes

[Austin Godber]

Hi Justin,
     I have verified this issue.  Its not quite what it seems.  The real 
issue at hand is that the CLUSTER_USER gets created with the same UID as 
the existing ubuntu user.  So anything that uses a UID is going to 
report back the 'ubuntu' user rather than the CLUSTER_USER.  Starcluster 
needs to get rid of or replace the ubuntu user or use a new starting 
UID/GID.  But we would have to be careful to make sure that sudo still 
works, since that is indexed by name rather than uid.  In this case, its 
just luck that sudo works for the CLUSTER_USER since the UID matches the 
ubuntu user.  The GIDs collide as well.

     To reproduce, do the following:
pip install starcluster
pip install boto=1.9b  # to get the working version of boto
starcluster createvolume 1 use-east-1a
# edit your .starcluster/config to use the new volume and mount it at /home
starcluster start smallcluster

Here is a variety of the consequences:

$ grep 1000 /etc/passwd
ubuntu:x:1000:1000:Ubuntu,,,:/home/ubuntu:/bin/bash
sgeadmin:x:1000:1000::/home/sgeadmin:/bin/bash

$ grep 1000 /etc/group
ubuntu:x:1000:
sgeadmin:x:1000:

ubuntu at domU-12-31-38-04-C8-B5:~$ w
  13:30:30 up 19 min,  1 user,  load average: 0.00, 0.00, 0.00
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT
sgeadmin pts/1    oh-76-1-37-133.d 13:29    0.00s  0.25s  0.00s w

ubuntu at domU-12-31-38-04-C8-B5:~$ id
uid=1000(ubuntu) gid=1000(ubuntu) groups=1000(ubuntu)

ubuntu at domU-12-31-38-04-C8-B5:~$ ls -l /home/
total 20
drwx------ 2 root   root   16384 2010-10-15 13:06 lost+found
drwxr-xr-x 4 ubuntu ubuntu  4096 2010-10-15 13:20 sgeadmin

Austin

On 10/14/2010 04:58 PM, Justin Riley wrote:
>
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> Hi Adam,
>
> Sorry for the late response.
>
> There is some magic that occurs when creating users in order to avoid
> having to chmod /home folders which might contain hundreds of
> gigabytes of data. Basically, StarCluster inspects the top level
> folders under the /home folder and if the CLUSTER_USER's home folder
> already exists, then the CLUSTER_USER is created with the same uid/gid
> as the existing home folder to avoid a recursive chmod. Otherwise,
> StarCluster looks at the uid/gid of the other directories in /home and
> chooses the highest gid/uid combo plus 1 to be the uid/gid for the
> CLUSTER_USER. If that calculation ends up with a uid/gid less than
> 1000 then it defaults to 1000 for the gid/uid of CLUSTER_USER.
>
> A couple questions that might help me to understand what happened:
>
> 1. I'm assuming you must have had MOUNT_PATH=/home for the volume in
> your cluster template's VOLUME list, correct?
>
> 2. Did your volume already contain a 'sgeadmin' folder at the root of
> the volume?
>
> 3. What does "ls -l" look like on the root of the volume that exhibits
> this behavior?
>
> Also, you will find useful information about the uid/gid chosen by
> StarCluster for the CLUSTER_USER in your debug file:
>
> /tmp/starcluster-debug-<your_username>.log
>
> (if you're on mac, this file will be in the directory returned by
> "python -c 'import tempfile; print tempfile.gettempdir()'")
>
> Just grepping for gid or uid in your log file(s) should print out the
> relevant messages: "grep -ri gid /tmp/starcluster-*"
>
> ~Justin
>
>
> On 10/3/10 5:19 PM, Adam Marsh wrote:
> >
>
> > I've had some challenges to getting SC running correctly
> when EBS
>
> > volumes are mounted to the head node during configuration.
> I
>
> > initially setup the EBS volumes with database files by
> first
>
> > configuring and mounting the volume on any available EC2 VM
> I had
>
> > running at the time. By default, most of the time I was
> working as
>
> > user 'ubuntu'. However, whenever an EBS volume with files
> or folders
>
> > having 'ubuntu' as the owner and group were included in the
> VOLUMES
>
> > list of the SC config file and were mounted during setup to
> the head
>
> > node, two odd things occurred:
>
> > 1. when the cluster_user account was setup by SC (like
> 'sgeadmin'),
>
> > the owner and user of the /sgeadmin folder under /home was
> 'ubuntu';
>
> > 2. connecting via ssh to the sgeadmin account always
> defaulted to
>
> > logging in to the 'ubuntu' user account.
>
> >
>
> > I worked around the problem by changing own/grp settings on
> all EBS
>
> > folders/files to the cluster_user name used in the config
> file.
>
> > All works fine now.
>
> >
>
> > Is this just a rare instance of SC system behavior? If not,
> is there
>
> > a better way to prepare EBS volumes for use with SC to
> avoid own/grp
>
> > conflicts?
>
> >
>
> > Thanks,
>
> >
>
> > <Adam
>
> >
>
> >
>
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