[Beowulf] Contents of Compute Nodes Images vs. Login Node Images

[Ryan Novosielski]

We’ve always had separate images for the login nodes and compute nodes with Warewulf. We’re getting some complaints that there’s not enough stuff in the compute node images, and that we should just boot compute nodes to the login node image (this is problematic for other reasons, but that’s another story — the general consensus is they want all the same software). I know this happens relatively frequently (generally after a new service has been provided, so that perhaps some new libraries are needed that weren’t previously present) at our site, but nevertheless there’s been pressure to throw the whole kitchen sink in there. Was curious what other sites were doing.

> On Oct 23, 2018, at 1:43 PM, Prentice Bisbal via Beowulf <beowulf at beowulf.org> wrote:
> 
> Ryan,
> 
> When I was at IAS, I pared down what was on the compute nodes tremendously. I went through the comps.xml file practically line-by-line and reduced the number of packages installed on the compute nodes to only about 500 RPMs. I can't remember all the details, but I remember omitting the following groups of packages:
> 
> 1. Anything related to desktop environments, graphics, etc.
> 2. -devel packages
> 3. Any RPMS for wireless or bluetooth support.
> 4. Any kind of service that wasn't strictly needed by the compute nodes.
> 
> In this case, the user's desktops mounted the same home and project directories and shared application directory (/usr/local), so the user's had all the the GUI, post-processing, and devel packages they needed  right on their desktop, so the cluster was used purely for running non-interactive batch jobs. In fact, there was no way for a user to even get an interactive session on the cluster.  IAS  was a small environment where I had complete control over the desktops and the cluster, so I was able to this. I would do it all again just like that, given as similar environment.
> 
> I'm currently managing a cluster with PU, and PU only puts the -devel packages, etc. on the the login nodes so users can compile there apps there.
> 
> So yes, this is still being done.
> 
> There are definitely benefits to providing specialized packages lists like this:
> 
> 1. On the IAS cluster, a kickstart installation, including configuration with the post-install script, was very quick - I think it was 5 minutes at most.
> 2. You generally want as few services running on your compute nodes as possible. The easiest way to keep services from running on your cluster nodes is to not install those services in the first place.
> 3. Less software installed = smaller attack surface for security exploits.
> 
> Does this mean you are moving away from Warewulf, or are you creating different Warewulf images for login vs. compute nodes?
> 
> 
> Prentice
> 
> On 10/23/2018 12:15 PM, Ryan Novosielski wrote:
>> Hi there,
>> 
>> I realize this may not apply to all cluster setups, but I’m curious what other sites do with regard to software (specifically distribution packages, not a shared software tree that might be remote mounted) for their login nodes vs. their compute nodes. From what I knew/conventional wisdom, sites generally place pared down node images on compute nodes, only containing the runtime. I’m curious to see if that’s still true, or if there are people doing something else entirely, etc.
>> 
>> Thanks.
>> 
>> --
>> ____
>> || \\UTGERS,  	 |---------------------------*O*---------------------------
>> ||_// the State	 |         Ryan Novosielski - novosirj at rutgers.edu
>> || \\ University | Sr. Technologist - 973/972.0922 (2x0922) ~*~ RBHS Campus
>> ||  \\    of NJ	 | Office of Advanced Research Computing - MSB C630, Newark
>>      `'
>> 
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