SW:Singularity:Examples

Examples

Prebuilt images

HPRC provides (will provide) images using the steps below on ada/terra in /scratch/datasets/Singularity/images if you want to use a prebuilt image. At present(/soon) they include.

• Fedora28-HPRCLAB-40GB.img - a Fedora 28 image based on HPRC lab workstations with room to work
  • Note: this will not work on ada. Various versions of Fedora from 23 to 28 were tried and all failed on ada due to the older kernel in CentOS6.
• CentOS6-XXGB.img - a CentOS 6 image populated with packages based on HPRCLAB workstations (where possible) with room to work
• CentOS7-XXGB.img - a CentOS 7 image populated with packages based on HPRClab workstations (where possible) with room to work

Building your own images

In order to build Singularity images yourself you will need a system with a modern Linux distribution (e.g. Ubuntu/Fedora/CentOS/etc) that you have sudo/root on. HPRC users cannot do this on HPRC systems given the lack of sudo.

Fedora 28

Note that the final image requires a kernel newer than the one provided by CentOS6. This means it can not be used on ada (only on terra). Fedora version 23-28 were attempted but they eventually failed on ada. So if you plan to use a Fedora-based Singularity image you will need to use terra.

Objective

The objective in this case is a Fedora28-HPRCLAB.img file that has space for users to manuever around and install stuff:

1. that we can provide to users, a Singularity .img file (self-contained), for them to update as needed (as root on their own workstations) that also runs on our clusters.
2. is already populated with HPRCLAB RPMs
3. has plenty of disk space for the user to add files (as non-root) while on the cluster
4. Example below was created on HPRCLAB workstations.

Building an image on your Fedora 28 workstation

Gather information for package installation

• Before you start, create a list of RPMs (rpmlist) you want to install. Also make a file (repoURLs) listing the URLs for the repo install RPMs. Then place both in /root/forFedora28 on the host/build system. These will be used later while in the sandbox shell. For Fedora 28 we will use the RPMFusion repos and the package list from current HPRC lab workstations.

# cat /root/forFedora28/repoURLs 
https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-28.noarch.rpm
https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-28.noarch.rpm

# head -5 /root/forFedora28/rpmlist 
a2ps
a52dec
aajohan-comfortaa-fonts
aalib-libs
aalto-xml

Create/start a shell in a "sandbox"

• create a Singularity sandbox from one of Fedora's Docker images

sudo singularity build --sandbox Fedora28-HPRCLAB.sandbox docker://fedora:28

• start a shell in the sandbox for the next steps

sudo singularity shell --writable Fedora28-HPRCLAB.sandbox/

• go ahead and create bind points for HPRC cluster filesystems

mkdir /scratch /work

Populate the sandbox with packages =

• Install the RPMFUSION repos (needed for below)

dnf -y install `cat /root/forFedora28/repoURLs`

• populate the sandbox with all the RPMs (we do them in groups at first in case there a problems and then do all to see what those problems were. (get a snack, take a walk... it can take awhile)

for x in {a..z} ; do
  dnf -y --skip-broken install `grep ^$x /root/forFedora28/rpmlist`
done
dnf -y --skip-broken install `cat /root/forFedora28/rpmlist`

There will still be packages that have "No match" due to not including the repos for them.

• do NOT add users with useradd... if you do, be sure not to add your NetID or things will break.
• create bind directories for interfacing with HPRC clusters (Note: have to do this now while still in sudo shell)

mkdir /scratch /work

• once you are happy with the sandbox log out from it (logout/exit/Ctrl-D).

Create an image (.img)

• to make an .img file that provides space for the user to work in (e.g. download/install software). These steps do not require sudo since they don't really create anything in the image.
• first, determine the installed size of the sandbox

* Given that, add some space for the user to work in.  In this case, we will use 40GB (approx. sandbox size + 15G).
<pre>
singularity image.create Fedora28-HPRCLAB-40GB.img # create .img file
singularity image.expand -s 40960 Fedora28-HPRCLAB-40GB.img # expand to 40GB, get another snack while you wait

Note: works because there is no real filesystem yet [some ext3/4 filesystems seem to have a problem with expand]

• Now import the sandbox into the 40GB image (more snacks/time)

sudo tar -cvf - -C Fedora28-HPRCLAB.sandbox/ . | sudo singularity image.import Fedora28-HPRCLAB-40GB.img

(see the last/tar example in 'singularity image.import --help')

Test on host build system

• open a non-sudo shell and see if you can do "things"

singularity shell Fedora28-HPRCLAB-40GB.img

CentOS 6

[JACK: delete the duplication once absorbed above and point out slight differences for CentOS]

• Before you start, create a list of RPMs (rpmlist) you want to install. Also make a file (repoURLs) listing the URLs for the repo install RPMs. Then place both in /root/forCentOS6 on the host/build system. These will be used later while in the sandbox shell.

Create a sandbox

• create/start sandbox

sudo singularity build --sandbox CentOS6.sandbox docker://centos:6
sudo singularity shell --writable CentOS6.sandbox/

• create bind points for HPRC cluster filesystems

mkdir /scratch /work

• install repos for other RPMS (see the note you left above in /root with URL)

yum -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm

• populate sandbox with RPMs

for x in `cat /root/rpmlist` ; do yum -y install $x ; done
mkdir /scratch /work
exit

• exit sandbox shell

exit