Building a Container
caution: the next section is optional
This section is going to describe how the main container we prepared for this tutorial was developed. We highly encourage you to read and understand the development of this container because it will help you adapt this tutorial to fit the needs of your research project. However, if you are interested in completing this tutorial to set up Jupyter Notebooks on Hyak, complete this following step, and skip to the section titled Flexible Connections for your OS. This saves you an hour (you're welcome).
First navigate to your working directory, which you selected in the previous section titled, Getting Started. and issue the following command:
The briefest introduction to containers#
A container is some executable code packaged up with its dependencies, and the amount of dependencies can range from a handful of libraries to an entire operating system.
We're going to make a container with a whole operating system in it:
all the little pieces of software that we might want to use
interactively—cd, cat, vim, squeue, etc.—and we're going to use it like it's a virtual machine.
The difference between a virtual machine and a whole-OS container is fairly small: the VM will emulate hardware, the container won't. That works for us, since we want to use the klone's hardware anyway.
Jargon essentialists won't like it, but for the purposes of this guide you can just imagine that we're building a personal Linux machine.
Go to working directory before building your container#
Start by navigating to the working directory you selected for this tutorial. For example, we selected a directory under /gscratch/scrubbed named with our UWNetID. NOTE: this following step will be different for every user. Please see the Getting Started. Section for more information about how to set this up for you. Use something similar to the following command to navigate to your working directory:
Our general-purpose container definition file#
Apptainer containers are represented by a single file (normally suffixed .sif), and they're created from definition files (kind of like a recipe for your container).
We've already created the definition file we're going to use for this at /mmfs1/sw/hyak101/python/hyak-container.def. Next, make a copy of it in your working directory (we will use a shorthand where . will copy the file to the directory where the command is issued, in this case your working directory):
After copying the .def file to your working directory, you should see the file is there with the list command or ls, and you can print the .def file to the screen and take a look at its contents with the cat command
Now, let's take a look at the different sections of the definition, starting from the top.
Apptainer containers, can be built from Docker containers, noted by Bootstrap: docker.
Since we plan on using the node's hardware, we're going to try and keep our container OS as similar to our
host OS as possible. We're using Rocky Linux 8 and our current CUDA version is 11.8, so this container from
NVIDIA GPU Cloud will line up neatly with our nodes.
%setup and %files section#
Next we'll look at the %setup and %files sections which are for preparing for the build.
Be careful with the %setup step: these actions are performed on the host operating system, not on the container's.
For example, with the %setup section above, we're appending the user ID and group ID of the node's Slurm user into the container, using the ${APPTAINER_ROOTFS} variable.
In the %files section, we're copying over a few files from the host operating system (klone) to the container's:
- Hyak's Slurm package repository, so we can install & run Slurm commands,
- The
hyak-user-toolsvirtual environment in/opt, so we can run commands likehyakalloc, - And the user tools executables themselves, which are located on the nodes under
/usr/local/bin.
%post section for post-build instructions#
Once the container has been built, we have a fully functioning Rocky Linux 8 operating system within the container.
Rocky is downstream of FedoraLinux , and it uses the dnf package manager. We're installing a handful of things with dnf:
- The package group
core: these are the 'minimum' packages for an interactive operating system. - The package group
standard: this contains, as the name suggests, the "standard" packages for a Rocky Linux installation. This installs software liketar,vim,tree, etc. - The
slurmpackage: this will install Slurm from the Hyak package repository we copied in during the%filessection. - The
python39package: this is a dependency for Hyak user tools, e.g.hyakstorageorhyakalloc.
PRO TIP: Customization Opportunity
It is possible to change the version of Python that is available in this container by using a text editor like nano or vim to edit hyak-container.def and change the Python version (i.e., change python39 to something else). You might need to research the correct syntax for installing a different version of Python. We'll talk more about customization later in this section.
After we have these basic packages installed, we made a couple directories (with mkdir) and symbolic links (with ln -s). Here is why:
/scris the path to the node's local SSD storage. This is a default bind-mount for our Apptainer configuration./mmfs1is the path to our shared storage device, and this is also a default bind-mount. Like with/scr, we just need to provide an empty directory for it to bind to.- The symbolic links,
/sw,/data, and/gscratch, are—like on the nodes—shortcuts to commonly-used directories on/mmfs1.
%runscript: What the container does#
This is the last piece, and it involves just a touch of shell programming. We're using a case statement, and we're looking for patterns in the arguments given to the container. Thankfully, our "patterns" are very simplistic:
"": a blank string, i.e. what happens if you simply doapptainer run hyak-container.sif. The default behavior we want is to launch an interactive shell.*): everything else. Any input we receive, we will attempt to run as a command. We are emulating the behavior ofapptainer exechere, since we're going to try and keep our interactions withapptaineras uniform as possible.
Building containers on Hyak#
Container building should be performed in a job—interactive or batch—on a compute node.
Important: Klone-Login Acceptable Uses
Before we continue, here's a quick overview of what kind of activities are allowed on the login nodes:
- Downloading to or uploading from the cluster.
- File management like moving, copying, or renaming files and directories.
- Light text editing with
vim,nano, or another text editor. - Interacting with the Slurm scheduler, i.e. to submit jobs. CPU & memory are closely monitored on the login nodes as they are a finite, shared resource. If our automation detects unusually high activity, your account will be throttled & you'll receive an email warning.
In other words, resource-intensive actions like building a container should be done on a node.
We will use a sbatch script to build our container, but will submit the build job to a compute node and it will run in the background until it is complete. First, copy the script to your working directory from /mmfs1/sw/hyak101/python:
Let's take a look at the script:
The #SBATCH lines tell Slurm what we want: a single CPU and 16GB of RAM, in the ckpt partition, with a time limit of 60 minutes.
Using sbatch is the best way to submit non-interactive jobs on the cluster, and there are quite a few options.
Check out the official Slurm documentation for more details.
This job is only a few commands. First:
mkdir /tmp/$USER: We're going to build the container in /tmp, so we'll make a subdirectory for our work there.$USERis a default environment variable that expands to your username.
Then, the build:
apptainer build: the Apptainer executable and subcommand./tmp/$USER/hyak-container.sif: a temporary place to build the container image. Important: building the image in/tmp/$USERavoids permissions issues with GPFS, so don't skip this.hyak-container.def: the path to the container definition we made in our working directory.
Finally, saving our container:
cp /tmp/$USER/hyak-container.sif .: Copy the container image we made in/tmpto our working directory (.; it is also an option to edit this to show the absolute path to your working directory).
As is, the container is ~4GB and so, you will occupy ~4GB of storage in your working directory. This is why we have stressed several times to thoughtfully select your working directory for this tutorial. Review Getting Started. for reasons why this is important. Regardless of where you put the final container image, make sure the destination exists & has sufficient space before you submit your job.
pro tip: stroage monitoring
You can use the hyakstorage command to see your file & space quotas, in your home directory and the gscratch directories you can access.
Here's our documentation for that command.
Submitting the job#
Submit the job to build the container with sbatch.
Use the watch command with the squeue command to monitor the job in real time. watch -n30 will issue the squeue every 30 seconds. Use Ctrl + C to exit the watch command.
Additionally, you can watch the output messages as the container is built by monitoring the output file that the sbatch script requested, which will appear in your working directory beginning with container-build_XXXXXX.out where the X's are the jobID assigned to the job by Slurm. For example (Use Ctrl + C to exit the tail command):
Remember that if for some reason this doesn't work, the container image has already been created and you can find it /mmfs1/sw/hyak101/python/hyak-container.sif, and use it with a symbolic link in your working directory (command show at the top of this section. Go back to the top).
Customizing the hyak-container.sif for your research project#
You now have a generalized container for hyak that you can edit or add your own software to. There are two options for customizing your container:
- Edit the
%postsection ofhyak-container.defto install more packages. - Start a new
.deffile that builds a new container based onhyak-container.sifrather than rebuilding the container everytime you want to make a change.
PRO TIP
Option 2 above is truely PRO MODE. You can pull ANY container from the internet and make a new .def file based on it. This means you can customize ANY container image with your choice of software. For example, the below can be applied to NVIDIA containers, Python containers, Linux foundation containers, YOU NAME IT YOU BUILD IT.
Option 1 container customization: edit hyak-container.def#
Make a copy of hyak-container.def for your custom build.
Open hyak-container-custom.def with a text editor and add additional installation instructions to the %post section. For example, I want to install matplotlib with pip, so I will add pip install matplotlib to hyak-container-custom.def as shown below:
Also make a copy of container-build.job to submit this job using the new definition file.
Edit the sbatch script container-build-custom.job as follows:
- Replacing
hyak-container.defwithhyak-container-custom.def - Replace
hyak-container.sifwithhyak-container-custom.sifto avoid overwriting the original version of the container - Change the
--job-nameline tocontainer-build-custom
Submit the build job.
When that is complete, the bottom of container-build-custom_XXXXXX.out will show that matplotlib and its dependencies were successfully installed with pip. local-custom.sif is the name of your customized version of hyak-container-custom.sif with matplotlib.
Option 2 container customization: build on a local container with a new .def#
We can build custom containers on top of existing containers, which comes with a few benefits:
- Saves time during the build because the existing container doesn't have to be rebuilt to install new software.
- Avoids errors that could occur from edition the original
.deffile for the container.
Create an empty text document called local-custom.def with the touch command:
Use a text editor to open local-custom.def and add the following lines:
Also make a copy of container-build.job to submit this job using the new definition file.
Edit the sbatch script local-custom-build.job as follows:
- Replacing
hyak-container.defwithlocal-custom.def - Replace
hyak-container.sifwithlocal-custom.sifto avoid overwriting the original version of the container - Change the
--job-nameline tolocal-custom-build
Submit the build job.
When that is complete, the bottom of local-custom-build_XXXXXX.out will show that matplotlib and its dependencies were successfully installed with pip. local-custom.sif is the name of your customized version of hyak-container.sif with matplotlib.