====== Sample Container Definitions ======

This page provides a number of sample [[advanced:apptainer|Apptainer]] definition files which you may wish to make use of when developing your own container solutions for Comet if an option is not already in our [[:advanced:software|software pages]] or directly named in our [[:advanced:software_list|software and existing containers list]].

Please ensure that you read the [[advanced:apptainer|Apptainer]] guide for Comet //first//.

Remember to set the ''APPTAINER_TMPDIR'' variable before creating a container:

<code>
$ export APPTAINER_TMPDIR=/scratch/
</code>

This ensures that temporary files are created under ''/scratch'' on the local drive, so it should be (a) faster, and (b) not run out of space by using the system ''/tmp'' directory.

==== Generic Container Helper ====

You can customise this helper script (which we will call ''helper.sh'' for simplicity) for //any// container image you create - just adjust the path and filename to your image.

<code lang=bash title=helper.sh>
#!/bin/bash
module load apptainer
IMAGE_NAME=/path/to/your/container.sif

container.run() {
    # Run a command inside the container...
    # automatically bind the /scratch and /nobackup dirs
    # pass through any additional parameters given on the command line
    apptainer exec --nv --bind /scratch:/scratch --bind /nobackup:/nobackup ${IMAGE_NAME} $@
}
</code>

We always recommend using the container helper to run applications inside the container, as you don't then have to remember all of the various ''apptainer exec'' options each time. To run //my_app// from inside your container, then just:

<code lang=bash>
$ source helper.sh
$ container.run my_app
</code>

----
===== Ubuntu LTS =====

This uses the officially published Ubuntu docker image. This uses Ubuntu //Noble// - or 24 LTS. Multiple versions of Ubuntu are available; see the listed tags: https://hub.docker.com/_/ubuntu

<code title=ubuntu.def>
Bootstrap: docker
From: ubuntu:noble

%post
	# Prevent interactive prompts
	export DEBIAN_FRONTEND=noninteractive

	# Update & install only necessary packages
	apt-get update
    
	# Base stuff everything will need
	apt-get install -y aptitude wget zip git less vim
	
	# Remove any downloaded package files - so they don't remain in the built image	
	apt-get clean
%environment

%runscript
</code>

Build as:

<code lang=bash>
$ module load apptainer
$ apptainer build ubuntu.sif ubuntu.def
</code>

The base image size as defined above is **~120MB** as the default image is //very// basic. 
----

===== Ubuntu LTS with Development Tools =====

This uses the officially published Ubuntu docker image and adds C, C++, Fortran and Python development tools. Multiple versions of Ubuntu are available; see the listed tags: https://hub.docker.com/_/ubuntu

This example also ensures that compilers are using the most updated version and are configured to generate code tuned for the AMD Epyc CPU architecture of Comet. 

If you are compiling software from C or C++ source code, then **we would always recommend using GCC 14 using the supplied CFLAGS parameters** to generate the most optimal binaries for Comet.

<code title=ubuntu_dev.def>
Bootstrap: docker
From: ubuntu:noble

%post
	# Prevent interactive prompts
	export DEBIAN_FRONTEND=noninteractive

	# Update & install only necessary packages
	apt-get update
    
	# Base stuff everything will need
	apt-get install -y aptitude wget zip git less vim apt-utils autoconf automake build-essential cmake gcc-14 g++-14 gfortran-14 git less unzip vim wget python3 python3-pip

	# For anything we compile during the image build
	export CFLAGS="-O3 -march=znver5 -pipe"
	export CXXFLAGS="-O3 -march=znver5 -pipe"

	update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-14 20
	update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-14 20
	update-alternatives --install /usr/bin/gfortran gfortran /usr/bin/gfortran-14 20
		
	# Remove any downloaded package files and any Python cached packages - so they don't remain in the built image	
	apt-get clean
	pip3 cache purge

%environment
	# For anything we build after the image is created using the installed compilers
	export CFLAGS="-O3 -march=znver5 -pipe"
	export CXXFLAGS="-O3 -march=znver5 -pipe"

%runscript
</code>

Build as:

<code lang=bash>
$ module load apptainer
$ apptainer build ubuntu_dev.sif ubuntu_dev.def
</code>

The final image size as defined above is **~350MB** with the additional software included over the base image. 
----
===== Nvidia CUDA/CUDNN =====

This uses the official Nvidia docker image (itself based on top of Ubuntu LTS). There are multiple versions available, see the tags list at: https://hub.docker.com/r/nvidia/cuda

<code title=nvidia_cuda.def>
Bootstrap: docker
From: nvidia/cuda:12.8.1-cudnn-devel-ubuntu24.04

%post
   export DEBIAN_FRONTEND=noninteractive
   apt-get update
   apt-get install -y aptitude wget zip git less vim
   apt-get clean		
%environment

%runscript
</code>

The base Nvidia image already includes most of the development tools (Python, GCC) and libraries, hence the lack of additional software in the ''apt-get'' line.

Build as:

<code lang=bash>
$ module load apptainer
$ apptainer build nvidia_cuda.sif nvidia_cuda.def
</code>

Final image size is approximately **5.9GB**.

----

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