TO DO STILL.txt

Please note that you need to replace /path/to/desktop-${desktop_type,,}.sif and /path/to/hello-world-mpi.sif with the actual paths to your Singularity container images on the Parallel Works cluster.

This script is designed to be executed by the Parallel Works workflow engine, which will substitute the $num_nodes, $partition, and $time_limit variables with the values provided by the user through the workflow interface defined in interactive-desktop-workflow.xml



Here is the completed source code for the `hello-world-mpi-container.def` file:

```
Bootstrap: docker
From: ubuntu:20.04

%post
    # Install required packages
    apt-get update
    apt-get install -y wget build-essential libopenmpi-dev

    # Download and install Miniconda
    wget https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86_64.sh
    bash Miniconda3-latest-Linux-x86_64.sh -b -p /opt/conda
    rm Miniconda3-latest-Linux-x86_64.sh

    # Set up Conda environment
    /opt/conda/bin/conda init
    /opt/conda/bin/conda create -y -n mpi_env
    /opt/conda/bin/conda activate mpi_env
    /opt/conda/bin/conda install -y -c conda-forge openmpi

    # Compile Hello World MPI program
    mkdir /opt/hello-world
    echo '#include <mpi.h>
#include <stdio.h>

int main(int argc, char** argv) {
    int world_size, world_rank, name_len;
    char hostname[MPI_MAX_PROCESSOR_NAME];

    MPI_Init(&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &world_size);
    MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);
    MPI_Get_processor_name(hostname, &name_len);

    printf("Hello world from processor %s, rank %d out of %d processors\n", hostname, world_rank, world_size);

    MPI_Finalize();
    return 0;
}' > /opt/hello-world/hello.c

    mpicc /opt/hello-world/hello.c -o /opt/hello-world/hello

%environment
    export PATH=/opt/conda/bin:$PATH
    source /opt/conda/etc/profile.d/conda.sh
    conda activate mpi_env

%runscript
    /opt/conda/bin/mpirun /opt/hello-world/hello
```

Notes:
- This Singularity definition file starts from an Ubuntu 20.04 base image.
- It installs the required packages (wget, build-essential, libopenmpi-dev) for building and running the MPI hello world program.
- It downloads and installs Miniconda, creates a Conda environment named `mpi_env`, and installs OpenMPI in that environment.
- It creates a directory `/opt/hello-world` and compiles a simple "Hello World" MPI program in C.
- The `%environment` section sets up the environment to activate the `mpi_env` Conda environment by default.
- The `%runscript` section defines the default run behavior to execute the compiled `hello` program with `mpirun`.

This Singularity definition file can be used to build the container image for the MPI hello world job. The resulting container image will be named `hello-world-mpi.sif` (or any other name you choose) and can be used with the `interactive-desktop-workflow.sh` script and the `hello-world-mpi.sbatch` script.

To build the container image, you can use the following command:

```
sudo singularity build hello-world-mpi.sif hello-world-mpi-container.def
```

This will create the `hello-world-mpi.sif` container image based on the instructions in the `hello-world-mpi-container.def` file.

After building the container image, you need to update the paths in the `interactive-desktop-workflow.sh` and `hello-world-mpi.sbatch` scripts to point to the correct location of the `hello-world-mpi.sif` image.