Chapter 24. Using Podman in HPC environment

Procedure

1. Install Open MPI:

   # dnf install openmpi

2. To activate the environment modules, type:

   $ . /etc/profile.d/modules.sh

3. Load the mpi/openmpi-x86_64 module:

   $ module load mpi/openmpi-x86_64

   Optionally, to automatically load mpi/openmpi-x86_64 module, add this line to the .bashrc file:

   $ echo "module load mpi/openmpi-x86_64" >> .bashrc

4. To combine mpirun and podman, create a container with the following definition:

   $ cat Containerfile
   FROM registry.access.redhat.com/ubi9/ubi
   
   RUN dnf -y install openmpi-devel wget && \
       dnf clean all
   
   RUN wget https://raw.githubusercontent.com/open-mpi/ompi/master/test/simple/ring.c && \
       /usr/lib64/openmpi/bin/mpicc ring.c -o /home/ring && \
       rm -f ring.c

5. Build the container:

   $ podman build --tag=mpi-ring .

6. Start the container. On a system with 4 CPUs this command starts 4 containers:

   $ mpirun \
      --mca orte_tmpdir_base /tmp/podman-mpirun \
      podman run --env-host \
       -v /tmp/podman-mpirun:/tmp/podman-mpirun \
       --userns=keep-id \
       --net=host --pid=host --ipc=host \
       mpi-ring /home/ring
   Rank 2 has cleared MPI_Init
   Rank 2 has completed ring
   Rank 2 has completed MPI_Barrier
   Rank 3 has cleared MPI_Init
   Rank 3 has completed ring
   Rank 3 has completed MPI_Barrier
   Rank 1 has cleared MPI_Init
   Rank 1 has completed ring
   Rank 1 has completed MPI_Barrier
   Rank 0 has cleared MPI_Init
   Rank 0 has completed ring
   Rank 0 has completed MPI_Barrier

   As a result, mpirun starts up 4 Podman containers and each container is running one instance of the ring binary. All 4 processes are communicating over MPI with each other.