try single command openmpi install

conf/real-from-ideal/proj.yaml

 spack:
-  url: git@gitlab.physik.uni-muenchen.de:LDAP_rbg/spack.git
-  branch: lmu/ubuntu20.04-icon
-  compiler: gcc@11.3.0
+  #url: git@gitlab.physik.uni-muenchen.de:LDAP_rbg/spack.git
+  #branch: lmu/ubuntu20.04-icon
+  #compiler: gcc@11.3.0
+  url: https://github.com/spack/spack.git
+  branch: develop
+  compiler: gcc@12.2.0
+  root: %HPCROOTDIR%/spack # path to a spack install, will be cloned with git if not present
+  user_cache_path: %HPCROOTDIR%/spack_user_cache_path # spack puts data here when bootstrapping, leave empty to use home folder
+  disable_local_config: true # if false, spack install into home folder
 
 icon:
-  version: 2.6.5-nwp0
+  spack_cmd: openmpi%${SPACK_COMPILER}+pmi+legacylaunchers schedulers=slurm fabrics=ucx ucx%${SPACK_COMPILER}+dc+dm+ib_hw_tm+mlx5_dv+rc+rdmacm+thread_multiple+ud+verbs ^gettext@0.20.2%${SPACK_COMPILER}
+  version: master
 
 python_environment:
   # Name of the virtual environment in the remote platform experiment folder

platforms/common/spack_utils.sh

 function spack_env() {
-export SPACK_SETUP_ENV=spack/share/spack/setup-env.sh
-export SPACK_VENV=spack_icon_env
-export SPACK_USER_CACHE_PATH=${WORKDIR}/SPACK_USER_CACHE_PATH
-export SPACK_DISABLE_LOCAL_CONFIG=true
+export SPACK_URL=%spack.url%
+export SPACK_BRANCH=%spack.branch%
+export SPACK_ROOT=%spack.root%
+export SPACK_COMPILER=%spack.compiler%
+export SPACK_DISABLE_LOCAL_CONFIG=%spack.disable_local_config%
+
+if [ ! -z "%spack.user_cache_path%" ]; then
+  echo "setting SPACK_USER_CACHE_PATH=%spack.user_cache_path%"
+  export SPACK_USER_CACHE_PATH=%spack.user_cache_path%
+fi
+
+export SPACK_SETUP_ENV=$SPACK_ROOT/share/spack/setup-env.sh
 }
 
 function install_spack() {
 spack_env
 
-#TODO: Would be good to enable the re-utilization of existing spack packages (via packages.yaml or upstreams.yaml)
-if [ ! -f ${SPACK_SETUP_ENV} ]; then
-  git clone ${SPACK_URL} -b ${SPACK_BRANCH}
+if [ ! -f ${SPACK_ROOT} ]; then
+  git clone ${SPACK_URL} -b ${SPACK_BRANCH} ${SPACK_ROOT}
 fi
 
 . ${SPACK_SETUP_ENV}
-spack env create $SPACK_VENV
-spack env activate -p $SPACK_VENV
-spack compiler find
+
+if [[ $(spack compiler info ${SPACK_COMPILER}) ]]; then
+  echo "Found Compiler $(spack compiler info ${SPACK_COMPILER})"
+else
+  echo "could not find compiler, will now try to install it... this may take a while"
+  spack install ${SPACK_COMPILER}
+  spack compiler add $(spack location --install-dir $SPACK_COMPILER)
+fi
 }
 
 function load_spack() {
 spack_env
-if [ ! -f ${SPACK_SETUP_ENV} ]; then install_spack; fi
+if [ ! -f ${SPACK_ROOT} ]; then install_spack; fi
 . ${SPACK_SETUP_ENV}
-spack env activate -p $SPACK_VENV
 }
+

templates/common/build_icon.sh

 # Get some variables provided by autosubmit.
 # TODO: What do we do to ensure that these variables are defined in the proj file?
 WORKDIR=%HPCROOTDIR%
-ICON_VERSION=%ICON_VERSION%
-SPACK_URL=%spack.url%
-SPACK_BRANCH=%spack.branch%
-SPACK_COMPILER=%spack.compiler%
+ICON_VERSION=%icon.version%
 
 # If the workdir directory does not exist create it
 if [ ! -d ${WORKDIR} ]; then
@@ -17,27 +14,12 @@ cd ${WORKDIR}
 . ${WORKDIR}/proj/platforms/common/spack_utils.sh
 load_spack
 
-if [ $(
-  spack find icon-nwp@${ICON_VERSION} &>/dev/null
-  echo $?
-) -ne 0 ]; then
-  echo "Installing icon-nwp@${ICON_VERSION}."
-
-  if [[ $(spack compiler info ${SPACK_COMPILER}) ]]; then
-    echo "Found Compiler"
-  else
-    echo "could not find compiler, try to install it... this may take a while"
-    spack add ${SPACK_COMPILER}
-    spack install
-    spack compiler add $(spack location --install-dir $SPACK_COMPILER)
-  fi
-
-  spack add ucx%${SPACK_COMPILER}+dc+dm+ib_hw_tm+mlx5_dv+rc+rdmacm+thread_multiple+ud+verbs~cuda
-  spack add openmpi%${SPACK_COMPILER}+pmi+legacylaunchers~cuda schedulers=slurm fabrics=ucx
-  spack add icon-nwp@${ICON_VERSION}%${SPACK_COMPILER} ^openmpi%${SPACK_COMPILER}
-  spack install
-else
-  echo "icon-nwp@${ICON_VERSION} already installed!"
+SPACK_BUILD_ICON=%icon.spack_cmd%
+if [ ! -z $SPACK_BUILD_ICON ]; then
+  echo "Installing ICON with spack!"
+  echo "cmd=$SPACK_BUILD_ICON"
+  spack install $SPACK_BUILD_ICON
+  spack load $SPACK_BUILD_ICON
 fi
 
 # Need to get ECCODES DWD definitions: