Add capability for tasks to fall back to default modulefile (#204)

This PR adds the capability for tasks to fall back to default modulefile if task-specific modulefile does not exist. In doing so, it gets rid of the old, hacky way I got post to build on Cheyenne, and replaces it with a build and run process that utilizes a new cheyenne.default modulefile.

This should allow us to condense down builds on new machines to use fewer task-specific modulefiles.

modulefiles/cheyenne.default

@@ -0,0 +1,16 @@
+#%Module#####################################################
+## Default module file for NCAR/UCAR Cheyenne, intel, mpt
+#############################################################
+module purge
+module load ncarenv/1.3
+module load intel/19.0.2
+module load ncarcompilers/0.5.0
+module load mpt/2.19
+module load netcdf/4.6.3
+# No hdf5 loaded since netcdf and hdf5 reside together on cheyenne
+
+# Add directory to path that contains binaries needed for the regional workflow on Cheyenne
+prepend-path PATH /glade/p/ral/jntp/UFS_CAM/bin
+
+# Set NCEPLIBS_DIR, used by post
+setenv NCEPLIBS_DIR /glade/p/ral/jntp/UPP/pre-compiled_libraries/NCEPlibs_intel_18.0.5

ush/load_modules_run_task.sh

@@ -200,7 +200,9 @@ jjob_fp="$2"
 machine=${MACHINE,,}
 modules_dir="$HOMErrfs/modulefiles/tasks/$machine"
 modulefile_name="${task_name}"
-
+default_modules_dir="$HOMErrfs/modulefiles"
+default_modulefile_name="${machine}.default"
+use_default_modulefile=0
 # Dom says that a correct modules.fv3 file is generated by the forecast
 # model build regardless of whether building with or without CCPP.  
 # Thus, we can have a symlink named "run_fcst" that points to that file
@@ -229,26 +231,31 @@ modulefile_name="${task_name}"
 #
 #-----------------------------------------------------------------------
 #
-
-if [ "${task_name}" = "${RUN_POST_TN}" ] && [ "${machine}" = "cheyenne" ]; then
+if [ "${machine}" = "unknown" ]; then
+    # This if statement allows for graceful exit in the case where module files are not needed.
+    # This is not currently used but reserved for future development. 
     print_info_msg "Modulefile not required for task \"${task_name}\" on machine \"${machine}\""
-
 else
 
    modulefile_path=$( readlink -f "${modules_dir}/${modulefile_name}" )
 
    if [ ! -f "${modulefile_path}" ]; then
+     if [ -f "${default_modules_dir}/${default_modulefile_name}" ]; then
+        #If the task-specific modulefile does not exist but a default one does, use it!
+        print_info_msg "$VERBOSE" "
+        Task-specific modulefile (${modulefile_path}) does not exist
+        Will attempt to use default modulefile (${default_modules_dir}/${default_modulefile_name}) ..."
+        modules_dir=$default_modules_dir
+        use_default_modulefile=1
 
-     if [ "${task_name}" = "${MAKE_OROG_TN}" ] || \
+     elif [ "${task_name}" = "${MAKE_OROG_TN}" ] || \
         [ "${task_name}" = "${MAKE_SFC_CLIMO_TN}" ] || \
         [ "${task_name}" = "${MAKE_ICS_TN}" ] || \
         [ "${task_name}" = "${MAKE_LBCS_TN}" ] || \
         [ "${task_name}" = "${RUN_FCST_TN}" ]; then
 
        print_err_msg_exit "\
-The target (modulefile_path) of the symlink (modulefile_name) in the 
-task modules directory (modules_dir) that points to module file for this
-task (task_name) does not exist:
+The target modulefile does not exist for this task name:
   task_name = \"${task_name}\"
   modulefile_name = \"${modulefile_name}\"
   modules_dir = \"${modules_dir}\"
@@ -277,43 +284,50 @@ does not exist:
    #
    print_info_msg "$VERBOSE" "
 Loading modules for task \"${task_name}\" ..."
- 
+
    module purge
 
    module use "${modules_dir}" || print_err_msg_exit "\
 Call to \"module use\" command failed."
 
-   #
-   # Some of the task module files that are symlinks to module files in the
-   # external repositories are in fact shell scripts (they shouldn't be; 
-   # such cases should be fixed in the external repositories).  For such
-   # files, we source the "module" file.  For true module files, we use the
-   # "module load" command.
-   #
-   case "${task_name}" in
-   #
-   "${MAKE_ICS_TN}" | "${MAKE_LBCS_TN}" | "${MAKE_SFC_CLIMO_TN}")
-     . ${modulefile_path} || print_err_msg_exit "\                                                                                           
+   if [ $use_default_modulefile -eq 0 ]; then
+     #
+     # Some of the task module files that are symlinks to module files in the
+     # external repositories are in fact shell scripts (they shouldn't be; 
+     # such cases should be fixed in the external repositories).  For such
+     # files, we source the "module" file.  For true module files, we use the
+     # "module load" command.
+     #
+     case "${task_name}" in
+     #
+     "${MAKE_ICS_TN}" | "${MAKE_LBCS_TN}" | "${MAKE_SFC_CLIMO_TN}")
+       . ${modulefile_path} || print_err_msg_exit "\                                                                                           
 Sourcing of \"module\" file (modulefile_path; really a shell script) for
 the specified task (task_name) failed:
   task_name = \"${task_name}\"
   modulefile_path = \"${modulefile_path}\""
-  ;;
-   #
-   *)
-     module load ${modulefile_name} || print_err_msg_exit "\
+       ;;
+     #
+     *)
+       module load ${modulefile_name} || print_err_msg_exit "\
 Loading of module file (modulefile_name; in directory specified by mod-
 ules_dir) for the specified task (task_name) failed:
   task_name = \"${task_name}\"
   modulefile_name = \"${modulefile_name}\"
   modules_dir = \"${modules_dir}\""
-     ;;
-   #
-   esac
-
-fi #End if statement for tasks that load no modules
+       ;;
+     #
+     esac
+   else # using default modulefile
+     module load ${default_modulefile_name} || print_err_msg_exit "\
+Loading of default module file failed:
+  task_name = \"${task_name}\"
+  default_modulefile_name = \"${default_modulefile_name}\"
+  default_modules_dir = \"${default_modules_dir}\""
+   fi
 
 module list
+fi #End if statement for tasks that load no modules
 #
 #-----------------------------------------------------------------------
 #