siac buildnml and python 3.7.6

[rljacob]

While doing some hand testing on anvil, I loaded python 3.7.6 with: module load anaconda3/2020.02

then tried to create a simple F-case: --compset FC5AV1C-L --res ne4_ne4 and got an error curing case.setup:

   Running /gpfs/fs1/home/jacob/E3SM2/components/stub_comps/siac/cime_config/buildnml 
/usr/bin/env: python3: No such file or directory
ERROR: /gpfs/fs1/home/jacob/E3SM2/components/stub_comps/siac/cime_config/buildnml /gpfs/fs1/home/jacob/E3SM2/cime/scripts/Fcasekok FAILED, see above
Exit 1

Turns out siac buildnml only had this code:

#!/usr/bin/env python3

"""
build stub model namelist
"""
# DO NOTHING

while the other stub model's buildnml's had:

#!/usr/bin/env python3

"""
build stub model namelist
"""
# DO NOTHING
#pylint: disable=unused-argument
def buildnml(case, caseroot, compname):
    pass

BUT: python 3.8.3, also available on anvil, did NOT have any error with the incomplete buildnml.

Why doesn't anyone else see this on another platfrom? All cases run the siac buildnml.

[jgfouca]

@rljacob , ah, I think I see the problem. Python isn't complaining about the script, it's complaining that there's no python3 in your PATH. It seems like that particular python installation was not done correctly.

[rljacob]

But wouldn't all the other buildnml's give an error then? And so would create_newcase ?

[rljacob]

Here is the full output of case.setup:

[jacob@blueslogin4 Fcasekok]$ ./case.setup
Machine/Decomp/Pes configuration has already been done ...skipping
If an old case build already exists, might want to run 'case.build --clean' before building
Generating component namelists as part of setup
  2021-07-08 16:42:57 atm 
Create namelist for component eam
   Calling /gpfs/fs1/home/jacob/E3SM2/components/eam//cime_config/buildnml
  2021-07-08 16:42:58 lnd 
Create namelist for component elm
   Calling /gpfs/fs1/home/jacob/E3SM2/components/elm//cime_config/buildnml
  2021-07-08 16:42:58 ice 
Create namelist for component cice
   Calling /gpfs/fs1/home/jacob/E3SM2/components/cice/cime_config/buildnml
  2021-07-08 16:42:59 ocn 
Create namelist for component docn
   Calling /gpfs/fs1/home/jacob/E3SM2/components/data_comps/docn/cime_config/buildnml
  2021-07-08 16:42:59 rof 
Create namelist for component srof
   Calling /gpfs/fs1/home/jacob/E3SM2/components/stub_comps/srof/cime_config/buildnml
  2021-07-08 16:42:59 glc 
Create namelist for component sglc
   Calling /gpfs/fs1/home/jacob/E3SM2/components/stub_comps/sglc/cime_config/buildnml
  2021-07-08 16:42:59 wav 
Create namelist for component swav
   Calling /gpfs/fs1/home/jacob/E3SM2/components/stub_comps/swav/cime_config/buildnml
  2021-07-08 16:42:59 iac 
Create namelist for component siac
   Running /gpfs/fs1/home/jacob/E3SM2/components/stub_comps/siac/cime_config/buildnml 
/usr/bin/env: python3: No such file or directory
ERROR: /gpfs/fs1/home/jacob/E3SM2/components/stub_comps/siac/cime_config/buildnml /gpfs/fs1/home/jacob/E3SM2/cime/scripts/Fcasekok FAILED, see above
Exit 1

[jgfouca]

@rljacob , CIME is finding a buildnml function in those other files, so it's calling them as a python library. It failed to find one in siac's, so attempted to invoke as a shell command which then failed. If create_newcase is finding python3, then there must be something in the environment setup in config_machines.xml for anvil that is removing python.

[rljacob]

When adding that anaconda module, it says:

[jacob@blueslogin4 cime_config]$ which python
/soft/anaconda3/2020.02/bin/python
[jacob@blueslogin4 cime_config]$ python  --version
Python 3.7.6

Maybe it is particular to how that python is configured on anvil but I should still fix that discrepancy in the siac buildnml.

[jgfouca]

@rljacob , all CIME python scripts are now explicitly looking for an executable called python3

[rljacob]

Ok. I'll open a separate issue for this python3.7.6 module on anvil. It has problems.

[rljacob]

Will continue in #4392