Fix DB upgrade machinery (#216)

* use correct interpreter for community.mysql.mysql_query

* parameterise

* add pexpect system python package

Author: sjpb

README.md

@@ -234,6 +234,10 @@ for the accounting storage database, e.g. `mysql`. If this is defined this
 service is stopped before the backup and restarted after, to allow for physical
 backups. Default is the empty string, which does not stop/restart any service.
 
+`openhpc_mysql_interpreter`: Optional. Value of `ansible_python_interpreter`
+to use for `community.mysql.mysql_query` module - should be set to whatever
+was used to install `pymysql`.
+
 ## Facts
 
 This role creates local facts from the live Slurm configuration, which can be

defaults/main.yml

@@ -167,3 +167,4 @@ openhpc_slurm_accounting_storage_backup_cmd: ''
 openhpc_slurm_accounting_storage_backup_host: "{{ openhpc_slurm_accounting_storage_host }}"
 openhpc_slurm_accounting_storage_backup_become: true
 openhpc_slurm_accounting_storage_client_package: mysql
+openhpc_mysql_interpreter: /usr/bin/python3.9 # Need non-default python to use installed recent pymysql version, with fixed SQL injection vulnerability

tasks/upgrade.yml

@@ -11,6 +11,8 @@
     query: SHOW TABLES
     config_file: ''
   register: _openhpc_slurmdb_tables
+  vars:
+    ansible_python_interpreter: "{{ openhpc_mysql_interpreter }}"
 
 - name: Check if slurm database requires an upgrade
   ansible.builtin.command: slurmdbd -u

vars/main.yml

@@ -17,6 +17,7 @@ ohpc_slurm_packages:
     - "{{ 'lmod-ohpc' if openhpc_module_system_install else '' }}"
   database:
     - "slurm-slurmdbd-ohpc"
+    - "python3-pexpect"
 
 openhpc_merged_config: "{{ openhpc_default_config | combine(openhpc_config) }}"
 ...