I was mistaken about this only affecting CentOS 8, it affects CentOS 7 also.
More worryingly, CentOS 7's postgres 9.6 (from an SCL) only supports non-FIPS-compliant MD5 password hashes.
Therefore, my fix in development to use SHA256 will not suffice.
For the sake of #7884, I will continue to use the old version of the role. Which I suspect uses plaintext passwords.
ASK [geerlingguy.postgresql : Ensure PostgreSQL users are configured correctly.] ***
An exception occurred during task execution. To see the full traceback, use -vvv. The error was: ValueError: error:060800A3:digital envelope routines:EVP_DigestInit_ex:disabled for fips
failed: [pulp3-sandbox-centos7-fips] (item={'name': 'pulp', 'password': 'pulp', 'role_attr_flags': 'CREATEDB'}) => {"ansible_loop_var": "item", "changed": false, "item": {"name": "pulp", "password": "pulp", "role_attr_flags": "CREATEDB"}, "module_stderr": "Traceback (most recent call last):
File \"<stdin>\", line 102, in <module>
File \"<stdin>\", line 94, in _ansiballz_main
File \"<stdin>\", line 40, in invoke_module
File \"/usr/lib64/python2.7/runpy.py\", line 176, in run_module
fname, loader, pkg_name)
File \"/usr/lib64/python2.7/runpy.py\", line 82, in _run_module_code
mod_name, mod_fname, mod_loader, pkg_name)
File \"/usr/lib64/python2.7/runpy.py\", line 72, in _run_code
exec code in run_globals
File \"/tmp/ansible_postgresql_user_payload_0hSOAq/ansible_postgresql_user_payload.zip/ansible/modules/database/postgresql/postgresql_user.py\", line 974, in <module>
File \"/tmp/ansible_postgresql_user_payload_0hSOAq/ansible_postgresql_user_payload.zip/ansible/modules/database/postgresql/postgresql_user.py\", line 921, in main
File \"/tmp/ansible_postgresql_user_payload_0hSOAq/ansible_postgresql_user_payload.zip/ansible/modules/database/postgresql/postgresql_user.py\", line 384, in user_alter
File \"/tmp/ansible_postgresql_user_payload_0hSOAq/ansible_postgresql_user_payload.zip/ansible/modules/database/postgresql/postgresql_user.py\", line 350, in user_should_we_change_password
ValueError: error:060800A3:digital envelope routines:EVP_DigestInit_ex:disabled for fips
", "module_stdout": "", "msg": "MODULE FAILURE