Fix revoke only grant

[markuman]

SUMMARY

When only grant is revoked by mysql_user, it results in a 2nd sql query, where empty privs are tried to revoked.

ISSUE TYPE

• Bugfix Pull Request

COMPONENT NAME

plugs/module_utils/user.py

[markuman]

here is a playbook that show the current bug:

---
- name: prepare mariadb container
  hosts: localhost
  connection: local

  tasks:
    - name: test
      vars:
        mysql_parameters: &mysql_params
          login_user: root
          login_password: mariadb
          login_host: 127.0.0.1
          login_port: 33066
      block:
        - name: start nextcloud container
          register: out
          community.docker.docker_container:
            name: mariadb_test_container
            image: mariadb:10.6
            state: started
            auto_remove: true
            recreate: true
            container_default_behavior: no_defaults
            published_ports:
              - "127.0.0.1:{{ mysql_parameters.login_port }}:3306"
            env:
              MARIADB_ROOT_PASSWORD: "{{ mysql_parameters.login_password }}"

        - name: mariadb container needs some sec for initialization
          pause:
            seconds: 10

        - name: create user with two grants
          mysql_user:
            <<: *mysql_params
            name: testuser
            password: testpassword
            update_password: on_create
            priv: '*.*:SELECT,GRANT'

        - name: >
            user must have only one priv. grant priv must be dropped
            this is the bug that is fixed in https://github.com/ansible-collections/community.mysql/pull/503
          register: result
          mysql_user:
            <<: *mysql_params
            name: testuser
            password: testpassword
            update_password: on_create
            priv: '*.*:SELECT'

        - assert:
            that:
              - result is not failed
              - result is changed

        - name: immutable - user must have only one priv, grant priv must be dropped
          register: result
          mysql_user:
            <<: *mysql_params
            name: testuser
            password: testpassword
            update_password: on_create
            priv: '*.*:SELECT'

        - assert:
            that:
              - result is not failed
              - result is not changed

      always:
        - name: stop mariadb test container
          community.docker.docker_container:
            name: mariadb_test_container
            state: absent

it results in

PLAY [prepare nextcloud container] ********************************************************************************************************************************

TASK [Gathering Facts] ********************************************************************************************************************************************
ok: [localhost]

TASK [start mariadb container] **********************************************************************************************************************************
changed: [localhost]

TASK [mariadb container needs some sec for initialization] ********************************************************************************************************
Pausing for 10 seconds
(ctrl+C then 'C' = continue early, ctrl+C then 'A' = abort)
ok: [localhost]

TASK [create user with two grants] ********************************************************************************************************************************
changed: [localhost]

TASK [user must have only one priv. grant priv must be dropped] ***************************************************************************************************
fatal: [localhost]: FAILED! => {"changed": false, "msg": "(1064, \"You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'ON *.* FROM 'testuser'@'localhost'' at line 1\")"}

TASK [stop mariadb test container] ********************************************************************************************************************************
changed: [localhost]

PLAY RECAP ********************************************************************************************************************************************************
localhost                  : ok=5    changed=3    unreachable=0    failed=1    skipped=0    rescued=0    ignored=0 

while this PR fixes it

PLAY [prepare mariadb container] ********************************************************************************************************************************

TASK [Gathering Facts] ********************************************************************************************************************************************
ok: [localhost]

TASK [start nextcloud container] **********************************************************************************************************************************
changed: [localhost]

TASK [mariadb container needs some sec for initialization] ********************************************************************************************************
Pausing for 10 seconds
(ctrl+C then 'C' = continue early, ctrl+C then 'A' = abort)
ok: [localhost]

TASK [create user with two grants] ********************************************************************************************************************************
changed: [localhost]

TASK [user must have only one priv. grant priv must be dropped] ***************************************************************************************************
changed: [localhost]

TASK [assert] *****************************************************************************************************************************************************
ok: [localhost] => {
    "changed": false,
    "msg": "All assertions passed"
}

TASK [immutable - user must have only one priv, grant priv must be dropped] ***************************************************************************************
ok: [localhost]

TASK [assert] *****************************************************************************************************************************************************
ok: [localhost] => {
    "changed": false,
    "msg": "All assertions passed"
}

TASK [stop mariadb test container] ********************************************************************************************************************************
changed: [localhost]

PLAY RECAP ********************************************************************************************************************************************************
localhost                  : ok=9    changed=4    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   

[Andersson007]

@markuman thanks for the contribution!

[patchback]

Backport to stable-2: 💚 backport PR created

✅ Backport PR branch: patchback/backports/stable-2/b34c23d07d1fd2097767a5e16e153cbf20ed8973/pr-503

Backported as #504

🤖 @patchback
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