YAQL engine properties don't get initialized properly

[Renat Akhmerov]

When we launch Mistral with launch.py script then initialization of YAQL engine in the module yaql_expression.py happens before parsing the config file by oslo.cfg. This is because YAQL engine class is declared as a static module level variable (constant) and its initialization is caused by the chain if imports starting from launch.py module. However, parsing config file runs only in main() function of launch.py.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/709951

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/train
Review: https://review.opendev.org/709957

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/709951
Committed: https://git.openstack.org/cgit/openstack/mistral/commit/?id=753f1bc03fc5ae464d6a3c8266e025dce3cceccb
Submitter: Zuul
Branch: master

commit 753f1bc03fc5ae464d6a3c8266e025dce3cceccb
Author: Renat Akhmerov <email address hidden>
Date: Wed Feb 26 11:38:51 2020 +0700

    Fix YAQL engine initialization

    * When Mistral is launched via launch.py script then YAQL engine class
      initialization logic doesn't use the right properties from the config
      file. This is because this initialization is caused by the chain of
      imports taking its start in launch.py, and this happens before
      the config file is parsed in the main() function of launch.py.
      Using lazy initialization of YAQL engine class (YAQL_ENGINE in
      yaql_expression.py module) solves this issue because now Mistral
      doesn't initialize it immediately before parsing the config and
      waits for the first usage of it.
    * Minor style changes per Mistral coding guidelines.

    Change-Id: If3367493803b57ef8bc281b1f64f2a223ac86f85
    Closes-Bug: #1864785

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/709957
Committed: https://git.openstack.org/cgit/openstack/mistral/commit/?id=3df8162946144cda694ec6a750812a58e0ccfdf0
Submitter: Zuul
Branch: stable/train

commit 3df8162946144cda694ec6a750812a58e0ccfdf0
Author: Renat Akhmerov <email address hidden>
Date: Wed Feb 26 11:38:51 2020 +0700

    Fix YAQL engine initialization

    * When Mistral is launched via launch.py script then YAQL engine class
      initialization logic doesn't use the right properties from the config
      file. This is because this initialization is caused by the chain of
      imports taking its start in launch.py, and this happens before
      the config file is parsed in the main() function of launch.py.
      Using lazy initialization of YAQL engine class (YAQL_ENGINE in
      yaql_expression.py module) solves this issue because now Mistral
      doesn't initialize it immediately before parsing the config and
      waits for the first usage of it.
    * Minor style changes per Mistral coding guidelines.

    Change-Id: If3367493803b57ef8bc281b1f64f2a223ac86f85
    Closes-Bug: #1864785

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/mistral 10.0.0.0b3 development milestone.