tools/mlock_report.py can't import psutil module

[serenico]

When enabling 'memory_tracker' service and using Python3, memory_tracker.sh fails to run because tools/mlock_report.py is unable to import psutil module:

2020-01-23 19:16:50.727 | + functions-common:service_check:1622 : sudo systemctl is-enabled devstack@memory_tracker.service
2020-01-23 19:16:50.777 | enabled
2020-01-23 19:16:50.789 | + functions-common:service_check:1626 : sudo systemctl status devstack@memory_tracker.service --no-pager
2020-01-23 19:16:50.838 | ● devstack@memory_tracker.service - DevStack devstack@memory_tracker.service
2020-01-23 19:16:50.839 | Loaded: loaded (/etc/systemd/system/devstack@memory_tracker.service; enabled; vendor preset: disabled)
2020-01-23 19:16:50.839 | Active: failed (Result: exit-code) since Thu 2020-01-23 19:15:20 UTC; 1min 30s ago
2020-01-23 19:16:50.839 | Main PID: 28314 (code=exited, status=1/FAILURE)
2020-01-23 19:16:50.839 |
2020-01-23 19:16:50.839 | Jan 23 19:15:20 centos-7-fortnebula-regionone-0014112762 memory_tracker.sh[28314]: [[[
2020-01-23 19:16:50.839 | Jan 23 19:15:20 centos-7-fortnebula-regionone-0014112762 memory_tracker.sh[28314]: Thu Jan 23 19:15:20 UTC 2020
2020-01-23 19:16:50.839 | Jan 23 19:15:20 centos-7-fortnebula-regionone-0014112762 memory_tracker.sh[28314]: ---
2020-01-23 19:16:50.839 | Jan 23 19:15:20 centos-7-fortnebula-regionone-0014112762 memory_tracker.sh[28314]: Traceback (most recent call last):
2020-01-23 19:16:50.839 | Jan 23 19:15:20 centos-7-fortnebula-regionone-0014112762 memory_tracker.sh[28314]: File "/opt/stack/devstack/tools/mlock_report.py", line 7, in <module>
2020-01-23 19:16:50.839 | Jan 23 19:15:20 centos-7-fortnebula-regionone-0014112762 memory_tracker.sh[28314]: import psutil
2020-01-23 19:16:50.839 | Jan 23 19:15:20 centos-7-fortnebula-regionone-0014112762 memory_tracker.sh[28314]: ImportError: No module named psutil
2020-01-23 19:16:50.839 | Jan 23 19:15:20 centos-7-fortnebula-regionone-0014112762 systemd[1]: devstack@memory_tracker.service: main process exited, code=exited, status=1/FAILURE
2020-01-23 19:16:50.839 | Jan 23 19:15:20 centos-7-fortnebula-regionone-0014112762 systemd[1]: Unit devstack@memory_tracker.service entered failed state.
2020-01-23 19:16:50.840 | Jan 23 19:15:20 centos-7-fortnebula-regionone-0014112762 systemd[1]: devstack@memory_tracker.service failed.

My best guess is that the python script is using python command, while DevStack made available psutil package to python3 command. I think DevStack should now use 'python3' command by default and use 'python' command only as fallback interpreter.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/704110

[Radosław Piliszek (yoctozepto)]

DevStack no longer installs psutil since https://review.opendev.org/#/c/561597/

[OpenStack Infra (hudson-openstack)]

Change abandoned by Federico Ressi (<email address hidden>) on branch: master
Review: https://review.opendev.org/704110

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/704134

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/704104
Committed: https://git.openstack.org/cgit/openstack/devstack/commit/?id=3555b48ff45a109e6456923d597fa174084387ab
Submitter: Zuul
Branch: master

commit 3555b48ff45a109e6456923d597fa174084387ab
Author: Federico Ressi <email address hidden>
Date: Fri Jan 24 06:49:03 2020 +0100

    Switch to python3 for memory_peak service

    When starting 'memory_peak' service is using python command instead of
    python3, while psutil (required package) is most probably being
    installed into the python3 environment (as we are dropping python2.7
    support).

    Closes-Bug: #1860753
    Change-Id: Ia2b7e2e33d784560443131e2965f520b361a54e3

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/704134
Committed: https://git.openstack.org/cgit/openstack/devstack/commit/?id=19e4d972884e422d691c4cc1fe9e7ed3a03a2c01
Submitter: Zuul
Branch: master

commit 19e4d972884e422d691c4cc1fe9e7ed3a03a2c01
Author: Federico Ressi <email address hidden>
Date: Fri Jan 24 11:44:46 2020 +0100

    Install psutil required by tools/mlock_report.py script

    'tools/mlock_report.py' script requires 'psutil' package to be
    installed. This ensures it is done before memory_peak service is
    started.

    Partial-Bug: #1860753
    Change-Id: I7b2b6eaf9856c6057e1a4a0054d15074150a6cb6