[Django] #28835: Development server doesn't shut down on SIGTERM

[Django]

#28835: Development server doesn't shut down on SIGTERM
-------------------------------------+-------------------------------------
Reporter: Slavek | Owner: nobody
Kabrda |
Type: Bug | Status: new
Component: Core | Version: 1.11
(Management commands) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 1
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
Hi, I've already opened a PR to fix this [1], but have been notified in a
comment that I'll need to open a Trac ticket, so here it is. The
explanation of this issue is at [1], but I'll C&P it here as well for
clarity:

I've run into an issue where shutting down django devserver in a container
(e.g. in kubernetes/openshift environment) doesn't work well. The original
report is at [2].

Explanation:

* kubernetes/openshift send SIGTERM to PID 1 in the container when
shutting the container down.
* If `manage.py runserver` is an entrypoint, it gets executed as PID 1 in
container.
* Linux kernel won't propagate SIGTERM to any process that is PID 1 (in or
outside of container) if it doesn't have a handler installed for this
signal.

The implication of this is that the container with django devserver will
not do "soft" shutdown on SIGTERM and Kubernetes/Openshift will wait for
timeout and kill the container with SIGKILL. Therefore the container will
keep hanging and occupying system resources during the whole timeout.

Even though I understand that people should only use devserver for
development and not for deployment, I think it's quite common to first
make the container working with devserver for development and then
consider Gunicorn or similar solution when moving from early stage of the
project. IOW, I think this would really be beneficial for people using
Kubernetes like environments to develop/deploy Django apps.

Thanks for considering!

[1] https://github.com/django/django/pull/9338
[2] https://github.com/sclorg/s2i-python-container/issues/93

--
Ticket URL: <https://code.djangoproject.com/ticket/28835>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.

[Django]

#28835: Development server doesn't shut down on SIGTERM
-------------------------------------+-------------------------------------

Reporter: Slavek Kabrda | Owner: nobody
Type: Bug | Status: new
Component: Core (Management | Version: 1.11
commands) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 1 | Patch needs improvement: 0

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Claude Paroz):

* needs_tests: 0 => 1
* stage: Unreviewed => Accepted

--
Ticket URL: <https://code.djangoproject.com/ticket/28835#comment:1>

[Django]

#28835: Development server doesn't shut down on SIGTERM
-------------------------------------+-------------------------------------

Reporter: Slavek Kabrda | Owner: nobody
Type: Bug | Status: new

Component: Core (Management | Version: 1.11
commands) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0
Needs tests: 1 | Patch needs improvement: 0

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Slavek Kabrda):

I amended the PR with tests, so I believe it's now ready for review.
[https://github.com/django/django/pull/9338 PR]

--
Ticket URL: <https://code.djangoproject.com/ticket/28835#comment:2>

[Django]

#28835: Development server doesn't shut down on SIGTERM
-------------------------------------+-------------------------------------

Reporter: Slavek Kabrda | Owner: nobody
Type: Bug | Status: new

Component: Core (Management | Version: 1.11
commands) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Claude Paroz):

* needs_better_patch: 0 => 1
* needs_tests: 1 => 0

Comment:

Please uncheck `Patch needs improvement` when the Windows issue is solved.

--
Ticket URL: <https://code.djangoproject.com/ticket/28835#comment:3>

[Django]

#28835: Development server doesn't shut down on SIGTERM
-------------------------------------+-------------------------------------

Reporter: Slavek Kabrda | Owner: nobody
Type: Bug | Status: new

Component: Core (Management | Version: 1.11
commands) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Slavek Kabrda):

* needs_better_patch: 1 => 0

Comment:

I marked the test to be skipped on Windows, as I believe this is actually
not (easily) achievable on Windows. The Windows behavior is unaffected by
my patch. All tests pass now, I'm unchecking "Patch needs improvement".

--
Ticket URL: <https://code.djangoproject.com/ticket/28835#comment:4>

[Django]

#28835: Development server doesn't shut down on SIGTERM
-------------------------------------+-------------------------------------

Reporter: Slavek Kabrda | Owner: nobody
Type: Bug | Status: new

Component: Core (Management | Version: 1.11
commands) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Carlton Gibson):

Patch itself looks good.

There is some discussion on the PR as to whether this is quite the right
fix: in the ideal case this probably isn't Django's responsibility vs it's
a small change that should help some avoid a ??? moment, especially when
just experimenting.

Given this was initially Accepted (rather than DDN, or wontfix), I'm going
to mark this Ready for checkin, wherein it'll get a final review.

--
Ticket URL: <https://code.djangoproject.com/ticket/28835#comment:5>

[Django]

#28835: Development server doesn't shut down on SIGTERM
-------------------------------------+-------------------------------------

Reporter: Slavek Kabrda | Owner: nobody
Type: Bug | Status: new

Component: Core (Management | Version: 1.11
commands) |
Severity: Normal | Resolution:

Keywords: | Triage Stage: Ready for
| checkin
Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Carlton Gibson):

* stage: Accepted => Ready for checkin

--
Ticket URL: <https://code.djangoproject.com/ticket/28835#comment:6>

[Django]

#28835: Development server doesn't shut down on SIGTERM
-------------------------------------+-------------------------------------

Reporter: Slavek Kabrda | Owner: nobody
Type: Bug | Status: new

Component: Core (Management | Version: 1.11
commands) |
Severity: Normal | Resolution:

Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Carlton Gibson):

* needs_better_patch: 0 => 1
* stage: Ready for checkin => Accepted

--
Ticket URL: <https://code.djangoproject.com/ticket/28835#comment:7>

[Django]

#28835: Development server doesn't shut down on SIGTERM
-------------------------------------+-------------------------------------

Reporter: Slavek Kabrda | Owner: nobody

Type: Bug | Status: closed

Component: Core (Management | Version: 1.11
commands) |

Severity: Normal | Resolution: wontfix
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Carlton Gibson):

* status: new => closed
* resolution: => wontfix

Comment:

After discussion on the PR we're going to close this off in favour of
#21978 (having runserver use gunicorn).

In the meantime a specialised init process (or docker's `--init` flag) is
probably the way to go.

--
Ticket URL: <https://code.djangoproject.com/ticket/28835#comment:8>