Django管理命令在cron中不起作用 [英] Django management command won't work in cron

问题描述

我在与用户crontab一起安排 manage.py celery调用myapp.tasks.mytask 时遇到问题，因为当cron尝试运行作业时，它得到了在stderr中（该邮件以 / var / mail / kal 的形式发送给我）

I am having problems scheduling a manage.py celery call myapp.tasks.mytask with my user crontab, in that when cron tries to run the job, it gets this in stderr (which gets mailed to me, as /var/mail/kal)

Unknown command: 'celery'
Type 'manage.py help' for usage.

同一命令完全可以在常规bash登录shell中使用，但在crontab中不起作用。

The same command works completely from a regular bash login shell, but it won't work in crontab.

我正在Debian Wheezy上执行此操作：

I am doing this on Debian wheezy:

$ lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Debian GNU/Linux 7.0 (wheezy)
Release:        7.0
Codename:       wheezy

我在StackOverflow上阅读了许多类似的问题，并尝试了许多建议的解决方案。到目前为止，他们都没有为我工作。以下是到目前为止我尝试过的解决方案：

I have read many similar questions on StackOverflow and tried many of the suggested solutions. None of them have worked for me so far. Here are the solutions I have tried so far:

首先，我确保在crontab中指定相关的环境变量：

First, I made sure to specify relevant environment variables in the crontab:

SHELL=/bin/bash
PATH=/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games

注意：这些在以下所有解决方案中都保持不变。

NOTE: these stay in place in all of the following solutions.

* * * * * /home/kal/.virtualenvs/foo_dev/bin/python /home/kal/foo/manage.py celery call myapp.tasks.mytask

2。 cd首先进入项目路径

2. cd'ing into the project path first

* * * * * cd /home/kal/foo && /home/kal/.virtualenvs/foo_dev/bin/python ./manage.py celery call myapp.tasks.mytask

3。用bash脚本包装所有内容

〜/ mytask.sh的内容：

3. Wrapping everything in a bash script

Content of ~/mytask.sh:

#!/usr/bin/env bash
source /home/kal/.virtualenvs/foo_dev/bin/activate;
cd /home/kal/foo;
./manage.py celery call myapp.tasks.mytask;

crontab行：

* * * * * ~/mytask.sh

我什至修改了 myproj / settings.py 输出 sys.path 和 sys.executable 到stderr并比较了cron和登录shell之间的输出，它们是完全相同的：

I even modified myproj/settings.py to output sys.path and sys.executable to stderr and compared the output between cron and the login shell, and they are exactly the same:

cron作业的输出：

Output from cron job:

sys.executable:
    /home/kal/.virtualenvs/foo_dev/bin/python

Content of sys.path:
    /home/kal/foo
    /home/kal/.virtualenvs/foo_dev/src/bootstrap
    /home/kal/.virtualenvs/foo_dev/src/django-json-rpc
    /home/kal/.virtualenvs/foo_dev/lib/python2.7
    /home/kal/.virtualenvs/foo_dev/lib/python2.7/plat-linux2
    /home/kal/.virtualenvs/foo_dev/lib/python2.7/lib-tk
    /home/kal/.virtualenvs/foo_dev/lib/python2.7/lib-old
    /home/kal/.virtualenvs/foo_dev/lib/python2.7/lib-dynload
    /usr/lib/python2.7
    /usr/lib/python2.7/plat-linux2
    /usr/lib/python2.7/lib-tk
    /home/kal/.virtualenvs/foo_dev/local/lib/python2.7/site-packages
    /home/kal/foo

Bash登录shell的输出：

Output from Bash login shell:

sys.executable:
    /home/kal/.virtualenvs/foo_dev/bin/python

Content of sys.path:
    /home/kal/foo
    /home/kal/.virtualenvs/foo_dev/src/bootstrap
    /home/kal/.virtualenvs/foo_dev/src/django-json-rpc
    /home/kal/.virtualenvs/foo_dev/lib/python2.7
    /home/kal/.virtualenvs/foo_dev/lib/python2.7/plat-linux2
    /home/kal/.virtualenvs/foo_dev/lib/python2.7/lib-tk
    /home/kal/.virtualenvs/foo_dev/lib/python2.7/lib-old
    /home/kal/.virtualenvs/foo_dev/lib/python2.7/lib-dynload
    /usr/lib/python2.7
    /usr/lib/python2.7/plat-linux2
    /usr/lib/python2.7/lib-tk
    /home/kal/.virtualenvs/foo_dev/local/lib/python2.7/site-packages
    /home/kal/foo

我完全感到困惑。

推荐答案

我找到了问题的原因。

它非常非常 非常。

问题有两个：

1. 没有 USER cron作业中的环境变量；仅 LOGNAME ;


2. 在下运行 manage.py 时一个指定的管理命令，如果在导入设置模块期间引发异常，则Django 安静地会故障转移为空白设置。

1. There is no USER environment variable in a cron job; only LOGNAME;
2. When manage.py is run with a management command specified, Django quietly fails over to blank settings if an exception is raised during the import of the settings module.

我的设置模块正在尝试引用 os.environ ['USER'] ，在cron的环境中不存在。因此，导入设置模块会引发异常，而Django会悄悄地故障转移为空白设置，这意味着空白 INSTALLED_APPS 且没有 celery 命令！

My settings module was trying to reference os.environ['USER'], which doesn't exist in cron's environment. So importing the settings module causes an exception to be raised, and Django quietly fails over to blank settings, which means blank INSTALLED_APPS and no celery command!

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