Make requirements with only the packages you need

项目导入的 module 越多，导出的依赖库就越多，尤其是很多系统自带的库一并给导出来来了。

pip freeze 导出效果：

asgiref==3.3.4
async-timeout==4.0.3
certifi==2021.5.30
chardet==4.0.0
coreapi==2.3.3
coreschema==0.0.4
Django==3.2.3
django-admin-lightweight-date-hierarchy==1.1.0
django-comment-migrate==0.1.5
django-cors-headers==3.10.1
django-crontab==0.7.1
django-export-xls==0.1.1
django-filter==21.1
django-ranged-response==0.2.0
django-redis==5.2.0
django-restql==0.15.4
django-simple-captcha==0.5.14
django-simpleui==2022.7.29
django-timezone-field==4.2.3
djangorestframework==3.12.4
djangorestframework-simplejwt==5.1.0
drf-yasg==1.20.0
et-xmlfile==1.1.0
idna==2.10
inflection==0.5.1
itypes==1.2.0
Jinja2==3.0.1
MarkupSafe==2.0.1
openpyxl==3.0.9
packaging==20.9
paho-mqtt==1.6.1
Pillow==8.3.1
PyJWT==2.1.0
PyMySQL==1.0.2
pyparsing==2.4.7
pyPEG2==2.15.2
pypinyin==0.46.0
pypng==0.20220715.0
pytz==2021.1
qrcode==7.4.2
redis==5.0.8
requests==2.25.1
ruamel.yaml==0.18.6
ruamel.yaml.clib==0.2.8
simplejson==3.18.4
six==1.16.0
smmap==4.0.0
sqlparse==0.4.1
typing-extensions==3.10.0.0
tzlocal==2.1
ua-parser==0.10.0
uritemplate==3.0.1
urllib3==1.26.6
user-agents==2.2.0
whitenoise==5.3.0
xlwt==1.3.0

pip-chill 导出效果：

asgiref==3.3.4
async-timeout==4.0.3
certifi==2021.5.30
chardet==4.0.0
coreapi==2.3.3
coreschema==0.0.4
Django==3.2.3
django-admin-lightweight-date-hierarchy==1.1.0
django-comment-migrate==0.1.5
django-cors-headers==3.10.1
django-crontab==0.7.1
django-export-xls==0.1.1
django-filter==21.1
django-ranged-response==0.2.0
django-redis==5.2.0
django-restql==0.15.4
django-simple-captcha==0.5.14
django-simpleui==2022.7.29
django-timezone-field==4.2.3
djangorestframework==3.12.4
djangorestframework-simplejwt==5.1.0
drf-yasg==1.20.0
et-xmlfile==1.1.0
idna==2.10
inflection==0.5.1
itypes==1.2.0
Jinja2==3.0.1
MarkupSafe==2.0.1
openpyxl==3.0.9
packaging==20.9
paho-mqtt==1.6.1
Pillow==8.3.1
PyJWT==2.1.0
PyMySQL==1.0.2
pyparsing==2.4.7
pyPEG2==2.15.2
pypinyin==0.46.0
pypng==0.20220715.0
pytz==2021.1
qrcode==7.4.2
redis==5.0.8
requests==2.25.1
ruamel.yaml==0.18.6
ruamel.yaml.clib==0.2.8
simplejson==3.18.4
six==1.16.0
smmap==4.0.0
sqlparse==0.4.1
typing-extensions==3.10.0.0
tzlocal==2.1
ua-parser==0.10.0
uritemplate==3.0.1
urllib3==1.26.6
user-agents==2.2.0
whitenoise==5.3.0
xlwt==1.3.0z

整体减掉了差不多一半多，同样在构建环境的时候也少了很多可能出问题的包，尤其是跨平台 install 的时候。

官方用法：

Suppose you have installed in your virtualenv a couple packages. When you run pip freeze, you'll get a list of all packages installed, with all dependencies. If one of the packages you installed ceases to depend on an already installed package, you have to manually remove it from the list. The list also makes no distinction about the packages you actually care about and packages your packages care about, making the requirements file bloated and, ultimately, inaccurate.

On your terminal, run:

$ pip-chill
bandit==1.7.0
bumpversion==0.6.0
click==7.1.2
coverage==5.3.1
flake8==3.8.4
nose==1.3.7
pip-chill==1.0.1
pytest==6.2.1
...
Or, if you want it without version numbers:

$ pip-chill --no-version
bandit
bumpversion
click
coverage
flake8
nose
pip-chill
pytest
...
Or, if you want it without pip-chill:

$ pip-chill --no-chill
bandit==1.7.0
bumpversion==0.6.0
click==7.1.2
coverage==5.3.1
flake8==3.8.4
nose==1.3.7
pytest==6.2.1
...
Or, if you want to list package dependencies too:

$ pip-chill -v
bandit==1.7.0
bumpversion==0.6.0
click==7.1.2
coverage==5.3.1
flake8==3.8.4
nose==1.3.7
pip-chill==1.0.1
pytest==6.2.1
sphinx==3.4.3
tox==3.21.1
twine==3.3.0
watchdog==1.0.2
# alabaster==0.7.12 # Installed as dependency for sphinx
# appdirs==1.4.4 # Installed as dependency for virtualenv
# attrs==20.3.0 # Installed as dependency for pytest
# babel==2.9.0 # Installed as dependency for sphinx