python笔记40-环境迁移freeze生成requirements.txt
前言
我们用python在本地电脑上开发完成一个python自动化项目用例，或者开发完成一个django项目。
需要部署到另外一台电脑或者服务器上的时候，需要导入python相关的依赖包，可以用freeze一键生成requirements.txt文件
- pip freeze >requirements.txt # 生成一个迁移文件
- pip install -r requirements.txt # 安装依赖包
freeze生成文件
比如我在本地电脑开发完成了python的一个项目，会涉及到很多第三方的包，并且版本号都得一一对应，这样才能保证迁移过去不会有问题。
在不知道freeze这个功能的时候，我是先pip list 查看所有的第三方包，然后一个个pip安装，感觉挺傻的。
自从看到别人项目里面有个requirements.txt文件，才知道原来可以通过pip freeze一键生成
pip freeze >requirements.txt
[root@yoyo ~]# pip freeze >requirements.txt
[root@yoyo ~]# cat requirements.txt
APScheduler==3.5.3
asn1crypto==0.24.0
# ....太多省略了
xlrd==1.2.0
xlwt==1.3.0
[root@yoyo ~]#
这样在当前目录就会生成一个requirements.txt文件，包当前项目的所有第三方包和版本号都会导出来
pip 安装
requirements.txt文件生成后，我们不需要一个个pip安装，可以在requirements.txt文件当前目录使用pip一键安装
pip install -r requirements.txt
[root@yoyo ~]# pip install -r requirements.txt
Looking in indexes: http://mirrors.aliyun.com/pypi/simple/
Requirement already satisfied: APScheduler==3.5.3 in /usr/local/python3/lib/python3.6/site-packages (from -r requirements.txt (line 1)) (3.5.3)
Requirement already satisfied: asn1crypto==0.24.0 in /usr/local/python3/lib/python3.6/site-packages (from -r requirements.txt (line 2)) (0.24.0)
Requirement already satisfied: atomicwrites==1.3.0 in /usr/local/python3/lib/python3.6/site-packages (from -r requirements.txt (line 3)) (1.3.0)
# ....太多省略了
Requirement already satisfied: xlwt==1.3.0 in /usr/local/python3/lib/python3.6/site-packages (from -r requirements.txt (line 62)) (1.3.0)
Requirement already satisfied: setuptools>=0.7 in /usr/local/python3/lib/python3.6/site-packages (from APScheduler==3.5.3->-r requirements.txt (line 1)) (40.6.2)
[root@yoyo ~]#
本地安装
如果你们公司的服务器限制了网络下载，那么只能通过本地安装了，freeze也可以下载本地包安装。
假设A服务器是没有网络的，你需要在A服务器上安装python第三方包，那么你先找个可以连网络的服务器B，在服务器B上先下载需要的安装包
服务器B上下载安装包
先使用pip freeze到处需要安装的包，比如我想安装以下包
[root@yoyo site-pkg]# cat requirements.txt
ix==1.12.0
attrs==18.2.0
py==1.7.0
pluggy==0.6.0
atomicwrites==1.3.0
more-itertools==6.0.0
pytest==3.6.3
pip download下载相关安装包
pip download -r requirements.txt
如果是阿里云服务器，会出现如下报错,那么加个参数--trusted-host mirrors.aliyun.com即可
[root@yoyo site-pkg]# pip download -r requirements.txt
Looking in indexes: http://mirrors.aliyun.com/pypi/simple/
Collecting ix==1.12.0 (from -r requirements.txt (line 1))
The repository located at mirrors.aliyun.com is not a trusted or secure host and is being ignored.
If this repository is available via HTTPS we recommend you use HTTPS instead,
otherwise you may silence this warning and allow it anyway with '--trusted-host mirrors.aliyun.com'.
Could not find a version that satisfies the requirement ix==1.12.0 (from -r requirements.txt (line 1)) (from versions: )
No matching distribution found for ix==1.12.0 (from -r requirements.txt (line 1))
You are using pip version 18.1, however version 19.2.3 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
加上--trusted-host mirrors.aliyun.com参数
pip download -r requirements.txt --trusted-host mirrors.aliyun.com
[root@yoyo site-pkg]# pip download -r requirements.txt --trusted-host mirrors.aliyun.com
Looking in indexes: http://mirrors.aliyun.com/pypi/simple/
Collecting six==1.12.0 (from -r requirements.txt (line 1))
File was already downloaded /root/site-pkg/six-1.12.0-py2.py3-none-any.whl
Collecting attrs==18.2.0 (from -r requirements.txt (line 2))
Downloading http://mirrors.aliyun.com/pypi/packages/3a/e1/5f9023cc983f1a628a8c2fd051ad19e76ff7b142a0faf329336f9a62a514/attrs-18.2.0-py2.py3-none-any.whl
Saved ./attrs-18.2.0-py2.py3-none-any.whl
Successfully downloaded six attrs py pluggy atomicwrites more-itertools pytest setuptools
[root@yoyo site-pkg]# ll
total 968
-rw-r--r-- 1 root root 5885 Aug 25 23:17 atomicwrites-1.3.0-py2.py3-none-any.whl
-rw-r--r-- 1 root root 34713 Aug 25 23:17 attrs-18.2.0-py2.py3-none-any.whl
-rw-r--r-- 1 root root 52353 Aug 25 23:17 more_itertools-6.0.0-py3-none-any.whl
-rw-r--r-- 1 root root 13723 Aug 25 23:17 pluggy-0.6.0-py3-none-any.whl
-rw-r--r-- 1 root root 83960 Aug 25 23:17 py-1.7.0-py2.py3-none-any.whl
-rw-r--r-- 1 root root 195787 Aug 25 23:17 pytest-3.6.3-py2.py3-none-any.whl
-rw-r--r-- 1 root root 106 Aug 25 23:16 requirements.txt
-rw-r--r-- 1 root root 576332 Aug 25 23:17 setuptools-41.2.0-py2.py3-none-any.whl
-rw-r--r-- 1 root root 10586 Aug 25 23:17 six-1.12.0-py2.py3-none-any.whl
[root@yoyo site-pkg]#
这样就可以下载到.whl后缀的本地包了
服务器A上本地安装
由于服务器A上无法联网，可以先把上面下载到的相关包传到服务器A上，然后就可以使用pip本地安装了.
.whl后缀的包是可以直接使用pip本地安装的。
pip install pytest-3.6.3-py2.py3-none-any.whl
[root@yoyo site-pkg]# pip install pytest-3.6.3-py2.py3-none-any.whl
Looking in indexes: http://mirrors.aliyun.com/pypi/simple/
Requirement already satisfied: pytest==3.6.3 from file:///root/site-pkg/pytest-3.6.3-py2.py3-none-any.whl in /usr/local/python3/lib/python3.6/site-packages (3.6.3)
Requirement already satisfied: pluggy<0.7,>=0.5 in /usr/local/python3/lib/python3.6/site-packages (from pytest==3.6.3) (0.6.0)
Requirement already satisfied: six>=1.10.0 in /usr/local/python3/lib/python3.6/site-packages (from pytest==3.6.3) (1.12.0)
Requirement already satisfied: atomicwrites>=1.0 in /usr/local/python3/lib/python3.6/site-packages (from pytest==3.6.3) (1.3.0)
Requirement already satisfied: more-itertools>=4.0.0 in /usr/local/python3/lib/python3.6/site-packages (from pytest==3.6.3) (6.0.0)
Requirement already satisfied: attrs>=17.4.0 in /usr/local/python3/lib/python3.6/site-packages (from pytest==3.6.3) (18.2.0)
Requirement already satisfied: py>=1.5.0 in /usr/local/python3/lib/python3.6/site-packages (from pytest==3.6.3) (1.7.0)
Requirement already satisfied: setuptools in /usr/local/python3/lib/python3.6/site-packages (from pytest==3.6.3) (40.6.2)
[root@yoyo site-pkg]#
如果安装过程中有的包会有其他的依赖包，需先安装依赖包，一个个的安装就可以了。
(注意：windows系统上导出的包，在linux上安装可能会有失败的)
