python 你如何使用 pip、virtualenv 和 Fabric 来处理部署？

How do you use pip, virtualenv and Fabric to handle deployment?

提问by e-satis

What are your settings, your tricks, and above all, your workflow?

你的设置，你的技巧，最重要的是你的工作流程是什么？

These tools are great but there are still no best practices attached to their usage, so I don't know what is the most efficient way to use them.

这些工具很棒，但仍然没有与它们的使用相关的最佳实践，所以我不知道使用它们的最有效方法是什么。

• Do you use pipbundles or always download?
• Do you set up Apache/Cherokee/MySQL by hand or do you have a script for that?
• Do you put everything in virtualenvand use --no-site-packages?
• Do you use one virtualenv for several projects?
• What do you use Fabricfor (which part of your deployment do you script)?
• Do you put your Fabric scripts on the client or the server?
• How do you handle database and media file migration?
• Do you ever need a build tool such as SCons?
• What are the steps of your deployment? How often do you perform each of them?
• etc.

• 你使用pip包还是总是下载？
• 您是手动设置 Apache/Cherokee/MySQL 还是您有相应的脚本？
• 您是否将所有内容都放在virtualenv 中并使用--no-site-packages？
• 您是否为多个项目使用一个 virtualenv？
• 您将Fabric用于什么（您编写脚本部署的哪个部分）？
• 您将 Fabric 脚本放在客户端还是服务器上？
• 您如何处理数据库和媒体文件迁移？
• 您是否需要像SCons这样的构建工具？
• 您的部署步骤是什么？你每一次表演的频率是多少？
• 等等。

回答by Carl Meyer

"Best practices" are very context-dependent, so I won't claim my practices are best, just that they work for me. I work on mostly small sites, so no multiple-server deployments, CDNs etc. I do need to support Webfaction shared hosting deployment, as some clients need the cheapest hosting they can find. I do often have to deploy sites multiple times in different environments, so repeatable scripted deploys are critical.

“最佳实践”非常依赖于上下文，所以我不会声称我的实践是最好的，只是它们对我有用。我主要在小型站点上工作，所以没有多服务器部署、CDN 等。我确实需要支持 Webfaction 共享托管部署，因为有些客户需要他们能找到的最便宜的托管。我确实经常需要在不同的环境中多次部署站点，因此可重复的脚本部署至关重要。

• I don't use pip bundles, I install from a requirements.txt. I do run my own chishopserver with sdists of everything I need, so there aren't multiple single points of failure in the build process. I also use PIP_DOWNLOAD_CACHE on my development machines to speed up bootstrapping project environments, since most of my projects' requirements overlap quite a bit.
• I have Fabricscripts that can automatically set up and configure nginx + Apache/mod_wsgi on an Ubuntu VPS, or configure the equivalent on Webfactionshared hosting, and then deploy the project.
• I do not use --no-site-packages with virtualenv, because I prefer having slow-moving compiled packages (Python Imaging Library, psycopg2) installed at the system level; too slow and troublesome to do inside every virtualenv. I have not had trouble with polluted system site-packages, because I generally don't pollute it. And in any case, you can install a different version of something in the virtualenv and it will take precedence.
• Each project has its own virtualenv. I have some bash scripts (not virtualenvwrapper, though a lot of people use that and love it) that automate deploying the virtualenv for a given project to a known location and installing that project's requirements into it.
• The entire deployment process, from a bare Ubuntu server VPS or Webfaction shared hosting account to a running website, is scripted using Fabric.
• Fabric scripts are part of the project source tree, and I run them from a local development checkout.
• I have no need for SCons (that I am aware of).

• 我不使用 pip 包，我从 requirements.txt 安装。我确实使用我需要的所有东西的sdists运行我自己的chishop服务器，因此在构建过程中没有多个单点故障。我还在我的开发机器上使用 PIP_DOWNLOAD_CACHE 来加速引导项目环境，因为我的大多数项目的需求有很多重叠。
• 我有Fabric脚本，可以在 Ubuntu VPS 上自动设置和配置 nginx + Apache/mod_wsgi，或者在Webfaction共享主机上配置等效项，然后部署项目。
• 我不将 --no-site-packages 与 virtualenv 一起使用，因为我更喜欢在系统级别安装缓慢移动的编译包（Python Imaging Library，psycopg2）；在每个 virtualenv 中都做起来太慢也太麻烦了。我没有遇到受污染的系统站点包的问题，​​因为我通常不会污染它。无论如何，你可以在 virtualenv 中安装不同版本的东西，它会优先。
• 每个项目都有自己的 virtualenv。我有一些 bash 脚本（不是virtualenvwrapper，尽管很多人使用它并喜欢它），它们可以自动将给定项目的 virtualenv 部署到已知位置并将该项目的要求安装到其中。
• 整个部署过程，从裸 Ubuntu 服务器 VPS 或 Webfaction 共享托管帐户到正在运行的网站，都是使用 Fabric 编写的。
• Fabric 脚本是项目源代码树的一部分，我从本地开发结帐处运行它们。
• 我不需要 SCons（我知道）。

Deployment

部署

At the moment a fresh deployment is split into these steps:

目前，新部署分为以下步骤：

• fab staging bootstrap(server setup and initial code deploy)
• fab staging enable(enable the Apache/nginx config for this site)
• fab staging reload_server(reload Apache/nginx config).

• fab staging bootstrap（服务器设置和初始代码部署）
• fab staging enable（为此站点启用 Apache/nginx 配置）
• fab staging reload_server（重新加载 Apache/nginx 配置）。

Those can of course be combined into a single command line fab staging bootstrap enable reload_server.

这些当然可以组合成一个单一的命令行fab staging bootstrap enable reload_server。

Once these steps are done, updating the deployment with new code is just fab staging deploy.

完成这些步骤后，使用新代码更新部署只需fab staging deploy.

If I need to roll back an update, fab staging rollback. Nothing particularly magical in the rollback; it just rolls back the code to the last-deployed version and migrates the database to the previous state (this does require recording some metadata about the migration state of the DB post-deploy, I just do that in a text file).

如果我需要回滚更新，fab staging rollback. 回滚没有什么特别神奇的；它只是将代码回滚到上次部署的版本并将数据库迁移到以前的状态（这确实需要记录一些关于部署后数据库迁移状态的元数据，我只是在文本文件中这样做）。

Examples

例子

I haven't used the Fabric scripts described in this answer for a few years, so they aren't maintained at all and I disclaim responsibility for their quality :-) But you can see them at https://bitbucket.org/carljm/django-project-template- in fabfile.pyin the repo root, and in the deploy/subdirectory.

我已经有几年没有使用过这个答案中描述的 Fabric 脚本了，所以它们根本没有得到维护，我对它们的质量不承担任何责任 :-) 但是你可以在https://bitbucket.org/carljm 上看到它们/django-project-template- 在fabfile.pyrepo 根目录和deploy/子目录中。

回答by Rodrigue

I use fabric to build and deploy my code and assume a system already set up for that. I think that a tool like puppetis more appropriate to automate the installation of things like apache and mysql, though I have yet to really include it in my workflow.

我使用结构来构建和部署我的代码，并假设一个系统已经为此设置好了。我认为像puppet这样的工具更适合自动安装诸如 apache 和 mysql 之类的东西，尽管我还没有真正将它包含在我的工作流程中。

Also, I usually have a different virtualenv per project. They are created from a 'base' install of python where - as Carl pointed out - you can leave some global python libraries.

另外，我通常每个项目都有一个不同的 virtualenv。它们是从 python 的“基本”安装创建的，其中 - 正如卡尔指出的那样 - 您可以保留一些全局 python 库。

So in terms of workflow that would be:

因此，就工作流程而言，这将是：

1. puppet to install required services (web server, database, ssh server, ...)
2. puppet to set up required users and base folders
3. fabric to create virtualenv for the application
4. fabric to pip install from requirements.txt
5. fabric to deploy your app
6. fabric to deploy configuration files (web server, ...)

1. puppet 安装所需的服务（Web 服务器、数据库、ssh 服务器等）
2. puppet 设置所需的用户和基本文件夹
3. 为应用程序创建 virtualenv 的结构
4. 从requirements.txt到pip安装的fabric
5. 用于部署您的应用程序的结构
6. 用于部署配置文件的结构（Web 服务器，...）