用tsuru部署Python应用

概述

本文档是在tsuru中部署一个简单的Python应用的实战指南。例子应用是一个关联MySQL服务的很简单的Django项目。这些例子也适用于任何WSGI应用。

在tsuru中创建应用

使用app-create命令创建应用：

  1.     $ tsuru app-create <app-name> <app-platform>

对于Python来说，应用平台是，你猜，python！让我们脑洞打开，开发一个从未有人做过的教材应用：一个博客，而且它的名字也应该是很有创意，让我们叫他blog：

  1.     $ tsuru app-create blog python

使用platform-list命令列出所有的可用的平台。使用app-list查看你所有的应用。

  1.     $ tsuru app-list
  2.     +-------------+-------------------------+--------------------------+
  3.     | Application | Units State Summary     | Address                  |
  4.     +-------------+-------------------------+--------------------------+
  5.     | blog        | 0 of 0 units in-service | blog.192.168.50.4.nip.io |
  6.     +-------------+-------------------------+--------------------------+

然后就可以发送你的应用代码了。

应用的代码

本文档不会专注于介绍如何用Django实现博客，你可以从GitHub clone整个源代码：https://github.com/tsuru/tsuru-django-sample。 下面是我们在项目中所做的事情：

. 创建项目 (django-admin.py startproject). 启用django-admin. 安装South. 创建一个"posts"应用(django-admin.py startapp posts). 为应用添加"Post"model. 在django-admin中注册该model. 用South进行数据库迁移

通过Git部署

在创建新的应用时，tsuru会显示应该使用的Git远程分支。用app-info命令可以获得其信息：

  1.     $ tsuru app-info --app blog
  2.     Application: blog
  3.     Repository: git@192.168.50.4.nip.io:blog.git
  4.     Platform: python
  5.     Teams: admin
  6.     Address: blog.192.168.50.4.nip.io
  7.     Owner: admin@example.com
  8.     Team owner: admin
  9.     Deploys: 0
  10.     Pool: theonepool
  12.     App Plan:
  13.     +---------------+--------+------+-----------+--------+---------+
  14.     | Name          | Memory | Swap | Cpu Share | Router | Default |
  15.     +---------------+--------+------+-----------+--------+---------+
  16.     | autogenerated | 0 MB   | 0 MB | 100       |        | false   |
  17.     +---------------+--------+------+-----------+--------+---------+

Git远程分支被用来通过Git部署应用。当修改被推送到远程分支时，项目同时也被部署：

  1.     $ git push git@192.168.50.4.nip.io:blog.git master
  2.     Counting objects: 119, done.
  3.     Delta compression using up to 4 threads.
  4.     Compressing objects: 100% (53/53), done.
  5.     Writing objects: 100% (119/119), 16.24 KiB, done.
  6.     Total 119 (delta 55), reused 119 (delta 55)
  7.     remote:
  8.     remote:  ---> tsuru receiving push
  9.     remote:
  10.     remote: From git://cloud.tsuru.io/blog.git
  11.     remote:  * branch            master     -> FETCH_HEAD
  12.     remote:
  13.     remote:  ---> Installing dependencies
  14.     #####################################
  15.     #          OMIT (see below)         #
  16.     #####################################
  17.     remote:  ---> Restarting your app
  18.     remote:
  19.     remote:  ---> Deploy done!
  20.     remote:
  21.     To git@192.168.50.4.nip.io:blog.git
  22.        a211fba..bbf5b53  master -> master

如果遇到"Permission denied (publickey)."的错误，请确保你是团队一员并把公钥加到tsuru中。用key-add命令添加公钥：

  1.     $ tsuru key-add mykey ~/.ssh/id_rsa.pub

使用git remote add命令来避免每次push代码时都要输入整个远程仓库的链接：

  1.     $ git remote add tsuru git@192.168.50.4.nip.io:blog.git

然后运行：

  1.     $ git push tsuru master
  2.     Everything up-to-date

从此之后就可以省略掉—app标记:

  1.     $ tsuru app-info
  2.     Application: blog
  3.     Repository: git@192.168.50.4.nip.io:blog.git
  4.     Platform: python
  5.     Teams: admin
  6.     Address: blog.192.168.50.4.nip.io
  7.     Owner: admin@example.com
  8.     Team owner: admin
  9.     Deploys: 0
  10.     Pool: theonepool
  11.     Units: 1
  12.     +------------+---------+
  13.     | Unit       | State   |
  14.     +------------+---------+
  15.     | eab5151eff | started |
  16.     +------------+---------+
  18.     App Plan:
  19.     +---------------+--------+------+-----------+--------+---------+
  20.     | Name          | Memory | Swap | Cpu Share | Router | Default |
  21.     +---------------+--------+------+-----------+--------+---------+
  22.     | autogenerated | 0 MB   | 0 MB | 100       |        | false   |
  23.     +---------------+--------+------+-----------+--------+---------+

列出依赖

在上一个部分我们忽略了部署过程的依赖。在tsuru中，一个应用可以有两种依赖：

  • 操作系统级别的依赖, 以底层操作系统使用的包管理器为代表（比如: yum和apt-get）;
  • 平台依赖, 以平台/语言依赖的包管理工具为代表（在Python中是pip）。
    所有的apt-get依赖必须在requirements.apt文件中指定，放在应用的根目录，同理，pip的依赖也必须放在应用根目录名为requirements.txt的文件中。因为要用Django连接MySQL，我们需要用pip安装mysql-python，这个包依赖两个apt-get包：python-dev和libmysqlclient-dev，因此requirements.apt内容如下：
  1.     libmysqlclient-dev
  2.     python-dev

下面是requirements.txt的内容：

  2.     Django==1.4.1
  3.     MySQL-python==1.2.3
  4.     South==0.7.6

请注意文件中也包含了South，用于数据库移植，对于Django应用，这是很常见的。下面是安装这些依赖的完整输出：

  1.     % git push tsuru master
  2.     #####################################
  3.     #                OMIT               #
  4.     #####################################
  5.     remote: Reading package lists...
  6.     remote: Building dependency tree...
  7.     remote: Reading state information...
  8.     remote: python-dev is already the newest version.
  9.     remote: The following extra packages will be installed:
  10.     remote:   libmysqlclient18 mysql-common
  11.     remote: The following NEW packages will be installed:
  12.     remote:   libmysqlclient-dev libmysqlclient18 mysql-common
  13.     remote: 0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
  14.     remote: Need to get 2360 kB of archives.
  15.     remote: After this operation, 9289 kB of additional disk space will be used.
  16.     remote: Get:1 http://archive.ubuntu.com/ubuntu/ quantal/main mysql-common all 5.5.27-0ubuntu2 [13.7 kB]
  17.     remote: Get:2 http://archive.ubuntu.com/ubuntu/ quantal/main libmysqlclient18 amd64 5.5.27-0ubuntu2 [949 kB]
  18.     remote: Get:3 http://archive.ubuntu.com/ubuntu/ quantal/main libmysqlclient-dev amd64 5.5.27-0ubuntu2 [1398 kB]
  19.     remote: debconf: unable to initialize frontend: Dialog
  20.     remote: debconf: (Dialog frontend will not work on a dumb terminal, an emacs shell buffer, or without a controlling terminal.)
  21.     remote: debconf: falling back to frontend: Readline
  22.     remote: debconf: unable to initialize frontend: Readline
  23.     remote: debconf: (This frontend requires a controlling tty.)
  24.     remote: debconf: falling back to frontend: Teletype
  25.     remote: dpkg-preconfigure: unable to re-open stdin:
  26.     remote: Fetched 2360 kB in 1s (1285 kB/s)
  27.     remote: Selecting previously unselected package mysql-common.
  28.     remote: (Reading database ... 23143 files and directories currently installed.)
  29.     remote: Unpacking mysql-common (from .../mysql-common_5.5.27-0ubuntu2_all.deb) ...
  30.     remote: Selecting previously unselected package libmysqlclient18:amd64.
  31.     remote: Unpacking libmysqlclient18:amd64 (from .../libmysqlclient18_5.5.27-0ubuntu2_amd64.deb) ...
  32.     remote: Selecting previously unselected package libmysqlclient-dev.
  33.     remote: Unpacking libmysqlclient-dev (from .../libmysqlclient-dev_5.5.27-0ubuntu2_amd64.deb) ...
  34.     remote: Setting up mysql-common (5.5.27-0ubuntu2) ...
  35.     remote: Setting up libmysqlclient18:amd64 (5.5.27-0ubuntu2) ...
  36.     remote: Setting up libmysqlclient-dev (5.5.27-0ubuntu2) ...
  37.     remote: Processing triggers for libc-bin ...
  38.     remote: ldconfig deferred processing now taking place
  39.     remote: sudo: Downloading/unpacking Django==1.4.1 (from -r /home/application/current/requirements.txt (line 1))
  40.     remote:   Running setup.py egg_info for package Django
  41.     remote:
  42.     remote: Downloading/unpacking MySQL-python==1.2.3 (from -r /home/application/current/requirements.txt (line 2))
  43.     remote:   Running setup.py egg_info for package MySQL-python
  44.     remote:
  45.     remote:     warning: no files found matching 'MANIFEST'
  46.     remote:     warning: no files found matching 'ChangeLog'
  47.     remote:     warning: no files found matching 'GPL'
  48.     remote: Downloading/unpacking South==0.7.6 (from -r /home/application/current/requirements.txt (line 3))
  49.     remote:   Running setup.py egg_info for package South
  50.     remote:
  51.     remote: Installing collected packages: Django, MySQL-python, South
  52.     remote:   Running setup.py install for Django
  53.     remote:     changing mode of build/scripts-2.7/django-admin.py from 644 to 755
  54.     remote:
  55.     remote:     changing mode of /usr/local/bin/django-admin.py to 755
  56.     remote:   Running setup.py install for MySQL-python
  57.     remote:     building '_mysql' extension
  58.     remote:     gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -Dversion_info=(1,2,3,'final',0) -D__version__=1.2.3 -I/usr/include/mysql -I/usr/include/python2.7 -c _mysql.c -o build/temp.linux-x86_64-2.7/_mysql.o -DBIG_JOINS=1 -fno-strict-aliasing -g
  59.     remote:     In file included from _mysql.c:36:0:
  60.     remote:     /usr/include/mysql/my_config.h:422:0: warning: "HAVE_WCSCOLL" redefined [enabled by default]
  61.     remote:     In file included from /usr/include/python2.7/Python.h:8:0,
  62.     remote:                      from pymemcompat.h:10,
  63.     remote:                      from _mysql.c:29:
  64.     remote:     /usr/include/python2.7/pyconfig.h:890:0: note: this is the location of the previous definition
  65.     remote:     gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions -Wl,-Bsymbolic-functions -Wl,-z,relro build/temp.linux-x86_64-2.7/_mysql.o -L/usr/lib/x86_64-linux-gnu -lmysqlclient_r -lpthread -lz -lm -lrt -ldl -o build/lib.linux-x86_64-2.7/_mysql.so
  66.     remote:
  67.     remote:     warning: no files found matching 'MANIFEST'
  68.     remote:     warning: no files found matching 'ChangeLog'
  69.     remote:     warning: no files found matching 'GPL'
  70.     remote:   Running setup.py install for South
  71.     remote:
  72.     remote: Successfully installed Django MySQL-python South
  73.     remote: Cleaning up...
  74.     #####################################
  75.     #                OMIT               #
  76.     #####################################
  77.     To git@192.168.50.4.nip.io:blog.git
  78.        a211fba..bbf5b53  master -> master

运行应用

如你所见，部署的输出信息中有一个步骤叫做"重启你的应用"。在这个步骤中，如果应用在运行，tsuru会重启它，如果没有运行，tsuru会启动它。但是tsuru是如何启动一个应用呢？非常简单，它使用了一个Procfile（从Foreman中偷学的概念）。这个Procfile用于描述应用如何被启动。我们可以使用gunicorn去启动Django应用。如下是Procfile的内容：

  1.     web: gunicorn -b 0.0.0.0:$PORT blog.wsgi

现在我们提交文件并将其推送到tsuru的git服务器，再运行一次部署任务：

  1.     $ git add Procfile
  2.     $ git commit -m "Procfile: added file"
  3.     $ git push tsuru master
  4.     Counting objects: 5, done.
  5.     Delta compression using up to 4 threads.
  6.     Compressing objects: 100% (2/2), done.
  7.     Writing objects: 100% (3/3), 326 bytes, done.
  8.     Total 3 (delta 1), reused 0 (delta 0)
  9.     remote:
  10.     remote:  ---> tsuru receiving push
  11.     remote:
  12.     remote:  ---> Installing dependencies
  13.     remote: Reading package lists...
  14.     remote: Building dependency tree...
  15.     remote: Reading state information...
  16.     remote: python-dev is already the newest version.
  17.     remote: libmysqlclient-dev is already the newest version.
  18.     remote: 0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
  19.     remote: Requirement already satisfied (use --upgrade to upgrade): Django==1.4.1 in /usr/local/lib/python2.7/dist-packages (from -r /home/application/current/requirements.txt (line 1))
  20.     remote: Requirement already satisfied (use --upgrade to upgrade): MySQL-python==1.2.3 in /usr/local/lib/python2.7/dist-packages (from -r /home/application/current/requirements.txt (line 2))
  21.     remote: Requirement already satisfied (use --upgrade to upgrade): South==0.7.6 in /usr/local/lib/python2.7/dist-packages (from -r /home/application/current/requirements.txt (line 3))
  22.     remote: Cleaning up...
  23.     remote:
  24.     remote:  ---> Restarting your app
  25.     remote: /var/lib/tsuru/hooks/start: line 13: gunicorn: command not found
  26.     remote:
  27.     remote:  ---> Deploy done!
  28.     remote:
  29.     To git@192.168.50.4.nip.io:blog.git
  30.        81e884e..530c528  master -> master

现在我们碰到了一个错误：gunicorn: command not found。这意味需要在requirements.txt中添加gunicorn的依赖：

  1.     $ cat >> requirements.txt
  2.     gunicorn==0.14.6
  3.     ^D

提交修改，再次运行部署：

  1.     $ git add requirements.txt
  2.     $ git commit -m "requirements.txt: added gunicorn"
  3.     $ git push tsuru master
  4.     Counting objects: 5, done.
  5.     Delta compression using up to 4 threads.
  6.     Compressing objects: 100% (3/3), done.
  7.     Writing objects: 100% (3/3), 325 bytes, done.
  8.     Total 3 (delta 1), reused 0 (delta 0)
  9.     remote:
  10.     remote:  ---> tsuru receiving push
  11.     remote:
  12.     [...]
  13.     remote:  ---> Restarting your app
  14.     remote:
  15.     remote:  ---> Deploy done!
  16.     remote:
  17.     To git@192.168.50.4.nip.io:blog.git
  18.        530c528..542403a  master -> master

应用部署成功，可以通过app-list命令获得IP或者主机名，然后用浏览器去访问。比如，在下面的列表中：

  2.     $ tsuru app-list
  3.     +-------------+-------------------------+---------------------+
  4.     | Application | Units State Summary     | Address             |
  5.     +-------------+-------------------------+---------------------+
  6.     | blog        | 1 of 1 units in-service | blog.cloud.tsuru.io |
  7.     +-------------+-------------------------+---------------------+

可以通过http://blog.cloud.tsuru.io/admin/ 访问应用的管理界面。

使用服务

既然gunicorn在运行，我们就能通过浏览器访问应用，此时会碰到一个Django的错误："Can't connect to local MySQL server through socket'/var/run/mysqld/mysqld.sock' (2)"。这个错误的意思是我们不能在本地访问MySQL。这是因为我们不应该在本地连接MySQL，必须要使用服务。服务的工作流分为下面两步：

. 创建一个服务的实例. 将服务的实例绑定到应用但是如何知道哪些服务是可用的呢？这很简单，运行service-list命令：

  1.     $ tsuru service-list
  2.     +----------------+-----------+
  3.     | Services       | Instances |
  4.     +----------------+-----------+
  5.     | elastic-search |           |
  6.     | mysql          |           |
  7.     +----------------+-----------+

上面service-list的输出说明有两个可用的服务："elastic-search"和"mysql"，并且没有实例。通过service-add命令可以创建MySQL实例：

  1.     $ tsuru service-add mysql blogsql
  2.     Service successfully added.

现在，如果再次运行service-list命令，可以从输出中看到新的服务实例：

  1.     $ tsuru service-list
  2.     +----------------+-----------+
  3.     | Services       | Instances |
  4.     +----------------+-----------+
  5.     | elastic-search |           |
  6.     | mysql          | blogsql   |
  7.     +----------------+-----------+

使用service-bind命令将服务实例绑定到应用：

  1.     $ tsuru service-bind mysql blogsql
  2.     Instance blogsql is now bound to the app blog.
  4.     The following environment variables are now available for use in your app:
  6.     - MYSQL_PORT
  7.     - MYSQL_PASSWORD
  8.     - MYSQL_USER
  9.     - MYSQL_HOST
  10.     - MYSQL_DATABASE_NAME
  12.     For more details, please check the documentation for the service, using service-doc command.

从绑定的输出中我们看出，可以通过环境变量来连接MySQL服务器。下一步就是更新settings.py去使用这些环境变量去连接数据库：

  1.     import os
  3.     DATABASES = {
  4.         'default': {
  5.             'ENGINE': 'django.db.backends.mysql',
  6.             'NAME': os.environ.get('MYSQL_DATABASE_NAME', 'blog'),
  7.             'USER': os.environ.get('MYSQL_USER', 'root'),
  8.             'PASSWORD': os.environ.get('MYSQL_PASSWORD', ''),
  9.             'HOST': os.environ.get('MYSQL_HOST', ''),
  10.             'PORT': os.environ.get('MYSQL_PORT', ''),
  11.         }
  12.     }

现在提交修改，再次运行部署：

  1.     $ git add blog/settings.py
  2.     $ git commit -m "settings: using environment variables to connect to MySQL"
  3.     $ git push tsuru master
  4.     Counting objects: 7, done.
  5.     Delta compression using up to 4 threads.
  6.     Compressing objects: 100% (4/4), done.
  7.     Writing objects: 100% (4/4), 535 bytes, done.
  8.     Total 4 (delta 3), reused 0 (delta 0)
  9.     remote:
  10.     remote:  ---> tsuru receiving push
  11.     remote:
  12.     remote:  ---> Installing dependencies
  13.     #####################################
  14.     #               OMIT                #
  15.     #####################################
  16.     remote:
  17.     remote:  ---> Restarting your app
  18.     remote:
  19.     remote:  ---> Deploy done!
  20.     remote:
  21.     To git@192.168.50.4.nip.io:blog.git
  22.        ab4e706..a780de9  master -> master

如果再次尝试访问管理页面，会碰到另一个错误："Table 'blogsql.django_session' doesn't exist"。嗯，这意味着我们已经连接到了数据库，绑定起作用了，但是还没有建立数据库。需要在远程服务器运行syncdb和migrate（如果使用South的话）。使用app-run命令：

  1.     $ tsuru app-run -- python manage.py syncdb --noinput
  2.     Syncing...
  3.     Creating tables ...
  4.     Creating table auth_permission
  5.     Creating table auth_group_permissions
  6.     Creating table auth_group
  7.     Creating table auth_user_user_permissions
  8.     Creating table auth_user_groups
  9.     Creating table auth_user
  10.     Creating table django_content_type
  11.     Creating table django_session
  12.     Creating table django_site
  13.     Creating table django_admin_log
  14.     Creating table south_migrationhistory
  15.     Installing custom SQL ...
  16.     Installing indexes ...
  17.     Installed 0 object(s) from 0 fixture(s)
  19.     Synced:
  20.      > django.contrib.auth
  21.      > django.contrib.contenttypes
  22.      > django.contrib.sessions
  23.      > django.contrib.sites
  24.      > django.contrib.messages
  25.      > django.contrib.staticfiles
  26.      > django.contrib.admin
  27.      > south
  29.     Not synced (use migrations):
  30.      - blog.posts
  31.     (use ./manage.py migrate to migrate these)

migrate的使用类似.

部署钩子

每次部署后手动运行syncdb或者migrate会很烦人。所以我们可以配置一个自动的钩子，在每次应用重启前或者重启后运行。tsuru会解析一个名为tsuru.yaml的文件，并重启的钩子。如扩展所建议的那样，这是一个YAML文件，包含了一系列在重启前后要运行的命令。下面是一个tsuru.yaml文件的例子：

  1.     hooks:
  2.       build:
  3.         - python manage.py syncdb --noinput
  4.         - python manage.py migrate

更多内容，请查看tsuru.yaml中的钩子文档部分。tsuru会在项目的根目录查找这个文件。让我们提交并且部署它：

  2.     $ git add tsuru.yaml
  3.     $ git commit -m "tsuru.yaml: added file"
  4.     $ git push tsuru master
  5.     Counting objects: 4, done.
  6.     Delta compression using up to 4 threads.
  7.     Compressing objects: 100% (3/3), done.
  8.     Writing objects: 100% (3/3), 338 bytes, done.
  9.     Total 3 (delta 1), reused 0 (delta 0)
  10.     remote:
  11.     remote:  ---> tsuru receiving push
  12.     remote:
  13.     remote:  ---> Installing dependencies
  14.     remote: Reading package lists...
  15.     remote: Building dependency tree...
  16.     remote: Reading state information...
  17.     remote: python-dev is already the newest version.
  18.     remote: libmysqlclient-dev is already the newest version.
  19.     remote: 0 upgraded, 0 newly installed, 0 to remove and 15 not upgraded.
  20.     remote: Requirement already satisfied (use --upgrade to upgrade): Django==1.4.1 in /usr/local/lib/python2.7/dist-packages (from -r /home/application/current/requirements.txt (line 1))
  21.     remote: Requirement already satisfied (use --upgrade to upgrade): MySQL-python==1.2.3 in /usr/local/lib/python2.7/dist-packages (from -r /home/application/current/requirements.txt (line 2))
  22.     remote: Requirement already satisfied (use --upgrade to upgrade): South==0.7.6 in /usr/local/lib/python2.7/dist-packages (from -r /home/application/current/requirements.txt (line 3))
  23.     remote: Requirement already satisfied (use --upgrade to upgrade): gunicorn==0.14.6 in /usr/local/lib/python2.7/dist-packages (from -r /home/application/current/requirements.txt (line 4))
  24.     remote: Cleaning up...
  25.     remote:
  26.     remote:  ---> Restarting your app
  27.     remote:
  28.     remote:  ---> Running restart:after
  29.     remote:
  30.     remote:  ---> Deploy done!
  31.     remote:
  32.     To git@192.168.50.4.nip.io:blog.git
  33.        a780de9..1b675b8  master -> master

顺利完成！现在我们有了一个部署在tsuru上，使用MySQL服务的Django项目，

进一步探索

更多信息，可以查看tsuru文档，或者阅读tsuru命令完全使用指南。

原文: http://doc.oschina.net/tsuru-paas?t=52795