用tsuru部署Ruby应用

概述

本文档是在tsuru中部署一个简单的Ruby应用的实战指南。例子应用是一个关联MySQL服务的简单Rails项目。

在tsuru中创建应用

使用app-create命令创建应用：

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

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

  1.     $ tsuru app-create blog ruby

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 |             |
  6.     +-------------+-------------------------+-------------+

应用代码

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

. 创建项目 (rails new blog)

. 为Post生成脚手架(rails generate scaffold Post title:string body:text)

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: ruby
  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tsuru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: 86, done.
  3.     Delta compression using up to 4 threads.
  4.     Compressing objects: 100% (75/75), done.
  5.     Writing objects: 100% (86/86), 29.75 KiB, done.
  6.     Total 86 (delta 2), reused 0 (delta 0)
  7.     remote: Cloning into '/home/application/current'...
  8.     remote: requirements.apt not found.
  9.     remote: Skipping...
  10.     remote: /home/application/current /
  11.     remote: Fetching gem metadata from https://rubygems.org/.........
  12.     remote: Fetching gem metadata from https://rubygems.org/..
  13.     #####################################
  14.     #          OMIT (see below)         #
  15.     #####################################
  16.     remote:  ---> App will be restarted, please check its log for more details...
  17.     remote:
  18.     To git@192.168.50.4.nip.io:blog.git
  19.      * [new branch]      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: ruby
  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Ruby中是bundler）。
    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，ruby的依赖也必须放在应用根目录名为Gemfile的文件中。因为要用Rails连接MySQL，我们需要用gem安装mysql，这个包依赖于：libmysqlclient-dev，因此requirements.apt内容如下：
  1.     libmysqlclient-dev

下面是Gemfile的内容:

  2.     source 'https://rubygems.org'
  4.     gem 'rails', '3.2.13'
  5.     gem 'mysql'
  6.     gem 'sass-rails',   '~> 3.2.3'
  7.     gem 'coffee-rails', '~> 3.2.1'
  8.     gem 'therubyracer', platforms: 'ruby'
  9.     gem 'uglifier', '>= 1.0.3'
  10.     gem 'jquery-rails'

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: The following extra packages will be installed:
  9.     remote:   libmysqlclient18 mysql-common
  10.     remote: The following NEW packages will be installed:
  11.     remote:   libmysqlclient-dev libmysqlclient18 mysql-common
  12.     remote: 0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
  13.     remote: Need to get 2360 kB of archives.
  14.     remote: After this operation, 9289 kB of additional disk space will be used.
  15.     remote: Get:1 http://archive.ubuntu.com/ubuntu/ quantal/main mysql-common all 5.5.27-0ubuntu2 [13.7 kB]
  16.     remote: Get:2 http://archive.ubuntu.com/ubuntu/ quantal/main libmysqlclient18 amd64 5.5.27-0ubuntu2 [949 kB]
  17.     remote: Get:3 http://archive.ubuntu.com/ubuntu/ quantal/main libmysqlclient-dev amd64 5.5.27-0ubuntu2 [1398 kB]
  18.     remote: Fetched 2360 kB in 2s (1112 kB/s)
  19.     remote: Selecting previously unselected package mysql-common.
  20.     remote: (Reading database ... 41063 files and directories currently installed.)
  21.     remote: Unpacking mysql-common (from .../mysql-common_5.5.27-0ubuntu2_all.deb) ...
  22.     remote: Selecting previously unselected package libmysqlclient18:amd64.
  23.     remote: Unpacking libmysqlclient18:amd64 (from .../libmysqlclient18_5.5.27-0ubuntu2_amd64.deb) ...
  24.     remote: Selecting previously unselected package libmysqlclient-dev.
  25.     remote: Unpacking libmysqlclient-dev (from .../libmysqlclient-dev_5.5.27-0ubuntu2_amd64.deb) ...
  26.     remote: Setting up mysql-common (5.5.27-0ubuntu2) ...
  27.     remote: Setting up libmysqlclient18:amd64 (5.5.27-0ubuntu2) ...
  28.     remote: Setting up libmysqlclient-dev (5.5.27-0ubuntu2) ...
  29.     remote: Processing triggers for libc-bin ...
  30.     remote: ldconfig deferred processing now taking place
  31.     remote: /home/application/current /
  32.     remote: Fetching gem metadata from https://rubygems.org/..........
  33.     remote: Fetching gem metadata from https://rubygems.org/..
  34.     remote: Using rake (10.1.0)
  35.     remote: Using i18n (0.6.1)
  36.     remote: Using multi_json (1.7.8)
  37.     remote: Using activesupport (3.2.13)
  38.     remote: Using builder (3.0.4)
  39.     remote: Using activemodel (3.2.13)
  40.     remote: Using erubis (2.7.0)
  41.     remote: Using journey (1.0.4)
  42.     remote: Using rack (1.4.5)
  43.     remote: Using rack-cache (1.2)
  44.     remote: Using rack-test (0.6.2)
  45.     remote: Using hike (1.2.3)
  46.     remote: Using tilt (1.4.1)
  47.     remote: Using sprockets (2.2.2)
  48.     remote: Using actionpack (3.2.13)
  49.     remote: Using mime-types (1.23)
  50.     remote: Using polyglot (0.3.3)
  51.     remote: Using treetop (1.4.14)
  52.     remote: Using mail (2.5.4)
  53.     remote: Using actionmailer (3.2.13)
  54.     remote: Using arel (3.0.2)
  55.     remote: Using tzinfo (0.3.37)
  56.     remote: Using activerecord (3.2.13)
  57.     remote: Using activeresource (3.2.13)
  58.     remote: Using coffee-script-source (1.6.3)
  59.     remote: Using execjs (1.4.0)
  60.     remote: Using coffee-script (2.2.0)
  61.     remote: Using rack-ssl (1.3.3)
  62.     remote: Using json (1.8.0)
  63.     remote: Using rdoc (3.12.2)
  64.     remote: Using thor (0.18.1)
  65.     remote: Using railties (3.2.13)
  66.     remote: Using coffee-rails (3.2.2)
  67.     remote: Using jquery-rails (3.0.4)
  68.     remote: Installing libv8 (3.11.8.17)
  69.     remote: Installing mysql (2.9.1)
  70.     remote: Using bundler (1.3.5)
  71.     remote: Using rails (3.2.13)
  72.     remote: Installing ref (1.0.5)
  73.     remote: Using sass (3.2.10)
  74.     remote: Using sass-rails (3.2.6)
  75.     remote: Installing therubyracer (0.11.4)
  76.     remote: Installing uglifier (2.1.2)
  77.     remote: Your bundle is complete!
  78.     remote: Gems in the groups test and development were not installed.
  79.     remote: It was installed into ./vendor/bundle
  80.     #####################################
  81.     #                OMIT               #
  82.     #####################################
  83.     To git@192.168.50.4.nip.io:blog.git
  84.        9515685..d67c3cd  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用来描述应用如何被启动。如下是Procfile的内容：

  1.     web: bundle exec rails server -p $PORT -e production

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.     #####################################
  5.     #                OMIT               #
  6.     #####################################
  7.     remote:  ---> App will be restarted, please check its log for more details...
  8.     remote:
  9.     To git@192.168.50.4.nip.io:blog.git
  10.        d67c3cd..f2a5d2d  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.     +-------------+-------------------------+---------------------+

使用服务

应用没有成功运行，原因在于rails不能连接到MySQL服务器，而我们在rails应用和MySQL实例之间添加了关联关系。要实现这点，必须使用一个服务.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conf/database.yml去使用这些环境变量去连接数据库：

  2.     production:
  3.       adapter: mysql
  4.       encoding: utf8
  5.       database: <%= ENV["MYSQL_DATABASE_NAME"] %>
  6.       pool: 5
  7.       username: <%= ENV["MYSQL_USER"] %>
  8.       password: <%= ENV["MYSQL_PASSWORD"] %>
  9.       host: <%= ENV["MYSQL_HOST"] %>

现在提交修改，再次运行部署：

  1.     $ git add conf/database.yml
  2.     $ git commit -m "database.yml: 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

如果现在尝试访问admin页面，会得到另外一个错误："Table 'blogsql.django_session' doesn't exist"。这意味着绑定成功，可以访问数据库服务器，但是数据库还没有建立。需要在远程服务器运行rake db:migrate。我们可以使用app-run在机器上执行命令，所以对于运行rake db:migrate，可以这么写：

  1.     $ tsuru app-run -- RAILS_ENV=production bundle exec rake db:migrate
  2.     ==  CreatePosts: migrating ====================================================
  3.     -- create_table(:posts)
  4.        -> 0.1126s
  5.     ==  CreatePosts: migrated (0.1128s) ===========================================

部署钩子

每次部署后手动运行rake db: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，运行重启的钩子。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.       restart:
  3.         before-each:
  4.           - RAILS_ENV=production bundle exec rake db: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：

  1.     $ git add tsuru.yaml
  2.     $ git commit -m "tsuru.yaml: added file"
  3.     $ git push tsuru master
  4.     #####################################
  5.     #                OMIT               #
  6.     #####################################
  7.     To git@192.168.50.4.nip.io:blog.git
  8.        a780de9..1b675b8  master -> master

在应用重启前，有必要编译资源文件。可以用rake assets:precompile命令实现。让我们把这个命令加入tsuru.yaml文件中：

  1.     hooks:
  2.       build:
  3.         - RAILS_ENV=production bundle exec rake assets:precompile
  1.     $ git add tsuru.yaml
  2.     $ git commit -m "tsuru.yaml: added file"
  3.     $ git push tsuru master
  4.     #####################################
  5.     #                OMIT               #
  6.     #####################################
  7.     To git@192.168.50.4.nip.io:blog.git
  8.        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Rails项目，现在我们可以访问app-info返回的blog app的URL了。

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=52818