deployment - 具有不相关默认符号链接(symbolic link)的 Chef 部署

Question

我正在尝试使用 Chef 部署我的应用程序代码，该代码适用于一个节点，但在另一个节点上失败。我无法确定为什么它适用于一个节点而不适用于另一个节点(当它们具有完全相同的配置时)，但我至少可以尝试调试失败节点上的问题。

  deploy_revision app_config['deploy_dir'] do
    scm_provider Chef::Provider::Git 
    repo app_config['deploy_repo']
    revision app_config['deploy_branch']
    if secrets["deploy_key"]
      git_ssh_wrapper "#{app_config['deploy_dir']}/git-ssh-wrapper" # For private Git repos 
    end
    enable_submodules true
    shallow_clone false
    symlink_before_migrate({}) # Symlinks to add before running db migrations
    purge_before_symlink [] # Directories to delete before adding symlinks
    create_dirs_before_symlink [] # Directories to create before adding symlinks
    # symlinks()
    action :deploy
    restart_command do
      service "apache2" do action :restart; end
    end
  end

这是我部署代码的秘诀。请注意，我已尝试完全禁用符号链接(symbolic link)，因为 Chef 总是将其自己的默认值塞进去。即使如此，我也会收到错误:

================================================================================
Error executing action `deploy` on resource 'deploy_revision[/var/www]'
================================================================================


Chef::Exceptions::FileNotFound
------------------------------
Cannot symlink /var/www/shared/config/database.yml to /var/www/releases/7404041cf8859a35de90ae72091bea1628391075/config/database.yml before migrate: No such file or directory - /var/www/shared/config/database.yml or /var/www/releases/7404041cf8859a35de90ae72091bea1628391075/config/database.yml

Resource Declaration:
---------------------
# In /var/chef/cache/cookbooks/kapture/recipes/api.rb

 68: 
 69:   deploy_revision app_config['deploy_dir'] do
 70:     scm_provider Chef::Provider::Git 
 71:     repo app_config['deploy_repo']
 72:     revision app_config['deploy_branch']
 73:     if secrets["deploy_key"]
 74:       git_ssh_wrapper "#{app_config['deploy_dir']}/git-ssh-wrapper" # For private Git repos 
 75:     end
 76:     enable_submodules true

Compiled Resource:
------------------
# Declared in /var/chef/cache/cookbooks/kapture/recipes/api.rb:69:in `from_file'

deploy_revision("/var/www") do
  destination "/var/www/shared/cached-copy"
  symlink_before_migrate {"config/database.yml"=>"config/database.yml"}
  updated_by_last_action true
  restart_command #<Proc:0x00007f40f366e5a0@/var/chef/cache/cookbooks/kapture/recipes/api.rb:82>
  repository_cache "cached-copy"
  retries 0
  keep_releases 5
  create_dirs_before_symlink ["tmp", "public", "config"]
  updated true
  provider Chef::Provider::Deploy::Revision
  enable_submodules true
  deploy_to "/var/www"
  current_path "/var/www/current"
  recipe_name "api"
  revision "HEAD"
  scm_provider Chef::Provider::Git
  purge_before_symlink ["log", "tmp/pids", "public/system"]
  git_ssh_wrapper "/var/www/git-ssh-wrapper"
  remote "origin"
  shared_path "/var/www/shared"
  cookbook_name "kapture"
  symlinks {"log"=>"log", "system"=>"public/system", "pids"=>"tmp/pids"}
  action [:deploy]
  repo "git@github.com:kapture/api.git"
  retry_delay 2
end

[2012-09-24T15:42:07+00:00] ERROR: Running exception handlers
[2012-09-24T15:42:07+00:00] FATAL: Saving node information to /var/chef/cache/failed-run-data.json
[2012-09-24T15:42:07+00:00] ERROR: Exception handlers complete
[2012-09-24T15:42:07+00:00] FATAL: Stacktrace dumped to /var/chef/cache/chef-stacktrace.out
[2012-09-24T15:42:07+00:00] FATAL: Chef::Exceptions::FileNotFound: deploy_revision[/var/www] (kapture::api line 69) had an error: Chef::Exceptions::FileNotFound: Cannot symlink /var/www/shared/config/database.yml to /var/www/releases/7404041cf8859a35de90ae72091bea1628391075/config/database.yml before migrate: No such file or directory - /var/www/shared/config/database.yml or /var/www/releases/7404041cf8859a35de90ae72091bea1628391075/config/database.yml

在这里你可以看到它提到了database.yml、tmp/、system/和pids文件夹，所有这些都是 Chef 喜欢设置的默认值(请参阅 related bug )

问题1

这些符号链接(symbolic link)的用途是什么以及我如何知道我是否需要任何符号链接(symbolic link)。我正在符号链接(symbolic link)什么类型的东西？我将使用迁移，因此如果它们对迁移有用，那么我将需要它们工作。

我已经多次阅读该文档，但它并没有解释这是简单的英语 - 至少我没有找到。

问题2

如果我不需要它们，如何完全禁用符号链接(symbolic link)？遵循该错误报告中的示例并没有帮助。

Answer 1

清除所有符号链接(symbolic link)属性。

deploy_revision("/var/www") do
  # ...
  symlink_before_migrate.clear
  create_dirs_before_symlink.clear
  purge_before_symlink.clear
  symlinks.clear
end