Question

I am trying to deploy my application code with Chef, which is working for one node and failing on another. I cannot determine why it works for one node and not another when they have the exact same config, but I can at least try to debug the problem on the node that fails.

  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

This is my recipe for deploying the code. Notice that I have tried disabling symlinking entirely, as Chef always jams its own defaults in. Even with this I get the error:

================================================================================
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 "[e-mail]: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

Here you can see it mention database.yml, tmp/, system/ and pids folders, all of which are defaults that Chef likes to set (see related bug)

Question 1

What are these symlinks for and how do I know if I even need any. What sort of things am I symlinking? I will be using migrations, so if they are useful for the migration then I’ll need them working.

I have read the documentation many times and it just doesn’t explain this is plain English – at least not that I have found.

Question 2

If I do not require them, how can I disable symlinking entirely? Following the examples in that bug report have not helped.

Answer 1

Clear out all the symlink attributes.

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