Can't connect to MySQL socket

database.yml

production:
 adapter: mysql2
 encoding: utf8
 reconnect: false
 database: mailserver
 pool: 5
 username: mailposty
 password: mailposty
 socket: mysql socket path (/var/run/mysqld/mysqld.sock)
development:
 adapter: mysql2
 encoding: utf8
 reconnect: false
 database: mailserver
 pool: 5
 username: mailposty
 password: mailposty
 socket: mysql socket path (/var/run/mysqld/mysqld.sock)
test:
 adapter: mysql2
 encoding: utf8
 reconnect: false
 database: mailserver
 pool: 5
 username: mailposty
 password: mailposty
 socket: mysql socket path (/var/run/mysqld/mysqld.sock)

Error message

$  ls -l /var/run/mysqld/mysqld.sock 
srwxrwxrwx 1 mysql mysql 0 Mar  8 20:39 /var/run/mysqld/mysqld.sock


$ sudo rake db:migrate
rake aborted!
Can't connect to local MySQL server through socket 'mysql socket path (/var/run/mysqld/mysqld.sock)' (2)
/var/lib/gems/1.9.1/gems/mysql2-0.3.11/lib/mysql2/client.rb:44:in `connect'
/var/lib/gems/1.9.1/gems/mysql2-0.3.11/lib/mysql2/client.rb:44:in `initialize'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/mysql2_adapter.rb:16:in `new'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/mysql2_adapter.rb:16:in `mysql2_connection'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:315:in `new_connection'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:325:in `checkout_new_connection'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:247:in `block (2 levels) in checkout'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `loop'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `block in checkout'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:239:in `checkout'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:102:in `block in connection'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:101:in `connection'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:410:in `retrieve_connection'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_specification.rb:171:in `retrieve_connection'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_specification.rb:145:in `connection'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:662:in `initialize'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:570:in `new'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:570:in `up'
/var/lib/gems/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:551:in `migrate'
/opt/posty_api/Rakefile:17:in `block (2 levels) in <top (required)>'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:246:in `call'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:246:in `block in execute'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:241:in `each'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:241:in `execute'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:184:in `block in invoke_with_call_chain'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:177:in `invoke_with_call_chain'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:170:in `invoke'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:143:in `invoke_task'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:101:in `block (2 levels) in top_level'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:101:in `each'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:101:in `block in top_level'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:110:in `run_with_threads'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:95:in `top_level'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:73:in `block in run'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:160:in `standard_exception_handling'
/var/lib/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:70:in `run'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

my.cnf

#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
# 
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html

# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
[client]
port		= 3306
socket		= /var/run/mysqld/mysqld.sock

# Here is entries for some specific programs
# The following values assume you have at least 32M ram

# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket		= /var/run/mysqld/mysqld.sock
nice		= 0

[mysqld]
#
# * Basic Settings
#
user		= mysql
pid-file	= /var/run/mysqld/mysqld.pid
socket		= /var/run/mysqld/mysqld.sock
port		= 3306
basedir		= /usr
datadir		= /var/lib/mysql
tmpdir		= /tmp
lc-messages-dir	= /usr/share/mysql
skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address		= 127.0.0.1
#
# * Fine Tuning
#
key_buffer		= 16M
max_allowed_packet	= 16M
thread_stack		= 192K
thread_cache_size       = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover         = BACKUP
#max_connections        = 100
#table_cache            = 64
#thread_concurrency     = 10
#
# * Query Cache Configuration
#
query_cache_limit	= 1M
query_cache_size        = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file        = /var/log/mysql/mysql.log
#general_log             = 1
#
# Error logging goes to syslog due to /etc/mysql/conf.d/mysqld_safe_syslog.cnf.
#
# Here you can see queries with especially long duration
#log_slow_queries	= /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
#       other settings you may need to change.
#server-id		= 1
#log_bin			= /var/log/mysql/mysql-bin.log
expire_logs_days	= 10
max_binlog_size         = 100M
#binlog_do_db		= include_database_name
#binlog_ignore_db	= include_database_name
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem



[mysqldump]
quick
quote-names
max_allowed_packet	= 16M

[mysql]
#no-auto-rehash	# faster start of mysql but no tab completition

[isamchk]
key_buffer		= 16M

#
# * IMPORTANT: Additional settings that can override those from this file!
#   The files must end with '.cnf', otherwise they'll be ignored.
#
!includedir /etc/mysql/conf.d/