Linux Archives - Page 15 of 24

Yesterday I've started (after trying to restart Passenger) to see this exception coming out from Apache error.log:

[ pid=5098 thr=5896300 file=utils.rb:176 time=2012-08-31 19:00:45.293 ]:
*** Exception PhusionPassenger::UnknownError in 
PhusionPassenger::ClassicRails::ApplicationSpawner ((<unknown>): 
found a tab character that violate intendation while scanning a plain scalar at line 49 in 11
(Psych::SyntaxError)) (process 5098, thread #<Thread:0x00000000b3f0d8>):

Passenger ApplicationSpawner was endlessly creating new instances of my app, because the previous onces needed to be shutdown because of this error. It was quite obvious for me, that the error came from invalid yaml file (Psych::SyntaxError), however stack trace looked like this:

from /usr/local/lib/ruby/1.9.1/psych.rb:203:in `parse'
from /usr/local/lib/ruby/1.9.1/psych.rb:203:in `parse_stream'
from /usr/local/lib/ruby/1.9.1/psych.rb:151:in `parse'
from /usr/local/lib/ruby/1.9.1/psych.rb:127:in `load'
from /gems/settingslogic-2.0.8/lib/settingslogic.rb:114:in `initialize'
from /gems/settingslogic-2.0.8/lib/settingslogic.rb:71:in `new'
from /gems/settingslogic-2.0.8/lib/settingslogic.rb:71:in `instance'
from /gems/settingslogic-2.0.8/lib/settingslogic.rb:77:in `method_missing'
from /home/httpd/v5.senpuu.net/releases/20120829194758/config/initializers/resque.rb:5
from /gems/activesupport-3.2.8/lib/active_support/dependencies.rb:245:in `load'
from /gems/activesupport-3.2.8/lib/active_support/dependencies.rb:245:in `block in load'
from /gems/activesupport-3.2.8/lib/active_support/dependencies.rb:236:in `load_dependency'
from /gems/activesupport-3.2.8/lib/active_support/dependencies.rb:245:in `load'
from /gems/railties-3.2.8/lib/rails/engine.rb:588:in `block (2 levels) in <class:Engine>'
from /gems/railties-3.2.8/lib/rails/engine.rb:587:in `each'
from /gems/railties-3.2.8/lib/rails/engine.rb:587:in `block in <class:Engine>'
from /gems/railties-3.2.8/lib/rails/initializable.rb:30:in `instance_exec'
from /gems/railties-3.2.8/lib/rails/initializable.rb:30:in `run'
from /gems/railties-3.2.8/lib/rails/initializable.rb:55:in `block in run_initializers'
from /gems/railties-3.2.8/lib/rails/initializable.rb:54:in `each'
from /gems/railties-3.2.8/lib/rails/initializable.rb:54:in `run_initializers'
from /gems/railties-3.2.8/lib/rails/application.rb:136:in `initialize!'
from /gems/railties-3.2.8/lib/rails/railtie/configurable.rb:30:in `method_missing'

Ok, bot how to find the file with invalid yaml syntax? In my case, this exception was raised when SettingsLogic could not parse the given yaml file. So I've decided to hookup into it, just before the parsing, so I would be able to print out the invalid file. To do so I've edited /gems/settingslogic-2.0.8/lib/settingslogic.rb file. If you go to line 114 of this file, you will see something like this:

hash = YAML.load(ERB.new(File.read(hash_or_file)).result).to_hash
if self.class.namespace
  hash = hash[self.class.namespace] or return missing_key("Missing setting '#{self.class.namespace}' in #{hash_or_file}")
end

So in order to print the invalid file name we just need to add:

p hash_or_file

just before the YAML.load method execution. After this, it was really easy to find an invalid line in my yaml file.

Easier than I thought (all stuff as SU or using SUDO):

First we need to install some Mysql-Munin perl libraries:

apt-get install libipc-sharelite-perl

Also some Perl stuff will be needed:

perl -MCPAN -eshell
install IPC::ShareLite

Next let's activate Munin Mysql plugin:

# Assuming you have already installed both munin & mysql
ln -s /usr/share/munin/plugins/mysql_* /etc/munin/plugins

Create a user for a Mysql database (so Munin will be able to get stats as this user):

mysql> CREATE USER `munin` @`localhost` IDENTIFIED BY 'somepassword';
mysql> GRANT SUPER ON *.* TO `munin` @`localhost`;
mysql> FLUSH PRIVILEGES;

Edit /etc/munin/plugin-conf.d/munin-node file and find [mysql*] section:

[mysql*]
user root
env.mysqlopts --defaults-file=/etc/mysql/debian.cnf
env.mysqluser munin

Let's also disable WARN: MySQL InnoDB free tablespace information (in most cases it is not valid):

Create a file /etc/munin/plugin-conf.d/mysql_innodb and place following lines into it:

[mysql_innodb]
env.warning 0
env.critical 0

or if You don't need InnoDB part, just turn it off by removing the symlink:

rm /etc/munin/plugins/mysql_innodb

Restart both Apache & Munin:

/etc/init.d/apache2 restart
/etc/init.d/munin-node restart
su munin -c /usr/bin/munin-cron

Wait until charts regenerate and You're ready to go! Example (generated for the first time):

Category: Linux

PhusionPassenger::UnknownError: Psych::SyntaxError – tab character that violate intendation

Making Munin work with Mysql on Debian