So there I was, with my ruby model code happily sending out SNMP traps….or was it? For development (and test and qa) I set up the yaml file to send SNMP traps to localhost (port 162 is the default). I just needed a way to recieve them.
Enter snmptrapd.
Yes! A command line tool to catch the traps and log them the stdout! This turned out to be pretty easy on my MacBookPro - net-snmp is already installed.
The hardest part is setting up the authorization model. Do this: Create a file called snmptrapd.conf in the current directory. Add the line “disableAuthorization yes” to it. Heheh. No need for security - we just want to see them.
Now run the snmptrapd in the foreground, logging everything to stdout:
sudo snmptrapd -f -Lo -c snmptrapd.conf
Done. Now your messages will show up in that console window. This was not as nearly as painful as I expected!
So in the yml file, I will configure the snmp_trap_destination to be localhost for all environments except production. If there is no daemon running, they will quietly be ignored (UDP rocks). If there is one running (debugging qa, development) then they can be logged. Life is good, even when working with a 20 year old protocol.
(and thanks to atlantageek for one of the only blog posts out there about snmp and ruby!)
]]><%= render :partial => ‘p1′, :layout => ‘layouts/p_layout’ %> <%= render :partial => ‘p2′, :layout => ‘layouts/p_layout’ %>
layouts/p_layout.html.erb
<%= yield :top %> <%= yield %> <%= yield :bottom %> <hr/>
_p1.html.erb
<% content_for :top, 'HeaderFor1' %> <% content_for :bottom, 'FooterFor1' %> Content!
_p2.html.erb
<% content_for :top, 'HeaderFor2' %> <% content_for :bottom, 'FooterFor2' %> Content!
Did you expect this?
HeaderFor1 Content! FooterFor1
Nope. You get this:
HeaderFor1 Content! FooterFor1
The instance variables in the layout object retain their values, even between invocations of render. My workaround (since I’m not sure if some would call this a “feature”)…clear the instance variables at the end of your layout.
<%= yield :top %> <%= yield %> <%= yield :bottom %> <hr/> <% @content_for_top, @content_for_bottom = nil %>
Now it works as I expected.
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$ find services -name *.java -exec wc {} \; | awk '{a+=$1;print a}' |tail -1
64793
At my current client, we are writing a Rails web application. It’s been a living project for almost 2 years.
$ find app -name *.rb -exec wc {} \; | awk '{a+=$1;print a}' |tail -1
5133
$ find lib -name *.rb -exec wc {} \; | awk '{a+=$1;print a}' |tail -1
1141
$ find app -name *.erb -exec wc {} \; | awk '{a+=$1;print a}' |tail -1
3104
]]>Here’s the erb template for httpd.conf:
#
# Apache httpd.conf
# generated by cap. run by <%= user %> at <%= Time.now %>
#
ServerRoot “<%= current_release %>”
PidFile “<%= current_release %>/tmp/pids/httpd.pid”
LockFile “<%= current_release %>/log/accept.lock”
ServerName localhost
ServerAdmin “me”
Listen <%= web_port %>
# prefork MPM
# StartServers: number of server processes to start
# MinSpareServers: minimum number of server processes which are kept spare
# MaxSpareServers: maximum number of server processes which are kept spare
# MaxClients: maximum number of server processes allowed at a time
# MaxRequestsPerChild: maximum number of requests a server process serves until death
StartServers <%= apache_processes %>
MinSpareServers <%= apache_processes %>
MaxSpareServers <%= apache_processes %>
MaxClients 100
MaxRequestsPerChild 0
ErrorLog “<%= current_release %>/log/apache_error_log”
# Possible values include: debug, info, notice, warn, error, crit, alert, emerg
LogLevel info
LogFormat “%h %l %u %t \”%r\” %>s %b \”%{Referer}i\” \”%{User-Agent}i\”" combined
CustomLog “<%= current_release %>/log/apache_access_log” combined
#RewriteLog “<%= current_release %>/log/apache_rewrite_log”
# 0-9, 0 = off, 2 and 3 is good for debugging
#RewriteLogLevel 3
ServerTokens Prod
ServerSignature Off
DefaultType text/plain
TypesConfig /usr/local/apache2/conf/mime.types
AddType application/x-compress .Z
AddType application/x-gzip .gz .tgz
<% if behind_https %>
# for envs that sit behind an https load balancer
RequestHeader set X-FORWARDED_PROTO https
<% end %>
# using Passenger (http://www.modrails.com/) to serve Rails
LoadModule passenger_module <%= gem_home %>/passenger-1.0.1/ext/apache2/mod_passenger.so
RailsSpawnServer <%= gem_home %>/passenger-1.0.1/bin/passenger-spawn-server
RailsRuby <%= ruby_binary %>
RailsUserSwitching off
# max number of Rails processes to be spawned at a time
RailsMaxPoolSize <%= max_rails_processes %>
# spawner processes will be killed if idle for 60 minutes
RailsPoolIdleTime 3600
RailsEnv <%= environment %>
RailsAllowModRewrite on
RewriteEngine On
# Check for maintenance file and redirect all requests
RewriteCond %{DOCUMENT_ROOT}/system/maintenance.html -f
RewriteCond %{SCRIPT_FILENAME} !maintenance.html
RewriteRule ^.*$ %{DOCUMENT_ROOT}/system/maintenance.html [L]
DocumentRoot “<%= current_release %>/public”
<Directory <%= current_release %>/public>
Options FollowSymLinks
AllowOverride None
Order allow,deny
Allow from all
# Set the max size for file uploads to 10M
LimitRequestBody 10485760
</Directory>
<Directory />
Options FollowSymLinks
AllowOverride None
Order Deny,Allow
Deny from all
</Directory>
Here is the cap task to generate httpd.conf and upload it to the server:
desc "Generate the apache httpd.conf file from the template"
task :generate_apache_httpd_conf_file, :roles => :app do
require 'erb'
# set up defaults for some vars to go into the template. others are required.
apache_processes = fetch(:www_procs, 2)
max_rails_processes = fetch(:max_rails_procs, 2)
ruby_binary = fetch(:ruby_binary, "ruby")
gem_home = fetch(:gem_home, '/usr/local/lib/ruby/gems/1.8/gems')
behind_https = fetch(:fronted_by_https, false)
template = ERB.new(File.read('config/templates/httpd.conf.erb'), nil, '<>‘)
result = template.result(binding)
put(result, “#{current_release}/httpd.conf”)
end
It runs in an after_update_code task. This way, all server configs are under code control. This is huge! Each deployed environment’s settings are known and tracked - not just loosely keyed on each server. I treat Apache as part of our application - not a service that happens to be running that we deploy into. Using this technique, along with vendor_everything, we’ve minimized our host dependencies.
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