Tag Archives: merb

Chef Server – Threading Merb – Chef Server API Service

This will only make your api system faster if you have enough cpus to support it.
It should be 1 merb worker per core ( * i think * )

Install Apache and enable the necessary mods

$ apt-get -y install apache2
$ mkdir -p /usr/share/chef-server/public
$ for i in rewrite proxy status proxy_http proxy_balancer headers ; do a2enmod $i ; done

Stop Chef-Server

$ /etc/init.d/chef-server stop

Edit your Chef configuration file ( Replace Worker Threads and Port Numbers as needed )

$ sed -i s/PORT=4000/PORT=5000/g /etc/default/chef-server
$ echo "WORKERTHREADS=4" | tee -a /etc/default/chef-server

Edit the Chef init script ( Back it up first )

$ cp /etc/init.d/chef-server /etc/init.d/chef-server.original
$ sed -i '35s/DAEMON_OPTS="-p/DAEMON_OPTS="-c $WORKERTHREADS -p/g' /etc/init.d/chef-server
$ sed -i '42s/(ps/#(ps/g' /etc/init.d/chef-server
$ sed -i '/#(ps/ i (ps -fp $pid | egrep -q "merb.*( chef-server .*api.* spawner|worker .* $PORT)") || return 1' /etc/init.d/chef-server

Run diff to see the init script differences

$ diff /etc/init.d/chef-server /etc/init.d/chef-server.original
35c35
< DAEMON_OPTS="-c $WORKERTHREADS -p $PORT -e production -d -a $ADAPTER -P $PIDFILE -L $LOGFILE -C $CONFIG -u $USER -G $GROUP -V" --- > DAEMON_OPTS="-p $PORT -e production -d -a $ADAPTER -P $PIDFILE -L $LOGFILE -C $CONFIG -u $USER -G $GROUP -V"
42,43c42
< (ps -fp $pid | egrep -q "merb.*( chef-server .*api.* spawner|worker .* $PORT)") || return 1
<   #(ps -fp $pid | egrep -q "merb.*(merb : master|worker.*$PORT)") || return 1 --- >   (ps -fp $pid | egrep -q "merb.*(merb : master|worker.*$PORT)") || return 1

Get variables from your Chef config for apache config construction

$ THREADSCT=$(grep "WORKERTHREADS" /etc/default/chef-server |awk -F"=" '{print $2}')
$ NEWCOUNT=$(( THREADSCT -- ))
$ PORTPREFIX=$(grep "PORT" /etc/default/chef-server |awk -F"=" '{print $2}'| sed -e s/[0-9][0-9]$//g )
$ MYHOST=$(hostname -f)

Generate Your Apache Config – Generate the Load Balance Members

$ cd /etc/apache2/sites-available
$ echo "Listen 4000" |tee -a chef_loadbalancer
$ echo '<VirtualHost *:4000>' |tee -a chef_loadbalancer
$ echo "ServerName $MYHOST" |tee -a chef_loadbalancer
$ echo "" |tee -a chef_loadbalancer
$ echo "<Proxy balancer://cheflb>" | tee -a chef_loadbalancer
$ seq -w 00 $NEWCOUNT | while read i ; do echo "BalancerMember http://127.0.0.1:${PORTPREFIX}${i}" |tee -a chef_loadbalancer ; done

Append your Apache config with the rest of the relevant information

$ cat>>chef_loadbalancer<<EOF
</Proxy>
ProxyPass / balancer://cheflb
ProxyPassReverse / balancer://cheflb
DocumentRoot /usr/share/chef-server/public
LogLevel info
ErrorLog /var/log/chef/chef_server_apache2-error.log
CustomLog /var/log/chef/chef_server_apache2-access.log combined
RewriteEngine On
RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} !-f
RewriteRule ^/(.*)$ balancer://cheflb%{REQUEST_URI} [P,QSA,L]
</VirtualHost>
EOF

Enable your new apache config and start Apache and Chef-Server

$ a2ensite chef_loadbalancer
$ /etc/init.d/apache2 restart
$ /etc/init.d/chef-server start

Test your chef server

$ time knife node list
$ time knife role list

Reference:

Much of this information was stolen from : http://mrmiller.nonesensedomains.com/2010/06/15/chef-performance-tuning-part-1/
If this technique is outdated please make me aware of it or if my apache configuration is awful ( which i’m sure it is, i’m just too lazy to improve it )

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