Category Archives: Centos

cento tomcat

CentOS Tomcat server installation is easy!

CentOS Tomcat installation

CentOS Tomcat

centos tomcat

“Apache Tomcat is an open source software implementation of the Java Servlet and JavaServer Pages technologies. The Java Servlet and JavaServer Pages specifications are developed under the Java Community Process.” from Tomcat homepage.

 

Prerequisities

  • CentOS 6.x (I haven’t tested this on older versions but it should probably work as well) 

Check your Java installation

before we’ll continue the installation of Tomcat, the JDK (Java Development Kit) should be installed on your CentOS machine. to check for Java support use the command:

java -version

javanotfound

if bash returns ‘command not found‘ then continue to the next step and install the JDK, else skip the step and continue to Tomcat server installation.

 

Install Java Development Kit (JDK)

To install the jdk we have 2 options:

  1. Install OpenJDK – Using YUM.
  2. Install Oracle JDK – Install manually.

I’ll explore both:

Option 1: Install Open-JDK using YUM

For beginners and testing purposes you should go with this option.

Why should I use the Oracle JDK over the OpenJDK, or vice-versa? [closed]

The command to install JDK using YUM is very simple:

yum install java

yuminstall java

  • Note: use sudo if you are not logged-in with root.
  • the command will install the latest jdk (1.7 as for this date). If you want to install older version use the full name (search using: $ yum search jdk)yum-search-jdk
    You can see you can install the 1.6 version by typing: yum install java-1.6.0

Check you have installed it right:

javafound

 

Option 2: Install JDK manually

Download your required JDK here.

Note: I can’t give you an WGET command to download, because you need to Accept License Agreement before downloading any file.

You can download and install using the RPM or the tar.gz (both with x86 or x64) on your CentOS machine:

downloadjava

 

 

In case of our CentOS we can download and install the .rpm file or the .tar.gz file.

RPM can be installed ONLY by the root.
TAR.GZ can be installed be any user on the computer.

 

Option A: Install using .rpm

make sure to uninstall older installations (if any):

rpm –e <package name>

To install the jdk using the downloaded rpm use the rpm command:

rpm –ivh jdk-7u45-linux-x64.rpm

If you just want to upgrade a package you’ve already installed use the -Uvh parameter.

rpm –Uvh jdk-7u45-linux-x64.rpm

Delete the .rpm file if you want to save disk space.

Read more about installation of Oracle Java on Centos here on ItekBlog

 

Use alternatives :

alternatives –install /usr/bin/java java /usr/java/latest/jre/bin/java 20000
alternatives –install /usr/bin/javaws javaws /usr/java/latest/jre/bin/javaws 20000

alternatives

and config your default jdk (if you have more then one) using:

using:

alternatives –config java

alternatives-config

 

Test your environment

Just as in the first step: type java -version to see if your have jdk installed.

oraclejavaversion

 

Option B: Install using tar.gz

The advantage of tar.gz installation of the JDK is that we can able to install multiple version of java if required.

The archive can be installed by anyone (not only root users), in any location that you can write to. However, only the root user can install the JDK into the system location.

You need to unpack the .tar.gz file (using tar -xzf) into the  the location where you would like the JDK to be installed.

Unpack the tarball and install the jdk:

tar zxvf jdk-7u<version>-linux-i586.tar.gz

Delete the .tar.gz file if you want to save disk space.

 

Use alternatives :

alternatives –install /usr/bin/java java /path/to/jdk1.7.0_45/bin/java 2
alternatives –config java

read more about installation of jdk in the oracle documentation.

for extended installation tutorial read this post by adam in this blog.

 

JDK 1.6 vs JDK 1.7

read more on What is the difference between jdk 1.6 and 1.7 ?

 

Environment Variables

1
JAVA_HOME

 is a 

1
environment

 variable (in Unix terminologies), or a PATH variable (in Windows terminology) you need to create to point to where Java is installed. ($JAVA_HOME/bin/java should execute the Java runtime).

Why doesn’t the Java SDK installer set JAVA_HOME?

To set it for your current session type at bash:

export JAVA_HOME=/usr/java/jdk1.7.0_05
export PATH=$PATH:$JAVA_HOME/bin

To set the JAVA_HOME permanently we need to add the commands to the ~/.bash_profile file of the user.
We can also add it /etc/profile and then source it to give to all users.

 

Test Environment Variables

use the echo command to check you’ve configured the variables:

echo $JAVA_HOME
echo $PATH

echovars

 

Installing Tomcat

After we have java installed and tested we can continue to the installation of the Tomcat server.

Download Tomcat

Since Apache Tomcat is distributed as binaries, all you have to do is to download it and start it.

Download apache-tomcat-x.x.xx.tar.gz (latest version or any) from Apache Tomcat Homepage

I’ll go with the tomcat 8 – tar.gz package.

centos tomcat

centos tomcat

and using command:

cd /usr/share
wget http://apache.spd.co.il/tomcat/tomcat-8/v8.0.0-RC10/bin/apache-tomcat-8.0.0-RC10.tar.gz

tomcat-wget

verify and extract the download using::

md5sum apache-tomcat-8.0.0-RC10.tar.gz
tar xvzf apache-tomcat-8.0.0-RC10.tar.gz

and I have a /usr/share/apache-tomcat-8.0.0-RC10 folder now.

 

Test Tomcat server

Tomcat by default start on port 8080 you can start the server now by typing at bash:

cd apache-tomcat-8.0.0-RC10
./bin/startup.sh

tomcat-start

 

Now Access the tomcat by connecting your server with a web browser on port 8080.

http://localhost:8080

tomcat

If you cannot access the above Tomcat page, make sure to stop iptables (since CentOS has iptables on by default set to block the Tomcat’s default listening port 8080).

service iptables stop

to permanently disable iptables (NOT RECOMMENDED AT ALL) use:

chkconfig iptables off

Change the Tomcat server port

Locate server.xml in {Tomcat installation folder}/conf/ which is at /usr/share/apache-tomcat-8.0.0-RC10/conf in our case

Find the following:

 <!-- Define a non-SSL HTTP/1.1 Connector on port 8180 -->
    <Connector port="8080" maxHttpHeaderSize="8192"
               maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
               enableLookups="false" redirectPort="8443" acceptCount="100"
               connectionTimeout="20000" disableUploadTimeout="true" />

and change the 8080 port to your required port.

 

Start on boot

To start the tomcat service on system boot create the file /etc/init.d/tomcat8 (I am using vi /etc/init.d/tomcat8) and fill it with:

#!/bin/bash 
# description: Tomcat Start Stop Restart 
# processname: tomcat 
# chkconfig: 234 20 80 
JAVA_HOME=/usr/java/jdk1.7.0_05 
export JAVA_HOME 
PATH=$JAVA_HOME/bin:$PATH 
export PATH 
CATALINA_HOME=/usr/share/apache-tomcat-8.0.0-RC10
 
case $1 in 
start) 
sh $CATALINA_HOME/bin/startup.sh 
;; 
stop) 
sh $CATALINA_HOME/bin/shutdown.sh 
;; 
restart) 
sh $CATALINA_HOME/bin/shutdown.sh 
sh $CATALINA_HOME/bin/startup.sh 
;; 
esac 
exit 0

Now set the permissions on the file and the catalina.sh file:

chmod a+x /etc/init.d/tomcat8
chmod a+x /usr/share/apache-tomcat-8.0.0-RC10/bin/catalina.sh

to start/stop/restart the service use:

service tomcat8 start
service tomcat8 restart
service tomcat8 stop

to start the service on boot use:

chkconfig --add tomcat8
chkconfig tomcat8 on

to disable it later you can use off instead of on:

chkconfig tomcat8 off

 

 

That’s it! you have your CentOS Tomcat server working and runing… 

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G-WAN

CentOS G-WAN server installation instructions

CentOS G-WAN Server

CentOS G-WAN server

G-WAN is a web server with scripts in Asm, C, C++, C#, D, Go, Java, Javascript, Lua, Objective-C, Perl, PHP, Python, Ruby and Scala.

G-WAN better uses CPU Cores
to make the Internet of Things
fly thousand times higher !

Leverage legacy servers and
low-consumption CPUs to
do more with less!

G-WAN works best on Linux distributions like Debian or CentOS, both of which offer ‘Desktop’ and ‘Server’ flavors.

 

CentOS G-WAN server installation instructions

CentOS G-WAN installation instructions

 

Installation

choose a location for your installation. for demonstration purposes we’ll install G-WAN to /opt

cd /opt
wget http://gwan.com/archives/gwan_linux64-bit.tar.bz2
tar -xjf gwan_linux64-bit.tar.bz2; cd gwan_linux64-bit
sudo ./gwan
centos g-wan

centos g-wan

use the 32bit version instead (http://gwan.com/archives/gwan_linux32-bit.tar.bz2) if you need.

Test

Then, type http://localhost:8080/ in your browser

centos g-wan

centos g-wan server default homepage

and play with the/gwan/.../csp samples.

 

Programming Languages

If you want to install more Programming Languages read the FAQ – Setup of Programming Languages

To install all 15 languages using the bash script donated by generous user on many Linux distributions (Debian, LinuxMint, CentOS, Fedora, RedHat, Manjaro, Arch Linux and Bridge) use:

cd /opt
wget http://www.as2.com/linux/tools/G-WAN_full-install.tar.bz2
tar -xjf G-WAN_full-install.tar.bz2
./G-WAN_full-install

The installation menu is available in English, German, French and Spanish!

 

Service mode

To start G-WAN as a service (make it start automatically at boot time) use this instructions

with one exception for CentOS in the manual:

instead of:

sudo update-rc.d gwan defaults 95 5

use:

sudo chkconfig gwan on

and you don’t need to restart.

 

What’s next?

check the API and Frequently Asked Questions.

Stackoverflow lists many more examples and will let you search for replies to common questions.

 

And that’s it. you have G-WAN server.

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Linux_Logo_Photos

iptables examples on CentOS

Overview

“iptables is a user space application program that allows a system administrator to configure the tables provided by the Linux kernel firewall (implemented as different Netfilter modules) and the chains and rules it stores.
Different kernel modules and programs are currently used for different protocols; iptables applies to IPv4, ip6tables to IPv6, arptables to ARP, and ebtables to Ethernet frames.”

In this tutorial I will give a few essential examples of how to use iptables on CentOS

iptables

There are several ways to configure iptables on CentOS.
The simplest way is to use the command system-config-firewall/system-config-firewall-tui, it will help you set up standard rules like Web Server, FTP Server and a few more.
The second way is to use iptables command to edit the configuration – this method is best for testing since it will NOT save the settings until you run the command:

/etc/init.d/iptables save

The third way is to edit the file /etc/sysconfig/iptables and that is what I will show you today.

iptables chains

First we clear the content of /etc/sysconfig/iptables using:

echo > /etc/sysconfig/iptables

Set all the default chains to DROP and save the file:

*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT DROP [0:0]

Now we are ready to insert the necessary rules to our chains.

Stateful configuration

Using a stateful rule to allow all established connections:

#Allow all Established connections
-A INPUT -p all -m state --state ESTABLISHED -j ACCEPT
-A OUTPUT -p all -m state --state ESTABLISHED -j ACCEPT

Some services requires you to allow related connections (ftp,tftp…):

#Allow all Related connections
-A INPUT -p all -m state --state RELATED -j ACCEPT
-A OUTPUT -p all -m state --state RELATED -j ACCEPT

iptables examples

Allow LocalHost

First we need to insert a rule to allow localhost to communicate:

#All localhost
-A INPUT -i lo -j ACCEPT
-A OUTPUT -o lo -j ACCEPT

Allow Web Browsing

#Out Internet Access
-A OUTPUT -p tcp --dport 80 -m state --state NEW -j ACCEPT

#Out Internet Access SSL
-A OUTPUT -p tcp --dport 443 -m state --state NEW -j ACCEPT

Allow Outgoing SSH

#Out SSH
-A OUTPUT -p tcp --dport 22 -m state --state NEW -j ACCEPT

Allow Incoming SSH

Allow Incoming SSH from a specified subnet/ip address

#In SSH
-A INPUT -p tcp -s 10.0.0.0/24 --dport 22 -m state --state NEW -j ACCEPT

Allow Incoming SSH from all

#In SSH
-A INPUT -p tcp --dport 22 -m state --state NEW -j ACCEPT

Allow Incoming Web Server

#In Internet Access Port 80
-A INPUT -p tcp --dport 80 -m state --state NEW -j ACCEPT

#In Internet Access SSL Port 443
-A INPUT -p tcp --dport 443 -m state --state NEW -j ACCEPT

Allow DHCP Client

#In/Out DHCP Client
-A INPUT -p udp --sport 67 --dport 68 -j ACCEPT
-A OUTPUT -p udp --sport 68 --dport 67 -j ACCEPT

Allow DHCP Server

#In/Out DHCP Server
-A INPUT -p udp --sport 68 --dport 67 -j ACCEPT
-A OUTPUT -p udp --sport 67 --dport 68 -j ACCEPT

Allow DNS requests

#Out DNS
-A OUTPUT -p udp --dport 53 -m state --state NEW -j ACCEPT

Allow Incoming ping

#In ping
-A INPUT -p icmp --icmp-type echo-request -j ACCEPT
-A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT

Allow Outgoing ping

#Out ping
-A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT
-A INPUT -p icmp --icmp-type echo-reply -j ACCEPT

Allow Zabbix Agent

#In Zabbix Agent
-A INPUT -p tcp --dport 10050 -m state --state NEW -j ACCEPT

Allow Outgoing RDP

#Out RDP
-A OUTPUT -p tcp --dport 3389 -m state --state NEW -j ACCEPT

Allow Incoming RDP Server

#In RDP
-A INPUT -p tcp --dport 3389 -m state --state NEW -j ACCEPT

Allow SMTP Server

#In SMTP
-A INPUT -p tcp --dport 25 -m state --state NEW -j ACCEPT

Allow SMTP Client

#Out SMTP
-A OUTPUT -p tcp --dport 25 -m state --state NEW -j ACCEPT

Allow SMTPs Server

#In SMTPs
-A INPUT -p tcp --dport 465 -m state --state NEW -j ACCEPT

Allow SMTPs Client

#Out SMTPs
-A OUTPUT -p tcp --dport 465 -m state --state NEW -j ACCEPT

Allow SMTP TLS Server

#In SMTP TLS
-A INPUT -p tcp --dport 587 -m state --state NEW -j ACCEPT

Allow SMTP TLS Client

#Out SMTP TLS
-A OUTPUT -p tcp --dport 587 -m state --state NEW -j ACCEPT

Allow POP Server

#In POP
-A INPUT -p tcp --dport 110 -m state --state NEW -j ACCEPT

Allow POP Client

#Out POP
-A OUTPUT -p tcp --dport 110 -m state --state NEW -j ACCEPT

Allow POPs Server

#In POPs
-A INPUT -p tcp --dport 995 -m state --state NEW -j ACCEPT

Allow POPs Client

#Out POPs
-A OUTPUT -p tcp --dport 995 -m state --state NEW -j ACCEPT

Allow IMAP Server

#In IMAP
-A INPUT -p tcp --dport 143 -m state --state NEW -j ACCEPT

Allow IMAP Client

#Out IMAP
-A OUTPUT -p tcp --dport 143 -m state --state NEW -j ACCEPT

Allow IMAPs Server

#In IMAPs
-A INPUT -p tcp --dport 993 -m state --state NEW -j ACCEPT

Allow IMAPs Client

#Out IMAPs
-A OUTPUT -p tcp --dport 993 -m state --state NEW -j ACCEPT

Allow mySQL Server

#In mySQL
-A INPUT -p tcp --dport 3306 -m state --state NEW -j ACCEPT

Allow mySQL Client

#Out mySQL
-A OUTPUT -p tcp --dport 3306 -m state --state NEW -j ACCEPT

Allow NTP Server

#In NTP
-A INPUT -p udp --dport 123 -m state --state NEW -j ACCEPT

Allow NTP Client

#Out NTP
-A OUTPUT -p udp --dport 123 -m state --state NEW -j ACCEPT

Allow rsync

#In rsync
-A INPUT -p tcp --dport 873 -m state --state NEW -j ACCEPT

#Out rsync
-A OUTPUT -p tcp --dport 873 -m state --state NEW -j ACCEPT

Allow rsyslogd

#In rsyslogd
-A INPUT -p tcp --dport 514 -m state --state NEW -j ACCEPT
-A INPUT -p udp --dport 514 -m state --state NEW -j ACCEPT

#Out rsyslogd
-A OUTPUT -p tcp --dport 514 -m state --state NEW -j ACCEPT
-A OUTPUT -p udp --dport 514 -m state --state NEW -j ACCEPT

Allow SAMBA Server

#In Samba
-A INPUT -p udp --dport 137:139 -m state --state NEW -j ACCEPT
-A INPUT -p tcp -m multiport --dport 139,445 -m state --state NEW -j ACCEPT

Allow NFS Server

NFS uses random ports on startup so we need to fix the port numbers, add the following lines to ‘/etc/sysconfig/nfs’:

RQUOTAD_PORT=875
LOCKD_TCPPORT=32803
LOCKD_UDPPORT=32769
MOUNTD_PORT=892
STATD_PORT=662
STATD_OUTGOING_PORT=2020
RDMA_PORT=20049

#In NFS
-A INPUT -p tcp -m multiport --dport 111,662,875,892,2020,2049,20049,32803 -m state --state NEW -j ACCEPT
-A INPUT -p udp -m multiport --dport 111,662,875,892,2020,2049,20049,32769 -m state --state NEW -j ACCEPT

Allow TFTP Server

TFTP needs an iptables module called “nf_conntrack_tftp”, edit ‘/etc/sysconfig/iptables-config’ and make sure you have:

IPTABLES_MODULES="nf_conntrack_tftp"

#In TFTP
-A INPUT -p tcp --dport 69 -m state --state NEW -j ACCEPT
-A INPUT -p udp --dport 69 -m state --state NEW -j ACCEPT

#You also need to allow related OUTPUT
-A OUTPUT -p all -m state --state RELATED -j ACCEPT

Allow Routing

Allow routing between Network-1 to Network-2 using 2 different NICs:

#Allow routing from eth0 to eth1
-A FORWARD -i eth0 -o eth1 -j ACCEPT

Specify port range

For example allow all communication from ports 100-200 to ports 200-300:

-A OUTPUT --sport 100:200 --dport 200:300 -j ACCEPT

Speciy IP Address range

IP Address range requires the ‘iprange’ module,
For example allow all communication to and from 10.0.0.1-10.0.0.100:

-A OUTPUT -m iprange --dst-range 10.0.0.1-10.0.0.100 -j ACCEPT
-A INPUT -m iprange --src-range 10.0.0.1-10.0.0.100 -j ACCEPT

Enjoy!

VMWare Workstation start on boot CentOS

SSL handshake failed: SSL error: Key usage violation in certificate has been detected CentOS

SSL handshake failed: SSL error: Key usage violation in certificate has been detected CentOS

Overview

SSL handshake failed: SSL error: Key usage violation in certificate has been detected.

SSL handshake failed: SSL error: Key usage violation in certificate has been detected CentOS.

SSL handshake failed: SSL error: Key usage violation in certificate has been detected CentOS.

 

Fix

You may experience the issue if both of the following conditions are met:

  • VisualSVN Server has a self-signed certificate applied and
  • Subversion client is built against the GnuTLS library.

GnuTLS library is an open-source alternative to OpenSSL. Most Subversion clients for Windows are built against OpenSSL and are not affected by this issue. While some Subversion packages (available mostly on Linux-based operating systems – The subversion that comes with EL 6 is linked against GnuTLS which is a change from older releases which linked against OpenSSL) are built against GnuTLS and are affected.

The server is using an SSL cert was created with the ‘key usage’ extension, and the client is using the gnutls SSL library which doesn’t understand the extension. The solution is either to have the client use the openssl library or to have the server use a cert that doesn’t use the ‘key usage’ extension.

It’s recommended to fix the issue on your server side, but you can workaround it from the client side too.

 

Fix (Server side)

Here is what visualsvn.com say:

It’s not recommended to use a self-signed certificate in a production environment. We advise to use a certificate issued by your domain or a third-party certificate authority instead of a self-signed one.

If you have to use a self-signed certificate please follow the instruction to generate a cerificate without specifying ‘Key Usage’ extension:

Add the following registry value to the Windows registry:

for 32-bit system:

[HKEY_LOCAL_MACHINE\SOFTWARE\VisualSVN\VisualSVN Server]
“CreateGnuTLSCompatibleCertificate”=dword:00000001

for 64-bit system:

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\VisualSVN\ VisualSVN Server]
“CreateGnuTLSCompatibleCertificate”=dword:00000001

Start VisualSVN Server Manager.
Go to Action | Properties | Certificate.
Click Change certificate… and follow the wizard instructions to generate a new self-signed certificate.

The certificate will be generated without the ‘Key Usage’ extension and will be compatible both with GnuTLS and OpenSSL.

 

Fix (Client side)

The options for client side fix are:

 

That’s it.

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vmware

VMWare Workstation start on boot CentOS

VMWare Workstation start on boot CentOS

vmware workstation start on boot centos

If you are like me, using VMWare workstation on Linux (CentOS 6.4), and you want to start your virtual machines on boot, I have the answer.

Prerequisities

  • CentOS 6.x. – although the vmrun command may be working in other distributions too.
  • VMWare Workstation 4.0+

 

 VMWare Workstation start on boot CentOS

VMWare Workstation start on boot CentOS

 

The Solution

Edit rc.local

add to the end of the following file:

/etc/rc.d/rc.local

the following:

vmrun -T ws start /path/to/machine.vmx nogui

create new line for each machine you want to start on boot.

 

that’s it! that how you run vmware workstation start on boot centos

 

That’s it.

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python-logo

Django CentOS 6.4 installation instructions for noobs.

Django Centos 6.4 installation instructions for noobs.

So you want to build your first django centos 6.4 based web site? This is quite easy to install and configure. I’ll cover how to install Python/Django on your centos.

Django Centos

Prerequisite

  • CentOS 6.4 (For the matter of fact, this tutuorial is good for all the CentOS 6.x series)
  • Apache (httpd)

 

What is Python?

Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Its syntax is said to be clear and expressive.” from Wikipedia.

Visit http://www.python.org/

 

What is Django?

“Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design.” from https://www.djangoproject.com/

Installing Python

Prerequisites

you may need the EPEL repositories for Centos.

cd /opt/
wget http://mirrors.nl.eu.kernel.org/fedora-epel/6/i386/epel-release-6-8.noarch.rpm
rpm -Uvh epel-release-6-8.noarch.rpm
rm epel-release-6-8.noarch.rpm -f

 

Installation Process

Simple as:

yum install python

test python by typing: “python” and you should see something similar to: (CTRL+D to exit)

At the time of writing (September 30 2013), the version of python@EPEL is 2.6.6

Django works with any Python version from 2.6.5 to 2.7. It also features experimental support for versions 3.2 and 3.3. All these versions of Python include a lightweight database called SQLite so you won’t need to set up a database just yet unless you need other SQL

 

Installing SQL

Django works with several DB engines. for simplicity, Install SQLite:

yum install sqlite

If you need other SQL Server else then SQLite,  you can follow:
MySQL/MongoDB/CouchDB on RHEL/Centos 6.3
If you don’t need SQL and you installed Python 2.5 or later, you can skip this step for now.

 

 

 

 

Installing Django

You can install using EPEL repositories any yum (like in the old article I wrote), but I recommend to use the easy_install method from the python-setuptools package, which I’ll show next:

yum install python-setuptools
easy_install django

 

Testing Django

Test Django by typing python on your command and then:

import django
print django.get_version()

python-django-1.5.4

As you can see, the RPM version is version 1.5.4, while the current release in the EPEL version is 1.3.1. Internationalization: in template code is not available in 1.3.1 for example but only from Django 1.4

 

 

Creating Project

From the command, cd into a directory where you’d like to store your app, then run the following command:

django-admin.py startproject mysite
cd mysite

 Note: if you are installing Django using EPEL repos, the command will be django-admin and not django-admin.py.

Starting Server

python manage.py runserver

You’ve started the Django development server, a lightweight Web server – easier to startwithout having to deal with configuring a production server — such as Apache — until you’re ready for production.

Browse to http://127.0.0.1:8000/ with your Web browser. You’ll see a “Welcome to Django” page. It worked!

To change port:

python manage.py runserver 8080

If you need to start the server to answer not only locally, use:

python manage.py runserver 0.0.0.0:8000

 

Remember: Apache loads Django environment when starting and keep running it even when source is changed! I suggest you to use Django ‘runserver’ (which automatically restarts on source code changes) in development sessions, unless you need some Apache-specific features.

 

Configure more…

Config Database

Edit mysite/settings.py. It’s a normal Python module with module-level variables representing Django settings.

Help here.

 

Django using Apache

To run your Django application inside apache – use either mod_python or mod_wsgi, Support for mod_python will be deprecated in a future release of Django. If you are configuring a new deployment, you are strongly encouraged to consider using mod_wsgi or any of the other supported backends.

 

OPTION A: Install mod_python (NOT recommended)

For this to work, you must have apache installed and configured.

yum install mod_python

python using mod_python

you need to configure you apache/VirtualHost to:


    AddHandler mod_python .py
    PythonHandler mod_python.publisher | .py
    AddHandler mod_python .psp .psp_
    PythonHandler mod_python.psp | .psp .psp_
    PythonDebug On

 

Testing mod_python

Create a ‘test.py’ file in your apache server. put inside:

<% req.write("Hello World!") %>

and browse to www.your.server/test.py and you should see the “Hello World!” there.

Django using mod_python

Edit your httpd.conf file:


<Location "/mysite/">
    SetHandler python-program
    PythonHandler django.core.handlers.modpython
    SetEnv DJANGO_SETTINGS_MODULE mysite.settings
    PythonOption django.root /mysite
    PythonDebug On
</Location>

read more…

 

 

Option B: Install mod_wsgi (RECOMMENDED)

Deploying Django with Apache and mod_wsgi is the recommended way to get Django into production.

yum install mod_wsgi

 

to use mod_wsgi, create an apache folder inside your project and create a django.wsgi file:

import os, sys
sys.path.append('/var/www/django')
sys.path.append('/var/www/django/mysite')
os.environ['DJANGO_SETTINGS_MODULE'] = 'mysite.settings'

import django.core.handlers.wsgi

application = django.core.handlers.wsgi.WSGIHandler()

 

and configure your apache with:

<VirtualHost *:80>

ServerName www.example.com
ServerAlias www.example.com
WSGIScriptAlias / /var/www/django/mysite/apache/django.wsgi

# Alias /robots.txt /var/www/django/mysite/static/robots.txt
# Alias /favicon.ico /var/www/django/mysite/static/favicon.ico
Alias /static/admin/ /usr/lib/python2.6/site-packages/django/contrib/admin/media/
Alias /static/ /var/www/django/mysite/static/
Alias /media/ /var/www/django/mysite/media/

<Directory /var/www/django/mysite>
Order allow,deny
Allow from all
</Directory>

<Directory /var/www/django/mysite/media>
Order deny,allow
Allow from all
</Directory>

<Directory /var/www/django/mysite/static>
Order deny,allow
Allow from all
</Directory>
</VirtualHost>

 

read more on: multiple django sites with apache & mod_wsgi

 

 

That’s it!

 

You’ve Python / Django installed on your Centos 6.4 and a new project template waiting for you to work on.

 

Continue reading…

* this article is an edited version of an older article.

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VMware Tools CentOS 6.x easy installation guide.

VMware Tools CentOS 6.x easy installation guide.

Prerequisities

if you have installed new setup of centos or you haven’t installed yet, you need make, gcc, kernel-devel..

Continue reading

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VMWare Workstation start on boot CentOS

CentOS RPMForge Installation Instructions (for Centos 6.x)

CentOS RPMForge Installation Instructions (for Centos 6.x)

Overview

If you want to add the RPMForge repo to your CentOS, use the following instructions

 

Downloading RPMForge repo

cd /tmp
# for 32 bit:
wget http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.i686.rpm
# for 64 bit:
wget http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm

Note: Visit here to see if newer version exist.

Installing RPMForge

rpm –import http://apt.sw.be/RPM-GPG-KEY.dag.txt

# for 32 bit:
rpm -i rpmforge-release-0.5.3-1.el6.rf.i686.rpm
# for 64 bit:
rpm -i rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm

yum clean all

Open Extra Repo

If you want, you can enable the extra repo using:

cd /etc/yum.repos.d

edit using vi/vom/mc rpmforge.repo:
change the enabled flag to enabled=1 in the section [rpmforge-extras].

 

Update all

yum update

 

That’s it!

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Update Git CentOS – to version 1.7.11+ (on CentOS 6.x)

Update Git Centos – to version 1.7.11+ (on CentOS 6.x)

Overview

If you want to update your Git to newer version then on CentOS repository, use the following instructions

 

Downloading RPMForge repo

cd /tmp
# for 32 bit:
wget http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.i686.rpm
# for 64 bit:
wget http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm

Note: Visit here to see if newer version exist.

Installing RPMForge

rpm –import http://apt.sw.be/RPM-GPG-KEY.dag.txt
# for 32 bit:
rpm -i rpmforge-release-0.5.3-1.el6.rf.i686.rpm
# for 64 bit:
rpm -i rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm

Open Extra Repo

yum clean all

cd /etc/yum.repos.d

edit using vi/vom/mc rpmforge.repo:
change the enabled flag to enabled=1 in the section [rpmforge-extras].

 

Update Git

yum update git

yum provides git will help you see all versions available.

git –version

Will show you have the new release installed. (1.7.11.3 for me)

 

That’s it!

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bash

Copy SSH public key to another server instructions

copy ssh public key

Prerequisities

You need to have a public key. If you haven’t generated keys before use:

ssh-keygen -t rsa

copy ssh public key is very simple. there are some ways to achieve this:

Using ssh-copy-id (recommended)

ssh-copy-id user@host

with this very simple command you can copy your public key to any user@host combination

Using scp

scp .ssh/id_rsa.pub user@host2:.ssh/authorized_keys

cd ~/ before.

The different is that scp will create a new file called authorized_keys while ssh-copy-id will add to id.

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Python vs PyPy installation and comparison (on Centos 6.x)

Python vs PyPy

in this article: Python vs PyPy I’ll explain how-to install both compilers (Python (CPython) and PyPy) on CentOS and the difference between them.

Requirements for examples:

  • Centos 6.x

 

Overview

The Download section of the Python official website (python.org) include list of several Alternative Implementations for python complier. some of them for Linux, some for Windows (.NET) and others.

I am going to review the default Python compiler vs PyPy on my CentOS 6.x machine.

 

python-logo

Python (nicknamed CPython)

Installation

yum install python

From Official website:

Python is a programming language that lets you work more quickly and integrate your systems more effectively. You can learn to use Python and see almost immediate gains in productivity and lower maintenance costs.

Python (nicknamed CPython) is the default Python Compiler you get with you installing Python.

Example

Create a file named ‘example.py‘ and fill it with:

print 'Hello, world!'

and type on bash:

python example.py

Note: you can also insert the following line as the first line in your .py file and then chmod +x this file to execute it as script:

#!/usr/lib/env python
print “Hello, world!”

and then on bash:

chmod +x example.py

and you can run the script (code) using:

./example.py

 

 

pypy-logo

PyPy

fast python implementation with a JIT compiler (generate native code on the fly) written in RPython and currently translated partly to C.
Arguments against PyPy compiled in Python are everywhere, but when C compiler gcc is implemented in C, is there any reason for the Python compiler to not be written in Python?

From Wikipedia:

PyPy is a Python interpreter and just-in-time compiler. PyPy focuses on speed, efficiency and compatibility with the original CPython interpreter.[1]

PyPy started out as a Python interpreter written in the Python language itself. Current PyPy versions are translated from RPython to C code and compiled. The PyPy JIT compiler is capable of turning Python code into machine code at run time.

 

Mission

The mission of PyPy is:

We aim to provide:

  • a common translation and support framework for producing implementations of dynamic languages, emphasizing a clean separation between language specification and implementation aspects. We call this the RPython toolchain.
  • a compliant, flexible and fast implementation of the Python Language which uses the above toolchain to enable new advanced high-level features without having to encode the low-level details. We call this PyPy.

By separating concerns in this way, our implementation of Python – and other dynamic languages – is able to automatically generate a Just-in-Time compiler for any dynamic language. It also allows a mix-and-match approach to implementation decisions, including many that have historically been outside of a user’s control, such as target platform, memory and threading models, garbage collection strategies, and optimizations applied, including whether or not to have a JIT in the first place.

 

How can it possibly beat CPython?

Manual memory management (which is what CPython does with its counting) can be slower than automatic management in some cases.

Limitations in the implementation of the CPython interpreter preclude certain optimisations that PyPy can do (eg. fine grained locks).

The JIT. Being able to on the fly confirm the type of an object can save you the need to do multiple pointer dereferences to finally arrive at the method you want to call.

 

Installation

yum install pypy

 

Using PyPy

To use pypy instead of your default CPython compiler you need to run your .py file with the pypy compiler.

to use pypy compiler you type at bash:

and type on bash:

pypy myapp.py

 

Summary

Python compiler (CPython) is the default and probably the safe choice so most python applications and modules will work; where PyPy can break some.

You should play with them both. Install them both on your CentOS and test / benchmark your applications using both compilers.

PyPy can rebust your web applcations (or any other code).

For example, Django app can be run on top of PyPy, with drawbacks.

 

Read more…

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gevent

gevent CentOS 6.x Installation Guide

gevent CentOS 6.x Installation Guide

gevent CentOS 6.x Installation Guide

Installation

Requirments

  • yum install python python-devel
  • yum install libevent-devel

 

Install Setuptools

install python-setuptools (for easy_install)

yum install python-setuptools

Install greenlet

Install greenlet:

easy_install greenlet

Install gevent

There are several ways to install gevent:

using easy_install (recommended)

easy as:

easy_install gevent

centos gevent

from source

You need wget to download source:

yum install wget

Now, installing gevent: (Check here for the latest package)

cd /tmp wget http://pypi.python.org/packages/source/g/gevent/gevent-0.13.8.tar.gz tar -xvzf gevent-0.13.8.tar.gz cd gevent-0.13.8 python setup.py install

U may need to add –no-check-certificate to the wget if something is wrong.

from GitHub

You can also install gevent from github using pip.

Test

to test simply run in bash:

python

and then:

import gevent

if no error found, you have installed it correctly python-import-gevent

First App

Example taken from the community documentation:

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from gevent.wsgi import WSGIServer
 
def application(environ, start_response):
    status = '200 OK'
    body = '<p>Hello World</p>'
 
    headers = [
        ('Content-Type', 'text/html')
    ]
 
    start_response(status, headers)
    return [body]
 
WSGIServer(('', 8000), application).serve_forever()
from gevent.wsgi import WSGIServer

def application(environ, start_response):
    status = '200 OK'
    body = '<p>Hello World</p>'

    headers = [
        ('Content-Type', 'text/html')
    ]

    start_response(status, headers)
    return [body]

WSGIServer(('', 8000), application).serve_forever()

copy the example into a file (server.py for ex), and start the server by:

python server.py

and that’s it! browse to the machine on port 8000 using something like this:

http://[ip of the machine]:8000

gevent-working

What’s next..?

 

Production

In production you can host your gevent after several WSGI server racks like: Gunicorn, Circus, Meinheld, uWSGI, etc..

Gunicorn is the most common WSGI server to host gevent applications. one benchmark shows that Circus is faster then Gunicorn. other tested uWSGI vs Gunicorn and found that uWSGI is faster.

recommend you run them behind a reverse proxy such as nginx. Additional advantages of running them behind a reverse proxy include improved handling of slow clients and bad HTTP requests

 

SocketIO

You need socketio? you may want to install it:

easy_install gevent-socketio

 

Read more…

 

need microframework? (flask/bottle)?

You can use a python web framework on top of gevent.

 

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