Category Archives: Work

Step by Step Procedure To Setup Cassandra Cluster On Any Linux Distribution

Step by Step procedure to set-up Cassandra Cluster On Any Linux Distribution

1. What is Cassandra : Cassandra is an open source distributed database management system designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure.

2. Cassandra Cluster: A cluster is arranged as a ring of nodes. Clients send read/write requests to any node in the ring; that node takes on the role of coordinator node, and forwards the request to the node responsible for servicing it. A partitioner decides which nodes store which rows. The recommended partitioners assign rows to nodes based on a hash value of the row key. Nodes are assigned tokens that evenly divide the full range of possible hash values.

3. Prerequisites :
Setup iptables, allow below Cassandra ports.
For Centos:
iptables -A INPUT -p tcp -m tcp –dport 9160 -j ACCEPT
iptables -A INPUT -p tcp -m tcp –dport 7000 -j ACCEPT
iptables -A INPUT -p tcp -m tcp –dport 7001 -j ACCEPT
service iptables restart

For Ubuntu:
iptables -A INPUT -p tcp -m tcp –dport 9160 -j ACCEPT
iptables -A INPUT -p tcp -m tcp –dport 7000 -j ACCEPT
iptables -A INPUT -p tcp -m tcp –dport 7001 -j ACCEPT
sudo sh -c “iptables-save > /etc/iptables.rules”
sudo iptables-apply /etc/iptables.rules
Applying new iptables rules from ‘/etc/iptables.rules’… done.
Can you establish NEW connections to the machine? (y/N) y
… then my job is done. See you next time.

4. Installing Cassandra and Configuring: Login to Remote machine, where you want to install Cassandra.
Below are the steps to install and configure Cassandra Cluster.

Get Cassandra tar-ball
wget “http://downloads.datastax.com/community/dsc-cassandra-2.1.7-bin.tar.gz” -P /usr/share/
Setup Cassandra environment under /usr/share
tar -xvzf /usr/share/dsc-cassandra-2.1.7-bin.tar.gz -C /usr/share/

Delete tar file
rm -rf /usr/share/dsc-cassandra-2.1.7-bin.tar.gz

Cassendra configuration change cluster_name : change clustername with your Cluster
sed -i ‘s/Test Cluster/{{clustername}}/g’ /usr/share/dsc-cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change listen_address : hostname=serverip
sed -i ‘s/listen_address\:\ localhost/listen_address\:\ {{hostname}}/g’ /usr/share/dsc-cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change rpc_address
sed -i ‘s/rpc_address\:\ localhost/rpc_address\:\ 0.0.0.0/g’ /usr/share/dsc-cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change endpoint_snitch
sed -i ‘s/endpoint_snitch\:\ SimpleSnitch/endpoint_snitch\:\ GossipingPropertyFileSnitch/g’ /usr/share/dsc-
cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change broadcast_rpc_address hostname=serverip
sed -i ‘s/^# broadcast_rpc_address\:\ 1.2.3.4/broadcast_rpc_address\:\ {{hostname}}/g’ /usr/share/dsc-cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change seeds hostname=serverip seeds=seedsip
sed -i ‘s/- seeds\:\ “127.0.0.1”/- seeds\:\ “{{seeds}},{{hostname}}”/g’ /usr/share/dsc-cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change data_file_directories
sed -i ‘s/# data_file_directories/data_file_directories/g’ /usr/share/dsc-cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change /var/lib/cassandra/data
sed -i” ‘107 s/^#//’ /usr/share/dsc-cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change commitlog_directory
sed -i ‘s/# commitlog_directory/commitlog_directory/g’ /usr/share/dsc-cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change saved_caches_directory
sed -i ‘s/# saved_caches_directory/saved_caches_directory/g’ /usr/share/dsc-cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change thrift_framed_transport_size_in_mb
sed -i ‘s/thrift_framed_transport_size_in_mb\:\ 15/thrift_framed_transport_size_in_mb\:\ 100/g’ /usr/share/dsc-
cassandra-2.1.7/conf/cassandra.yaml

Cassendra configuration change phi_convict_threshold
sed -i ‘s/# phi_convict_threshold\:\ 8/phi_convict_threshold\:\ 10/g’ /usr/share/dsc-cassandra-2.1.7/conf/cassandra.yaml

Start Cassandra service
nohup sh /usr/share/dsc-cassandra-2.1.7/bin/cassandra

5. Command to check Cassandra cluster:
/usr/share/dsc-cassandra-2.1.7/bin/nodetool status
Address Status State Load Owns Token
113427455640312821154458202477256070484
10.1.1.7 Up Normal 459.27 MB 33.33% 0
10.1.1.8 Up Normal 382.53 MB 33.33% 56713727820156410577229101238628035242
10.1.1.6 Up Normal 511.34 MB 33.33% 113427455640312821154458202477256070484

Step by Step procedure to install and Configure ANSIBLE on Ubuntu

Step by step procedure to install and configure ansible on ubuntu

Before installing ANSIBLE, let us understand,

What is ANSIBLE ?

1.Ansible Introduction :

Ansible is an IT automation tool. It can configure systems, deploy software, and orchestrate more advanced IT tasks such as continuous deployments or zero
downtime rolling updates.
Ansible’s goals are foremost those of simplicity and maximum ease of use. It also has a strong focus on security and reliability, featuring a minimum of moving parts, usage of OpenSSH for transport (with an accelerated socket mode and pull modes as alternatives),
and a language that is designed around auditability by humans – even those not familiar with the program.

While there are many popular configuration management systems available for Linux systems, such as Chef and Puppet, these are often more complex than many people want or need.Ansible is a great alternative to these options because it has a much smaller overhead to get started.

for more information visit, Ansible docs.
http://docs.ansible.com/

Assumptions
● You have a ubuntu 12.04 and you are logged-in as root.

2.How Does Ansible Work :
Ansible works by configuring client machines from an computer with Ansible components
installed and configured.
It communicates over normal SSH channels in order to retrieve information from remote
machines, issue commands, and copy files. Because of this, an Ansible system does not require any additional software to be installed on the client computers.
This is one way that Ansible simplifies the administration of servers.
Configuration files are mainly written in the YAML data  format due to its
expressive nature and its similarity to popular markup languages.Ansible can interact with clients through either command line tools or through its configuration scripts called Playbooks.

3. Install Ansible on an Ubuntu 12.04 :
To begin exploring Ansible , we need to install the Ansible package on at least one machine. I have used ubuntu 12.04

git clone git@github.com:ansible/ansible.git
cd ansible
source ./hacking/env-setup
sudo pip install paramiko PyYAML jinja2 --upgrade

We now have all of the software required to administer our servers through Ansible.
Set Up SSH Keys , Ansible primarily communicates with client computers through SSH.While it certainly has the ability to handle password-based SSH authentication, SSH keys help keep things simple.

4. Creating a SSH Pair :
@Server:~> ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/a/.ssh/id_rsa):
Created directory ‘/home/a/.ssh’.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/a/.ssh/id_rsa.
Your public key has been saved in /home/a/.ssh/id_rsa.pub.
The key fingerprint is:
3e:4f:05:79:3a:9f:96:7c:3b:ad:e9:58:37:bc:37:e4 a@A
Now use ssh to create a directory ~/.ssh as user b on Client. (The directory may already exist,
which is fine):
@Server:~> ssh root@123.123.123.123 mkdir -p .ssh
root@Client’s password:
Finally append a’s new public key to root@123.123.123.123:.ssh/authorized_keys and enter
client’s password one last time:
root@Server:~> cat .ssh/id_rsa.pub | ssh root@123.123.123.123 ‘cat >> .ssh/authorized_keys’
root@Client’s password:
From now on you can log into Client as root from A as a without password:
@Server:~> ssh root@123.123.123.123

5. Configuring Ansible Host:
Ansible keeps record of all of the servers that it know through a “hosts” file. We need to configure this file first before we can begin to communicate with our other computers.
Open the file and add,

vim /etc/ansible/hosts
[hosts]
devops ansible_ssh_host=123.123.123.123

Where hosts is list of nodes
devops = host name of one of the client.
123.123.123.123 is hosts ip.
To do this, we will create a directory in the Ansible configuration structure called group_vars.
Within this folder, we can create YAML-formatted files for each group we want to configure:

sudo mkdir /etc/ansible/group_vars
sudo nano /etc/ansible/group_vars/hosts

We can put our configuration in here. YAML files start with “—“, so make sure you don’t forget that part.

ansible_ssh_user: root
Save and close this file when you are finished.

6. Ansible test Examples:

Using Simple Ansible Commands
Now that we have our hosts set up and enough configuration details to allow us to
successfully connect to our hosts, we can try out our very first command.
Ping all of the servers you configured by typing:
root@server:/etc/ansible# ansible -m ping hosts
devops | success >> {
“changed”: false,
“ping”: “pong”
}
This is a basic test to make sure that Ansible has a connection to all of its hosts.

ansible -m shell -a ‘ifconfig’ devops

devops | success | rc=0 >>
eth0 Link encap:Ethernet HWaddr 00:0c:29:a2:42:c4
inet addr:123.123.123.123 Bcast:10.27.111.255 Mask:255.255.255.0

ansible -m shell -a ‘free -m’ devops
devops | success | rc=0 >>
total used free shared buffers cached
Mem: 487 440 47 0 108 173
-/+ buffers/cache: 158 329
Swap: 507 66 441

Lets install sendmail on client from Ansible server, to do that create playbook.yml file in
/etc/ansible 100 Jul 5 02:48 playbook.yml

root@server:/etc/ansible# cat playbook.yml

– hosts: devops
tasks:
– name: 1. install sendmail
apt: name=sendmail state=present

Now execute below command to install on remote server.
ansible-playbook –inventory-file=hosts playbook.yml –sudo –verbose
Below is the result,

ansible 1

Before executing above command, sendmail was not installed. ansible 2

Later after execution, sendmail installed on the remote host.

Advantages of Automation,

,Automation-Advantages

Hence we have Installed and Configured ANSIBLE, Enjoy !!!

shell script to replace a string in a file

shell script to replace a string in a file

Some times during automating any task, we may require to replace a string in a file.
Example:- I want to change “Linux” string with “Waseem” in a file called string.txt

cat replacestring.sh
#!/bin/bash
# Shell Script to replace string in a file
/bin/sed -i “s/Linux/Waseem/g” /PATH/TO/FILE/string.txt
exit 0;

Before:-
—————–
cat string.txt
Linux

Run the script:-
——————-
sh replacestring.sh

After:-
——————
cat string.txt
Waseem

Another way we can replace string by passing parameter,so that the script will be used dynamically.
cat replacestring.sh
#!/bin/bash
# Shell Script to replace string in a file
/bin/sed -i “s/$1/$2/g” /PATH/TO/FILE/string.txt
exit 0;

Run the script:-
—————–
sh replacestring.sh Linux Waseem

How to protect file with HTAccess

Protection with htaccess is an important way to protect your files from unwanted access. Most people  protect an entire directory or website, you can also protect files with password.

Here’s How:

Example:

I want to protect file “password.ini”

path = /var/www/html/mydomain.com/password.ini

Go to cd /var/www/html/mydomain.com

Open a new text file called .htaccess

  1. .htaccess
  2. Add the following to the file:

<Files “password.ini”>
deny from all
</Files>

save it.

now go to your browser and type, http://mydomain.com/password.ini

Forbidden ,You don’t have permission to access /password.ini  on this server.!!!

Installing Apache and PHP from source

I’ve just been through the process of installing the latest versions (as of this writing) of Apache 2.4.2 and PHP 5.4.5 from source on a new Debian 6 virtual machine for the first time.

I had some small issues along the way and thought I’d do a short post on the process I went through to get it working and resolve various errors which may help someone out. First we will install Apache, followed by PHP.

Prerequisites

Before starting you will need make, gcc and g++ installed.

apt-get install make gcc g++
I also had the latest version of MySQL installed (5.5.25a), as I wanted to use this later on. The latest version was downloaded from the Dotdeb repository

Installing Apache 2.4.2 from source

Apache was then downloaded from http://httpd.apache.org/download using wget on one of the mirrors in my country and then extracted.

wget http://apache.mirror.uber.com.au//httpd/httpd-2.4.2.tar.gz
tar xf httpd-2.4.2.tar.gz
cd httpd-2.4.2/
./configure –enable-so

Configuring Apache Portable Runtime library …
checking for APR… no
configure: error: APR not found. Please read the documentation.
–enable-so is needed later on for PHP.

At this point I downloaded APR 1.4.6 from apr.apache.org/download using wget and then extracted it.

cd ..
wget http://apache.mirror.uber.com.au//apr/apr-1.4.6.tar.gz
tar xf apr-1.4.6.tar.gz
cd apr-1.4.6/
./configure
make
make install
Apache will also need APR-util installed, which can be downloaded from the apr.apache.org/download page too. When you run configure you will have to specify where the apr config is, you should see this location in the output from make install after finishing apr above.

cd ..
wget http://apache.mirror.uber.com.au//apr/apr-util-1.4.1.tar.gz
tar xf apr-util-1.4.1.tar.gz
cd apr-util-1.4.1/
./configure –with-apr=/usr/local/apr/bin/apr-1-config
make
make install
Now that’s complete we can try Apache again.

cd ../httpd-2.4.2/
./configure –enable-so

checking for pcre-config… false
configure: error: pcre-config for libpcre not found. PCRE is required and available from http://pcre.org/
pcre-8.30.tar.gz was then downloaded from http://pcre.org and for something different, I uploaded it to the server with SFTP to the root directory.

cd ..
tar xf pcre-8.30.tar.gz
cd pcre-8.30/
./configure
make
make install
Now to try Apache again…

cd ../httpd-2.4.2/
./configure –enable-so
make
make install
That’s it, Apache should now be ready to go, let’s move into the default installation and start it up.

cd /usr/local/apache2/bin/
./apachectl start
/usr/local/apache2/bin/httpd: error while loading shared libraries: libpcre.so.1: cannot open shared object file: No such file or directory
ldconfig
./apachectl start
./apachectl -v
Server version: Apache/2.4.2 (Unix)
Server built: Jul 26 2012 20:51:23
That error relating to the shared libraries was resolved by running ldconfig, see the man page on that for more information.

Browsing to the IP address in my web browser now brings up the Apache default page. As ServerSignature is enabled by default, using Firebug for FireFox I can see “Apache/2.4.2 (Unix)” as the Server header in the response headers, confirming the new install of Apache has served my page.

Installing PHP 5.4.5 from source

PHP was downloaded from http://au.php.net/get/php-5.4.5.tar.gz/from/a/mirror and then uploaded to the root directory on the server using SFTP.

I’m configuring PHP with apxs, this wasn’t working for me unless Apache was configured with –enable-so. I was after MySQL support, feel free to leave –with-mysql off.

cd /root
tar xf php-5.4.5.tar.gz
cd php-5.4.5/
./configure –with-apxs2=/usr/local/apache2/bin/apxs –with-mysql=mysqlnd

configure: error: xml2-config not found. Please check your libxml2 installation.
apt-get install libxml2-dev
./configure –with-apxs2=/usr/local/apache2/bin/apxs –with-mysql=mysqlnd
make
make install
php -v
PHP 5.4.5 (cli) (built: Jul 26 2012 21:18:58)
Configuration

Once you have both Apache and PHP installed and running there is a bit of configuration to do so that Apache knows how to use PHP. I created a phpinfo file here /usr/local/apache2/htdocs/phpinfo.php and it will not display in a browser prior to configuration.

First off, let’s copy the library file over to Apache.

cp /root/php-5.4.5/libs/libphp5.so /usr/local/apache2/modules/
Next you will want to edit the Apache configuration file in /usr/local/apache2/conf/httpd.conf and add the following lines into it.

AddType text/html .php
AddHandler php5-script .php
This line should already be in there, referring to the .so file that was previously copied.

LoadModule php5_module modules/libphp5.so
You probably want to edit DirectoryIndex index.html and include index.php after this.

Once complete, restart Apache.

cd /usr/local/apache2/bin/
./apachectl restart