Install MHA on RHEL6 / CentOS6 for mySQL

Configure Proxy for Internet

#export http_proxy=http://proxy.xxxx.intra:00
#export https_proxy=https://proxy.xxxx.intra:00

Note: My environment is using a proxy server for Internet access, if you have direct access to internet ignore this step.

Configure RedHat subscription for yum

#subscription-manager register –username admin-example –password secret –auto-attach

Download epel-release package on machine


Note: the package will be downloaded on the path you are standing – verify from “pwd” command

Install epel-package

#yum install -y epel-release-latest-6.noarch.rpm

Install perl packages

#yum -y install perl-DBD-MySQL perl-Config-Tiny perl-Log-Dispatch perl-Parallel-ForkManager perl-Config-IniFiles ncftp perl-Params-Validate perl-CPAN perl-Test-Mock-LWP.noarch perl-LWP-Authen-Negotiate.noarch perl-devel

Install more perl packages

#yum install perl-ExtUtils-CBuilder perl-ExtUtils-MakeMaker

Download MHA Packages (Node & Manager)

– MHA Manager 0.56 rpm RHEL6 – mha4mysql-manager-0.56-0.el6.noarch.rpm
– MHA Node 0.56 rpm RHEL6 – mha4mysql-node-0.56-0.el6.noarch.rpm

Once downloaded copy to server via WinSCP or SSH (somehow it is not working properly in wget for me)

Install MHA Packages

#yum -y install mha4mysql-node-0.56-0.el6.noarch.rpm

#yum -y install mha4mysql-manager-0.56-0.el6.noarch.rpm

Note: Move to directory where packages are downloaded

ANSIBLE – Basic Cheat Sheet – CentOS 6


To install Ansible:

# wget epel-release

# yum install epel-release-6-8.noarch.rpm

# yum update

# yum install ansible -y

Add remote hosts:

$ vim /etc/ansible/hosts (your remote server IP) or
hostname.hostname.local (your remote server hostname)

Ping remote hosts: (if using ssh keys for authentication –ask-pass is not required)

$ ansible all -m ping –ask-pass

Ping remote hosts with specific account: (if using ssh keys for authentication –ask-pass is not required)

$ ansible all -m ping –ask-pass -u root

Execute command on remote server shell:

$ ansible all -m shell -a “mkdir /home/ansible/testdirectory” –ask-pass -u root

Remove file from remote server:

$ ansible all -m file -a “dest=/tmp/ state=absent” –ask-pass -u root

Install apache on remote server:

$ ansible all -m yum -a “name=httpd state=latest” -u root

Change file permissions:

$ ansible all -m file -a “dest=/home/ansible/testfile.txt mode=600 owner=ansible group=anisble”

Confirm if package installed but do not update

$ ansible all -m yum -a “name=telnet state=present”

Confirm package is latest version

$ ansible all -m yum -a “name=telnet state=latest”

Confirm package is not installed

$ ansible all -m yum -a “name=telnet state=absent”

Start service

$ ansible all -m service -a “name=httpd state=started”

Restart service

$ ansible all -m service -a “name=httpd state=restarted”

Stop serivce

$ ansible all -m service -a “name=httpd state=stopped”


Gathering Facts

$ ansible all -m setup

Distribute Linux flavors in Ansible host file:

$ vim /etc/ansible/hosts


Only send instructions on RHEL hosts:

$ ansible RHEL  -m shell -a “mkdir /home/ansible/testfolder” 

Ansible use YaML for Automation and known as Playbook in Ansible

create a playbook i.e an .yaml file eg: telnetPlaybook.yaml

– hosts: SUSE
remote_user: root
– zypper: name=telnet state=latest
– hosts: RHEL
remote_user: root
– yum: name=telnet state=latest

Run playbook with Ansible: (-f switch allow the execution to be performed on multiple hosts parallel)

$ ansible-playbook telnetPlaybook.yaml -f 10

Ansible Modules (-m): These are few but there is huge list.

command – execute commands and this is default module of Ansible.
copy – copy files
shell – use remote shell to execute
file – file operations
ping – ping remote hosts
yum – Redhat package manager
git – use GIT
user – user creation, manipulation
service – manage services

If you find it interesting, spread the word 🙂

How to Change Font Colors in CentOS / RedHat

Red & Turquoise Terminal
Red & Turquoise Terminal

One of my monitor display was bothering my eyes, therefore I decided to change the colors being displayed on the monitor I am using, especially for the directory as it was dark blue and I had to dig myself inside the screen to actually read in that color. (my eyes are not week but I love small fonts)

I was not sure how to do it but knew it can be changed as I studied them long time ago, did some research and found out there are multiple ways to perform it.

As my environment is an Ansible lab therefore it did not click me to just change it for a specific user therefore I changed in environment base:

This is what I did: (from root user)

vim /etc/DIR_COLORS
DIR 01;96

Just above DIR value, I found out FILE parameter but it was commented, so i edited it to

vim /etc/DIR_COLORS
FILE 01;91

Now my terminal is displaying 96  = turquoise as DIR and 91  = light red as FILE and I like it !!

For you reference color codes:

0 = default colour
1 = bold
4 = underlined
5 = flashing text
7 = reverse field
31 = red
32 = green
33 = orange
34 = blue
35 = purple
36 = cyan
37 = grey
40 = black background
41 = red background
42 = green background
43 = orange background
44 = blue background
45 = purple background
46 = cyan background
47 = grey background
90 = dark grey
91 = light red
92 = light green
93 = yellow
94 = light blue
95 = light purple
96 = turquoise
100 = dark grey background
101 = light red background
102 = light green background
103 = yellow background
104 = light blue background
105 = light purple background
106 = turquoise background

I did not try it but if you are interested in changing it for specific user you can try this:

cp /etc/DIR_COLORS to $HOME/.dir_colors

once copied, edit you local copy i.e .dir_colors and play with it.

Don’t forget you need to re-initialize the shell or logout and login back for changes to take affect.

Install iftop, htop and NetHogs on RHEL / CentOS 6.x x86_64 [Internet Required]

Recently I was given a task to create two CentOS 6.5 Jump Servers in the environment I am working currently.

There was a specific requirement for the following packages.

  • iftop – Network Bandwidth Monitoring
  • htop – Linux Process Monitoring
  • NetHogs – Monitor per process Network Bandwidth

We have an internal secure proxy server via which Internet was easily available for my servers. This is how I did:

Step 1 – Enable EPEL (Extra Packages for Enterprise Linux) and install rpm

cd /tmp


rpm -ivh epel-release-6-8.noarch.rpm

Step 2 – Verify EPEL Repo

yum repolist

(it should display EPEL repo in the output)

Step 3 – Install packages

yum -y install iftop

yum -y install htop

yum – y install NetHogs

Note: Just in case you face the following error:

yum error “Cannot retrieve metalink for repository: epel. Please verify its path and try again”

You will have to edit the following repo’s by commenting entries ‘mirrorlist=..’ and un-comment entries ‘baseurl=…’

  • /etc/yum.repos.d/epel.repo
  • /etc/yum.repos.d/epel-testing.repo