1. Install ansible on your workstation (machine which will be the controller) $ sudo yum install ansible $ ansible --version 2. Create env variable $ export ANSIBLE_HOSTS=~/ansible/ansible_hosts 3. Create hosts file $ echo -e "perf-c690\nperf-c691" > ~/ansible/ansible_hosts 4. Do a quick ping $ ansible all -m ping --ask-pass 5. Now, let's create ssh keys (Should typically run using your own user account, have used root here for convenience) # ssh-keygen -t rsa 6. Copy public key to the remote machines $ ansible all -m copy -a "src=/root/.ssh/id_rsa.pub dest=/tmp/id_rsa.pub" --ask-pass -c paramiko Warning: error message: "Aborting, target uses selinux but python bindings (libselinux-python) aren't installed!" Which means we need to install libselinux-python on the remote machine prior to copying the files there. We can use ansible to do that for us. Install libselinux-python on remote machines $ ansible all -m yum -a "name=libselinux-python state=latest" -u root --ask-pass -c paramiko Now we can go back to copying the public key 7. Let's add the public key to the remote machines $ ansible all -m shell -a "cat /tmp/id_rsa.pub >> /root/.ssh/authorized_keys" --ask-pass -c paramiko 8. Test if we actually don't need any password $ ansible all -m shell -a "hostname" 9. Now we can do or install whatever on the remote machines, let's try installing expect $ ansible all -m yum -a "name=expect state=latest" -u root 10. We can remotely reboot all machines at once $ ansible all -a "/sbin/reboot" -u root
3.12.2015
Ansible for Configuration Management and IT automation
Wow, Ansible is a great tool for configuration management and IT automation. I got this reference from here and here.
3.10.2015
Install Ruby via RVM on CentOS 6.5
Got install from here.
RVM best practices here.
How to use RVM gemsets here.
How to use Bundler here.
RVM best practices here.
How to use RVM gemsets here.
How to use Bundler here.
1. Install pre-requisites # yum groupinstall -y development 2. Install RVM # curl -L get.rvm.io | bash -s stable 3. Create system environment for RVM # source /etc/profile.d/rvm.sh 4. Install Ruby # rvm reload # rvm install 2.2.1 5. Check version of ruby installed # ruby --version 6. To see all rubies installed # rvm list rubies rvm rubies =* ruby-2.2.1 [ x86_64 ] # => - current # =* - current && default # * - default 7. To set a Ruby version as the default # rvm use 2.2.1 --default Using /usr/local/rvm/gems/ruby-2.2.1 8. Shortcut - create a new gemset along with a fresh .rvmrc in our project directory # cd projects/dev/phoenix # rvm --rvmrc --create use 2.2.1@phoenix ruby-2.2.1 - #gemset created /usr/local/rvm/gems/ruby-2.2.1@phoenix ruby-2.2.1 - #generating phoenix wrappers.......... Using /usr/local/rvm/gems/ruby-2.2.1 with gemset phoenix 9. To ignore rmvrc warnings ... # rvm rvmrc warning ignore all.rvmrcs 10. Now when we cd to our project directory we get a confirmation which ruby-version and gemset we are using... dev]# cd phoenix/ Using: /usr/local/rvm/gems/ruby-2.2.1@phoenix 11. Let's make use of bundler to make it easy to track and install the exact gems and versions for our project # gem install bundler 12. Create a Gemfile # bundle init Writing new Gemfile to /root/projects/dev/phoenix/Gemfile 13. Add gems to Gemfile # vi Gemfile source "https://rubygems.org" # 1. de facto XML/HTML parsing library gem 'nokogiri' 14. Now, let's install all gems we listed in the Gemfile # bundle install To create and use gemsets the longer way: a. Create gemset # rvm gemset create my_proj b. Use the gemset # rvm gemset use my_proj c. Install a gem # gem install package_name d. Wipe all gems installed # rvm gemset empty my_proj e. Delete the gemset # rvm gemset delete my_proj f. Check your current gemset # rvm gemset name
2.19.2015
Open HTTP port 80 on CentOS
Got from here.
1. Look at the current iptables # iptables --line -vnL Chain INPUT (policy ACCEPT 0 packets, 0 bytes) num pkts bytes target prot opt in out source destination 1 0 0 ACCEPT udp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:53 2 0 0 ACCEPT tcp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:53 3 0 0 ACCEPT udp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:67 4 0 0 ACCEPT tcp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:67 5 195K 212M ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 6 3 252 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 7 74 5440 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 8 16 864 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22 9 170K 39M REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited 2. Inject rule, as long as it's before the REJECT line # iptables -I INPUT 5 -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT 3. Save # service iptables save 4. Add httpd_t to the list of permissive domains (So we don't need to turn off selinux) # yum install policycoreutils-python # semanage permissive -a httpd_t
Perl specific installs for Centos 6.6
1. Enable RPMForge Repository # wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm # rpm -Uvh rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm # rpm --import http://dag.wieers.com/rpm/packages/RPM-GPG-KEY.dag.txt 2. Install perl installs MANUAL: 1. Dependency of Net::SSH::Perl # wget http://download.opensuse.org/repositories/home:/csbuild:/Perl/CentOS_CentOS-6/x86_64/perl-Math-GMP-2.04-2.5.x86_64.rpm # rpm -Uvh perl-Math-GMP-2.04-2.5.x86_64.rpm 2. Dependency of gnuplot for Chart::Graph::Gnuplot # wget http://www.my-guides.net/en/images/stories/fedora12/msttcore-fonts-2.0-3.noarch.rpm # rpm -Uvh msttcore-fonts-2.0-3.noarch.rpm YUM: # yum install perl-Math-BigInt-GMP # yum install perl-Math-Pari # yum install perl-Archive-Zip # yum install perl-Chart # yum install perl-DBI # yum install perl-DBD-MySQL # yum install perl-Data-Compare # yum install perl-Date-Manip # yum install perl-JSON # yum install perl-Net-Telnet # yum install perl-NetAddr-IP # yum install perl-Statistics-Descriptive # yum install perl-Text-Table # yum install perl-XML-Simple # yum install perl-XML-Writer # yum install gnuplot CPAN: # cpan Data::Diff # cpan HTML::TextToHTML # cpan XML::SemanticDiff # cpan Chart::Graph - this didn't install Force installed: cpan[1]> force install Net::Telnet::Brcd
2.13.2015
Install different versions of Perl on Linux using Perlbrew
Got from here and here.
What is perlbrew.
1. Install perfbrew $ curl -kL http://install.perlbrew.pl | bash 2. Modify .bashrc and add: source ~/perl5/perlbrew/etc/bashrc 3. Initialize $ perlbrew init 4. Select mirror $ perlbrew mirror 5. See what's available $ perlbrew available perl-5.20.1 perl-5.18.4 perl-5.16.3 perl-5.14.4 6. Install perls $ perlbrew install perl-5.20.1 # did not work for Centos 6.5 $ perlbrew --notest install perl-5.20.1 7. See what were installed $ perlbrew list 8. Swith to an installation and set it as default $ perlbrew switch perl-5.20.1 9. Temporarily use another version only in current shell. $ perlbrew use perl-5.20.1 $ perl -v 10. Or turn it off completely. Useful when you messed up too deep. Or want to go back to the system Perl. $ perlbrew off 11. Use 'switch' command to turn it back on. $ perlbrew switch perl-5.20.1 12. Exec something with all perlbrew-ed perls $ perlbrew exec -- perl -E 'say $]' 13. Install cpanm $ perlbrew install-cpanm 14. Install cpan modules $ cpanm install File::Copy::Recursive XML::Simple etc
2.07.2015
Ruby Notes
While reading RubyMonk tutorials
1. Truthiness of objects in Ruby
Only objects false and nil equates to false. Every other object like say 1, 0, "" are all evaluated to be true.
2. Use break in infinite loops
1. Truthiness of objects in Ruby
Only objects false and nil equates to false. Every other object like say 1, 0, "" are all evaluated to be true.
2. Use break in infinite loops
loop do monk.meditate break if monk.nirvana? end3. Append to an array, use << operator
[1, 2, 3, 4, 5] << 'woot' [1, 2, 3, 4, 5, "woot"]4. Filter elements of an array, use 'select'
names = ['rock', 'paper', 'scissors', 'lizard', 'spock']
names.select { |word| word.length > 5 }
5. Delete elements of an array, use 'delete_if'
[1,2,3,4,5,6,7,8,9].delete_if { |i| i % 2 == 0 }
6. Methods are themselves objects, and responds using 'call'
next_method_object = 1.method("next")
puts next_method_object.call
7. Beware of shallow object copies, to do a deep copy use Marshal
new_job = Marshal.load(Marshal.dump(job))8. Use heredoc for convenient multiline strings. The dash ignores spaces before placeholder. The gsub takes care of removing spaces at beginning of each line.
def long_message
puts <<-EOT.gsub(/^\s*/, '')
Here goes a very long message...
Sincerely,
Dr. Foobear
EOT
end
7. Use 'send' when testing private methods
# obj.send(:method_name, args) @parser.send(:running?, test_strings)
1.21.2015
Use iperf to measure network link bandwidth
Nice writeup on how to use iperf. Another example, writeup.
Bandwidth : Refers how fast a device can send data over a single communication channel.
Throughput: Refers how fast a device is actually sending data over the communication channel.
1. Install iperf $ sudo yum install iperf 2. Start server on another system: $ iperf -s ------------------------------------------------------------ Server listening on TCP port 5001 TCP window size: 85.3 KByte (default) ------------------------------------------------------------ [ 4] local 10.1.1.1 port 5001 connected with 10.0.0.1 port 46699 [ ID] Interval Transfer Bandwidth [ 4] 0.0-10.3 sec 107 MBytes 87.7 Mbits/sec 3. Start client from your system specifying server ip: $ iperf -c 10.1.1.1 ------------------------------------------------------------ Client connecting to 10.1.1.1, TCP port 5001 TCP window size: 85.0 KByte (default) ------------------------------------------------------------ [ 3] local 10.0.0.1 port 46699 connected with 10.1.1.1 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.1 sec 107 MBytes 89.0 Mbits/sec 4. Use options, e.g., -t duration, -i interval between measurements $ iperf -c 10.1.1.1 -t 20 -i 2 ------------------------------------------------------------ Client connecting to 10.1.1.1, TCP port 5001 TCP window size: 85.0 KByte (default) ------------------------------------------------------------ [ 3] local 10.0.0.1 port 46761 connected with 10.1.1.1 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0- 2.0 sec 17.6 MBytes 73.9 Mbits/sec [ 3] 2.0- 4.0 sec 22.5 MBytes 94.4 Mbits/sec [ 3] 4.0- 6.0 sec 21.2 MBytes 89.1 Mbits/sec [ 3] 6.0- 8.0 sec 22.6 MBytes 94.9 Mbits/sec [ 3] 8.0-10.0 sec 22.5 MBytes 94.4 Mbits/sec [ 3] 10.0-12.0 sec 21.2 MBytes 89.1 Mbits/sec [ 3] 12.0-14.0 sec 22.6 MBytes 94.9 Mbits/sec [ 3] 14.0-16.0 sec 22.5 MBytes 94.4 Mbits/sec [ 3] 16.0-18.0 sec 21.2 MBytes 89.1 Mbits/sec [ 3] 18.0-20.0 sec 22.5 MBytes 94.4 Mbits/sec [ 3] 0.0-20.1 sec 217 MBytes 90.6 Mbits/secJust want to take note: Bandwidth vs Throughput
Bandwidth : Refers how fast a device can send data over a single communication channel.
Throughput: Refers how fast a device is actually sending data over the communication channel.
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