Solving “Can’t locate File/Which.pm in @INC (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .)”

To solve this problem:

 Can't locate File/Which.pm in @INC (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) 
 BEGIN failed--compilation aborted

you just need to install perl-File-Which package:

yum install perl-File-Which

Free SSL certificates set up on Ubuntu in 5 min

Install certbot:

wget https://dl.eff.org/certbot-auto ; chmod a+x certbot-auto ; ./certbot-auto

Add the required location to nginx:

vim /etc/nginx/sites-enabled/443-pydelion.com:
location ~ /.well-known { allow all; }
sudo service nginx restart

Run and follow the instruction:

root@host:~# ./certbot-auto certonly -d pydelion.com
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Failed to find apache2ctl in PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

How would you like to authenticate with the ACME CA?
-------------------------------------------------------------------------------
1: Place files in webroot directory (webroot)
2: Spin up a temporary webserver (standalone)
-------------------------------------------------------------------------------
Select the appropriate number [1-2] then [enter] (press 'c' to cancel):1
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for pydelion.com

Select the webroot for for pydelion.com:
-------------------------------------------------------------------------------
1: Enter a new webroot
-------------------------------------------------------------------------------
Press 1 [enter] to confirm the selection (press 'c' to cancel):
Input the webroot for pydelion.com: (Enter 'c' to cancel):/usr/share/nginx/html
Waiting for verification...
Cleaning up challenges
Generating key (2048 bits): /etc/letsencrypt/keys/0000_key-certbot.pem
Creating CSR: /etc/letsencrypt/csr/0000_csr-certbot.pem

IMPORTANT NOTES:
- Congratulations! Your certificate and chain have been saved at
/etc/letsencrypt/live/pydelion.com/fullchain.pem. Your cert will
expire on 2017-04-20. To obtain a new or tweaked version of this
certificate in the future, simply run certbot-auto again. To
non-interactively renew *all* of your certificates, run
"certbot-auto renew"
- If you like Certbot, please consider supporting our work by:

Donating to ISRG / Let's Encrypt: https://letsencrypt.org/donate
Donating to EFF: https://eff.org/donate-le

Add SSL config to nginx:

    ssl_certificate /etc/letsencrypt/live/pydelion.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/keys/0000_key-certbot.pem;
    ssl_protocols TLSv1  TLSv1.1 TLSv1.2;
    ssl_ciphers 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!3DES:!MD5:!PSK';

Monitoring Galera cluster using Percona Nagios plugins on Debian

1. Download the repository packages:

wget https://repo.percona.com/apt/percona-release_0.1-3.$(lsb_release -sc)_all.deb

2. Install it:

dpkg -i percona-release_0.1-3.$(lsb_release -sc)_all.deb

3. Update the packages list:

apt-get update

4. Install

apt-get install percona-nagios-plugins

5. Grant the privileges:

GRANT USAGE, SELECT, REPLICATION CLIENT on *.* to 'test'@'localhost' IDENTIFIED BY 'password';

6. Test:

/usr/lib64/nagios/plugins/pmp-check-mysql-status -x wsrep_cluster_status -C == -T str -c non-Primary -l test -p password