Introduction

This tutorial covers how to manage and monitor swap on Linux, including how to determine the amount of swap space available and how much is currently in use.

Swap space plays an important role in system performance, so it’s crucial to understand how to manage it effectively.

How much swap on Linux do you need?

The recommendation is to swap the space used to double your RAM. If your system has a lot of memory, you may never need to use swap space.

RAM         Swap        Swap (with hibernation)
256MB       256MB       512MB
512MB       512MB       1GB
1GB         1GB         2GB
2GB         1GB         3GB
3GB         2GB         5GB
4GB         2GB         6GB
6GB         2GB         8GB
8GB         3GB         11GB
12GB        3GB         15GB
16GB        4GB         20GB
24GB        5GB         29GB
32GB        6GB         38GB
64GB        8GB         72GB

To determine if your system can hibernate

$ which pm-hibernate

You can test it by running this command:

$ sudo pm-hibernate

View the amount of swap space on Linux

$ swapon --show
$ free -m 
$ sar -S 1 3
$ lsblk

The output terminal is as follows

[vagrant@localhost ~]$ swapon --show
NAME      TYPE SIZE USED PRIO
/swapfile file   2G   9M   -2
[vagrant@localhost ~]$ free -m
              total        used        free      shared  buff/cache   available
Mem:            486         146          93           2         247         325
Swap:          2047           9        2038
[vagrant@localhost ~]$ sar -S 1 3
Linux 3.10.0-1127.el7.x86_64 (localhost.localdomain)    09/13/2021      _x86_64_        (1 CPU)

09:51:08 PM kbswpfree kbswpused  %swpused  kbswpcad   %swpcad
09:51:09 PM   2087884      9264      0.44       416      4.49
09:51:10 PM   2087884      9264      0.44       416      4.49
09:51:11 PM   2087884      9264      0.44       416      4.49
Average:      2087884      9264      0.44       416      4.49
[vagrant@localhost ~]$ lsblk
NAME   MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda      8:0    0  40G  0 disk
└─sda1   8:1    0  40G  0 part /
[vagrant@localhost ~]$

Creating a swap file

$ sudo dd if=/dev/zero of=/swapfile bs=1M count=8192
$ sudo chmod 600 /swapfile
$ sudo mkswap /swapfile
$ sudo swapon -a
$ swapon --show

Turn to swap off.

$ sudo swapoff -v /swapfile

# The output terminal
[vagrant@localhost ~]$ sudo swapoff -v /swapfile
swapoff /swapfile
[vagrant@localhost ~]$

Turn to swap on Linux.

$ sudo swapon -v /swapfile
$ swapon --show

Conclusion

You have a Managing and monitoring swap on Linux. I hope will this your helpful. Thank you for reading the DevopsRoles page!

Introduction

In this tutorial. How to install pip on Centos 8. Pip is a package management system that allows you to install, remove, and otherwise manage software packages written in Python.

How to Install PIP on Centos 8

Two Python versions are Python 2 and Python 3.

Install pip3 for Python 3

sudo dnf install python3

The output is as below:

[devopsroles@server1 ~]$ sudo dnf install python3
[sudo] password for devopsroles: 
Last metadata expiration check: 0:07:32 ago on Wed 02 Sep 2020 09:15:00 PM +07.
Dependencies resolved.
==========================================================================================================
 Package                  Architecture Version                                      Repository       Size
==========================================================================================================
Installing:
 python36                 x86_64       3.6.8-2.module_el8.1.0+245+c39af44f          AppStream        19 k
Installing dependencies:
 python3-pip              noarch       9.0.3-16.el8                                 AppStream        19 k
 python3-setuptools       noarch       39.2.0-5.el8                                 BaseOS          162 k
Enabling module streams:
 python36                              3.6                                                               

Transaction Summary
==========================================================================================================
Install  3 Packages

Total download size: 201 k
Installed size: 466 k
Is this ok [y/N]: y
Downloading Packages:
(1/3): python36-3.6.8-2.module_el8.1.0+245+c39af44f.x86_64.rpm            7.3 kB/s |  19 kB     00:02    
(2/3): python3-pip-9.0.3-16.el8.noarch.rpm                                7.1 kB/s |  19 kB     00:02    
(3/3): python3-setuptools-39.2.0-5.el8.noarch.rpm                          52 kB/s | 162 kB     00:03    
----------------------------------------------------------------------------------------------------------
Total                                                                      43 kB/s | 201 kB     00:04     
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                                                  1/1 
  Installing       : python3-setuptools-39.2.0-5.el8.noarch                                           1/3 
  Installing       : python36-3.6.8-2.module_el8.1.0+245+c39af44f.x86_64                              2/3 
  Running scriptlet: python36-3.6.8-2.module_el8.1.0+245+c39af44f.x86_64                              2/3 
  Installing       : python3-pip-9.0.3-16.el8.noarch                                                  3/3 
  Running scriptlet: python3-pip-9.0.3-16.el8.noarch                                                  3/3 
  Verifying        : python3-pip-9.0.3-16.el8.noarch                                                  1/3 
  Verifying        : python36-3.6.8-2.module_el8.1.0+245+c39af44f.x86_64                              2/3 
  Verifying        : python3-setuptools-39.2.0-5.el8.noarch                                           3/3 

Installed:
  python3-pip-9.0.3-16.el8.noarch                            python3-setuptools-39.2.0-5.el8.noarch       
  python36-3.6.8-2.module_el8.1.0+245+c39af44f.x86_64       

Complete!

Check version pip

pip3 --version

The output as below

[devopsroles@server1 ~]$ pip3 --version
pip 9.0.3 from /usr/lib/python3.6/site-packages (python 3.6)

To install and build Python modules with pip, you need to install the Development tools:

sudo yum install python3-devel
sudo yum groupinstall 'development tools'

Installing pip2 for Python 2

sudo dnf install python2
pip2 --version
sudo yum install python2-devel
sudo yum groupinstall 'development tools'

For example, I have installed two python3 and python2 on Centos 8 as below

[devopsroles@server1 ~]$ sudo yum list installed | grep pip
libpipeline.x86_64                          1.5.0-2.el8                           @anaconda 
platform-python-pip.noarch                  9.0.3-16.el8                          @anaconda 
python2-pip.noarch                          9.0.3-16.module_el8.2.0+381+9a5b3c3b  @AppStream
python2-pip-wheel.noarch                    9.0.3-16.module_el8.2.0+381+9a5b3c3b  @AppStream
python3-pip.noarch                          9.0.3-16.el8                          @AppStream
python3-pip-wheel.noarch                    9.0.3-16.el8                          @anaconda 

Managing Python Packages with pip

Typically, you should use pip inside a virtual environment only. It is used when separating the Python execution environment, such as when you want to change the Python execution environment for each project or you do not want to keep the local environment dirty venv.

In this section, we will go through several basic pip commands.

To install a package

pip install flask

If you want to install a specific version of the package

pip install flask==1.0.0

Uninstall a package

pip uninstall package_name

Search packages

pip search "package_name"

View the full list of packages

pip list

List outdated packages:

pip list --outdated

To upgrade an already installed package

pip3 install --upgrade package_name

Check pip dependencies

pip check

List of packages that need updating

pip list -o

Show packages by package name == version

pip freeze

Useful when outputting to requirements.txt

pip freeze > requirements.txt

Package update

pip install  -U package_name

Update pip itself

pip install  -U pip

Checking the details of the package

pip show package-name

Conclusion

How to install pip on CentOS 8 and how to easily install and uninstall Python modules with pip. Thank you for reading the DevopsRoles page!

In this tutorial, How to Monitor the PHP-fpm using Netdata on Centos 7. Netdata is a free open source. It is very easy to install and configure for real-time monitoring. Now, let’s go to Netdata to Monitor PHP-FPM.

PHP-FPM (FastCGI Process Manager) is an alternative PHP FastCGI. It is commonly used in LEMP ( Linux Nginx MySQL/MariaDB PHP) stack; Nginx uses PHP FastCGI for serving dynamic HTTP content.

Steps install and configure

• Centos 7 Server or RHEL 7 Server
• Install PHP and enable PHP-FPM status
• Install Netdata and configure Monitor for PHP-FPM status.

1. How to Install PHP

For example, How to install PHP version 7.3 on Centos 7.

2. Enable the PHP-FPM status page.

Check php-fpm running on your system.

[root@DevopsRoles vagrant]# netstat -nplt | grep php-fpm
tcp        0      0 127.0.0.1:9000          0.0.0.0:*               LISTEN      4328/php-fpm: maste 
[root@DevopsRoles vagrant]# ps -ef | grep php
root      4328     1  0 21:50 ?        00:00:00 php-fpm: master process (/etc/opt/remi/php73/php-fpm.conf)
apache    4329  4328  0 21:50 ?        00:00:00 php-fpm: pool www
apache    4330  4328  0 21:50 ?        00:00:00 php-fpm: pool www
apache    4331  4328  0 21:50 ?        00:00:00 php-fpm: pool www
apache    4332  4328  0 21:50 ?        00:00:00 php-fpm: pool www
apache    4333  4328  0 21:50 ?        00:00:00 php-fpm: pool www
root      4381  3003  0 21:52 pts/0    00:00:00 grep --color=auto php

Configure file php-fpm status as shown.

$ sudo vim /etc/php-fpm.d/www.conf 
OR
$ sudo vim /etc/opt/remi/php73/php-fpm.d/www.conf	#for PHP versions 7.0, 7.1,7.3 vvv

You find and uncomment the variable pm.status_path = /status as shown in the screenshot.

[root@DevopsRoles vagrant]# cat /etc/opt/remi/php73/php-fpm.d/www.conf | grep pm.status_path
pm.status_path = /status

Save the changes and exit the file.

Check the PHP-FPM configuration file for any errors

$ sudo php-fpm -t
OR
$ sudo systemctl restart php73-php-fpm

Create a new Nginx config for PHP-FPM as shown

[root@DevopsRoles ~]# vi /etc/nginx/conf.d/php-fpm.conf

# The content as below:

    server {

        listen       80;
        #listen       [::]:80 default_server;
        server_name  127.0.0.1;

    location  /status {
        access_log off;
        allow 127.0.0.1;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_index index.php;
        deny all;
        include fastcgi_params;
        fastcgi_pass 127.0.0.1:9000;
   }
   }

Reload PHP-FPM and Nginx config for changes to take effect.

[root@DevopsRoles ~]# systemctl reload php73-php-fpm
[root@DevopsRoles ~]# systemctl reload nginx

Now, Use the curl command to check php-fpm status.

root@DevopsRoles ~]# curl http://127.0.0.1/status
pool:                 www
process manager:      dynamic
start time:           18/Jul/2020:10:16:17 +0700
start since:          878
accepted conn:        14
listen queue:         0
max listen queue:     0
listen queue len:     128
idle processes:       4
active processes:     1
total processes:      5
max active processes: 1
max children reached: 0
slow requests:        0

Memo: meaning of different values of PHP-FPM Status

-pool – the name of the pool.
-process manager – possible values static, dynamic or ondemand. We never use static.  Trying ondemand is on todo list.
-start time – the date and time FPM has started or reloaded.
-start since – number of seconds since FPM has started
-accepted conn – the number of request accepted by the pool
-listen queue – the number of request in the queue of pending connections. If this number is non-zero, then you better increase number of process FPM can spawn.
-max listen queue – the maximum number of requests in the queue of pending connections since FPM has started
-listen queue len – the size of the socket queue of pending -connections
-idle processes – the number of idle processes
-active processes – the number of active processes
-total processes – the number of idle + active processes
-max active processes – the maximum number of active processes since FPM has started
-max children reached – number of times, the process limit has been reached, when pm tries to start more children. If that value is not zero, then you may need to increase max process limit for your PHP-FPM pool. Like this, you can find other useful information to tweak your pool better way.
-slow requests – Enable php-fpm slow-log before you consider this. If this value is non-zero you may have slow php processes. Poorly written mysql queries are generally culprit.

3. Install Netdata on Centos 7 here

4. Configure Netdata to Monitor PHP-FPM

The Netdata configure for Nginx in folder /etc/netdata/python.d which is written in YAML format.

You can open it or create a new file php-fpm.conf as shown

[root@DevopsRoles python.d]# cat /etc/netdata/python.d/php-fpm.conf 
# The output as below:
localhost:
  name : 'local'
  url  : 'http://localhost/status'

localipv4:
  name : 'local'
  url  : 'http://127.0.0.1/status'

Restart Netdata Server

[root@DevopsRoles ~]# systemctl restart netdata 

5. Using Netdata to Monitor PHP-FPM

Open a web browser access the netdata web UI.

http://NETDATA_SERVER_IP:19999
or
http://DOMAIN_NAME:19999

The result as the picture below

Conclusion

Through the article, you can use Netdata to monitor PHP-FPM. I hope will this your helpful. Thank you for reading the DevopsRoles page!

In this tutorial, How to Monitor the Nginx using Netdata on Centos 7. Netdata is a free open source. It is very easy to install and configure for real-time monitoring.

Steps install and configure

• Centos 7 Server or RHEL 7 Server
• Install Web Server Nginx
• Install Netdata and configure Monitor for Web Server Nginx.

1. Install Web Server Nginx

Enable EPEL repository

[root@DevopsRoles ~]# yum install epel-release

Install the Nginx package, as follows.

[root@DevopsRoles ~]# yum install nginx

Start and enable Nginx Web Server, as follows.

[root@DevopsRoles ~]# systemctl start nginx
[root@DevopsRoles ~]# systemctl enable nginx
[root@DevopsRoles ~]# systemctl status nginx

If you are running a firewall. You need to open port 80/443 for Nginx Webserver.

Enable Nginx Stub_Status Module

I will enable the stub_status module which netdata uses to collect metrics from your Nginx web server.

[root@DevopsRoles ~]# vi /etc/nginx/nginx.conf

Copy and paste the location configuration as below

location /server_status {
 	stub_status;
 	allow 127.0.0.1;	#only allow requests from localhost
 	deny all;		#deny all other hosts	
 }

restart the Nginx service to effect

[root@DevopsRoles ~]# nginx -t
[root@DevopsRoles ~]# systemctl restart nginx

Now, Use curl command to check

curl http://127.0.0.1/server_status

# The output terminal as below:
[root@DevopsRoles ~]# curl http://127.0.0.1/server_status
Active connections: 1 
server accepts handled requests
 1 1 1 
Reading: 0 Writing: 1 Waiting: 0

3. Install Netdata on Centos 7 here

4. Configure Netdata to Monitor Nginx

The Netdata configure for Nginx in folder /etc/netdata/python.d which is written in YAML format.

You can open it or create a new file nginx.conf as below

[root@DevopsRoles python.d]# cat /etc/netdata/python.d/nginx.conf 
# The output as below:
localhost:
  name : 'local'
  url  : 'http://localhost/server_status'

localipv4:
  name : 'local'
  url  : 'http://127.0.0.1/server_status'

Restart Netdata Server

[root@DevopsRoles ~]# systemctl restart netdata 

5. Using Netdata to Monitor Nginx Web Server

Open a web browser access the netdata web UI.

http://NETDATA_SERVER_IP:19999
or
http://DOMAIN_NAME:19999

The result as the picture below

Conclusion

Through the article, you can use Netdata to monitor Nginx. I hope will this your helpful. Thank you for reading the DevopsRoles page!

In this tutorial, How to Monitor the MariaDB database using Netdata on Centos 7. Netdata is a free open source. It is very easy to install and configure for real-time monitoring.

Steps install and configure

• Centos 7 Server or RHEL 7 Server
• Install MariaDB Database
• Install Netdata and configure Monitor for MariaDB Database.

1. Install MariaDB Database

Adding MariaDB YUM software repository.

[root@DevopsRoles ~]# vim /etc/yum.repos.d/MariaDB.repo

The content file MariaDB.repo is as follows.

[mariadb]
name = MariaDB
baseurl = http://yum.mariadb.org/10.1/centos7-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1

Install the MariaDB package, as follows.

[root@DevopsRoles ~]# yum install MariaDB-server MySQL-python MariaDB-client -y

Start and enable MariaDB Database Server, as follows.

[root@DevopsRoles ~]# systemctl start mariadb
[root@DevopsRoles ~]# systemctl enable mariadb
[root@DevopsRoles ~]# systemctl status mariadb

By default, the MySQL installation is unsecure and you need to secure it, as follows

[root@DevopsRoles ~]# mysql_secure_installation

To create this user MariaDB

MariaDB [(none)]> create user 'netdata'@'localhost'; 
MariaDB [(none)]> grant usage on *.* to 'netdata'@'localhost'; 
MariaDB [(none)]> flush privileges; 

If you are running a firewall. You need to open the port 3306 for MariaDB Database

3. Install Netdata on Centos 7 here

4. Configure Netdata to Monitor MariaDB

The netdata configure for MariaDB in folder /etc/netdata/python.d which is written in YAML format.

You can open it or create a new file mysql.conf as below

[root@DevopsRoles python.d]# cat /etc/netdata/python.d/mysql.conf 
localhost:
  name : 'local'
  user : 'netdata'
  port : '3306'

Restart Netdata Server

[root@DevopsRoles ~]# systemctl restart netdata 

5. Using Netdata to Monitor MariaDB Database

Open a web browser access the netdata web UI.

http://NETDATA_SERVER_IP:19999
or
http://DOMAIN_NAME:19999

The result as the picture below

Netdata debug for mariadb

/usr/libexec/netdata/plugins.d/python.d.plugin 1 debug mysql

Error netdata for MariaDB code (Fixed)

2020-07-05 16:32:37: python.d ERROR: mysql[localhost] : MySQLdb or PyMySQL module is needed to use mysql.chart.py plugin

On My Centos missing MySQL-python package

Conclusion

Through the article, you can use Netdata to Monitor MariaDB Database. I hope will this your helpful.

In this tutorial, How to Monitor Apache Performance using Netdata on Centos 7. Netdata is a free open source. It is very easy to install and configure for real-time monitoring.

Steps install and configure

• Centos 7 Server or RHEL 7 Server
• Install Apache HTTP Server with mod_status_module enabled
• Install Netdata and configure Monitor for Apache HTTP Server.

1. Install Apache HTTP server

First, install the Apache HTTP server on Centos. I will Yum package manager to install Apache.

[root@DevopsRoles ~]# yum install httpd

Start and enable Apache HTTP server.

[root@DevopsRoles ~]# systemctl start httpd
[root@DevopsRoles ~]# systemctl enable httpd
[root@DevopsRoles ~]# systemctl status httpd

If you are running a firewall. You need to open ports 80 and 443 for Apache.

2. Enable mod_status module in Apache

You need to enable and configure the mod_status module in apache, This is required by Netdata.

[root@DevopsRoles ~]# cat /etc/httpd/conf.modules.d/00-base.conf | grep mod_status
LoadModule status_module modules/mod_status.so

Create a server-status.conf for the Apache server-status page as below

[root@DevopsRoles ~]# cat /etc/httpd/conf.d/server-status.conf
<Location "/server-status">
    SetHandler server-status
    #Require host localhost           #uncomment to only allow requests from localhost 
</Location>

Restart Apache HTTP Server

[root@DevopsRoles ~]# systemctl restart httpd

Test working Apache Server status page.

[root@DevopsRoles ~]# curl http://localhost/server-status  

3. Install Netdata on Centos 7 here

4. Configure Netdata to Monitor Apache Performance

The Netdata configure for Apache in folder /etc/netdata/python.d

You can open it or create new file apache.conf as below

[root@DevopsRoles ~]# cat /etc/netdata/python.d/apache.conf
localhost:
  name : 'local'
  url  : 'http://localhost/server-status?auto'

localipv4:
  name : 'local'
  url  : 'http://127.0.0.1/server-status?auto'

Restart netdata server

[root@DevopsRoles ~]# systemctl restart netdata 

5. Using Netdata to Monitor Apache Performance

Open a web browser access the Netdata web UI.

http://NETDATA_SERVER_IP:19999
or
http://DOMAIN_NAME:19999

The result as below

Conclusion

Thought the article, you can use Netdata to monitor Apache Performance. I hope will this your helpful.