Start an application using systemd
Systemd Journal
Ubuntu Configure systemd-resolved
Run a script on boot using systemd on Ubuntu 18.04
Ubuntu 18.04 MariaDB 10.2 Too many open files
Application Performance Monitor (APM)
Application Performance Monitor (APM) is used to monitor application performance. This help you identify problems with your application. If you are developing an application, this is very helpful as you can see changes in application performance during a software upgrade, this allow you to identify perofrmance issues related to changes in your application.
Here are some useful sites that provide Application Performance Monitoring solutions.
serverpilot
serverpilot is a SAAS hosting control panel for web servers.
It use nginx as proxy with apache web server as backend. Services used by serverpilot are
|
1 2 3 4 5 6 |
systemctl status nginx-sp systemctl status apache-sp systemctl status mysql systemctl status php7.1-fpm-sp systemctl status php7.2-fpm-sp systemctl status php7.3-fpm-sp |
Config file locations
|
1 2 |
/etc/nginx-sp/ /etc/apache-sp/ |
Web site specific configuratoons stored in vhosts.d folder inside apache/nginx config folders.
Apache installed at
|
1 2 |
/opt/sp/apache/bin/apachectl start /opt/sp/apache/bin/apachectl configtest |
How to enable gzip on Plesk Nginx
To enable gzip on Plesk server with Nginx proxy, go to
|
1 |
Plesk > Domains |
Click on the domain for which you need gzip compression enbaled.
click on “Apache & nginx Settings”. On next page, scroll down, add following to “Additional nginx directives” text box.
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 |
gzip on; gzip_http_version 1.1; gzip_comp_level 5; gzip_min_length 256; gzip_proxied any; gzip_vary on; gzip_types application/atom+xml application/javascript application/x-javascript application/json application/rss+xml application/vnd.ms-fontobject application/x-font-ttf application/x-web-app-manifest+json application/xhtml+xml application/xml font/opentype image/svg+xml image/x-icon text/css text/plain text/x-component; |
To verify gzip is working, you can open a file directly in browser. Check response headers in browser develoer tool, you should see gzip.
See Plesk
Redirect a folder to another
To redirect a folder to another using .htaccess, create
|
1 |
RedirectMatch 301 ^/OLD_FOLDER/(.*)$ /NEW_FOLDER/$1 |
Or
|
1 2 |
RewriteEngine On RewriteRule ^OLD_FOLDER/(.*)$ /NEW_FOLDER/$1 [R=301,NC,L] |
Or
|
1 |
Redirect 301 /OLD_FOLDER /NEW_FOLDER |
if new folder is on another domain, you can use https://new-domain.com/OLD_FOLDER
See Redirect
MySQL Database Character Set and Collation
To change MySQL database char set and collation, run
|
1 |
ALTER DATABASE DB_NAME_HERE CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci; |
To usee current char set and collation, run
|
1 2 |
USE DB_NAME_HERE; SELECT @@character_set_database, @@collation_database; |
You can specify char set when creating database with following syntax
|
1 |
CREATE DATABASE DB_NAME_HERE CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci; |
sysdig
sysdig is a tool like top, but more powerful, it is a combination of tools like htop, iftop, lsof.
To install sysdig on ubuntu, run
|
1 |
apt-get install sysdig |
To see files using top IO, run
|
1 |
sysdig -c topfiles_bytes |
To access top like GU, run
|
1 |
csysdig |
Password Protect Site using htaccess
To password protect a web site or a sub folder using .htaccess, create a .htaccess file in the folder.
|
1 |
vi .htaccess |
Add following content
|
1 2 3 4 |
AuthType Basic AuthName "Restricted Content" AuthUserFile /etc/apache2/site-logins Require valid-user |
In this case, i used /etc/apache2/site-logins as AuthUserFile, this will store all user and password. You can change this file path to whatever you need. Make sure it is not accessable from public, so keep it outside of document root of your web site.
Now create a user with command
|
1 |
htpasswd -c /etc/apache2/site-logins USER_NAME_HERE |
CageFS command not working for user
I have flvtool2 installed on the server. Path to binary file location was added in file /etc/cagefs/conf.d/vshare.cfg
|
1 2 3 4 5 |
[root@server22 ~]# cat /etc/cagefs/conf.d/vshare.cfg [vshare] comment=vShare Youtube Clone Requirements paths=/usr/bin/ffmpeg, /usr/bin/mencoder, /usr/bin/mplayer, /usr/bin/flvtool2, /usr/bin/lame, /usr/bin/yamdi, /usr/bin/qt-faststart, /usr/bin/MP4Box, /usr/bin/mediainfo, /usr/bin/neroAacEnc [root@server22 ~]# |
The binary program works properly when running as root, but it fail when switching to a user that use CageFS.
|
1 2 3 4 5 6 7 8 |
[root@server22 ~]# /usr/bin/flvtool2 -V FLVTool2 1.0.6 [root@server22 ~]# su - socialwe Last login: Thu May 28 06:33:33 UTC 2020 on pts/0 [socialwe@server22 ~]$ /usr/bin/flvtool2 -V <internal:gem_prelude>:1:in `require': cannot load such file -- rubygems.rb (LoadError) from <internal:gem_prelude>:1:in `<compiled>' [socialwe@server22 ~]$ |
The problem is fixed by editing file /etc/cagefs/cagefs.mp
|
1 |
vi /etc/cagefs/cagefs.mp |
Add following lines
|
1 2 3 4 |
!/usr/lib64/ruby/ !/usr/share/rubygems/ !/usr/share/ruby/ !/usr/local/share/ruby/ |
Now remount cagefs with
|
1 |
cagefsctl --remount-all |
See cagefs
Monitor OpenLiteSpeed with monit
To monitor OpenLiteSpeed with monit on Ubuntu Server, create file
|
1 |
vi /etc/monit/conf-enabled/openlitespeed |
Add following content
|
1 2 3 |
check process OpenLiteSpeed with pidfile /tmp/lshttpd/lshttpd.pid start program = "/usr/bin/systemctl start lshttpd" stop program = "/usr/bin/systemctl stop lshttpd" |
Reload monit with
|
1 |
monit reload |
Now monit will monitor OpenLiteSpeed, restart if required. You can check status with
|
1 |
monit status |
If you want to monitor if web server is responding to request, you can use
|
1 2 3 4 |
check process OpenLiteSpeed with pidfile /tmp/lshttpd/lshttpd.pid start program = "/usr/bin/systemctl start lshttpd" stop program = "/usr/bin/systemctl stop lshttpd" if failed host localhost port 80 protocol http then restart |