Apache Tomcat

Application Servers

i) JBoss or Wildfly 

From 1.x to 7.x called JBoss and from 8.x called Wildfly

ii) Tomcat
iii) WAS (WebSphere Application Server)
iv) Weblogic

Tomcat Directory Structure 

i) bin

startup.sh
startup.bat
shutdown.sh
shutdown.bat
catalina.sh start/stop
catalina.bat 
version.sh
version.bat

ii) conf

tomcat-users.xml
server.xml

iii)lib
jar files

iv)logs

catalina.out

v)webapps

It stores 5 default applications. However, you can deploy any number of applications.

vi)work

After deploying the applications, it will store some application-related files which will use.

vii)temp

Temporary directory

Tomcat Server installation 

The pre-requisite is java to be installed

download link for tomcat zip file


Step-1: Download and install java

Step-2: Download and install tomcat 

# wget https://mirrors.estointernet.in/apache/tomcat/tomcat-9/v9.0.41/bin/apache-tomcat-9.0.41.zip

# ls -lrt apache-tomcat-9.0.41.zip
-rw-r--r--. 1 root root 11983597 Dec  3 12:42 apache-tomcat-9.0.41.zip

Step-3: unzip the zip file

# unzip apache-tomcat-9.0.41.zip

# ls -lrt apache-tomcat-9.0.41
total 136
-rw-r--r--. 1 root root 16984 Dec  3 11:45 RUNNING.txt
-rw-r--r--. 1 root root  7072 Dec  3 11:45 RELEASE-NOTES
-rw-r--r--. 1 root root  3336 Dec  3 11:45 README.md
-rw-r--r--. 1 root root  2401 Dec  3 11:45 NOTICE
-rw-r--r--. 1 root root 58153 Dec  3 11:45 LICENSE
-rw-r--r--. 1 root root  5545 Dec  3 11:45 CONTRIBUTING.md
-rw-r--r--. 1 root root 19540 Dec  3 11:45 BUILDING.txt
drwxr-xr-x. 2 root root  4096 Dec  3 11:45 lib
drwxr-xr-x. 7 root root    81 Dec  3 11:45 webapps
drwxr-xr-x. 2 root root    30 Dec  3 11:45 temp
drwxr-xr-x. 2 root root  4096 Dec  3 11:46 bin
drwxr-xr-x. 3 root root    22 Dec 14 03:05 work
drwxr-xr-x. 3 root root   254 Dec 14 03:29 conf
drwxr-xr-x. 2 root root  4096 Dec 15 10:45 logs


Step-4: Check the installed tomcat version

# sh version.sh
Using CATALINA_BASE:   /opt/apache-tomcat-9.0.41
Using CATALINA_HOME:   /opt/apache-tomcat-9.0.41
Using CATALINA_TMPDIR: /opt/apache-tomcat-9.0.41/temp
Using JRE_HOME:        /usr
Using CLASSPATH:       /opt/apache-tomcat-9.0.41/bin/bootstrap.jar:/opt/apache-tomcat-9.0.41/bin/tomcat-juli.jar
Using CATALINA_OPTS:
Server version: Apache Tomcat/9.0.41
Server built:   Dec 3 2020 11:43:00 UTC
Server number:  9.0.41.0
OS Name:        Linux
OS Version:     4.18.0-240.1.1.el8_3.x86_64
Architecture:   amd64
JVM Version:    1.8.0_131-b11
JVM Vendor:     Oracle Corporation


Step-5: Create a soft link for easy maintenance of tomcat 

# ln -s /opt/apache-tomcat-9.0.41/bin/startup.sh /usr/bin/startTomcat
# ln -s /opt/apache-tomcat-9.0.41/bin/shutdown.sh /usr/bin/stopTomcat


# ls -rlt /usr/bin/startTomcat
lrwxrwxrwx. 1 root root 40 Dec 14 03:04 /usr/bin/startTomcat -> /opt/apache-tomcat-9.0.41/bin/startup.sh
# ls -lrt /usr/bin/stopTomcat
lrwxrwxrwx. 1 root root 41 Dec 14 03:05 /usr/bin/stopTomcat -> /opt/apache-tomcat-9.0.41/bin/shutdown.sh

to startup -> startTomcat
to shutdown/stop -> stopTomcat

Commands:

1. Startup Tomcat

]# startTomcat
Using CATALINA_BASE:   /opt/apache-tomcat-9.0.41
Using CATALINA_HOME:   /opt/apache-tomcat-9.0.41
Using CATALINA_TMPDIR: /opt/apache-tomcat-9.0.41/temp
Using JRE_HOME:        /usr
Using CLASSPATH:       /opt/apache-tomcat-9.0.41/bin/bootstrap.jar:/opt/apache-tomcat-9.0.41/bin/tomcat-juli.jar
Using CATALINA_OPTS:
Tomcat started.

OR

# sh startup.sh
Using CATALINA_BASE:   /opt/apache-tomcat-9.0.41
Using CATALINA_HOME:   /opt/apache-tomcat-9.0.41
Using CATALINA_TMPDIR: /opt/apache-tomcat-9.0.41/temp
Using JRE_HOME:        /usr
Using CLASSPATH:       /opt/apache-tomcat-9.0.41/bin/bootstrap.jar:/opt/apache-tomcat-9.0.41/bin/tomcat-juli.jar
Using CATALINA_OPTS:
Tomcat started.

OR

# sh catalina.sh start
Using CATALINA_BASE:   /opt/apache-tomcat-9.0.41
Using CATALINA_HOME:   /opt/apache-tomcat-9.0.41
Using CATALINA_TMPDIR: /opt/apache-tomcat-9.0.41/temp
Using JRE_HOME:        /usr
Using CLASSPATH:       /opt/apache-tomcat-9.0.41/bin/bootstrap.jar:/opt/apache-tomcat-9.0.41/bin/tomcat-juli.jar
Using CATALINA_OPTS:
Tomcat started.


# ps -ef |grep tomcat
root        2927       1  3 19:45 pts/0    00:00:03 /usr/bin/java -Djava.util.logging.config.file=/opt/apache-tomcat-9.0.41/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /opt/apache-tomcat-9.0.41/bin/bootstrap.jar:/opt/apache tomcat-9.0.41/bin/tomcat-juli.jar -Dcatalina.base=/opt/apache-tomcat-9.0.41 -Dcatalina.home=/opt/apache-tomcat-9.0.41 -Djava.io.tmpdir=/opt/apache-tomcat-9.0.41/temp org.apache.catalina.startup.Bootstrap start
root        2973    2243  0 19:46 pts/0    00:00:00 grep --color=auto tomcat


2. Shutdown/Stop Tomcat 

# stopTomcat
Using CATALINA_BASE:   /opt/apache-tomcat-9.0.41
Using CATALINA_HOME:   /opt/apache-tomcat-9.0.41
Using CATALINA_TMPDIR: /opt/apache-tomcat-9.0.41/temp
Using JRE_HOME:        /usr
Using CLASSPATH:       /opt/apache-tomcat-9.0.41/bin/bootstrap.jar:/opt/apache-tomcat-9.0.41/bin/tomcat-juli.jar
Using CATALINA_OPTS:

OR

# sh shutdown.sh
Using CATALINA_BASE:   /opt/apache-tomcat-9.0.41
Using CATALINA_HOME:   /opt/apache-tomcat-9.0.41
Using CATALINA_TMPDIR: /opt/apache-tomcat-9.0.41/temp
Using JRE_HOME:        /usr
Using CLASSPATH:       /opt/apache-tomcat-9.0.41/bin/bootstrap.jar:/opt/apache-tomcat-9.0.41/bin/tomcat-juli.jar
Using CATALINA_OPTS:

OR

# sh catalina.sh stop
Using CATALINA_BASE:   /opt/apache-tomcat-9.0.41
Using CATALINA_HOME:   /opt/apache-tomcat-9.0.41
Using CATALINA_TMPDIR: /opt/apache-tomcat-9.0.41/temp
Using JRE_HOME:        /usr
Using CLASSPATH:       /opt/apache-tomcat-9.0.41/bin/bootstrap.jar:/opt/apache-tomcat-9.0.41/bin/tomcat-juli.jar
Using CATALINA_OPTS:


# ps -ef |grep tomcat
root        3044    2243  0 19:47 pts/0    00:00:00 grep --color=auto tomcat


Steps to access tomcat server from Remote location or Desktop

Step-1: Go to Security tab and select Security group and click on Launch Wizard named and click on Add Rule in AWS console and enable the port 8080

Security -> Security Group -> Launch Wizard -> Edit Inbout Rules -> Add Rules -> add you port numbers

Step-2:  Use server host and port to launch tomcat portal

http://<Server_ip_address>:<port_number>

Example: http://13.127.218.70:8080


Types of Log files in the log directory:

localhost
manager
host-manger
catalina.out


# ls -rlt
total 20
-rw-r-----. 1 root root    0 Jan 11 04:32 manager.2021-01-11.log
-rw-r-----. 1 root root    0 Jan 11 04:32 host-manager.2021-01-11.log
-rw-r-----. 1 root root    0 Jan 11 04:32 localhost_access_log.2021-01-11.txt
-rw-r-----. 1 root root  408 Jan 11 04:32 localhost.2021-01-11.log
-rw-r-----. 1 root root 5814 Jan 11 04:32 catalina.out
-rw-r-----. 1 root root 5814 Jan 11 04:32 catalina.2021-01-11.log


Steps to create users in the tomcat 

Step-1: We can add users using the "tomcat-users.xml" file in the Tomcat "conf" directory 

Tomcat home -> conf -> tomcat-users.xml

# pwd
/opt/apache-tomcat-9.0.41/conf
# ls -rlt
total 236
-rw-r--r--. 1 root root 177096 Dec  3 11:45 web.xml
-rw-r--r--. 1 root root   2617 Dec  3 11:45 tomcat-users.xsd
-rw-r--r--. 1 root root   7759 Dec  3 11:45 server.xml
-rw-r--r--. 1 root root   4223 Dec  3 11:45 logging.properties
-rw-r--r--. 1 root root   2365 Dec  3 11:45 jaspic-providers.xsd
-rw-r--r--. 1 root root   1172 Dec  3 11:45 jaspic-providers.xml
-rw-r--r--. 1 root root   1431 Dec  3 11:45 context.xml
-rw-r--r--. 1 root root   7468 Dec  3 11:45 catalina.properties
-rw-r--r--. 1 root root  13132 Dec  3 11:45 catalina.policy
drwxr-x---. 3 root root     23 Dec 14 03:05 Catalina
-rw-r--r--. 1 root root   2289 Dec 14 03:15 tomcat-users.xml

Add these below lines into "tomcat-users.xml" file.

Extracts lines from "tomcat-users.xml" :

<tomcat-users>
<user username="user_name" password="password" roles="manager-gui,admin-gui"/>
</tomcat-users>

Step-2: Comment out the value className from the context.xml file in the manager folder 

Tomcat home -> webapps -> manager -> META-INF -> context.xml 

Comment out the below line in "context.xml" file. If you don't comment out you may see "Access Denied" Or Forbidden Error.

Extract lines from context.xml file:

<!--  <Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1" />
-->


Step-3: Comment out the value className from the context.xml file in the host-manager

Tomcat home -> webapps -> host-manager -> META-INF -> context.xml 

Extract lines from context.xml file:

<!--  <Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1" />
-->


When to restart the tomcat server?
only if we do any changes in the server.xml file


What are the default applications with tomcat? 

/
/docs
/examples
/host-manager
/manager


Tomcat Roles

manager-gui  --- able to access manager app and server status
admin-gui     ---- able to access host manager 
manager-script 


Reserve Ports:

22 - SSH
25: SMTP
8080: Http
443: HTTPS

Note: Jboss/Wildfly/tomcat/jenkins default port is 8080


How to change the default Tomcat port (8080)

Step-1: Change the port from tomcat home location in "server.xml" file.

update your required port number in the place of 8080 port:

<Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />

Make sure to modify the correct port since there would be multiple entires for 8080 port.

Note: Since you have modified "server.xml" file you must restart the tomcat server to take effect the new changes.

Step-2: Restart the tomcat server

sh shutdown.sh
sh startup.sh

# ls -lrt
total 236
-rw-r--r--. 1 root root 177096 Dec  3 11:45 web.xml
-rw-r--r--. 1 root root   2617 Dec  3 11:45 tomcat-users.xsd
-rw-r--r--. 1 root root   7759 Dec  3 11:45 server.xml
-rw-r--r--. 1 root root   4223 Dec  3 11:45 logging.properties
-rw-r--r--. 1 root root   2365 Dec  3 11:45 jaspic-providers.xsd
-rw-r--r--. 1 root root   1172 Dec  3 11:45 jaspic-providers.xml
-rw-r--r--. 1 root root   1431 Dec  3 11:45 context.xml
-rw-r--r--. 1 root root   7468 Dec  3 11:45 catalina.properties
-rw-r--r--. 1 root root  13132 Dec  3 11:45 catalina.policy
drwxr-x---. 3 root root     23 Dec 14 03:05 Catalina
-rw-r--r--. 1 root root   2289 Dec 14 03:15 tomcat-users.xml



Deployment

Tomat page Manager -> Deploy -> 2 Options => Deploy using WAR file located on server OR WAR file to deploy.

The deployment files would be available at "webapps" directory in the tomcat software home location


Before: 

# pwd
/opt/apache-tomcat-9.0.41/webapps
# ls -rlt
total 4
drwxr-xr-x.  3 root root  223 Dec  3 11:45 ROOT
drwxr-xr-x. 15 root root 4096 Dec  3 11:45 docs
drwxr-xr-x.  6 root root  114 Dec  3 11:45 manager
drwxr-xr-x.  6 root root   79 Dec  3 11:45 host-manager
drwxr-xr-x.  7 root root   99 Dec  3 11:45 examples

 
Post deployment:

[root@ip-172-31-34-208 webapps]# ls -rlt
total 5216
drwxr-xr-x.  3 root root     223 Dec  3 11:45 ROOT
drwxr-xr-x. 15 root root    4096 Dec  3 11:45 docs
drwxr-xr-x.  6 root root     114 Dec  3 11:45 manager
drwxr-xr-x.  6 root root      79 Dec  3 11:45 host-manager
drwxr-xr-x.  7 root root      99 Dec  3 11:45 examples
-rw-r-----.  1 root root 5335645 Jan 11 06:45 maven-web-application.war
drwxr-x---.  6 root root      63 Jan 11 06:45 maven-web-application  ---------- deployed (default) 


# ls -rlt
total 5216
drwxr-xr-x.  3 root root     223 Dec  3 11:45 ROOT
drwxr-xr-x. 15 root root    4096 Dec  3 11:45 docs
drwxr-xr-x.  6 root root     114 Dec  3 11:45 manager
drwxr-xr-x.  6 root root      79 Dec  3 11:45 host-manager
drwxr-xr-x.  7 root root      99 Dec  3 11:45 examples
-rw-r-----.  1 root root 5335645 Jan 11 07:58 fin_proj1.war
drwxr-x---.  6 root root      63 Jan 11 07:58 fin_proj1  ---------- deployed (Custom)

How to access deployed applications?
With the help of the context path and by default, the context path is the war file name. However, you could define your own context pathname.

Example: 

Default: 
http://13.126.233.74:9743/maven-web-application

Customize: http://13.126.233.74:9743/fin_proj1

Deployment Options:

Default => WAR file to deploy.
Custom => Deploy using WAR file located on the server


Types of Deployment


Normal Deployment
Hot Fixes/Hot Deployment



Configure service as systemctl


Difference between Tomcat and JBoss



Web Servers

Apatch Https Server
Naginx (Read as Engine X)
IHS (IBM Http Server)
Oracle IPlanet

Apps Server vs Web Server

Application Server:
Application server process the business logic. Like War, Ear files

Web server:
It can be used to host Static contents. Like, html, css, js and images)
It is used for load balancing



What file used to configure all the load balancing URLs.
httpd.conf
By default, it follows a round-robin algorithm. We could modify the request by setting the parameter "load factor".

What are the dedicated load balancing servers?

HAProxy (Open source)
F5  (It's a CISCO product and it requires a license)








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