updated tomcat file:

Author: ValaxyTech

Tomcat/tomcat_installation.MD

@@ -1,26 +1,28 @@
 # Tomcat installation on EC2 instance
-
+Follow this video lecture in Valaxy Technologies **[YouTube Channel](https://youtu.be/68WNroQBUts)**
+Complete DevOps Project course on [Udemy](https://www.udemy.com/course/valaxy-devops/?referralCode=8147A5CF4C8C7D9E253F)
 ### Pre-requisites
 1. EC2 instance with Java v1.8.x 
-
 ### Install Apache Tomcat
 1. Download tomcat packages from  https://tomcat.apache.org/download-80.cgi onto /opt on EC2 instance
+   > Note: Make sure you change `<version>` with the tomcat version which you download. 
    ```sh 
    # Create tomcat directory
    cd /opt
    wget http://mirrors.fibergrid.in/apache/tomcat/tomcat-8/v8.5.35/bin/apache-tomcat-8.5.35.tar.gz
-   tar -xvzf /opt/apache-tomcat-8.5.35.tar.gz
+   tar -xvzf /opt/apache-tomcat-<version>.tar.gz
    ```
 1. give executing permissions to startup.sh and shutdown.sh which are under bin. 
    ```sh
-   chmod +x /opt/apache-tomcat-8.5.35/bin/startup.sh 
-   shutdown.sh
+   chmod +x /opt/apache-tomcat-<version>/bin/startup.sh 
+   chmod +x /opt/apache-tomcat-<version>/bin/shutdown.sh
    ```
-
+   > Note: you may get below error while starting tomcat incase if you dont install Java 
+   `Neither the JAVA_HOME nor the JRE_HOME environment variable is defined At least one of these environment variable is needed to run this program`
 1. create link files for tomcat startup.sh and shutdown.sh 
    ```sh
-   ln -s /opt/apache-tomcat-8.5.35/bin/startup.sh /usr/local/bin/tomcatup
-   ln -s /opt/apache-tomcat-8.5.35/bin/shutdown.sh /usr/local/bin/tomcatdown
+   ln -s /opt/apache-tomcat-<version>/bin/startup.sh /usr/local/bin/tomcatup
+   ln -s /opt/apache-tomcat-<version>/bin/shutdown.sh /usr/local/bin/tomcatdown
    tomcatup
    ```
   #### Check point :
@@ -29,7 +31,7 @@ access tomcat application from browser on port 8080
 
   Using unique ports for each application is a best practice in an environment. But tomcat and Jenkins runs on ports number 8080. Hence lets change tomcat port number to 8090. Change port number in conf/server.xml file under tomcat home
    ```sh
- cd /opt/apache-tomcat-8.5.35/conf
+ cd /opt/apache-tomcat-<version>/conf
 # update port number in the "connecter port" field in server.xml
 # restart tomcat after configuration update
 tomcatdown
@@ -45,13 +47,18 @@ Access tomcat application from browser on port 8090
    find / -name context.xml
    ```
 1. above command gives 3 context.xml files. comment (<!-- & -->) `Value ClassName` field on files which are under webapp directory. 
-After that restart tomcat services to effect these changes
+After that restart tomcat services to effect these changes. 
+At the time of writing this lecture below 2 files are updated. 
    ```sh 
-   tomcatdown
+   /opt/tomcat/webapps/host-manager/META-INF/context.xml
+   /opt/tomcat/webapps/manager/META-INF/context.xml
+   
+   # Restart tomcat services
+   tomcatdown  
    tomcatup
    ```
 1. Update users information in the tomcat-users.xml file
-goto tomcat home directory and Add below users to conf/tomcat-user.xml file
+goto tomcat home directory and Add below users to conf/tomcat-users.xml file
    ```sh
 	<role rolename="manager-gui"/>
 	<role rolename="manager-script"/>