How to setup Tomcat so to use mysql for ALL Flowable UI applications

Flowable Engine
1

Dear all,

I am new to Java, Tomcat, MySQL and Flowable, so please bear with me.

I don’t have luck in making Tomcat to use MySQL for all Flowable UI applications. (Follow the section 2,3 of the doc, I am able to get that Java command line app to use mysql.)

Machine: (Virtual Machine) Linux Mint 18.2 (based on Ubuntu 16.04)
Flowable: 6.3.1
Tomcat: Version 8.5.31
Java: 8
MySQL: Ver 14.14 Distrib 5.7.22, for Linux (x86_64) using EditLine wrapper (install via: sudo apt install tomcat-server at terminal)
MySQL Connector/J : Version 8.0.11 (download from mysql.com)
(Install Tomcat using this method, but skip step 2 and 4.)

In section 3.4.1 Database configuration, it says instead of going into each WAR, modify the content and rebuild WAR, it is better to do it at Tomcat. According to doc, I should modify this file: $CATALINA_BASE/conf/Catalina/localhost/flowable-app.xml

Seeing this, I create a flowable-modeler.xml and have the following content:

<?xml version="1.0" encoding="UTF-8"?>
<Context antiResourceLocking="true" path="/flowable-modeler">
    <Resource auth="Container"
        name="jdbc/flowableDB"
        type="javax.sql.DataSource"
        description="JDBC DataSource"
        url="jdbc:mysql://localhost:3306/flowable_modeler?autoReconnect=true&amp;useSSL=false"
        driverClassName="com.mysql.jc.jdbc.Driver"
        username="root"
        password="password"
        defaultAutoCommit="false"
        initialSize="5"
        maxWait="5000"
        maxActive="120"
        maxIdle="5"/>
</Context>
  1. [Context] Instead of “anitJARLocking”, I use “antiResourceLocking” as Tomcat version is now 8.
  2. [Context] Path is updated.
  3. [Resource URL] A database is created for modeler.
  4. [Resource URL] Disable SSL.
  5. [Resource driverClassName] Update JDBC driver to be “com.mysql.jc.jdbc.Driver”.
  6. I have another 4 XML files with each one for each Flowable UI application.

I then start tomcat (sudo systemctl start tomcat), I get:
WARNING [localhost-startStop-1] org.apache.naming.NamingContext.lookup Unexpected exception resolving reference java.sql.SQLException: Cannot load JDBC driver class ‘com.mysql.jc.jdbc.Driver’

And then I get stuck in:
INFO 20310 — [ost-startStop-1] liquibase : Waiting for changelog lock…

Is there almost a step by step procedure on how to make those Flowable UI applictions to use MySQL? I know that one can modify the application.properties file (as stated in 14.1 of the doc), but that is for each application. I want an solution that is for the site level. Thank you.