How to Install Tomcat 9 on Ubuntu 18.04

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6 min read

Apache Tomcat is an open-source implementation of the Java Servlet, JavaServer Pages, Java Expression Language, and Java WebSocket technologies. It is one of the most widely adopted applications and web servers in the world today. Tomcat is simple to use and has a robust ecosystem of add-ons.

This tutorial explains to install and configure Tomcat 9 on Ubuntu 18.04. The same instructions apply for Ubuntu 16.04 and any Ubuntu-based distribution, including Linux Mint and Elementary OS.

Prerequisites

To be able to install packages on your Ubuntu system, you must be logged in as a user with sudo privileges.

Step 1: Install OpenJDK

Tomcat requires Java to be installed. We’ll install OpenJDK, which is the default Java development and runtime in Ubuntu 18.04.

The installation of Java is pretty simple. Begin by updating the package index:

sudo apt update

Install the OpenJDK package by running:

sudo apt install default-jdk

Step 2: Create Tomcat User

For security purposes, Tomcat should not be run under the root user. We will create a new system user and group with home directory /opt/tomcat that will run the Tomcat service:

sudo useradd -r -m -U -d /opt/tomcat -s /bin/false tomcat

Step 3: Install Tomcat

We will download the latest binary release of Tomcat 9 from the Tomcat 9 downloads page.

At the time of writing, the latest version is 9.0.27. Before continuing with the next step, you should check the download page for a new version. If there is a new version, copy the link to the Core tar.gz file, which is under the Binary Distributions section.

Start by download the Tomcat archive in the /tmp directory using the following wget command:

wget http://www-eu.apache.org/dist/tomcat/tomcat-9/v9.0.27/bin/apache-tomcat-9.0.27.tar.gz -P /tmp

Once the download is complete, extract the Tomcat archive and move it to the /opt/tomcat directory:

sudo tar xf /tmp/apache-tomcat-9*.tar.gz -C /opt/tomcat

To have more control over Tomcat versions and updates, create symbolic link called latest that points to the Tomcat installation directory:

sudo ln -s /opt/tomcat/apache-tomcat-9.0.27 /opt/tomcat/latest

Later if you want to upgrade your Tomcat instance, simply unpack the newer version and change the symlink to point to the latest version.

As we mentioned in the previous section Tomcat will run under the tomcat user. This user needs to have access to the tomcat installation directory.

The following command changes the directory ownership to user and group tomcat:

sudo chown -RH tomcat: /opt/tomcat/latest

The scripts inside bin directory must have executable flag:

sudo sh -c 'chmod +x /opt/tomcat/latest/bin/*.sh'

Step 4: Create a systemd Unit File

To run Tomcat as a service you need to create a new unit file.

Open your text editor and create a file named tomcat.service in the /etc/systemd/system/:

sudo nano /etc/systemd/system/tomcat.service

Paste the following configuration:

/etc/systemd/system/tomcat.service
[Unit]
Description=Tomcat 9 servlet container
After=network.target

[Service]
Type=forking

User=tomcat
Group=tomcat

Environment="JAVA_HOME=/usr/lib/jvm/default-java"
Environment="JAVA_OPTS=-Djava.security.egd=file:///dev/urandom -Djava.awt.headless=true"

Environment="CATALINA_BASE=/opt/tomcat/latest"
Environment="CATALINA_HOME=/opt/tomcat/latest"
Environment="CATALINA_PID=/opt/tomcat/latest/temp/tomcat.pid"
Environment="CATALINA_OPTS=-Xms512M -Xmx1024M -server -XX:+UseParallelGC"

ExecStart=/opt/tomcat/latest/bin/startup.sh
ExecStop=/opt/tomcat/latest/bin/shutdown.sh

[Install]
WantedBy=multi-user.target
Modify the value of JAVA_HOME if the path to your Java installation is different.

Save and close the file and notify systemd that we created a new unit file:

sudo systemctl daemon-reload

Start the Tomcat service by executing:

sudo systemctl start tomcat

Check the service status with the following command:

sudo systemctl status tomcat
* tomcat.service - Tomcat 9 servlet container
   Loaded: loaded (/etc/systemd/system/tomcat.service; disabled; vendor preset: enabled)
   Active: active (running) since Wed 2018-09-05 15:45:28 PDT; 20s ago
  Process: 1582 ExecStart=/opt/tomcat/latest/bin/startup.sh (code=exited, status=0/SUCCESS)
 Main PID: 1604 (java)
    Tasks: 47 (limit: 2319)
   CGroup: /system.slice/tomcat.service

If there are no errors enable the Tomcat service to be automatically started at boot time:

sudo systemctl enable tomcat

Step 5: Adjust the Firewall

If your server is protected by a firewall and you want to access Tomcat from the outside of your local network, you need to open port 8080.

To allow traffic on port 8080 type the following command:

sudo ufw allow 8080/tcp
Usually when running a Tomcat application in a production environment you will have a load balancer or reverse proxy. It’s a best practice to restrict access to port 8080 only to your internal network.

Step 6: Configure Tomcat Web Management Interface

Now that Tomcat is installed and running, the next step is to create a user with access the web management interface.

Tomcat users and roles are defined in the tomcat-users.xml file. This file is a template with comments and examples describing how to configure the create a user or role.

sudo nano /opt/tomcat/latest/conf/tomcat-users.xml

To add a new user with access to the Tomcat web interface (manager-gui and admin-gui) we need to define the user in the tomcat-users.xml file, as shown below. Make sure you change the username and password to something more secure:

/opt/tomcat/latest/conf/tomcat-users.xml
<tomcat-users>
<!--
    Comments
-->
   <role rolename="admin-gui"/>
   <role rolename="manager-gui"/>
   <user username="admin" password="admin_password" roles="admin-gui,manager-gui"/>
</tomcat-users>

By default Tomcat web management interface is configured to restrict access to the Manager and Host Manager apps only from the localhost.

If you want to be able to access the web interface from a remote IP, you will have to remove these restrictions. This may have various security implications, and it is not recommended for production systems.

To enable access to the web interface from anywhere open the following two files and comment or remove the lines highlighted in yellow.

For the Manager app, open the following file:

sudo nano /opt/tomcat/latest/webapps/manager/META-INF/context.xml

For the Host Manager app, open the following file:

sudo nano /opt/tomcat/latest/webapps/host-manager/META-INF/context.xml
context.xml
<Context antiResourceLocking="false" privileged="true" >
<!--
  <Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1" />
-->
</Context>

Another option is to allow access to the to the Manager and Host Manager apps only from a specific IP. Instead of commenting the blocks you can simply add your IP address to the list.

For example if your public IP is 45.45.45.45 you would make the following change:

context.xml
<Context antiResourceLocking="false" privileged="true" >
  <Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1|45.45.45.45" />
</Context>

The list of allowed IP addresses is a list separated with vertical bar |. You can add single IP addresses or use a regular expressions.

Remember to restart the Tomcat service each time you edit Tomcat configuration files for changes to take effect:

sudo systemctl restart tomcat

Step 6: Test the Tomcat Installation

Open your browser and type: http://<your_domain_or_IP_address>:8080

Assuming the installation is successful, a screen similar to the following should appear:

Tomcat web application manager dashboard is available at http://<your_domain_or_IP_address>:8080/manager/html. From here, you can deploy, undeploy, start, stop, and reload your applications.

You can sign in with the user you have created in Step 6.

Tomcat virtual host manager dashboard is available at http://<your_domain_or_IP_address>:8080/host-manager/html. From here, you can create, delete and manage Tomcat virtual hosts.

Conclusion

You have successfully installed Tomcat 9 on your Ubuntu 18.04 system. You can now visit the official Apache Tomcat 8 Documentation and learn more about the Apache Tomcat features.

If you hit a problem or have feedback, leave a comment below.