[JAVA] Tomcat installation and autostart settings

Introduction

Environment used

• OS
• CentOS 7.7（1908）
• Java（Amazon Corretto）
• Java 1.8.0_242
• Tomcat
• Tomcat-9.0.30

Java installation

• Java downloaded Amazon Corretto 8 from the link on this page.
• Amazon Corretto can select RPM format, so it is installed with the yum command, which makes package management easy.

[root@akagi ~]# yum install -y https://corretto.aws/downloads/latest/amazon-corretto-8-x64-linux-jdk.rpm
[root@akagi ~]# java -version
openjdk version "1.8.0_242"
OpenJDK Runtime Environment Corretto-8.242.08.1 (build 1.8.0_242-b08)
OpenJDK 64-Bit Server VM Corretto-8.242.08.1 (build 25.242-b08, mixed mode)

Install tomcat

• Tomcat has downloaded Tomcat 9.0 from the link on this page.
• For the correspondence between Java and Tomcat versions, Correspondence table on this page is easy to understand.
• You can install Tomcat with the yum command, but since the version of Tomcat is 7.0, which is quite old, I downloaded it from the official website of Tomcat this time.
• Tomcat can only select zip format or tar.gz format, so the one downloaded with tar.gz is placed in the specified folder, then expanded and installed.
• Finally, use startup.sh and shutdown.sh to verify that Tomcat can be started / stopped normally.

Install tomcat

[root@akagi ~]# wget https://www-eu.apache.org/dist/tomcat/tomcat-9/v9.0.30/bin/apache-tomcat-9.0.30.tar.gz
[root@akagi ~]# mv apache-tomcat-9.0.30.tar.gz /usr/local/
[root@akagi ~]# cd /usr/local/
[root@akagi local]# tar zxvf apache-tomcat-9.0.30.tar.gz 
[root@akagi local]# ls
apache-tomcat-9.0.30         bin  games    lib    libexec  share
apache-tomcat-9.0.30.tar.gz  etc  include  lib64  sbin     src

Start and stop tomcat

[root@akagi local]# sh ./apache-tomcat-9.0.30/bin/startup.sh
Using CATALINA_BASE:   /usr/local/apache-tomcat-9.0.30
Using CATALINA_HOME:   /usr/local/apache-tomcat-9.0.30
Using CATALINA_TMPDIR: /usr/local/apache-tomcat-9.0.30/temp
Using JRE_HOME:        /usr
Using CLASSPATH:       /usr/local/apache-tomcat-9.0.30/bin/bootstrap.jar:/usr/local/apache-tomcat-9.0.30/bin/tomcat-juli.jar
Tomcat started.
[root@akagi local]# sh ./apache-tomcat-9.0.30/bin/shutdown.sh 
Using CATALINA_BASE:   /usr/local/apache-tomcat-9.0.30
Using CATALINA_HOME:   /usr/local/apache-tomcat-9.0.30
Using CATALINA_TMPDIR: /usr/local/apache-tomcat-9.0.30/temp
Using JRE_HOME:        /usr
Using CLASSPATH:       /usr/local/apache-tomcat-9.0.30/bin/bootstrap.jar:/usr/local/apache-tomcat-9.0.30/bin/tomcat-juli.jar

Tomcat autostart settings

Add symbolic link

• Add a symbolic link called tomcat9 to the Tomcat9 installation folder.
• By adding a symbolic link, for example, even if you upgrade the version of Tomcat, you only need to modify the symbolic link, so you do not have to modify the unit file described later.

Add symbolic link

[root@akagi local]# ln -s apache-tomcat-9.0.30 tomcat9
[root@akagi local]# ls -l | grep tomcat9
lrwxrwxrwx 1 root root 20 February 2 13:40 tomcat9 -> apache-tomcat-9.0.30

Creating a tomcat user

• Create a user named tomcat to use when starting Tomcat automatically.
• At this time, the tomcat user does not need a home directory, so the -M option is added to the ʻuseradd` command.

Creating a tomcat user

[root@akagi local]# useradd -M tomcat
[root@akagi local]# id tomcat
uid=1001(tomcat) gid=1001(tomcat) groups=1001(tomcat)

Change folder permissions

• Change the permissions under the Tomcat installation folder so that the tomcat user created earlier can start Tomcat.

Change folder permissions

[root@akagi local]# chown tomcat:tomcat -R ./tomcat9/
[root@akagi local]# ls -l | grep tomcat
drwxr-xr-x 9 tomcat tomcat 220 January 26 22:04 apache-tomcat-9.0.30
-rw-r--r--1 root root 11026056 December 8 02:16 apache-tomcat-9.0.30.tar.gz
lrwxrwxrwx 1 root root 20 February 2 13:40 tomcat9 -> apache-tomcat-9.0.30

Creating a unit file

• Create a unit file for systemd with the name tomcat9.service.
• Up to CentOS6 series, chkconfig was used, but from CentOS7 series, it seems that it is common to realize automatic startup using a mechanism called systemd.

tomcat9.service

[Unit]
Description=Apache Tomcat 9.0.30
ConditionPathExists=/usr/local/tomcat9

[Service]
User=tomcat
Group=tomcat
Type=oneshot

ExecStart=/usr/local/tomcat9/bin/startup.sh
ExecStop=/usr/local/tomcat9/bin/shutdown.sh
Restart=no
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

• For the items of the unit file, the following sites etc. were helpful.
• 10.6. Creating and Modifying SYSTEMD Unit Files-Official Red Hat Reference
• Introduction to Systemd (4) --configuration file for service type Unit
• Systemd memo
• How to write a * .service file for systemd
• Automatic start of program using systemd

Placement of unit files

• Place the created tomcat9.service under/ etc / systemd / system /and set Tomcat to start automatically.
• If the result of systemctl list-unit-files ... is bad instead of disabled, please review the following points.
• File permissions: I have granted 755 for other files and directories under / etc / systemd / system /.
• Syntax error: If [ is {, it will be bad.

Placement of unit files

[root@akagi ~]# chmod 755 tomcat9.service 
[root@akagi ~]# cp -a tomcat9.service /etc/systemd/system/
[root@akagi ~]# systemctl daemon-reload
[root@akagi ~]# systemctl list-unit-files --type=service | grep tomcat
tomcat9.service                               disabled

Auto start settings

• Set the automatic start with systemctl enable ..., and finally check the automatic start setting to complete.

Auto start settings

[root@akagi ~]# systemctl enable tomcat9
Created symlink from /etc/systemd/system/multi-user.target.wants/tomcat9.service to /etc/systemd/system/tomcat9.service.
[root@akagi ~]# systemctl list-unit-files -t service | grep tomcat9
tomcat9.service                               enabled 

Related article

• Link Apache and Tomcat
• Summarized how to make a request from Apache to Tomcat with a reverse proxy.