An example configuration for Tomcat as systemd service. #tomcat #systemd #systemd.service

README-tomcat-as-systemd-service.md

README

Let Tomcat is download and installed under /opt/tomcat. Also, let tomcat be a non-provileged user under which the server will be running.

We assume that we keep server's binaries under /opt/tomcat and we will create a server instance named foo under /var/tomcat/ (carrying its own conf, logs, webapps, work, lib directories). See also https://dzone.com/articles/running-multiple-tomcat.

Create a template service unit file at /etc/systemd/system/tomcat@.service:

[Unit]
Description=Tomcat - instance %i
After=syslog.target network.target

[Service]
Type=forking

User=tomcat
Group=tomcat

WorkingDirectory=/var/tomcat/%i

Environment="JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64/"
Environment="JAVA_OPTS=-Djava.security.egd=file:///dev/urandom"

Environment="CATALINA_PID=/var/tomcat/%i/run/tomcat.pid"
Environment="CATALINA_BASE=/var/tomcat/%i/"
Environment="CATALINA_HOME=/opt/tomcat/"
Environment="CATALINA_OPTS=-Xms512M -Xmx1024M -server -XX:+UseParallelGC"

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

#RestartSec=10
#Restart=always

[Install]
WantedBy=multi-user.target

Now, we can instantiate a service instance for our foo tomcat instance:

systemctl daemon-reload
systemctl enable tomcat@foo.service
systemctl start tomcat@foo.service

Addendum.

There is a problem using the ExecStart=/opt/tomcat-9.0.79/bin/catalina.sh run method to start tomcat.

The problem is that the run method outputs to stdout and stderr. It you use catalina.sh start instead, stdout and stderr get redirected to your catalina.out file by the startup script. Using startup.sh calls catalina.sh start so it behaves the same. This redirect does not happen with the run method and so you get no catalina.out file. It is possible to play around with the systemd unit file options StandardOutput=journal, StandardError=inherit and SyslogIdentifier=??? to output to the journal, but then you have to trap the messages in the journal using an rsyslogd configlet (if you use rsyslog) and this becomes more of a pain if you have multiple tomcats and you want multiple catalina.out log files one per tomcat ......... and then its permissions don't follow the tomcats etc.

Bottom line - don't use the run method to start your tomcat with systemd.

Systemd also allows to make unprivileged user's services, very convenient. No need to use sudo, etc.

# Create or edit service. You shouldn't execute "daemon-reload" after systemctl edit command
systemctl edit tomcat --user --full --force

Paste something like this:

[Unit]
Description=Tomcat
After=network.target

[Service]
# The "exec" type is better than "simple"
Type=exec
EnvironmentFile=-/etc/default/tomcat
SyslogIdentifier=tomcat
ExecStart=/usr/bin/java $JAVA_OPTS $CATALINA_OPTS org.apache.catalina.startup.Bootstrap start
ExecStop=/usr/bin/java $JAVA_OPTS org.apache.catalina.startup.Bootstrap stop
Restart=on-failure

[Install]
# For user's services, write "default.target", not "multi-user.target"
WantedBy=default.target

Exec type
default.target

By default, user's services work only when the user is logged-in. To allow user services working independently from logon, turn on lingering:

# It needs to be done only once
loginctl enable-linger $USER

# Check status (Linger: yes)
loginctl user-status

To control such services, add --user parameter to systemctl.

# Start and enable service
systemctl --user enable --now tomcat

# Status
systemctl --user status tomcat