systemd service file for Apache SOLR

solr.service

# put this file in /etc/systemd/system/ as root
# below paths assume solr installed in /opt/solr, SOLR_PID_DIR is /data
# and that all configuration exists in /etc/default/solr.in.sh which is the case if previously installed as an init.d service
# change port in pid file if differs
# note that it is configured to auto restart solr if it fails (Restart=on-faliure) and that's the motivation indeed :)
# to switch from systemv (init.d) to systemd, do the following after creating this file:
# sudo systemctl daemon-reload
# sudo service solr stop # if already running
# sudo systemctl enable solr
# systemctl start solr
# this was inspired by https://confluence.t5.fi/display/~stefan.roos/2015/04/01/Creating+systemd+unit+(service)+for+Apache+Solr
[Unit]
Description=Apache SOLR
ConditionPathExists=/opt/solr
After=syslog.target network.target remote-fs.target nss-lookup.target systemd-journald-dev-log.socket
Before=multi-user.target
Conflicts=shutdown.target
StartLimitIntervalSec=60

[Service]
User=solr
LimitNOFILE=1048576
LimitNPROC=1048576
PIDFile=/var/solr/solr-8983.pid
Environment=SOLR_INCLUDE=/etc/default/solr.in.sh
Environment=RUNAS=solr
Environment=SOLR_INSTALL_DIR=/opt/solr

ExecStart=/opt/solr/bin/solr start
ExecStop=/opt/solr/bin/solr stop

Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

The shipped systemd service definition is flawed (as of Solr v9.5.0) as it fails to restart the service in case it crashes. I figured that the hard way yesterday. Using this template for now.