Running Metabase jar file as a systems service on Ubuntu Server

I am trying to get the Metabase (v0.24.2) jar file running as a systemd service on Ubuntu Server 16.04 LTS with OpenJDK 1.8.0_131 installed

Running java -jar metabase.jar works perfectly, but I can't seem to get it going as a systemd service.

This is the metabase.service file I have:

[Unit]
Description=Metabase server
After=syslog.target
After=network.target

[Service]
ExecStart=/usr/bin/java -jar /var/metabase.jar
User=administrator
Type=simple
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=metabase
Restart=always

[Install]
WantedBy=multi-user.target

When I start the service, I get:

Metabase Initialization FAILED:  Assert failed: Unable to connect to Metabase h2 DB

I assume the issue is something incorrectly configured in the service file.. Any ideas?

Thanks!