Sidekiq service auto start for Ubuntu 16.04 using Systemd

sidekiq.service

#
# Sidekiq auto start using systemd unit file for Ubuntu 16.04
#
# Put this in /lib/systemd/system (Ubuntu).
# Run:
#   1. systemctl enable sidekiq (to enable sidekiq service)
#   2. systemctl {start,stop,restart} sidekiq (to start sidekiq service)
#
# This file corresponds to a single Sidekiq process.  Add multiple copies
# to run multiple processes (sidekiq-1, sidekiq-2, etc).
#
# See Inspeqtor's Systemd wiki page for more detail about Systemd:
# https://github.com/mperham/inspeqtor/wiki/Systemd
#
[Unit]
Description=sidekiq
# start us only once the network and logging subsystems are available,
# consider adding redis-server.service if Redis is local and systemd-managed.
After=syslog.target network.target

# See these pages for lots of options:
# http://0pointer.de/public/systemd-man/systemd.service.html
# http://0pointer.de/public/systemd-man/systemd.exec.html
[Service]
Type=simple
WorkingDirectory=/home/Public/Rails/your-rails-app
# If you use rbenv or rvm:
ExecStart=/bin/bash -lc 'bundle exec sidekiq -e production'
# If you use the system's ruby:
# ExecStart=bundle exec sidekiq -e production
User=your-username
Group=your-username
UMask=0002

# if we crash, restart
RestartSec=1
Restart=on-failure

# output goes to /var/log/syslog
StandardOutput=syslog
StandardError=syslog

# This will default to "bundler" if we don't specify it
SyslogIdentifier=sidekiq

[Install]
WantedBy=multi-user.target

I ran on a non-root user and encountered error: failed at step group spawning/bin/bash: operation root permitted.
My solution: just remove user and group from service file

To get cap production sidekiq:start to work, I followed this advice and also put the service file in /lib/systemd/user instead of /lib/systemd/system. But putting it in the user directory isn't really a fix: the service doesn't continue running when the non-root user isn't logged in.

Why would it not work for me in the system folder when it appears to have worked for others? Why did I need to remove User and Group when they specify my deploy user?