Systemd timer not starting its service unit

Question

Situation

I have written a custom systemd service unit and its companion shell script to renew a certificate from Let's Encrypt. Everything works fine when I run systemctl start letsencrypt-example_com.service. I want it to be run automatically every 60 days, so I wrote a systemd timer unit.

Issue

I ran systemctl enable letsencrypt-example_com.timer then systemctl start letsencrypt-example_com.timer. The timer seems to start but not the service.

# systemctl status letsencrypt-example_com.timer Created symlink from /etc/systemd/system/timers.target.wants/letsencrypt-example_com.timer to /etc/systemd/system/letsencrypt-example_com.timer. # systemctl start letsencrypt-example_com.timer # systemctl list-timers --all # systemctl list-timers NEXT LEFT LAST PASSED UNIT ACTIVATES n/a n/a ven. 2016-05-06 13:10:13 CEST 1h 51min ago letsencrypt-example_com.timer letsencrypt-example_com.service # systemctl status letsencrypt-example_com.timer ● letsencrypt-example_com.timer - Run letsencrypt-example_com every 60 days Loaded: loaded (/etc/systemd/system/letsencrypt-example_com.timer; enabled) Active: active (elapsed) since ven. 2016-05-06 15:01:57 CEST; 2min 50s ago # systemctl status letsencrypt-example_com.service ● letsencrypt-example_com.service - letsencrypt certificat renewal for example.com and subdomains Loaded: loaded (/etc/systemd/system/letsencrypt-example_com.service; static) Active: inactive (dead) 

Files

cat /etc/systemd/system/letsencrypt-example_com.service :

[Unit] Description=letsencrypt certificat renewal for example.com and subdomains Requires=nginx_reload.service Before=nginx_reload.service [Service] Type=simple ExecStart=/bin/sh /usr/local/bin/letsencrypt-renew.sh example.com www.example.com User=letsencrypt Group=www-data 

/usr/local/bin/letsencrypt-renew.sh :

#!/bin/sh letsencrypt certonly \ --server https://acme-v01.api.letsencrypt.org/directory \ --text \ --email [email protected] \ --agree-tos \ --rsa-key-size 4096 \ --authenticator webroot \ --webroot-path /srv/files/letsencrypt/www \ $( for fqdn in $@; do echo "--domain $fqdn"; done; ) \ --force-renew 

/etc/systemd/system/letsencrypt-example_com.timer :

[Unit] Description=Run letsencrypt-example_com every 60 days [Timer] OnUnitActiveSec=1min Persistent=true Unit=letsencrypt-example_com.service [Install] WantedBy=timers.target 

/etc/systemd/system/nginx_reload.service :

[Unit] Description=reload nginx conf [Service] Type=oneshot ExecStart=/bin/systemctl reload nginx 

Answer 1

Although timer units automatically gain a Before= dependency on the service they are supposed to activate, they apparently don't automatically have a Requires= dependency on it (which doesn't make any sense to me).

So I added the following line to the [Unit] section of the timer unit, and now it starts the service as intended :

Requires=letsencrypt-example_com.service 

I also set an AccuracySec (of 10s) in the [Timer] section.