Systemd Timers

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Some backend components like the API and Fastpath run as daemons. Many other run as Systemd timers at various intervals.

The latter approach ensures that a component will start again at the next time interval even if the previous run crashed out. This provides a moderate reliability benefit at the expense of having to perform initialization and shutdown at every run.

To show the existing timers and their next start time run:

systemctl list-timers

Summary of timers

Here is a summary of the most important timers used in the backend:

UNIT                           ACTIVATES
dehydrated.timer               dehydrated.service
detector.timer                 detector.service
ooni-api-uploader.timer        ooni-api-uploader.service
ooni-db-backup.timer           ooni-db-backup.service
ooni-download-geoip.timer      ooni-download-geoip.service
ooni-rotation.timer            ooni-rotation.service
ooni-update-asn-metadata.timer ooni-update-asn-metadata.service
ooni-update-citizenlab.timer   ooni-update-citizenlab.service
ooni-update-fingerprints.timer ooni-update-fingerprints.service

Ooni-developed timers have a matching unit file with .service extension.

To show the existing timers and their next start time run:

systemctl list-timers

This can be useful for debugging.

Dehydrated timer

Runs the Dehydrated ACME tool, see Dehydrated ⚙

is a simple script that provides ACME support for Letsencrypt. It’s integrated with Nginx or HaProxy with custom configuration or a small script as “glue”.

Source

Detector timer

Runs the social media blocking event detector ⚙. It is installed by the detector package 📦.

ooni-api-uploader timer

Runs the Measurement uploader ⚙. It is installed by the analysis package 📦. Runs /usr/bin/ooni_api_uploader.py

Source

ooni-db-backup timer

Runs the Database backup tool ⚙ as /usr/bin/ooni-db-backup Also installed by the analysis package 📦.

Source

ooni-download-geoip timer

Fetches GeoIP databases, installed by the ooni-api ⚙. Runs /usr/bin/ooni_download_geoip.py

Monitored with the GeoIP dashboard 📊

See GeoIP downloader ⚙

Source

ooni-rotation timer

Runs the test helper rotation script, installed by the analysis package 📦. Runs /usr/bin/rotation

Source

ooni-update-asn-metadata timer

Fetches ASN 💡 metadata, installed by the analysis package 📦. Runs /usr/bin/analysis --update-asnmeta

Source

ooni-update-citizenlab

Fetches CitizenLab data from GitHub, installed by the analysis package 📦. Runs /usr/bin/analysis --update-citizenlab

Source

ooni-update-fingerprints

Fetches fingerprints from GitHub, installed by the analysis package 📦. Runs /usr/bin/analysis --update-fingerprints

Source