Introduction and Goals

status.arc42.org exists to answer two questions about every site in the arc42 family: how many people are visiting it, and is it actually up.

Requirements Overview

• F-001 — publish current usage statistics of arc42 websites.
• F-002 — publish current repository statistics (issues, bugs) of arc42 websites.
• F-003 — store important results and events persistently for future reference.
• F-004 — inform owners of important system events, such as site availability outages, via Slack.
• F-005 — monitor availability of all arc42 websites and subdomains, storing uptime history and alerting owners on outages.

Quality Goals

• Accurate — site usage (pageviews, visitors) and availability measurements must be correct. Spam and bot traffic is excluded. Availability checks confirm an outage (2-of-3 retries) before recording it, so a single dropped packet never writes an incident.
• Understandable — at least 90% of users should be able to understand the displayed data without further instruction, as measured by a user survey.
• Environmentally friendly — reduce the computing resources used as much as possible.
• Reliable — the system achieves a minimum uptime of 99.9% per month. Recovery from any single point of failure should not exceed 5 minutes. Error rates should not exceed 0.1% of transactions.
• Available & responsive — statistics and availability data are available 24×7. A periodic cron trigger (cron-job.org) keeps the Fly.io machine warm, so visitors see no cold-start delay.
• Privacy-compliant — collection of statistics is compliant with European data-privacy regulations as far as possible: no cookies, no personal user information beyond browser/device type and coarse geolocation.

Stakeholders

Not spelled out as a table in the original documentation. Implicitly: the arc42 maintainers, who need trustworthy numbers to justify time spent on each site, and site visitors and committers, who see the published statistics and status pages.