Prometheus

If there are more than 3 WAL segments (older than 2 hours), something is wrong, check the logs (journalctl -u prometheus on Debian). Lots of options in /etc/default/prometheus. E.g. --web.enable-admin-api, --storage.tsdb.retention.time and --storage.tsdb.retention.size. Delete timeseries through admin-api: curl -X POST -g 'http://localhost:9090/api/v1/admin/tsdb/delete_series?match[]=apt_upgrades_pending&match[]={instance="rorschach.hjp.at:9100"}' (May be best option if you get weird error messages about a specific timeseries.) Speaking of retention.time, the default is 15 days.

Python Outlier Detection (PyOD)

Python Outlier Detection (PyOD)

checkmk

Periodic notifications during service problems in Service parameters Thresholds are in “check origin and parameters” (1st section in service parameters).

Postgres Observability

Postgres Observability

Apache /server-status vs WSGI

When writing web applications, it is often necessary (or at least more aesthetic) to make the home page part of the application. Using mod_wsgi, this looks like this: WSGIScriptAlias / /var/www/mysite/app/myapp/myapp/wsgi.py Static files can be exempted via aliases: Alias /robots.txt /var/www/mysite/htdocs/robots.txt Alias /favicon.ico /var/www/mysite/htdocs/favicon.ico Alias /static/ /var/www/mysite/htdocs/static/ If you want to enable mod_status the normal approach doesn’t work: <Location "/server-status"> SetHandler server-status· Require ip 192.0.2.0/24 </Location> /server-status will be passed to WSGI handler instead of the server-status handler, no matter how you arrange the directives.

BPF Compiler Collection (BCC)

Githug Project Page Examples: How to Use BCC Kernel Tracing Tools for Linux Performance Analysis How to measure Linux Performance Avoiding Most Typical Mistakes: CPU