Blackbox exporter

https://blog.devops.dev/prometheus-blackbox-exporter-with-kube-prometheus-stack-23a045ccbab2

curl http://blackbox-exporter-prometheus-blackbox-exporter.prometheus:9115/probe?target=example.com:443&module=tcp_connect&debug=true

https://blog.ruanbekker.com/cheatsheets/blackbox-exporter/

https://superuser.com/questions/1680156/prometheus-blackbox-exporter-tcp-probe-returns-value-of-0-even-when-port-is-ope

https://dmachard.github.io/posts/0043-blackbox-prometheus-dns/

https://github.com/prometheus/blackbox_exporter/blob/master/CONFIGURATION.md

Multiple Exporters from Single Job

• https://medium.com/geekculture/single-prometheus-job-for-dozens-of-blackbox-exporters-2a7ba492d6c8