Depends on signal-cli if you want
Signal notifications. curl, ping, grep, coreutils, nc, Bash and OpenSSL are
required for everything else to work. systemd is optional, you can also run
notify-down via cron if you prefer that.
Expects two files: ~/.config/notify-down/conf:
NOTIFY_DOWN_FROM="+15555892342" # Signal only
NOTIFY_DOWN_TO="+15550931337" # Signal only
NOTIFY_DOWN_SLACK="https://hooks.slack.com/services/SOMETHING/ORxOTHER/HEXADECIMALKEY" # Slack only
NOTIFY_DOWN_PREFIX="Something added in front of the notification text … "The NOTIFY_DOWN_FROM number has to be already set up with signal-cli for the
user that runs the script, the NOTIFY_DOWN_TO can only be a number that is
registered on the network.
NOTIFY_DOWN_PREFIX is probably only useful to @someone on Slack.
~/.config/notify-down/services is a comma separated list:
Example HTTP Service,example.org,80,http
Example TLS Service,example.net,443,tls
Example STARTTLS Service,eggs.gnu.org,25,starttls smtp
Example PING Service IPv4,example.com,,ping4
Example PING Service IPv6,example.com,,ping6
Example PING Service Protocol Agnostic,example.com,,ping
Example TCP Service,towel.blinkenlights.nl,23,tcp
FYI, TLS service checks also fail if there's a "verify error" found in the certificate chain.