Extract start/end dates of SSL certificates across a list of servers

This openssl command will extract the certificate start and end dates from a server:

HOST=randomnamehost.com
openssl s_client -showcerts -connect ${HOST}:443 </dev/null 2>/dev/null | \
openssl x509 -noout -dates

This is useful to extract the dates for monitoring/checking (although, about 1000 other solutions could work too).

Here's a quick application of that in a loop to check a list of servers I have saved:

for HOST in $(cat /host/name/file); do
echo "==========="
echo $HOST
openssl s_client -showcerts -connect ${host}:443 </dev/null 2>/dev/null | \
openssl x509 -noout -dates
done

There's most likely a python module to do the same which would make comparing dates easier in a monitoring script. I should look for one.