I'm not seeing this question asked any where else that I've looked. Long story short, NetworkManager brings down eth0 1 minute and 1 second after every hour for the reason of 'connection-removed'. Most of the time, the connection comes back up--although it obviously disconnects everything--within that same second. In some few and far between cases, it does not recover and despite being set with a static IPv4 address, will not recover until the network service is restarted.
The server is a virtual machine running in KVM by a remote hosting provider and takes place precisely within the first second of the first minute every hour. This is a recently installed stock, minimal install of CentOS 7 (trying it out for the first time since CentOS 4) with only one additional application installed: Cockpit.
Here are the logs of that second:
Feb 3 08:01:01 hyaena CROND: (root) CMD (run-parts /etc/cron.hourly) Feb 3 08:01:01 hyaena run-parts(/etc/cron.hourly): starting 0anacron Feb 3 08:01:01 hyaena run-parts(/etc/cron.hourly): finished 0anacron Feb 3 08:01:01 hyaena run-parts(/etc/cron.hourly): starting docker-cleanup Feb 3 08:01:01 hyaena run-parts(/etc/cron.hourly): finished docker-cleanup
#!/bin/sh # Check whether 0anacron was run today already if test -r /var/spool/anacron/cron.daily; then day=`cat /var/spool/anacron/cron.daily` fi if [ `date +%Y%m%d` = "$day" ]; then exit 0; fi # Do not run jobs when on battery power if test -x /usr/bin/on_ac_power; then /usr/bin/on_ac_power >/dev/null 2>&1 if test $? -eq 1; then exit 0 fi fi /usr/sbin/anacron -s
#!/bin/bash # Do nothing if neither docker nor docker-latest service is running if ! systemctl --quiet is-active docker-latest && ! systemctl --quiet is-active docker; then exit 0 fi # If there are no dead containers, exit. DEAD_CONTAINERS=`docker ps -aq -f status=dead` [ -z "$DEAD_CONTAINERS" ] && exit 0 # Try to cleanup dead containers docker rm $DEAD_CONTAINERS