Chapter 17 — When It Breaks: The Field Guide

ping <device-ip>                  # is it on the network at all?
ssh you@<device-ip> 'uptime'      # is it up, and did it just reboot?
ssh you@<device-ip> 'docker ps'   # what's actually running?

cd /srv/lab/compose/<app>
docker compose ps                 # Up? Restarting? Exited?
docker compose logs --tail 100    # the last thing it said

df -h                              # which filesystem
sudo du -xh --max-depth=2 /srv/lab | sort -h | tail -20   # what's big
docker system df                   # how much is Docker's

{ "log-driver": "json-file", "log-opts": { "max-size": "10m", "max-file": "3" } }

sudo fallocate -l 2G /swapfile && sudo chmod 600 /swapfile
sudo mkswap /swapfile && sudo swapon /swapfile
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab