Docker lessons from the front lines

• Be careful when mapping host volumes: filesystem types matter greatly in Docker, and something as simple as mapping /tmp or /dev from the host can result in obscure errors, e.g. Error response from daemon: Cannot start container xxxxxxx : [8] System error: no such file or directory

• Default log file locations for the Docker daemon vary by distribution, typically determined by the init system:
• /var/log/upstart/docker.log (Debian/Ubuntu)
• /var/log/docker.log (CentOS)

• Start Docker with debug logging.
• Directly from command line: 
• sudo DOCKER_OPTS='--log-level=debug' service docker start
• Also possible through settings in /etc/default/docker.conf

Linux resource monitoring tools

Command line tools for monitoring system resource utilization:

• top
• htop (visual version of top)
• iotop (disk I/O by process)
• iftop (network I/O by host)