Coherence

IMPORTANT: Coherence is now defunct and has been replaced by a much powerful server called Erratic

Coherence
Owner	Space
Status	Infra
Hostname	coherence
Tool	No
Tool category

Coherence

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What and where

• Runs Proxmox for KVM VMs and LXC containers
• https://coherence.lan.nurd.space:8006/

Specs

• Dell Optiplex 7010 donated by TechInc
• 4x 4GB RAM (all slots filled)
• Intel Core i5 3470 @ 3.2ghz
• 2 x 4TB Toshiba disks
• 120GB SSD for root etc

Old specs (this box broke)

• Asrock J4205-ITX
• 2 x 8GB DDR3 1866Mhz
• 2 x 4TB Toshiba disks
• 120GB SSD for root etc
• +- 25W power usage total (with one spinning disk)

Tips&Tricks

Find the container id of a running process

Since it is always an issue to find out to which LXC container some process belongs, a small helper script has been created which helps with finding this ID.

Example run:

root@coherence:~# find_pct_by_pid.sh 12088
105
root@coherence:~# find_pct_by_pid.sh 666
Error: No /proc entry found for 666
root@coherence:~# find_pct_by_pid.sh 1
Warning: 1 is not running inside an LXC container

Script:

#!/bin/bash

# Check if we are called correctly
if [[ ${#} -ne 1 ]]; then
  echo "Usage: $(basename ${0}) <pid>"
  exit 1
fi
PID=${1}

# Check if the process is actually running
if [[ ! -d "/proc/${PID}" ]]; then
  echo "Error: No /proc entry found for ${PID}"
  exit 1
fi

# Check if we are dealing with an LXC container
CPUSET="$(head -1 /proc/${PID}/cpuset)"
echo "${CPUSET}" | grep -q lxc
if [[ ${?} -ne 0 ]]; then
  echo "Warning: ${PID} is not running inside an LXC container"
  exit 0
fi

PCT_ID="$(echo ${CPUSET} | cut -d/ -f3)"

echo "${PCT_ID}"