Release Calico unused IPs from CIDR Block (Bug v3.3.x)

release_ips.sh

#!/bin/bash

# Works for /16 CIDR Blocks, change / upgrade the script if you need
CIDR_PREFIX="172.20"

for oct1 in {128..255}; do
  # Generate a new list of used IPs on every block
  calicoctl get wep --all-namespaces | awk '{print $4}' |cut -d "/" -f1 > valid_ips.txt
  for oct2 in {1..254}; do
    if grep "${CIDR_BLOCK}.$oct1.$oct2" ./valid_ips.txt; then
      echo " - Skipping ${CIDR_BLOCK}.$oct1.$oct2"
      continue
    fi
    echo " - Releasing ${CIDR_BLOCK}.$oct1.$oct2"
    calicoctl ipam release --ip=${CIDR_BLOCK}.$oct1.$oct2
  done
done