Detect confricted IPs

checkDockerIp.js

#!/usr/bin/env node
// eth0とdocker0がコンフリクトすると docker run によるコンテナが異常になる
// eth0とbr-xxxxがコンフリクトすると docker compose によるコンテナが異常になる

const { execSync } = require('child_process');

function ipAddr () {
  if (process.env.NODE_ENV === 'test') {
    return [
      'inet 172.17.53.125/20 brd 172.17.63.255 scope global eth0',
      'inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0',
      'inet 172.19.0.1/16 brd 172.19.255.255 scope global br-xxyyzzaabbcc',
      'inet 172.18.0.1/16 brd 172.18.255.255 scope global br-ddeeffgghhii'
    ];
  }
  return execSync('ip addr|grep global').toString().split(/[\r\n]+/);
}

function getMask (bits) {
  const mbits = 32n - bits;
  return (0xfffffffn >> mbits) << mbits;
}

function min_n (...values) {
  return values.reduce((sum, v) => {
    if (v < sum) return v;
    return sum;
  }, values[0]);
}

function resolveRange (str) {
  const bits = BigInt(str.split('/')[1]);
  const mask = getMask(bits);
  const addr = str.split('/')[0].split('.').map(v => BigInt(v))
    .reduce((sum, v) => {
      sum = sum << 8n;
      sum += v;
      return sum;
    }, 0n);
  const range = addr & mask;
  return { addr, range, bits };
}

const IPs = ipAddr()
  .map(line => line.trim().split(/ +/).filter((_v, i) => [1, 6].includes(i)))
  .filter(line => line[1]?.match(/^(eth|docker|br-)/))
  .reduce((sum, v) => {
    const [token, name] = v;
    const range = resolveRange(token);
    sum[name] = { ...range, token };
    return sum;
  }, {});

const minMask = getMask(min_n(...Object.values(IPs).map(v => v.bits)));
const eth0 = IPs.eth0.addr & minMask;
const confricted = Object.keys(IPs).filter(key => key !== 'eth0').reduce((sum, key) => {
  if (eth0 === (IPs[key].addr & minMask)) {
    console.log(`eth0 [${IPs.eth0.token}] and ${key} [${IPs[key].token}] is CONFRICTED.`);
    return 1;
  }
  return sum;
}, 0);
if (process.argv.includes('-v')) {
  console.log(IPs);
}
process.exit(confricted);