We have a lot of websites behind CloudFlare’s excellent firewall system.

Sometimes we need to move a server to a new IP address necessitating the manual modification of a large number of CloudFlare DNS records in a large number of CloudFlare Zones.

CloudFlare is great in that if you modify a DNS record the effect is immediate – so a change to the DNS ‘A’ record from one IP to another will instantly cause traffic to go to the new IP. Fab.

But if you have to do all changes manually it will take a very long time, and there will be a high likelihood of mistakes being made. And due to the timescales, there’s also a high chance of data passing to the old IP address during the process – making the new server out of sync.

Solution of course is to use the CloudFlare API to make this all happen automatically. Unfortunately you have to code this up yourself.

Fortunately, we’ve hacked together a simple PHP script to do the job for you.

Of course this is to be used entirely at your own risk! This code has the potential to wipe out your entire CloudFlare DNS setup so be careful. Run some tests first.

You will need to insert your Auth Email, Auth Code, Old IP and New IP.

<?php
// Form a list of all CF IP zones 
// For each zone, grab all A records and TXT records matching $oldip
// For each matching record, update it to the new IP address
	
// Does not deal with paginated zone results so there's currently
// a maximum of 50 zones managed by this tool

$authemail = "YOU @ YOUR EMAIL . COM";
$authkey   = "YOUR CLOUDFLARE API KEY";
	
// Old IP address to find
$oldip     = "ooo.ooo.ooo.ooo";

// New IP address to replace the old one with
$newip     = "nnn.nnn.nnn.nnn";

$ch = curl_init("https://api.cloudflare.com/client/v4/zones?page=1&per_page=50&match=all");
    curl_setopt($ch, CURLOPT_HTTPHEADER, array(
	    'X-Auth-Email: '.$authemail,
	    'X-Auth-Key: '.$authkey,
	    'Content-Type: application/json'
	    ));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$response = curl_exec($ch);
curl_close($ch);

$r = json_decode($response, true);
$result = $r['result'];

$count = 1;
foreach ($result as $zone)
{
    if (isset($zone['id']))
    {
        $zoneid   = $zone['id'];
        $zonename = $zone['name'];
        echo $count . ": " . $zonename . " " . $zoneid . "<br />\n";
	$count++;

        // List all DNS records for this domain
        $ch = curl_init("https://api.cloudflare.com/client/v4/zones/$zoneid/dns_records");
        curl_setopt($ch, CURLOPT_HTTPHEADER, array(
            'X-Auth-Email: '.$authemail,
            'X-Auth-Key: '.$authkey,
            'Content-Type: application/json'
          ));
			
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        $response = curl_exec($ch);
        curl_close($ch);
        $r = json_decode($response, true);

        $dnsrecs = $r['result'];

        foreach ($dnsrecs as $dns)
        {
            if (preg_match("/$oldip/", $dns['content']))
            {
                // OK! Change this DNS record.
                $newcontent = preg_replace("/$oldip/", $newip, $dns['content']);
                echo "oldcontent: " . $dns['content'];
                echo "newcontent: $newcontent<br />\n";

                // Swap the content then
                $dns['content'] = $newcontent;
                updateDNSRecord($dns);
            }
        }
        echo "<br />\n";
    }
}

function updateDNSRecord($dns)
{
    global $authemail, $authkey;
    $ch = curl_init("https://api.cloudflare.com/client/v4/zones/".$dns['zone_id']."/dns_records/".$dns['id']);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array(
        'X-Auth-Email: '.$authemail,
        'X-Auth-Key: '.$authkey,
        'Content-Type: application/json'
      ));

    $data_string = json_encode($dns);
    echo "JSON_DATA_STRING: $data_string";
    echo "<br />\n";

    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");
    curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $response = curl_exec($ch);
    curl_close($ch);
    $r = json_decode($response, true);

    print_r($r);
    print "<br />\n";
}
?>