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Manually failover DNS

Power outages, natural disasters, or fiber lines being cut in construction projects are just a few things that can cause outages. One of the most common Disaster Recovery (DR) methods is to have a secondary site where you can update the Domain Name System (DNS) record and be back online.

Updating the IP address of a DNS entry is quick and easy, but you are at the mercy of those changes being propagated throughout the Internet.

Infrastructure as a Service (IaaS) DNS failover

Popular IaaS providers such as Azure, AWS, or GCP provide a CLI to make it easy update your DNS record to point to another site with just a couple of commands.

The following example uses the Azure CLI to update the DNS record for www.octopussamples.com

Create the runbook

  1. To create a runbook, navigate to Project ➜ Operations ➜ Runbooks ➜ Add Runbook.
  2. Give the runbook a name and click SAVE.
  3. Click DEFINE YOUR RUNBOOK PROCESS, then click ADD STEP.
  4. Add a new Run an Azure Script step.
  5. Choose Inline source code (with optional package references)
  6. Enter the following PowerShell code, we recommend using variables instead of hard-coding entries.
$resourceGroup = $OctopusParameters["OctoFX.Azure.Resource.Group"]
$zoneName = $OctopusParameters["OctoFX.DNS.Name"]
$ipAddressDR = $OctopusParameters["OctoFX.DR.IP.Address"]
$ipAddressProd = $OctopusParameters["OctoFX.Production.IP.Address"]

az network dns record-set a add-record --resource-group $resourceGroup --zone-name $zoneName --record-set-name www --ipv4-address $ipAddressProd
az network dns record-set a remove-record --resource-group $resourceGroup --zone-name $zoneName --record-set-name www --ipv4-address $ipAddressDR

This script within a runbook lets your switch your DNS entry with the click of a button, so no matter when disaster strikes, it is easy to recover.

Samples

We have a Target - Windows Space on our Samples instance of Octopus. You can sign in as Guest to take a look at this example and more runbooks in the OctoFX project.

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Page updated on Sunday, January 1, 2023