<p>I am a little unsure about how to ensure I do not have overlapping CIDRs when using kops to create multiple clusters.</p>

<p>I know it's possible to specify the <code>--cluster-cidr</code> when using the <a href="https://kubernetes.io/docs/admin/kube-controller-manager/" rel="nofollow noreferrer">kube-control-manager</a>, but I can't seem to find a way of doing this when using kops.</p>

<p>First you check which CIDRs you are already using</p>

<pre><code>aws ec2 describe-vpcs | jq -cr '.Vpcs[] | [.CidrBlock, .VpcId, .Tags[0].Value]'
</code></pre>

<p>Than before you create the cluster, edit the main config</p>

<pre><code>kops edit cluster $NAME
</code></pre>

<p>Change networkCIDR, nonMasqueradeCIDR and subnets.cidr</p>

<p>Note that subnets.cidr MUST be inside networkCIDR range.</p>

<p>Also note that networkCIDR and nonMasqueradeCIDR MUST NOT overlap</p>

<p>Example of valid config:</p>

<pre><code>  networkCIDR: 10.80.0.0/16
  nonMasqueradeCIDR: 10.81.0.0/16
  subnets:
  - cidr: 10.80.0.0/24
</code></pre>
