<p>If I have two services ServiceA and ServiceB. Both are of ServiceType ClusterIP, so if I understand correctly both services are not accessible from outside of the cluster.</p>
<p>Do I then need to setup encryption for these services or is in-cluster-communication considered as secure?</p>

Matthias Gilch
<blockquote>
<p>Do I then need to setup encryption for these services or is in-cluster-communication considered as secure?</p>
</blockquote>
<p>The level of security you want to use is up to you. In regulated industries, e.g. in banks, it is popular to apply a <a href="https://rads.stackoverflow.com/amzn/click/com/1491962194" rel="nofollow noreferrer" rel="nofollow noreferrer">zero trust</a> security architecture, where no <strong>network</strong> is considered secure - e.g. in this case, it is common to use <a href="https://www.cloudflare.com/learning/access-management/what-is-mutual-tls/" rel="nofollow noreferrer">mutual TLS</a> between applications within the cluster - with both <em>authentication</em>, <em>authorization</em> and <em>encryption</em>. On Kubernetes its common to use a <em>service mesh</em> like e.g. Istio to implement this.</p>
<p>In-cluster networking is typically its own local network, it is up to you to consider that secure enough for your use-case.</p>
<blockquote>
<p>If I have two services ServiceA and ServiceB. Both are of ServiceType ClusterIP, so if I understand correctly both services are not accessible from outside of the cluster.</p>
</blockquote>
<p>Commonly, yes. But there are now common with load balancers that can route traffic to applications with Service type ClusterIP. This depends on what load balancer / Gateway you use.</p>
