<p>I have a pod in namespace Foo and a service account in namespace Bar.  Can I run the pod as the service account from the other namespace?  Or will the fact that the pod &amp; service account belong to different namespaces block me?</p>

<p>No, you cannot. Your pod and service account need to be in the same namespace. As, <strong>Service accounts and Pods are namespaced</strong>.</p>
<p>As far the k8s doc:</p>
<blockquote>
<p>When you create a pod, if you do not specify a service account, it is automatically assigned the default service account in the <strong>same namespace</strong>. The service account has to exist at the time the pod is created, or it will be rejected.</p>
</blockquote>
<p>It is also a logical thing, as they are namespaced object. So they need to be in the same namespace.</p>
<p>You cannot update the service account of an already created pod.</p>
<p>You can see the k8s <a href="https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/" rel="noreferrer">doc</a> and also <a href="https://kubernetes.io/docs/reference/access-authn-authz/service-accounts-admin/" rel="noreferrer">this</a></p>
