title: How many side-car proxy is too much in a pod
body: <p>I am currently studying distributed systems and have seen that many businesses relies on side-car proxy pattern for their services. For example, I know a company that uses an nginx proxy for authentication of their services and roles and permissions instead of including this business logic within their services.</p>
  <p>Another one makes use of a cloud-sql-proxy on GKE to use the Cloud SQL offering that comes on google cloud. So on top of deploying their services in a container which runs in a pod, they is a proxy just for communicating with the database.</p>
  <p>There is also istio which is a service mesh solution which can be deployed as a side-car proxy in a pod.</p>
  <p><strong>I am pretty sure there are other commonly know use-cases where this pattern is used but at some point how much is too much side-car proxy? How heavy is it on the pod running it and what are the complexity that comes with using 2, 3, or even 4 side car proxys on top of your service container?</strong></p>