<p>With default configurations, does istio-proxy(sidecar) manipulate incoming/outgoing requests from the application container?</p>

RMNull
<p>Comment posted by <a href="https://stackoverflow.com/users/10008173/david-maze" title="82,113 reputation">David Maze</a> is good and this could be part of an answer:</p>
<blockquote>
<p>There are a couple of cases like <a href="https://istio.io/latest/docs/tasks/observability/distributed-tracing/overview/#trace-context-propagation" rel="nofollow noreferrer">distributed tracing</a> and <a href="https://istio.io/latest/docs/tasks/security/authentication/authn-policy/#auto-mutual-tls" rel="nofollow noreferrer">mutual TLS</a> that add headers;</p>
</blockquote>
<p>These are the two methods by which you can manipulate the headers using istio. Additionally, in the official documentation you can find a <a href="https://istio.io/v1.4/docs/tasks/policy-enforcement/control-headers/" rel="nofollow noreferrer">simple tutorial</a> with yaml files, where you will learn how to manage headers. It is also displayed how you can create <a href="https://istio.io/v1.4/docs/tasks/policy-enforcement/control-headers/#request-header-operations" rel="nofollow noreferrer">request header operation</a>. However, take into account that this tutorial is based on an outdated version of Istio and you should use the latest supported version for your solution.</p>
