;unknown&#34;
</code></pre><p>For more information, see <a href=https://opensource.google/projects/cel>Common Expression Language</a>.</p><p>Istio exposes all standard <a href=https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/advanced/attributes>Envoy attributes</a>.
Peer metadata is available as attributes <code>upstream_peer</code> for outbound and <code>downstream_peer</code> for inbound with the following fields:</p><table><thead><tr><th>Field</th><th>Type</th><th>Value</th></tr></thead><t