networking/v1alpha3/sidecar.pb.html

---
title: Sidecar
description: Configuration affecting network reachability of a sidecar.
location: https://istio.io/docs/reference/config/networking/sidecar.html
layout: protoc-gen-docs
generator: protoc-gen-docs
schema: istio.networking.v1alpha3.Sidecar
aliases: [/docs/reference/config/networking/v1alpha3/sidecar]
number_of_entries: 8
---
<p><code>Sidecar</code> describes the configuration of the sidecar proxy that mediates
inbound and outbound communication to the workload instance it is attached to. By
default, Istio will program all sidecar proxies in the mesh with the
necessary configuration required to reach every workload instance in the mesh, as
well as accept traffic on all the ports associated with the
workload. The <code>Sidecar</code> configuration provides a way to fine tune the set of
ports, protocols that the proxy will accept when forwarding traffic to
and from the workload.</p>
<p>One the common usages of <code>Sidecar</code> is to limit the set of configuration for outbound traffic.
This configuration scoping, among <a href="/docs/ops/configuration/mesh/configuration-scoping/">other options</a>, is useful to prune
out unneeded configuration, to improve scalability of the mesh.
A common misunderstanding is that restricting the configuration amounts to <em>blocking</em> the traffic.
If requests are sent to destinations not included in the scoping, the traffic will be treated as
<a href="docs/ops/configuration/traffic-management/traffic-routing/#unmatched-traffic">unmatched traffic</a>, which is often still allowed.
The sidecar is not able to enforce an outbound traffic restriction (see <a href="/docs/tasks/traffic-management/egress/egress-gateway/">Egress Gateways</a> for how to achieve this).</p>
<p>Services and configuration in a mesh are organized into one or more
namespaces (e.g., a Kubernetes namespace or a CF org/space). A <code>Sidecar</code>
configuration in a namespace will apply to one or more workload instances in the same
namespace, selected using the <code>workloadSelector</code> field. In the absence of a
<code>workloadSelector</code>, it will apply to all workload instances in the same
namespace. When determining the <code>Sidecar</code> configuration to be applied to a
workload instance, preference will be given to the resource with a
<code>workloadSelector</code> that selects this workload instance, over a <code>Sidecar</code> configuration
without any <code>workloadSelector</code>.</p>
<p><strong>NOTE 1</strong>: <em><em>Each namespace can have only one <code>Sidecar</code>
configuration without any <code>workloadSelector</code></em> that specifies the
default for all pods in that namespace</em>. It is recommended to use
the name <code>default</code> for the namespace-wide sidecar. The behavior of
the system is undefined if more than one selector-less <code>Sidecar</code>
configurations exist in a given namespace. The behavior of the
system is undefined if two or more <code>Sidecar</code> configurations with a
<code>workloadSelector</code> select the same workload instance.</p>
<p><strong>NOTE 2</strong>: <em><em>A <code>Sidecar</code> configuration in the <code>MeshConfig</code>
<a href="https://istio.io/docs/reference/config/istio.mesh.v1alpha1/#MeshConfig">root namespace</a>
will be applied by default to all namespaces without a <code>Sidecar</code>
configuration</em></em>. This global default <code>Sidecar</code> configuration should not have
any <code>workloadSelector</code>.</p>
<p><strong>NOTE 3</strong>: <em><em>A <code>Sidecar</code> is not applicable to gateways, even though gateways are istio-proxies</em></em>.</p>
<p>The example below declares a global default <code>Sidecar</code> configuration
in the root namespace called <code>istio-config</code>, that configures
sidecars in all namespaces to configure egress traffic only to other
workloads in the same namespace as well as to services in the
<code>istio-system</code> namespace.</p>
<pre><code class="language-yaml">apiVersion: networking.istio.io/v1
kind: Sidecar
metadata:
  name: default
  namespace: istio-config
spec:
  egress:
  - hosts:
    - &quot;./*&quot;
    - &quot;istio-system/*&quot;
</code></pre>
<p>The example below declares a <code>Sidecar</code> configuration in the
<code>prod-us1</code> namespace that overrides the global default defined
above, and configures the sidecars in the namespace to configure egress
traffic to public services in the <code>prod-us1</code>, <code>prod-apis</code>, and the
<code>istio-system</code> namespaces.</p>
<pre><code class="language-yaml">apiVersion: networking.istio.io/v1
kind: Sidecar
metadata:
  name: default
  namespace: prod-us1
spec:
  egress:
  - hosts:
    - &quot;prod-us1/*&quot;
    - &quot;prod-apis/*&quot;
    - &quot;istio-system/*&quot;
</code></pre>
<p>The following example declares a <code>Sidecar</code> configuration in the
<code>prod-us1</code> namespace for all pods with labels <code>app: ratings</code>
belonging to the <code>ratings.prod-us1</code> service.  The workload accepts
inbound HTTP traffic on port 9080. The traffic is then forwarded to
the attached workload instance listening on a Unix domain
socket. In the egress direction, in addition to the <code>istio-system</code>
namespace, the sidecar proxies only HTTP traffic bound for port
9080 for services in the <code>prod-us1</code> namespace.</p>
<pre><code class="language-yaml">apiVersion: networking.istio.io/v1
kind: Sidecar
metadata:
  name: ratings
  namespace: prod-us1
spec:
  workloadSelector:
    labels:
      app: ratings
  ingress:
  - port:
      number: 9080
      protocol: HTTP
      name: somename
    defaultEndpoint: unix:///var/run/someuds.sock
  egress:
  - port:
      number: 9080
      protocol: HTTP
      name: egresshttp
    hosts:
    - &quot;prod-us1/*&quot;
  - hosts:
    - &quot;istio-system/*&quot;
</code></pre>
<p>If the workload is deployed without IPTables-based traffic capture,
the <code>Sidecar</code> configuration is the only way to configure the ports
on the proxy attached to the workload instance. The following
example declares a <code>Sidecar</code> configuration in the <code>prod-us1</code>
namespace for all pods with labels <code>app: productpage</code> belonging to
the <code>productpage.prod-us1</code> service. Assuming that these pods are
deployed without IPtable rules (i.e. the <code>istio-init</code> container)
and the proxy metadata <code>ISTIO_META_INTERCEPTION_MODE</code> is set to
<code>NONE</code>, the specification, below, allows such pods to receive HTTP
traffic on port 9080 (wrapped inside Istio mutual TLS) and forward
it to the application listening on <code>127.0.0.1:8080</code>. It also allows
the application to communicate with a backing MySQL database on
<code>127.0.0.1:3306</code>, that then gets proxied to the externally hosted
MySQL service at <code>mysql.foo.com:3306</code>.</p>
<pre><code class="language-yaml">apiVersion: networking.istio.io/v1
kind: Sidecar
metadata:
  name: no-ip-tables
  namespace: prod-us1
spec:
  workloadSelector:
    labels:
      app: productpage
  ingress:
  - port:
      number: 9080 # binds to proxy_instance_ip:9080 (0.0.0.0:9080, if no unicast IP is available for the instance)
      protocol: HTTP
      name: somename
    defaultEndpoint: 127.0.0.1:8080
    captureMode: NONE # not needed if metadata is set for entire proxy
  egress:
  - port:
      number: 3306
      protocol: MYSQL
      name: egressmysql
    captureMode: NONE # not needed if metadata is set for entire proxy
    bind: 127.0.0.1
    hosts:
    - &quot;*/mysql.foo.com&quot;
</code></pre>
<p>And the associated service entry for routing to <code>mysql.foo.com:3306</code></p>
<pre><code class="language-yaml">apiVersion: networking.istio.io/v1
kind: ServiceEntry
metadata:
  name: external-svc-mysql
  namespace: ns1
spec:
  hosts:
  - mysql.foo.com
  ports:
  - number: 3306
    name: mysql
    protocol: MYSQL
  location: MESH_EXTERNAL
  resolution: DNS
</code></pre>
<p>It is also possible to mix and match traffic capture modes in a single
proxy. For example, consider a setup where internal services are on the
<code>192.168.0.0/16</code> subnet. So, IP tables are setup on the VM to capture all
outbound traffic on <code>192.168.0.0/16</code> subnet. Assume that the VM has an
additional network interface on <code>172.16.0.0/16</code> subnet for inbound
traffic. The following <code>Sidecar</code> configuration allows the VM to expose a
listener on <code>172.16.1.32:80</code> (the VM&rsquo;s IP) for traffic arriving from the
<code>172.16.0.0/16</code> subnet.</p>
<p><strong>NOTE</strong>: The <code>ISTIO_META_INTERCEPTION_MODE</code> metadata on the
proxy in the VM should contain <code>REDIRECT</code> or <code>TPROXY</code> as its value,
implying that IP tables based traffic capture is active.</p>
<pre><code class="language-yaml">apiVersion: networking.istio.io/v1
kind: Sidecar
metadata:
  name: partial-ip-tables
  namespace: prod-us1
spec:
  workloadSelector:
    labels:
      app: productpage
  ingress:
  - bind: 172.16.1.32
    port:
      number: 80 # binds to 172.16.1.32:80
      protocol: HTTP
      name: somename
    defaultEndpoint: 127.0.0.1:8080
    captureMode: NONE
  egress:
    # use the system detected defaults
    # sets up configuration to handle outbound traffic to services
    # in 192.168.0.0/16 subnet, based on information provided by the
    # service registry
  - captureMode: IPTABLES
    hosts:
    - &quot;*/*&quot;
</code></pre>
<p>The following example declares a <code>Sidecar</code> configuration in the
<code>prod-us1</code> namespace for all pods with labels <code>app: ratings</code>
belonging to the <code>ratings.prod-us1</code> service.  The service accepts
inbound HTTPS traffic on port 8443 and the sidecar proxy terminates
one way TLS using the given server certificates.
The traffic is then forwarded to the attached workload instance
listening on a Unix domain socket.
It is expected that PeerAuthentication policy would be configured
in order to set mTLS mode to &ldquo;DISABLE&rdquo; on specific
ports.
In this example, the mTLS mode is disabled on PORT 80.
This feature is currently experimental.</p>
<pre><code class="language-yaml">apiVersion: networking.istio.io/v1
kind: Sidecar
metadata:
  name: ratings
  namespace: prod-us1
spec:
  workloadSelector:
    labels:
      app: ratings
  ingress:
  - port:
      number: 80
      protocol: HTTPS
      name: somename
    defaultEndpoint: unix:///var/run/someuds.sock
    tls:
      mode: SIMPLE
      privateKey: &quot;/etc/certs/privatekey.pem&quot;
      serverCertificate: &quot;/etc/certs/servercert.pem&quot;
---
apiVersion: v1
kind: Service
metadata:
  name: ratings
  labels:
    app: ratings
    service: ratings
spec:
  ports:
  - port: 8443
    name: https
    targetPort: 80
  selector:
    app: ratings
---
apiVersion: security.istio.io/v1
kind: PeerAuthentication
metadata:
  name: ratings-peer-auth
  namespace: prod-us1
spec:
  selector:
    matchLabels:
      app: ratings
  mtls:
    mode: STRICT
  portLevelMtls:
    80:
      mode: DISABLE
</code></pre>
<p>In addition to configuring traffic capture and how traffic is forwarded to the app,
it&rsquo;s possible to control inbound connection pool settings. By default, Istio pushes
connection pool settings from <code>DestinationRules</code> to both clients (for outbound
connections to the service) as well as servers (for inbound connections to a service
instance). Using the <code>InboundConnectionPool</code> and per-port <code>ConnectionPool</code> settings
in a <code>Sidecar</code> allow you to control those connection pools for the server separately
from the settings pushed to all clients.</p>
<pre><code class="language-yaml">apiVersion: networking.istio.io/v1
kind: Sidecar
metadata:
  name: connection-pool-settings
  namespace: prod-us1
spec:
  workloadSelector:
    labels:
      app: productpage
  inboundConnectionPool:
      http:
        http1MaxPendingRequests: 1024
        http2MaxRequests: 1024
        maxRequestsPerConnection: 1024
        maxRetries: 100
  ingress:
  - port:
      number: 80
      protocol: HTTP
      name: somename
    connectionPool:
      http:
        http1MaxPendingRequests: 1024
        http2MaxRequests: 1024
        maxRequestsPerConnection: 1024
        maxRetries: 100
      tcp:
        maxConnections: 100
</code></pre>

<h2 id="Sidecar">Sidecar</h2>
<section>
<p><code>Sidecar</code> describes the configuration of the sidecar proxy that mediates
inbound and outbound communication of the workload instance to which it is
attached.</p>

<table class="message-fields">
<thead>
<tr>
<th>Field</th>
<th>Type</th>
<th>Description</th>
<th>Required</th>
</tr>
</thead>
<tbody>
<tr id="Sidecar-workload_selector">
<td><code><a href="#Sidecar-workload_selector">workloadSelector</a></code></td>
<td><code><a href="#WorkloadSelector">WorkloadSelector</a></code></td>
<td>
<p>Criteria used to select the specific set of pods/VMs on which this
<code>Sidecar</code> configuration should be applied. If omitted, the <code>Sidecar</code>
configuration will be applied to all workload instances in the same namespace.</p>

</td>
<td>
No
</td>
</tr>
<tr id="Sidecar-ingress">
<td><code><a href="#Sidecar-ingress">ingress</a></code></td>
<td><code><a href="#IstioIngressListener">IstioIngressListener[]</a></code></td>
<td>
<p>Ingress specifies the configuration of the sidecar for processing
inbound traffic to the attached workload instance. If omitted, Istio will
automatically configure the sidecar based on the information about the workload
obtained from the orchestration platform (e.g., exposed ports, services,
etc.). If specified, inbound ports are configured if and only if the
workload instance is associated with a service.</p>

</td>
<td>
No
</td>
</tr>
<tr id="Sidecar-egress">
<td><code><a href="#Sidecar-egress">egress</a></code></td>
<td><code><a href="#IstioEgressListener">IstioEgressListener[]</a></code></td>
<td>
<p>Egress specifies the configuration of the sidecar for processing
outbound traffic from the attached workload instance to other
services in the mesh. If not specified, inherits the system
detected defaults from the namespace-wide or the global default Sidecar.</p>

</td>
<td>
No
</td>
</tr>
<tr id="Sidecar-inbound_connection_pool">
<td><code><a href="#Sidecar-inbound_connection_pool">inboundConnectionPool</a></code></td>
<td><code><a href="https://istio.io/docs/reference/config/networking/destination-rule.html#ConnectionPoolSettings">ConnectionPoolSettings</a></code></td>
<td>
<p>Settings controlling the volume of connections Envoy will accept from the network.
This default will apply for all inbound listeners and can be overridden per-port
in the <code>Ingress</code> field. This configuration mirrors the <code>DestinationRule</code>&rsquo;s
<a href="https://istio.io/latest/docs/reference/config/networking/destination-rule/#ConnectionPoolSettings"><code>connectionPool</code></a> field.</p>
<p>By default, Istio applies a service&rsquo;s <code>DestinationRule</code> to client sidecars
for outbound traffic directed at the service &ndash; the usual case folks think
of when configuring a <code>DestinationRule</code> &ndash; but also to the server&rsquo;s inbound
sidecar. The <code>Sidecar</code>&rsquo;s connection pool configures the server&rsquo;s inbound
sidecar directly, so its settings can be different than clients&rsquo;. This is
valuable, for example, when you have many clients calling few servers: a
<code>DestinationRule</code> can limit the concurrency of any single client, while
the <code>Sidecar</code> allows you to configure much higher concurrency on the server
side.</p>
<p>Connection pool settings for a server&rsquo;s inbound sidecar are configured in the
following precedence, highest to lowest:</p>
<ul>
<li>per-port <code>ConnectionPool</code> from the <code>Sidecar</code></li>
<li>top level <code>InboundConnectionPool</code> from the <code>Sidecar</code></li>
<li>per-port <code>TrafficPolicy.ConnectionPool</code> from the <code>DestinationRule</code></li>
<li>top level <code>TrafficPolicy.ConnectionPool</code> from the <code>DestinationRule</code></li>
<li>default connection pool settings (essentially unlimited)</li>
</ul>
<p>In every case, the connection pool settings are overridden, not merged.</p>

</td>
<td>
No
</td>
</tr>
<tr id="Sidecar-outbound_traffic_policy">
<td><code><a href="#Sidecar-outbound_traffic_policy">outboundTrafficPolicy</a></code></td>
<td><code><a href="#OutboundTrafficPolicy">OutboundTrafficPolicy</a></code></td>
<td>
<p>Set the default behavior of the sidecar for handling outbound
traffic from the application.</p>
<p>Default mode is <code>ALLOW_ANY</code>, which means outbound traffic to unknown destinations will be allowed.</p>

</td>
<td>
No
</td>
</tr>
</tbody>
</table>
</section>
<h2 id="IstioIngressListener">IstioIngressListener</h2>
<section>
<p><code>IstioIngressListener</code> specifies the properties of an inbound
traffic listener on the sidecar proxy attached to a workload instance.</p>

<table class="message-fields">
<thead>
<tr>
<th>Field</th>
<th>Type</th>
<th>Description</th>
<th>Required</th>
</tr>
</thead>
<tbody>
<tr id="IstioIngressListener-port">
<td><code><a href="#IstioIngressListener-port">port</a></code></td>
<td><code><a href="#SidecarPort">SidecarPort</a></code></td>
<td>
<p>The port associated with the listener.</p>

</td>
<td>
Yes
</td>
</tr>
<tr id="IstioIngressListener-bind">
<td><code><a href="#IstioIngressListener-bind">bind</a></code></td>
<td><code>string</code></td>
<td>
<p>The IP(IPv4 or IPv6) to which the listener should be bound.
Unix domain socket addresses are not allowed in
the bind field for ingress listeners. If omitted, Istio will
automatically configure the defaults based on imported services
and the workload instances to which this configuration is applied
to.</p>

</td>
<td>
No
</td>
</tr>
<tr id="IstioIngressListener-capture_mode">
<td><code><a href="#IstioIngressListener-capture_mode">captureMode</a></code></td>
<td><code><a href="#CaptureMode">CaptureMode</a></code></td>
<td>
<p>The captureMode option dictates how traffic to the listener is
expected to be captured (or not).</p>

</td>
<td>
No
</td>
</tr>
<tr id="IstioIngressListener-default_endpoint">
<td><code><a href="#IstioIngressListener-default_endpoint">defaultEndpoint</a></code></td>
<td><code>string</code></td>
<td>
<p>The IP endpoint or Unix domain socket to which
traffic should be forwarded to. This configuration can be used to
redirect traffic arriving at the bind <code>IP:Port</code> on the sidecar to a <code>localhost:port</code>
or Unix domain socket where the application workload instance is listening for
connections. Arbitrary IPs are not supported. Format should be one of
<code>127.0.0.1:PORT</code>, <code>[::1]:PORT</code> (forward to localhost),
<code>0.0.0.0:PORT</code>, <code>[::]:PORT</code> (forward to the instance IP),
or <code>unix:///path/to/socket</code> (forward to Unix domain socket).</p>

</td>
<td>
No
</td>
</tr>
<tr id="IstioIngressListener-tls">
<td><code><a href="#IstioIngressListener-tls">tls</a></code></td>
<td><code><a href="https://istio.io/docs/reference/config/networking/gateway.html#ServerTLSSettings">ServerTLSSettings</a></code></td>
<td>
<p>Set of TLS related options that will enable TLS termination on the
sidecar for requests originating from outside the mesh.
Currently supports only SIMPLE and MUTUAL TLS modes.</p>

</td>
<td>
No
</td>
</tr>
<tr id="IstioIngressListener-connection_pool">
<td><code><a href="#IstioIngressListener-connection_pool">connectionPool</a></code></td>
<td><code><a href="https://istio.io/docs/reference/config/networking/destination-rule.html#ConnectionPoolSettings">ConnectionPoolSettings</a></code></td>
<td>
<p>Settings controlling the volume of connections Envoy will accept from the network.
This setting overrides the top-level default <code>inboundConnectionPool</code> to configure
specific settings for this port. This configuration mirrors the <code>DestinationRule</code>&rsquo;s
<a href="https://istio.io/latest/docs/reference/config/networking/destination-rule/#TrafficPolicy-PortTrafficPolicy"><code>PortTrafficPolicy.connectionPool</code></a> field.
This port level connection pool has the highest precedence in configuration,
overriding both the <code>Sidecar</code>&rsquo;s top level <code>InboundConnectionPool</code> as well as any
connection pooling settings from the <code>DestinationRule</code>.</p>

</td>
<td>
No
</td>
</tr>
</tbody>
</table>
</section>
<h2 id="IstioEgressListener">IstioEgressListener</h2>
<section>
<p><code>IstioEgressListener</code> specifies the properties of an outbound traffic
listener on the sidecar proxy attached to a workload instance.</p>

<table class="message-fields">
<thead>
<tr>
<th>Field</th>
<th>Type</th>
<th>Description</th>
<th>Required</th>
</tr>
</thead>
<tbody>
<tr id="IstioEgressListener-port">
<td><code><a href="#IstioEgressListener-port">port</a></code></td>
<td><code><a href="#SidecarPort">SidecarPort</a></code></td>
<td>
<p>The port associated with the listener. If using Unix domain socket,
use 0 as the port number, with a valid protocol. The port if
specified, will be used as the default destination port associated
with the imported hosts. If the port is omitted, Istio will infer the
listener ports based on the imported hosts. Note that when multiple
egress listeners are specified, where one or more listeners have
specific ports while others have no port, the hosts exposed on a
listener port will be based on the listener with the most specific
port.</p>

</td>
<td>
No
</td>
</tr>
<tr id="IstioEgressListener-bind">
<td><code><a href="#IstioEgressListener-bind">bind</a></code></td>
<td><code>string</code></td>
<td>
<p>The IP(IPv4 or IPv6) or the Unix domain socket to which the listener should be bound
to. Port MUST be specified if bind is not empty. Format: IPv4 or IPv6 address formats or
<code>unix:///path/to/uds</code> or <code>unix://@foobar</code> (Linux abstract namespace). If
omitted, Istio will automatically configure the defaults based on imported
services, the workload instances to which this configuration is applied to and
the captureMode. If captureMode is <code>NONE</code>, bind will default to
127.0.0.1.</p>

</td>
<td>
No
</td>
</tr>
<tr id="IstioEgressListener-capture_mode">
<td><code><a href="#IstioEgressListener-capture_mode">captureMode</a></code></td>
<td><code><a href="#CaptureMode">CaptureMode</a></code></td>
<td>
<p>When the bind address is an IP, the captureMode option dictates
how traffic to the listener is expected to be captured (or not).
captureMode must be DEFAULT or <code>NONE</code> for Unix domain socket binds.</p>

</td>
<td>
No
</td>
</tr>
<tr id="IstioEgressListener-hosts">
<td><code><a href="#IstioEgressListener-hosts">hosts</a></code></td>
<td><code>string[]</code></td>
<td>
<p>One or more service hosts exposed by the listener
in <code>namespace/dnsName</code> format. Services in the specified namespace
matching <code>dnsName</code> will be exposed.
The corresponding service can be a service in the service registry
(e.g., a Kubernetes or cloud foundry service) or a service specified
using a <code>ServiceEntry</code> or <code>VirtualService</code> configuration. Any
associated <code>DestinationRule</code> in the same namespace will also be used.</p>
<p>The <code>dnsName</code> should be specified using FQDN format, optionally including
a wildcard character in the left-most component (e.g., <code>prod/*.example.com</code>).
Set the <code>dnsName</code> to <code>*</code> to select all services from the specified namespace
(e.g., <code>prod/*</code>).</p>
<p>The <code>namespace</code> can be set to <code>*</code>, <code>.</code>, or <code>~</code>, representing any, the current,
or no namespace, respectively. For example, <code>*/foo.example.com</code> selects the
service from any available namespace while <code>./foo.example.com</code> only selects
the service from the namespace of the sidecar. If a host is set to <code>*/*</code>,
Istio will configure the sidecar to be able to reach every service in the
mesh that is exported to the sidecar&rsquo;s namespace. The value <code>~/*</code> can be used
to completely trim the configuration for sidecars that simply receive traffic
and respond, but make no outbound connections of their own.</p>
<p>NOTE: Only services and configuration artifacts exported to the sidecar&rsquo;s
namespace (e.g., <code>exportTo</code> value of <code>*</code>) can be referenced.
Private configurations (e.g., <code>exportTo</code> set to <code>.</code>) will
not be available. Refer to the <code>exportTo</code> setting in <code>VirtualService</code>,
<code>DestinationRule</code>, and <code>ServiceEntry</code> configurations for details.</p>

</td>
<td>
Yes
</td>
</tr>
</tbody>
</table>
</section>
<h2 id="WorkloadSelector">WorkloadSelector</h2>
<section>
<p><code>WorkloadSelector</code> specifies the criteria used to determine if the
<code>Gateway</code>, <code>Sidecar</code>, <code>EnvoyFilter</code>, <code>ServiceEntry</code>, or <code>DestinationRule</code>
configuration can be applied to a proxy. The matching criteria
includes the metadata associated with a proxy, workload instance
info such as labels attached to the pod/VM, or any other info that
the proxy provides to Istio during the initial handshake. If
multiple conditions are specified, all conditions need to match in
order for the workload instance to be selected. Currently, only
label based selection mechanism is supported.</p>

<table class="message-fields">
<thead>
<tr>
<th>Field</th>
<th>Type</th>
<th>Description</th>
<th>Required</th>
</tr>
</thead>
<tbody>
<tr id="WorkloadSelector-labels">
<td><code><a href="#WorkloadSelector-labels">labels</a></code></td>
<td><code>map&lt;string,&nbsp;string&gt;</code></td>
<td>
<p>One or more labels that indicate a specific set of pods/VMs
on which the configuration should be applied. The scope of
label search is restricted to the configuration namespace in which the
the resource is present.</p>

</td>
<td>
No
</td>
</tr>
</tbody>
</table>
</section>
<h2 id="OutboundTrafficPolicy">OutboundTrafficPolicy</h2>
<section>
<p><code>OutboundTrafficPolicy</code> sets the default behavior of the sidecar for
handling unknown outbound traffic from the application.</p>

<table class="message-fields">
<thead>
<tr>
<th>Field</th>
<th>Type</th>
<th>Description</th>
<th>Required</th>
</tr>
</thead>
<tbody>
<tr id="OutboundTrafficPolicy-mode">
<td><code><a href="#OutboundTrafficPolicy-mode">mode</a></code></td>
<td><code><a href="#OutboundTrafficPolicy-Mode">Mode</a></code></td>
<td>
</td>
<td>
No
</td>
</tr>
</tbody>
</table>
</section>
<h2 id="SidecarPort">SidecarPort</h2>
<section>
<p>Port describes the properties of a specific port of a service.</p>

<table class="message-fields">
<thead>
<tr>
<th>Field</th>
<th>Type</th>
<th>Description</th>
<th>Required</th>
</tr>
</thead>
<tbody>
<tr id="SidecarPort-number">
<td><code><a href="#SidecarPort-number">number</a></code></td>
<td><code>uint32</code></td>
<td>
<p>A valid non-negative integer port number.</p>

</td>
<td>
No
</td>
</tr>
<tr id="SidecarPort-protocol">
<td><code><a href="#SidecarPort-protocol">protocol</a></code></td>
<td><code>string</code></td>
<td>
<p>The protocol exposed on the port.
MUST BE one of HTTP|HTTPS|GRPC|HTTP2|MONGO|TCP|TLS.
TLS can be either used to terminate non-HTTP based connections on a specific port
or to route traffic based on SNI header to the destination without terminating the TLS connection.</p>

</td>
<td>
No
</td>
</tr>
<tr id="SidecarPort-name">
<td><code><a href="#SidecarPort-name">name</a></code></td>
<td><code>string</code></td>
<td>
<p>Label assigned to the port.</p>

</td>
<td>
No
</td>
</tr>
</tbody>
</table>
</section>
<h2 id="OutboundTrafficPolicy-Mode">OutboundTrafficPolicy.Mode</h2>
<section>
<table class="enum-values">
<thead>
<tr>
<th>Name</th>
<th>Description</th>
</tr>
</thead>
<tbody>
<tr id="OutboundTrafficPolicy-Mode-REGISTRY_ONLY">
<td><code><a href="#OutboundTrafficPolicy-Mode-REGISTRY_ONLY">REGISTRY_ONLY</a></code></td>
<td>
<p>In <code>REGISTRY_ONLY</code> mode, unknown outbound traffic will be dropped.
Traffic destinations must be explicitly declared into the service registry through <code>ServiceEntry</code> configurations.</p>
<p>Note: Istio <a href="https://istio.io/latest/docs/ops/best-practices/security/#understand-traffic-capture-limitations">does not offer an outbound traffic security policy</a>.
This option does not act as one, or as any form of an outbound firewall.
Instead, this option exists primarily to offer users a way to detect missing <code>ServiceEntry</code> configurations by explicitly failing.</p>

</td>
</tr>
<tr id="OutboundTrafficPolicy-Mode-ALLOW_ANY">
<td><code><a href="#OutboundTrafficPolicy-Mode-ALLOW_ANY">ALLOW_ANY</a></code></td>
<td>
<p>In <code>ALLOW_ANY</code> mode, any traffic to unknown destinations will be allowed.
Unknown destination traffic will have limited functionality, however, such as reduced observability.
This mode allows users that do not have all possible egress destinations registered through <code>ServiceEntry</code> configurations to still connect
to arbitrary destinations.</p>

</td>
</tr>
</tbody>
</table>
</section>
<h2 id="CaptureMode">CaptureMode</h2>
<section>
<p><code>CaptureMode</code> describes how traffic to a listener is expected to be
captured. Applicable only when the listener is bound to an IP.</p>

<table class="enum-values">
<thead>
<tr>
<th>Name</th>
<th>Description</th>
</tr>
</thead>
<tbody>
<tr id="CaptureMode-DEFAULT">
<td><code><a href="#CaptureMode-DEFAULT">DEFAULT</a></code></td>
<td>
<p>The default capture mode defined by the environment.</p>

</td>
</tr>
<tr id="CaptureMode-IPTABLES">
<td><code><a href="#CaptureMode-IPTABLES">IPTABLES</a></code></td>
<td>
<p>Capture traffic using IPtables redirection.</p>

</td>
</tr>
<tr id="CaptureMode-NONE">
<td><code><a href="#CaptureMode-NONE">NONE</a></code></td>
<td>
<p>No traffic capture. When used in an egress listener, the application is
expected to explicitly communicate with the listener port or Unix
domain socket. When used in an ingress listener, care needs to be taken
to ensure that the listener port is not in use by other processes on
the host.</p>

</td>
</tr>
</tbody>
</table>
</section>