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@ -29,7 +29,7 @@ title: Using a Service to Expose Your App
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<p>Kubernetes <a href="/docs/concepts/workloads/pods/pod-overview/">Pods</a> are mortal. Pods in fact have a <a href="/docs/concepts/workloads/pods/pod-lifecycle/">lifecycle</a>. When a worker node dies, the Pods running on the Node are also lost. A <a href="/docs/user-guide/replication-controller/#what-is-a-replicationcontroller">ReplicationController</a> might then dynamically drive the cluster back to desired state via creation of new Pods to keep your application running. As another example, consider an image-processing backend with 3 replicas. Those replicas are fungible; the front-end system should not care about backend replicas or even if a Pod is lost and recreated. That said, each Pod in a Kubernetes cluster has a unique IP address, even Pods on the same Node, so there needs to be a way of automatically reconciling changes among Pods so that your applications continue to function.</p>
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<p>Enter <i>Services</i>. A Service in Kubernetes is an abstraction which defines a logical set of Pods and a policy by which to access them. Services enable a loose coupling between dependent Pods. A Service is defined using YAML <a href="/docs/concepts/configuration/overview/#general-config-tips">(preferred)</a> or JSON, like all Kubernetes objects. The set of Pods targeted by a Service is usually determined by a <i>LabelSelector</i> (see below for why you might want a Service without including <code>selector</code> in the spec).</p>
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<p>A Service in Kubernetes is an abstraction which defines a logical set of Pods and a policy by which to access them. Services enable a loose coupling between dependent Pods. A Service is defined using YAML <a href="/docs/concepts/configuration/overview/#general-config-tips">(preferred)</a> or JSON, like all Kubernetes objects. The set of Pods targeted by a Service is usually determined by a <i>LabelSelector</i> (see below for why you might want a Service without including <code>selector</code> in the spec).</p>
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<p>Although Pods each have a unique IP address, those IPs are not exposed outside the cluster without a Service. Services allow your applications to receive traffic. Services can be exposed in different ways by specifying a <code>type</code> in the ServiceSpec:</p>
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