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Reviewed-by: Eotvos, Oliver <oliver.eotvos@t-systems.com> Co-authored-by: proposalbot <proposalbot@otc-service.com> Co-committed-by: proposalbot <proposalbot@otc-service.com>
69 lines
2.2 KiB
ReStructuredText
69 lines
2.2 KiB
ReStructuredText
:original_name: cce_10_0398.html
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.. _cce_10_0398:
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Headless Service
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================
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The preceding types of Services allow internal and external pod access, but not the following scenarios:
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- Accessing all pods at the same time
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- Pods in a Service accessing each other
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This is where headless Service come into service. A headless Service does not create a cluster IP address, and the DNS records of all pods are returned during query. In this way, the IP addresses of all pods can be queried. :ref:`StatefulSets <cce_10_0048>` use headless Services to support mutual access between pods.
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.. code-block::
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apiVersion: v1
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kind: Service # Object type (Service)
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metadata:
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name: nginx-headless
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labels:
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app: nginx
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spec:
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ports:
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- name: nginx # - name: nginx # Name of the port for communication between pods
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port: 80 # Port number for communication between pods
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selector:
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app: nginx # Select the pod whose label is app:nginx.
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clusterIP: None # Set this parameter to None, indicating that a headless Service is to be created.
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Run the following command to create a headless Service:
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.. code-block::
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# kubectl create -f headless.yaml
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service/nginx-headless created
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After the Service is created, you can query the Service.
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.. code-block::
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# kubectl get svc
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NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
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nginx-headless ClusterIP None <none> 80/TCP 5s
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Create a pod to query the DNS. You can view the records of all pods. In this way, all pods can be accessed.
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.. code-block::
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$ kubectl run -i --tty --image tutum/dnsutils dnsutils --restart=Never --rm /bin/sh
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If you do not see a command prompt, try pressing Enter.
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/ # nslookup nginx-0.nginx
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Server: 10.247.3.10
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Address: 10.247.3.10#53
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Name: nginx-0.nginx.default.svc.cluster.local
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Address: 172.16.0.31
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/ # nslookup nginx-1.nginx
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Server: 10.247.3.10
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Address: 10.247.3.10#53
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Name: nginx-1.nginx.default.svc.cluster.local
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Address: 172.16.0.18
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/ # nslookup nginx-2.nginx
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Server: 10.247.3.10
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Address: 10.247.3.10#53
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Name: nginx-2.nginx.default.svc.cluster.local
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Address: 172.16.0.19
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