红帽全球峰会3.3.3.5.2. 使用无头服务进行端点发现
使用无头服务的好处是您可以直接发现 pod 的 IP 地址。标准服务充当负载均衡器或代理，并使用服务名称来提供对工作负载对象的访问。使用无头服务时，服务名称将解析为服务分组的 pod 的 IP 地址集合。
当您查找标准服务的 DNS A 记录时，您将获得服务的负载均衡 IP。
dig frontend.test A +search +short
$ dig frontend.test A +search +short输出示例
172.30.232.77
172.30.232.77但是，对于无头服务，您可以获取单个 pod 的 IP 列表。
dig frontend-headless.test A +search +short
$ dig frontend-headless.test A +search +short输出示例
172.17.0.3 172.17.0.6
172.17.0.3
172.17.0.6注意
对于使用带有 StatefulSet 的无头服务以及相关的用例，您需要在初始化和终止期间解析 pod 的 DNS，将 publishNotReadyAddresses 设置为 true （默认值为 false）。当 publishNotReadyAddresses 设为 true 时，这表示 DNS 实现必须发布与该服务关联的 Endpoints 子集的 notReadyAddresses。
'%20d='M201.5%20305.5c-13.8%200-24.9-11.1-24.9-24.6%200-13.8%2011.1-24.9%2024.9-24.9%2013.6%200%2024.6%2011.1%2024.6%2024.9%200%2013.6-11.1%2024.6-24.6%2024.6zM504%20256c0%20137-111%20248-248%20248S8%20393%208%20256%20119%208%20256%208s248%20111%20248%20248zm-132.3-41.2c-9.4%200-17.7%203.9-23.8%2010-22.4-15.5-52.6-25.5-86.1-26.6l17.4-78.3%2055.4%2012.5c0%2013.6%2011.1%2024.6%2024.6%2024.6%2013.8%200%2024.9-11.3%2024.9-24.9s-11.1-24.9-24.9-24.9c-9.7%200-18%205.8-22.1%2013.8l-61.2-13.6c-3-.8-6.1%201.4-6.9%204.4l-19.1%2086.4c-33.2%201.4-63.1%2011.3-85.5%2026.8-6.1-6.4-14.7-10.2-24.1-10.2-34.9%200-46.3%2046.9-14.4%2062.8-1.1%205-1.7%2010.2-1.7%2015.5%200%2052.6%2059.2%2095.2%20132%2095.2%2073.1%200%20132.3-42.6%20132.3-95.2%200-5.3-.6-10.8-1.9-15.8%2031.3-16%2019.8-62.5-14.9-62.5zM302.8%20331c-18.2%2018.2-76.1%2017.9-93.6%200-2.2-2.2-6.1-2.2-8.3%200-2.5%202.5-2.5%206.4%200%208.6%2022.8%2022.8%2087.3%2022.8%20110.2%200%202.5-2.2%202.5-6.1%200-8.6-2.2-2.2-6.1-2.2-8.3%200zm7.7-75c-13.6%200-24.6%2011.1-24.6%2024.9%200%2013.6%2011.1%2024.6%2024.6%2024.6%2013.8%200%2024.9-11.1%2024.9-24.6%200-13.8-11-24.9-24.9-24.9z'/%3e%3c/svg%3e){kind=small}