分享交流
合作共赢!

Kubernetes/K8S基础使用方法总结【五】——Service

Service有userspace、iptables、ipvs三种工作模式,可在配置文件/etc/sysconfig/kubelet中添加配置参数KUBE_PROXY_MODE=ipvs来改变kubernetes的工作模式(后续版本版本此配置路径可能发生更改,可以用rpm -ql kubelet来查看配置文件路径);ExternalName, ClusterIP, NodePort, and LoadBalancer五种service类型type,默认为ClusterIP;port、targetPort、nodePort三种端口选项,若使用NodePort类型,使用nodePort才生效。

实例:

apiVersion: v1
kind: Service
metadata:
  name: redis
  namespace: default
spec:
  selector:
    app: redis
    role: logstor
  clusterIP: 10.97.97.97
  type: ClusterIP
  ports:
  - port: 6379
    targetPort: 6379

默认clusterIP系统会自动分配,为了不造成IP冲突可以不指定,让系统自动分配;如果clusterIP设置为None,即没有service IP地址,直接调用pod的IP地址。

service配置清单spec主要包含如下选项:

[root@master1 yaml]# kubectl explain service.spec
KIND:     Service
VERSION:  v1

RESOURCE: spec <Object>

DESCRIPTION:
     Spec defines the behavior of a service.
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

     ServiceSpec describes the attributes that a user creates on a service.

FIELDS:
   clusterIP	<string>
     clusterIP is the IP address of the service and is usually assigned randomly
     by the master. If an address is specified manually and is not in use by
     others, it will be allocated to the service; otherwise, creation of the
     service will fail. This field can not be changed through updates. Valid
     values are "None", empty string (""), or a valid IP address. "None" can be
     specified for headless services when proxying is not required. Only applies
     to types ClusterIP, NodePort, and LoadBalancer. Ignored if type is
     ExternalName. More info:
     https://kubernetes.io/docs/concepts/services-networking/service/#virtual-ips-and-service-proxies

   externalIPs	<[]string>
     externalIPs is a list of IP addresses for which nodes in the cluster will
     also accept traffic for this service. These IPs are not managed by
     Kubernetes. The user is responsible for ensuring that traffic arrives at a
     node with this IP. A common example is external load-balancers that are not
     part of the Kubernetes system.

   externalName	<string>
     externalName is the external reference that kubedns or equivalent will
     return as a CNAME record for this service. No proxying will be involved.
     Must be a valid RFC-1123 hostname (https://tools.ietf.org/html/rfc1123) and
     requires Type to be ExternalName.

   externalTrafficPolicy	<string>
     externalTrafficPolicy denotes if this Service desires to route external
     traffic to node-local or cluster-wide endpoints. "Local" preserves the
     client source IP and avoids a second hop for LoadBalancer and Nodeport type
     services, but risks potentially imbalanced traffic spreading. "Cluster"
     obscures the client source IP and may cause a second hop to another node,
     but should have good overall load-spreading.

   healthCheckNodePort	<integer>
     healthCheckNodePort specifies the healthcheck nodePort for the service. If
     not specified, HealthCheckNodePort is created by the service api backend
     with the allocated nodePort. Will use user-specified nodePort value if
     specified by the client. Only effects when Type is set to LoadBalancer and
     ExternalTrafficPolicy is set to Local.

   ipFamily	<string>
     ipFamily specifies whether this Service has a preference for a particular
     IP family (e.g. IPv4 vs. IPv6). If a specific IP family is requested, the
     clusterIP field will be allocated from that family, if it is available in
     the cluster. If no IP family is requested, the cluster's primary IP family
     will be used. Other IP fields (loadBalancerIP, loadBalancerSourceRanges,
     externalIPs) and controllers which allocate external load-balancers should
     use the same IP family. Endpoints for this Service will be of this family.
     This field is immutable after creation. Assigning a ServiceIPFamily not
     available in the cluster (e.g. IPv6 in IPv4 only cluster) is an error
     condition and will fail during clusterIP assignment.

   loadBalancerIP	<string>
     Only applies to Service Type: LoadBalancer LoadBalancer will get created
     with the IP specified in this field. This feature depends on whether the
     underlying cloud-provider supports specifying the loadBalancerIP when a
     load balancer is created. This field will be ignored if the cloud-provider
     does not support the feature.

   loadBalancerSourceRanges	<[]string>
     If specified and supported by the platform, this will restrict traffic
     through the cloud-provider load-balancer will be restricted to the
     specified client IPs. This field will be ignored if the cloud-provider does
     not support the feature." More info:
     https://kubernetes.io/docs/tasks/access-application-cluster/configure-cloud-provider-firewall/

   ports	<[]Object>
     The list of ports that are exposed by this service. More info:
     https://kubernetes.io/docs/concepts/services-networking/service/#virtual-ips-and-service-proxies

   publishNotReadyAddresses	<boolean>
     publishNotReadyAddresses, when set to true, indicates that DNS
     implementations must publish the notReadyAddresses of subsets for the
     Endpoints associated with the Service. The default value is false. The
     primary use case for setting this field is to use a StatefulSet's Headless
     Service to propagate SRV records for its Pods without respect to their
     readiness for purpose of peer discovery.

   selector	<map[string]string>
     Route service traffic to pods with label keys and values matching this
     selector. If empty or not present, the service is assumed to have an
     external process managing its endpoints, which Kubernetes will not modify.
     Only applies to types ClusterIP, NodePort, and LoadBalancer. Ignored if
     type is ExternalName. More info:
     https://kubernetes.io/docs/concepts/services-networking/service/

   sessionAffinity	<string>
     Supports "ClientIP" and "None". Used to maintain session affinity. Enable
     client IP based session affinity. Must be ClientIP or None. Defaults to
     None. More info:
     https://kubernetes.io/docs/concepts/services-networking/service/#virtual-ips-and-service-proxies

   sessionAffinityConfig	<Object>
     sessionAffinityConfig contains the configurations of session affinity.

   topologyKeys	<[]string>
     topologyKeys is a preference-order list of topology keys which
     implementations of services should use to preferentially sort endpoints
     when accessing this Service, it can not be used at the same time as
     externalTrafficPolicy=Local. Topology keys must be valid label keys and at
     most 16 keys may be specified. Endpoints are chosen based on the first
     topology key with available backends. If this field is specified and all
     entries have no backends that match the topology of the client, the service
     has no backends for that client and connections should fail. The special
     value "*" may be used to mean "any topology". This catch-all value, if
     used, only makes sense as the last value in the list. If this is not
     specified or empty, no topology constraints will be applied.

   type	<string>
     type determines how the Service is exposed. Defaults to ClusterIP. Valid
     options are ExternalName, ClusterIP, NodePort, and LoadBalancer.
     "ExternalName" maps to the specified externalName. "ClusterIP" allocates a
     cluster-internal IP address for load-balancing to endpoints. Endpoints are
     determined by the selector or if that is not specified, by manual
     construction of an Endpoints object. If clusterIP is "None", no virtual IP
     is allocated and the endpoints are published as a set of endpoints rather
     than a stable IP. "NodePort" builds on ClusterIP and allocates a port on
     every node which routes to the clusterIP. "LoadBalancer" builds on NodePort
     and creates an external load-balancer (if supported in the current cloud)
     which routes to the clusterIP. More info:
     https://kubernetes.io/docs/concepts/services-networking/service/#publishing-services-service-types

kubectl patch svc myapp -p ‘{“spec”:{“sessionAffinity”:”ClientIP”}}’: 打补丁设置sessionAffinity为ClientIP后 ,是pod资源仅运行在某个node上面

赞(1) 打赏
未经允许不得转载:琼杰笔记 » Kubernetes/K8S基础使用方法总结【五】——Service
分享到: 更多 (0)

评论 抢沙发

  • 昵称 (必填)
  • 邮箱 (必填)
  • 网址

分享交流,合作共赢!

联系我们加入QQ群

觉得文章有用就打赏一下文章作者

支付宝扫一扫打赏

微信扫一扫打赏