148422597X Kubernetes Management Design Patterns [Vohra 2017-01-29] {E559F6BB}

Chapter 7 ■ Using Services
Another issue associated with services is that when a new RC is created, pods do not start immediately
and take a certain time (which could be a few seconds). A service representing the RC would need to know
when the containers in a pod are ready so that the service can route traffic to the pod.
Solution
The service is a REST object similar to a pod and provides object-oriented benefits such as modularity or
packaging, abstraction and reuse. Decoupling the service from the controller implements the SRP, and either
the service or controller may be modified or deleted without having to modify or delete the other. Multiple
replication controllers may be kept indefinitely, as shown in Figure 7-2, to meet the requirement of DevOps
teams. A replication controller only manages the pods, and a service only exposes endpoints to access pods.
Decoupling controller and service is a management design pattern.
Replication
Controller
Service
Replication
Controller
Replication
Controller
Figure 7-2. Service associated with multiple replication controllers
Another management pattern used in services is a readiness probe. A readiness probe is used to find
whether a pod’s containers are ready to receive traffic.
Overview
Table 7-1 describes the different ServiceTypes.
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