The popularity of Kubernetes has steadily increased, with more than four major releases in 2017. K8s also was the most discussed project in GitHub during 2017, and was the project with the second most reviews.
Kubernetes offers a new way to deploy applications using containers. It creates an abstraction layer which can be manipulated with declarative rather than imperative programming. This way, it is much simpler to deploy and upgrade services over time. The screenshot below shows the deployment of a replication controller which controls the creation of pods—the smaller K8S unit available. The file is almost self-explanatory: the definition gcr.io/google_containers/elasticsearch:v5.5.1- 1 indicates that a Docker Elasticsearch will be deployed. This image will have two replicas and uses persistent storage for persistent data.
There are many ways to deploy a tool. A Deployment, for example, is an upgrade from a replication controller that has mechanisms to perform rolling updates — updating a tool while keeping it available. Moreover, it is possible to configure Load Balancers, subnet, and even secrets through declarations.
Computing resources can occasionally remain idle; the main goal is to avoid excess, such as containing cloud environment costs. A good way to reduce idle time is to use namespaces as a form of virtual cluster inside your cluster.
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