Production-Grade Container Orchestration

Objectives Learn about Kubernetes Pods. Learn about Kubernetes Nodes. Troubleshoot deployed applications. Kubernetes Pods A Pod is a group of one or more application containers (such as Docker) and includes shared storage (volumes), IP address and information about how to run them. When you created a Deployment in Module 2, Kubernetes created a Pod to host your application instance. A Pod is a Kubernetes abstraction that represents a group of one or more application containers (such as Docker), and some shared resources for those containers.

This page shows how to create a Kubernetes Service object that external clients can use to access an application running in a cluster. The Service provides load balancing for an application that has two running instances. Before you begin You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts.

As the Kubernetes API evolves, APIs are periodically reorganized or upgraded. When APIs evolve, the old API is deprecated and eventually removed. This page contains information you need to know when migrating from deprecated API versions to newer and more stable API versions. Removed APIs by release v1.32 The v1.32 release stopped serving the following deprecated API versions: Flow control resources The flowcontrol.apiserver.k8s.io/v1beta3 API version of FlowSchema and PriorityLevelConfiguration is no longer served as of v1.

The Kubernetes API is a resource-based (RESTful) programmatic interface provided via HTTP. It supports retrieving, creating, updating, and deleting primary resources via the standard HTTP verbs (POST, PUT, PATCH, DELETE, GET). For some resources, the API includes additional subresources that allow fine-grained authorization (such as separate views for Pod details and log retrievals), and can accept and serve those resources in different representations for convenience or efficiency. Kubernetes supports efficient change notifications on resources via watches: in the Kubernetes API, watch is a verb that is used to track changes to an object in Kubernetes as a stream.

Production-Grade Container Orchestration

The kubectl tool supports JSONPath templates as an output format. A JSONPath template is composed of JSONPath expressions enclosed by curly braces: { and }. Kubectl uses JSONPath expressions to filter on specific fields in the JSON object and format the output. In addition to the original JSONPath template syntax, the following functions and syntax are valid: Use double quotes to quote text inside JSONPath expressions. Use the range, end operators to iterate lists.

Synopsis The Kubernetes scheduler is a control plane process which assigns Pods to Nodes. The scheduler determines which Nodes are valid placements for each Pod in the scheduling queue according to constraints and available resources. The scheduler then ranks each valid Node and binds the Pod to a suitable Node. Multiple different schedulers may be used within a cluster; kube-scheduler is the reference implementation. See scheduling for more information about scheduling and the kube-scheduler component.

Synopsis Create a resource quota with the specified name, hard limits, and optional scopes. kubectl create quota NAME [--hard=key1=value1,key2=value2] [--scopes=Scope1,Scope2] [--dry-run=server|client|none] Examples # Create a new resource quota named my-quota kubectl create quota my-quota --hard=cpu=1,memory=1G,pods=2,services=3,replicationcontrollers=2,resourcequotas=1,secrets=5,persistentvolumeclaims=10 # Create a new resource quota named best-effort kubectl create quota best-effort --hard=pods=100 --scopes=BestEffort Options --allow-missing-template-keys     Default: true If true, ignore any errors in templates when a field or map key is missing in the template.

Production-Grade Container Orchestration