Kubernetes main function
1, data volume
Sharing of data between the container Pod, the data volume may be used.
2, application health check
The container service may not process the request process blocked, you can set the monitor to check the policy to ensure application robustness.
3. Copy the application instance
The controller maintains Pod number of copies, to ensure that a number of Pod Pod or a similar group is always available.
4, elastically stretchable
Pod automatically scaled according to the number of copies set of indicators (CPU utilization).
5, Service Discovery
Use environment variable or DNS service plug-in program to ensure that the container was found Pod entry access address.
6, load balancing
Pod set assigned a private copy ClusterIP address, it forwards the request to the backend load balancing container. In a cluster of other Pod through this ClusterIP access applications.
7, rollover
Update Service is not interrupted, update a Pod, rather than delete the entire service.
8, service orchestration
By file describes the deployment of services, making application deployment becomes more efficient.
9, resource monitoring
Node node Component Integration cAdvisor resource collection tool that can be aggregated across the cluster nodes resource data through Heapster, and then stored in the database InfluxDB timing, again demonstrated by the Grafana.
10, provides authentication and authorization
Support Properties Access Control (ABAC), role-based access authentication and authorization policy control (RBAC).
Two, Kubernetes basic object concepts (resource object)
1, the basic objects:
1 Under
Pod deployment unit is the smallest, a Pod or more containers have a composition, the container Pod and shared storage network, Docker running on the same host.
2、Service
Service application service abstraction, defines a logical collection of Pod Pod and access policies in this collection.
Service Agent Pod is a set of external performance access entry, assign a cluster IP address requests from this IP load balancing forwarding container rear end in the Pod.
Service provides services through LableSelector select a group of Pod.
A pod play more tags
A label can call multi-pod
3、Volume
Data volume, data sharing Pod the container used.
4, Namespace Wuxi abortion how much money http://wapyyk.39.net/wx/zonghe/fc96e.html/
Namespace assignment on the object to a different logic Namespace, can be different items, such as user management to distinguish and set control strategies in order to achieve multi-tenancy.
Namespace also known as virtual cluster.
5、Lable
Label for distinguishing objects (such as Pod, Service), key / value pair is present; each object can have several labels, the label through an association object.
2, Kubernetes based on the basic target a higher level of abstraction
1、ReplicaSet
Next Generation ReplicationController. Pod ensure that any number of copies of a given time specified and provide declarative update functions.
RC and RS The only difference is the lableselector support, RS-based support for a new set of tags, RC supports only equation-based label.
2、Deployment
Deployment is a higher-level API objects, which manages ReplicaSets and Pod, and provides a declarative update functions.
The official recommended Deployment management ReplicaSets, rather than directly using ReplicaSets, which means that may never need to directly manipulate objects ReplicaSet.
3、StatefulSet
StatefulSet for the persistence of the application, there is a unique network identifier (IP), persistent storage, orderly deployment, extend, delete and rollover.
4、DaemonSet
demonSet ensure that all (or some) nodes run the same Pod. When a cluster node joins Kubernetes, Pod scheduled to be running on the node, when the node is removed from the cluster, DaemonSet the Pod is deleted. Delete DaemonSet will clean it all Pod created.
5、Job
A one-time task, after the run is completed Pod destroyed, no longer restart the new container. Tasks can also be run regularly.
3, understand and define the resource object Kubernetes
1 Under
Pod are each assigned a unique IP address, IP Kubernetes Pod referred to, a plurality of containers in the Pod Pod shared IP address. Kubernetes requirements of the underlying network support any TCP / IP direct communication between the two clusters within the Pod, which usually Layer virtual network technology to achieve, e.g. Flannel, Open vSwitch like. Thus, in the Kubernetes, the Pod in a container and the container further Pod host can communicate directly.
Pod There are two types: static and ordinary Pod Pod (Static Pod), static Pod etcd not stored in memory, but rather stored in a specific file on a specific Node in, and only started running on this Node . Once ordinary Pod is created, it will be stored in etcd in Kubernetes Master will then be scheduled on a specific Node and bindings (Binding), kubelet process will be on the Node Examples into a group of related the Docker container and start up. When a container is stopped in the Pod, Kubernetes will automatically detect this problem and restart the Pod (Pod restart all containers inside); Node downtime if Pod is located, it will be all on the Node Pod reschedule run to the other nodes.