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Last Updated: Jun 16, 2021

This topic describes the basic terms of Elastic Container Instance for you to understand the service before you use it.

Terms of Elastic Container Instance

The following table describes the terms of Elastic Container Instance.

Term

Description

container

A lightweight and executable standalone software package. A container is the running entity of an image.

container group

A set of containers that can be scheduled to the same host. The lifecycle of a container group is collectively determined by all containers in the group. These containers share the network and storage resources of the container group.

A container group is similar in concept to a pod in Kubernetes.

image

A file system that contains programs, library files, and configurations required for containerized applications. Docker image is in the standard packaging format of a containerized application. When you deploy a containerized application, you can specify an image from Docker Hub, Alibaba Cloud Container Registry, or your private image repository.

image cache

Used to accelerate image pulling and reduce the startup time of an elastic container instance. Image pulling is the main time-consuming operation of instance startup due to factors such as network conditions or the image size. You can accelerate the image pulling process by caching images in advance.

volume

The shared storage resource of a container group. You can mount external volumes to a container group. Volumes declared in a container group are shared by all containers in the container group.

tag

A key-value pair added to a container group. Tags can be specified only when you create a container group. Up to 10 tags can be added to a single container group, and each tag key must be unique.

Tags in Elastic Container Instance are similar to labels in Kubernetes.

virtual node

Used to connect Elastic Container Instance to Kubernetes based on Virtual Kubelet provided by the Kubernetes community. Elastic container instances do not run on a centralized real node. They are scattered across the global Alibaba Cloud resource pool.

Terms of Kubernetes

Before you use Kubernetes to manage your containerized applications, you must understand the terms used in Kubernetes. The following table describes the terms.

Term

Description

Master

The control node in a Kubernetes cluster. This node is used to manage and schedule the whole cluster.

Node

The worker node that runs workloads in a Kubernetes cluster. When a Node breaks down, workloads on the Node are transferred to another Node by the Master.

Pod

The smallest unit created or deployed in Kubernetes. A pod represents a running process on a cluster and encapsulates one or more closely-related containers.

Namespace

The logic isolation used in a cluster to allocate and manage resource objects.

Deployment

The abstraction of a pod that defines the information such as the number of replicas and versions of a set of pods.

Service

Used to provide a unified and stable access address for a set of pods.

Volume

The file directory that can be accessed by multiple containers in a pod. A volume can be mounted to the specified paths of one or more containers in a pod.

Labels

A series of key-value pairs that can be added to resource objects. You can add one or more labels to a specific object to manage resources by group in multiple dimensions.

For more information, see Kubernetes Documentation.

Terms of other services

The following table describes the container, network, and storage services provided by Alibaba Cloud that you may use together with Elastic Container Instance.

Term

Description

References

Container Service for Kubernetes (ACK)

A containerized application management service compatible with Kubernetes, including Managed Kubernetes and Serverless Kubernetes.

What is Container Service for Kubernetes?

Virtual Private Cloud (VPC)

A service that provides private networks customized on Alibaba Cloud. VPCs are logically isolated from each other. You can create and manage Elastic Container Instance resources in VPCs.

What is a VPC?

Elastic IP Address (EIP)

A service that provides public IP addresses that can be purchased and owned independently. If your elastic container instance needs to access the Internet, you can configure an EIP for the instance.

What is an EIP?

NAT Gateway

A service that provides enterprise-level Internet gateways. After the gateways are associated with EIPs, the gateways can provide NAT proxy features. You can configure a NAT gateway when all elastic container instances in a VPC need to access the Internet.

What is NAT Gateway?

Server Load Balancer (SLB)

A traffic distribution control service that distributes access traffic to backend services based on forwarding policies. You can add elastic container instances as backend servers to improve the service capabilities and availability of your applications.

What is SLB?

Apsara File Storage NAS (NAS)

A service that provides elastically scalable distributed file systems that can be accessed in a shared manner based on standard file accessing protocols such as NFS. You can mount NAS file systems to your elastic container instances.

What is Apsara File Storage NAS?

Object Storage Service (OSS)

A service that provides massive-scale storage space designed to store data such as images, audios, and videos on the Internet. OSS allows access by calling RESTful API operations but does not support random reading or writing of data. You can mount OSS buckets to your elastic container instances.

What is Object Storage Service?