The core concept of Elastic Container Instance (ECI) is the container group. This topic describes terms of ECI, including the container group.
A container group is a set of containers with shared storage and network. You can schedule multiple containers to the same host. The lifecycle of a container group is collectively determined by all containers in the group. A container group is similar in concept to a pod in Kubernetes. For more information, see Pod Overview.
You need to allocate resources to container groups during ECI deployment. The minimum resources that are needed for a container group are 0.25 vCPU and 0.5 GB memory. The resources used by a container in a container group cannot exceed the resource limit of the group. For example, a container group allocated with 1 vCPU can include two containers, each of which uses 0.5 vCPU.
Container group statuses
- Scheduling: The container group is being created.
- Pending: One or more containers in the container group are being started and none is running.
- Running: All containers in the container group are created, and at least one container is running or restarting.
- Restarting: The container group is restarting.
- Updating: The container group is being updated.
- Succeeded: All containers in the container group are terminated in success and will not be restarted.
- Failed: All containers in the container group are terminated, and at least one container is terminated in failure. That is, the container exits with a non-zero exit code or is terminated by the system.
- ScheduleFailed: The container group fails to be created. The container group will be automatically deleted after 24 hours. No fee is charged for a container group in this state.
- StartingFailed: The container group fails to be started. A container group automatically enters the StartingFailed state after it stays in the Pending state for 4 hours, and computing resources are released. No fee is charged for a container group in this state.
- WatingForDel: The container group is waiting to be deleted. A container group automatically enters the WatingForDel state after it stays in the ScheduleFailed state for 1 hour. No fee is charged for a container group in this state.
- Waiting: The container is waiting to be created and is not running. Generally, application containers remain in the Waiting state when an init container is running until the init container exits.
- Running: The container is created and running.
- Terminated: The container is terminated in success or in failure.
Containers in the same container group share an IP address and port. Currently, ECI supports Virtual Private Clouds (VPCs) and Elastic IP Addresses (EIPs). For more information, see What is a VPC? and What are Elastic IP Addresses? When you create an ECI, you must specify a VPC to ensure effective communications within the group. You can enable Internet access for an ECI in one of the following ways:
- Create an EIP and associate it with the network address translation (NAT) gateway of the VPC where the ECI resides.
- Directly associate an EIP with the ECI.
A tag is a key-value pair that is attached to a container group. You can attach tags to a container group when you create or update the container group. Each container group can have a maximum of 10 tags. The key must be unique for a given container group. Tags in ECI are similar to labels in Kubernetes.
Image is the standard packaging format of a containerized application in Docker. When you deploy applications, you can specify an image from Docker Hub, Alibaba Cloud Container Registry, or your private registry. An image ID is a unique identifier composed of the URI of the image repository and the image tag. The default tag is latest.
External volumes can be mounted to a specified container group. A volume has the same lifecycle as the container group to which the volume is mounted and only takes effect within the container group. Volumes claimed for a container group are shared by all containers in the container group.
For more information about Kubernetes, see official Kubernetes documentation and Comparison between Container Service for Kubernetes terms and native Kubernetes terms.