After you create an Elastic Compute Service (ECS) instance, you can customize the instance by performing operations such as installing software and deploying application environments and then create a custom image from the instance. Instances created from the custom image contain all of the customized items. This eliminates the need to configure these items for each new instance.

Prerequisites

Background information

When you create a custom image from an instance, a snapshot is automatically created for each disk on the instance. All the snapshots together constitute a complete custom image, as shown in the following figure. custom_image
You can use one of the following methods to create a custom image from an instance:

Precautions

Before you create a custom image from an instance, take note of the items described in the following table.

Item Description
Limits on regions A custom image resides within the same region as the instance from which the image was created. For information about how to use images across regions, see Copy an image.
Billing
  • A snapshot is automatically generated for each disk when you create a custom image. You are charged for the snapshots. For information about snapshot billing, see Snapshots.
  • Custom images are billed independently from the ECS instances that were used to create the images or were created from the images. For example, custom images created from subscription instances can be used to create pay-as-you-go instances.
Instance type You cannot create images that contain snapshots of system disks and data disks from instances that use local SSDs. For more information, see Overview.
Instance status
  • When you create a custom image from an instance, you do not need to stop the instance.
    Note When you create a custom image from an instance that is in the Running state, real-time data may not be saved to the image. To ensure data integrity, we recommend that you stop the instance before you use it to create a custom image. If you do not want to stop your instance, you can create a snapshot-consistent group from the instance and then use the snapshot-consistent group to create a custom image. For more information, see Create a snapshot-consistent group.
  • While a custom image is being created from an instance, do not change the state of the instance. For example, if you stop, start, or restart an instance while a custom image is being created from the instance, the image cannot be created.
  • You cannot create images from expired subscription instances. However, you can create snapshots for the system disks of the instances and then use the snapshots to create custom images. For more information, see Create a custom image from a snapshot.
  • You cannot create images from released instances. If you have stored a system disk snapshot of a released instance, you can use the snapshot to create a custom image. For more information, see Create a custom image from a snapshot.
Linux instance
When you create a custom image from a Linux instance, take note the following additional items:
  • Do not load data disk information to the /etc/fstab file. Otherwise, instances created from the image cannot be started.
  • Do not update the kernel or operating system version.
  • Do not adjust the system disk partitions. Only system disks with a single root partition are supported.
  • Do not modify critical system files such as /sbin, /bin, and /lib.
  • Do not modify the default logon username root.
Amount of time required to create an image The amount of time it takes to create an image from an instance depends on the disk size of the instance. Wait until the snapshot for each disk is created before you can use the image.

Create a custom image on the Images page

  1. Log on to the ECS console.
  2. In the left-side navigation pane, choose Instances & Images > Images.
  3. In the top navigation bar, select a region.
  4. In the Create Image section, click Create Custom Image.
    Create Image
  5. In the Create Custom Image dialog box, configure the parameters described in the following table.
    Parameter Description References
    Creation Method Select Instance. N/A
    Instance Select a created ECS instance from the drop-down list. N/A
    Image Name Enter a name for the custom image. N/A
    Image Family Optional. Select an image family when you create a custom image.

    Custom images that belong to an image family can be deprecated or restored to allow smooth image updates and rollbacks.

    Overview
    Image Description Optional. Enter a description for the custom image. N/A
    Tag Select one or more tags.
    • Tag is an optional parameter in most scenarios.
    • Tag is a required parameter when you log on as a Resource Access Management (RAM) user and a policy attached to the RAM user requires that tags be added. In this case, if you do not specify Tag, an error is reported and indicates insufficient permissions.
    Overview
    Resource Group Optional. Select a resource group to manage the custom image based on usage and permissions. Resource groups
  6. Click OK.

Create a custom image on the Instances page

  1. Log on to the ECS console.
  2. In the left-side navigation pane, choose Instances & Images > Instances.
  3. In the top navigation bar, select a region.
  4. Find the instance from which you want to create a custom image. In the Actions column, choose More > Disk and Image > Create Custom Image.
  5. In the Create Custom Image dialog box, configure the parameters described in the following table.
    Parameter Description References
    Image Name Enter a name for the custom image. N/A
    Image Family Optional. Select an image family when you create a custom image. Custom images that belong to an image family can be deprecated or restored to allow smooth image updates and rollbacks. Overview
    Image Description Optional. Enter a description for the custom image. N/A
    Tag Select one or more tags.
    • Tag is an optional parameter in most scenarios.
    • Tag is a required parameter when you log on as a RAM user and a policy attached to the RAM user requires that tags be added. In this case, if you do not specify Tag, an error is reported and indicates insufficient permissions.
    Overview
    Resource Group Optional. Select a resource group to manage the custom image based on usage and permissions. Resource groups
  6. Click OK.

What to do next