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    Elastic Container Instance:Troubleshoot application exceptions with coredumps

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    Elastic Container Instance:Troubleshoot application exceptions with coredumps

    Last Updated:Nov 18, 2025

    A core dump is a file that captures the memory state of a program at the moment it terminates abnormally or crashes. By analyzing this file, you can diagnose the root cause of the issue. This topic describes how to enable core dumps for an Elastic Container Instance (ECI) so you can view and analyze these files when a container fails.

    Background information

    In Linux, if a program terminates unexpectedly or crashes, the operating system records the program's memory state at that time and saves it to a file. This action is called a core dump. You can then view and analyze the generated core file to determine the cause of the problem.

    The following figure shows the signals that support core dumps in Linux. The Action for these signals is Core.

    For more information, see coredump file.

    Function overview

    By default, coredump is disabled for ECI instances to prevent service unavailability that can be caused by excessive disk usage. You can enable coredump in one of the following ways as needed:

    • Method 1: Use a one-time diagnostic task

      After you manually enable coredump, an O&M task is generated. When a container terminates abnormally or exits, the triggered coredump automatically saves the generated core file to Object Storage Service (OSS).

    • Method 2: Customize the save path for core files

      You can save core files to external storage. After you set the save path, coredump is automatically enabled. When a container terminates abnormally or exits, the triggered coredump saves the generated core file to the specified path in the external storage.

    Note

    • Method 1 is easy to use but has limitations on its validity period and the regions where it is available. It is suitable for temporary program debugging and diagnostics.

      • The generated O&M task is a one-time task. After the task runs successfully and retrieves a core file, coredump is disabled. The O&M task is valid for 12 hours. After this period, the task becomes invalid.

      • This method is not supported in the following regions: China (Ulanqab), China (Heyuan), China (Guangzhou), China (Nanjing - Local Region) (decommissioning), Philippines (Manila), South Korea (Seoul), and Thailand (Bangkok).

    • Method 2 requires you to configure external storage. This method is more robust for unstable programs as it persistently captures core files. However, a program stuck in a crash loop can quickly generate a large number of core files, consuming significant storage space.

    Method 1: Enable a coredump O&M task

    Console

    1. Log on to the Elastic Container Instance console.

    2. Enable coredump for the ECI instance.

      1. Click the ID of the target instance to go to the instance details page.

      2. Click the O&M tab, select the Core dump tab, and then click Enable.

        After coredump is enabled, an O&M task is generated. If coredump is not triggered, the task status is Pending.

        coredump-1

    3. Trigger coredump.

      Connect to the ECI instance. In the container, run the sleep 100 command and then press Ctrl+\ to trigger a coredump. The generated core file is automatically saved to OSS.coredump2

    4. Download the core file.

      After a coredump is triggered and a core file is generated, the O&M task status changes to Successful. Click Download in the Result column to save the core file to your local computer.

      coredump-2

      Note

      If the download does not start, check the website permission settings in your browser.

    OpenAPI

    1. Enable coredump for the ECI instance.

      Call the CreateInstanceOpsTask operation to create an O&M task. Specify the target ECI instance, set the OpsType parameter to coredump, and set the OpsValue parameter to enable. This enables coredump. For more information, see CreateInstanceOpsTask.

      Note

      Make sure that the `CorePattern` parameter was not set when the instance was created.

    2. Trigger coredump.

      Connect to the ECI instance. In the container, run the sleep 100 command and then press Ctrl+\ to trigger a coredump. The generated core file is automatically saved to OSS.coredump2

    3. Download the core file.

      Call the DescribeInstanceOpsRecords operation to view the O&M task result. The ResultContent in the response contains the URL of the core file in OSS. You can access this URL to download the core file.

    Method 2: Customize the save path for core files

    Core files are typically used for offline issue analysis. Therefore, you must set the save path for core files to external storage instead of a local path in the container. This prevents the core file from being lost if the container exits. ECI lets you customize the save path for core files. After you set the path, coredump is automatically enabled.

    When you call the CreateContainerGroup operation to create an ECI instance, you can pass the `CorePattern` parameter to set the save path for core files. The following table describes the related parameters. For more information, see CreateContainerGroup.

    Note

    This example uses NFSVolume. You must configure the Volume parameters based on your actual volume type.

    Name

    Type

    Example

    Description

    CorePattern

    String

    /data/dump-a/core

    The custom directory to save core dump files.

    Important

    The path cannot start with a vertical bar (|). You cannot use coredump to configure an executable program.

    Volume.N.Name

    String

    volume1

    The name of the volume.

    Volume.N.Type

    String

    NFSVolume

    The type of the volume. This topic uses NFSVolume as an example.

    Volume.N.NFSVolume.Path

    String

    /dump

    The path of the NFS volume.

    Volume.N.NFSVolume.Server

    String

    143b24****-gfn3.cn-beijing.nas.aliyuncs.com

    The address of the NFS server.

    If you use Alibaba Cloud File Storage NAS, this is the mount target address of the NAS file system.

    Container.N.VolumeMount.N.Name

    String

    volume1

    The name of the volume to mount to the container. The value must be the same as the value of `Volume.N.Name`.

    Container.N.VolumeMount.N.MountPath

    String

    /data/dump-a/

    The mount directory.

    The content in this directory is overwritten by the content of the volume. Make sure that you enter the correct directory.

    The following example shows how to use a NAS file system as external storage:

    1. Create an ECI instance named Instance A, mount a NAS file system, and set the save path for core files.

      When you call the CreateContainerGroup operation to create Instance A, pass the following parameters to mount the /dump/ directory of the NAS file system to the /data/dump-a/ directory of the container and set the save path for core files to /data/dump-a/core.

      ContainerGroupName=test-a
SecurityGroupId=sg-bp1daxpbz9lzpvvc****
VSwitchId=vsw-bp1gds63lmlm7ib05****
# Declare a volume
Volume.1.Name=volume1
Volume.1.Type=NFSVolume
Volume.1.NFSVolume.Path=/dump/
Volume.1.NFSVolume.Server=143b24****-gfn3.cn-beijing.nas.aliyuncs.com
# Mount the volume to the container
Container.1.Name=nginx
Container.1.Image=registry-vpc.cn-beijing.aliyuncs.com/eci_open/nginx:1.14.2
Container.1.VolumeMount.1.Name=volume1
Container.1.VolumeMount.1.MountPath=/data/dump-a/
# Set the save path for the core file
CorePattern=/data/dump-a/core

    2. Trigger a coredump in any directory of the container in Instance A.

      As shown in the following example, run the sleep 100 command in the container and then press the Ctrl and \ keys at the same time to trigger a coredump. The core file is saved to the /data/dump-a/ path in the container.

      coredump4

    3. Release ECI instance A.

    4. Mount the same NAS file system to another ECI instance, Instance B.

      When you call the CreateContainerGroup operation to create Instance B, pass the following parameters to mount the /dump/ directory of the same NAS file system to the /data/dump-b/ directory of the container.

      ContainerGroupName=test-nas-b
SecurityGroupId=sg-bp1daxpbz9lzpvvc****
VSwitchId=vsw-bp1gds63lmlm7ib05****
# Declare a volume
Volume.1.Name=volume1
Volume.1.Type=NFSVolume
Volume.1.NFSVolume.Path=/dump/
Volume.1.NFSVolume.Server=143b24****-gfn3.cn-beijing.nas.aliyuncs.com
# Mount the volume to the container
Container.1.Name=nginx
Container.1.Image=registry-vpc.cn-beijing.aliyuncs.com/eci_open/nginx:1.14.2
Container.1.VolumeMount.1.Name=volume1
Container.1.VolumeMount.1.MountPath=/data/dump-b/

    5. View the core file in the container of Instance B.

      As shown in the following example, you can find the core file in the /data/dump-b/ path of the container. This demonstrates that by saving the file to external storage, it persists even after the original instance is deleted, allowing for reliable offline analysis.

      coredump5

    FAQ

    After I trigger a coredump, the download does not start when I click Download in the console. What should I do?

    If the download does not start, check the website permission settings in your browser. For example, if you use the Chrome browser, you can grant the permission in the following way:

    1. Open the Elastic Container Instance console. In the address bar of your browser, click the 浏览器图标 icon and select Site Settings.浏览器设置1

    2. Set Insecure Content to Allow.浏览器设置2