Cloud-init

What is cloud-init?

Cloud-init is an open source tool that runs inside a CVM instance as a non-resident service. It is executed at startup and exits immediately after execution. It does not listen to any ports.
All the Linux public images of Tencent Cloud are pre-installed with the cloud-init service. You need to run the service as the root user because the service is mainly used for the initialization of CVM instances such as configuring DNS, hostname, and IP, and the execution of some custom scripts that users specify to be executed during the first boot when creating the CVM instances.

How do I check whether the cloud-init service inside a Linux instance is working properly?

Checking the operation of cloud-init

First, log in to the instance and execute the following commands to see if any error is returned. If the execution result is returned, it means that the service is running normally. Otherwise, an error will be returned. You can troubleshoot according to the error message.

1. Delete the cloud-init cache directory.

   rm -rf /var/lib/cloud

2. Perform complete cloud-init initialization.

   cloud-init init --local

3. Pull data from the configured data source.

   cloud-init init

4. Cloud-init initialization involves multiple stages. To ensure sufficient dependency between the stages, config stage is specified for the cloud-init modules.

   cloud-init modules --mode=config

5. Specify final stage for the cloud-init modules.

   cloud-init modules --mode=final

What initialization operations does cloud-init perform on instances?

Tencent Cloud implements all instance initialization operations through cloud-init, ensuring the transparency of the operations inside an instance. The following briefly covers some initialization operations. For more details, see cloud-init documentation.

How can I fix issues related to cloud-init?

1. Error due to the unmounting of cloud-init dependencies

• Problem description:
  When commands are used to check whether the cloud-init service is working properly, the following error is returned:

  Traceback (most recent call last):
  File "/usr/bin/cloud-init", line 5, in
    ********
    raise DistributionNotFound(req)
  pkg_resources.DistributionNotFound: pyyaml

• Problem analysis:
  “pkg_resources.DistributionNotFound: xxxxx” indicates that the cloud-init dependencies have been uninstalled.
• Solution:
  1. Reinstall the dependencies.
  2. Follow Checking the operation of cloud-init to see if the error is returned again.

2. Error due to the modification of the default Python interpreter

• Problem description:
  An error is returned when cloud-init is run on launch.
• Problem analysis:
  When cloud-init is installed, Python 2 is used as the default Python interpreter, which means that symbolic links, /usr/bin/python and /bin/python, are linked to Python 2. Users may change the default Python interpreter to Python 3 inside the instance by directing the symbolic links, /usr/bin/python and /bin/python, to Python 3. Due to compatibility issues, an error will be returned when cloud-init is run on startup.
• Solution:
  1. Modify the Python interpreter specified in the /usr/bin/cloud-init file by changing #/usr/bin/python or #/bin/python to #! user/bin/python.

     Do not use symbolic links. Point directly to a specific interpreter.

  2. Follow Checking the operation of cloud-init to see if the error is returned again.

Cloudbase-Init

What is Cloudbase-Init?

Like cloud-init, Cloudbase-Init is a bridge by which you can communicate with Windows CVM instances. The Cloudbase-Init service is run when an instance launches for the first time. The service will read the initialization configuration information of the instance and initialize it. Subsequent operations such as resetting the password and modifying IP addresses are also done through Cloudbase-Init.

How do I check whether the Cloudbase-Init service inside a Windows instance is working properly?

Checking the operation of the Cloudbase-Init service

1. Log in to the instance.

   If you forget your password or fail to reset your password because of Cloudbase-Init service exceptions, you can reset your password by following step 2.

2. Open Control Panel > Administrative Tools > Services.
3. Find the Cloudbase-Init service, right-click it, and go to Properties.
   • Check that “Startup type” is set to “Automatic”, as shown in the following figure.
     
   • View “Logon identity” and ensure that “Local System account” is selected, as shown in the following figure.
     
   • Manually launch the Cloudbase-Init service and see if any error is returned.
     If any error is returned, you need to fix the issue first and check whether you have installed any security software which may stop Cloudbase-Init from performing related operations.
     
   • Open the registry, find all “LocalScriptsPlugin” keys, and ensure that their values are 2, as shown in the following figure.
     
   • Check whether CD-ROM loading is disabled. If there is an optical disc drive as shown in the figure below, it means that the loading has not been disabled; otherwise, it means that it has been disabled and needs to be enabled.
     

How do I fix common issues related to Cloudbase-Init?

Failed to reset password during initialization

• Possible reasons:
  • The Cloudbase-Init account password is manually changed, which results in the failure to launch the Cloudbase-Init service, which further led to the failure of operations such as resetting password during initialization.
  • The Cloudbase-Init service is disabled, which led to the failure of operations such as resetting password during initialization.
  • The security software installed blocks the Cloudbase-Init service from resetting password so that the operation returns a successful result but actually failed.
• Solution:
  Follow the corresponding solution to each possible reason to fix the issue.
  1. Change the Cloudbase-Init service to LocalSystem service. For details, see step 2 in Checking the operation of the Cloudbase-Init service.
  2. Change the launch type of the Cloudbase-Init service to automatic. For details, see step 2 in Checking the operation of the Cloudbase-Init service.
  3. Unmount the security software involved or add the relevant operations of the Cloudbase-Init service to the allowlist of the security software.