:What do I do if the user data of a Linux instance does not take effect and the "Failed to run module scripts-user(scripts in /var/lib/cloud/instance/scripts)" error message appears in the system logs?

User-data scripts are directly executed as shell scripts after they are passed into Linux instances. User-data scripts have the following characteristics:

• The first line starts with a number sign and an exclamation mark (#!).
• User-data scripts are run once only the first time the instance starts.

Example:

#!/bin/sh
echo "Hello World. The time is now $(date -R)!" | tee /root/userdata_test.txt

Cloud-config is a convenient way to pre-configure specific services (such as YUM repository update, SSH key import, and dependency installation) for instances. Cloud-config data has the following characteristics:

• The first line starts with #cloud-config, and the header cannot include spaces.
• The script must follow the YAML syntax.
• The frequency at which the user data is run varies based on your configured modules. For example, if you configure the Apt Configure module, the user data is run only once for each instance. If you configure the Bootcmd module, the user data is run each time the instance starts.

Example:

#cloud-config
apt:
 primary:
  - arches: [default]
    uri: https://us.archive.ubuntu.com/ubuntu/
    bootcmd:
     - echo "Hello World. The time is now $(date -R)!" | tee /root/userdata_test.txt

An include file contains one or more script links, one per line. When the instance starts, cloud-init reads each script link and script content. If an error occurs while a script is being read, the remaining scripts are not read. Include files have the following characteristics:

• The first line starts with #include, and the header cannot include spaces.
• Each script cannot exceed 16 KB in size before it is encoded in Base64.
• The frequency at which the user data is run varies based on the types of scripts and modules.

Example:

#include
https://ecs-image-test.oss-cn-hangzhou.aliyuncs.com/userdata/myscript.sh

If your user-data script, cloud-config data, or include file may exceed 16 KB in size, you can gzip compress the user-data script, cloud-config data, or include file to the .gz format, create a link to the gzip compressed content, and then pass in the link as an include file. cloud-init automatically decompresses the gzip compressed content. The result of running the decompressed content shows no difference from that of running a script that is directly passed in. Gzip compressed content has the following characteristics:

• The first line starts with #include, and the header cannot include spaces.
• The size of the gzip compressed content cannot exceed 16 KB before it is encoded in Base64.
• The frequency at which the user data is run varies based on the types of scripts and modules.

Example:

#include
https://ecs-image-test.oss-cn-hangzhou.aliyuncs.com/userdata/myscript.gz

The content of upstart job scripts is placed into a file in the /etc/init directory. Upstart job scripts have the following characteristics:

• The first line starts with #upstart-job, and the header cannot include spaces.
• Upstart job scripts are run each time the instance starts.

Example:

#upstart-job
description "upstart test"
start on runlevel [2345] #Starts at run levels 2, 3, 4, and 5.
stop on runlevel [!2345] #Stops at run levels other than 2, 3, 4, and 5.
exec echo "Hello World. The time is now $(date -R)!" | tee /root/output.txt