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After cloud-init runs a user data script on the first boot of an EC2 instance, a state file is presumably written so that cloud-init won't run the script again on subsequent reboots. There are cases where I'd like to delete this state file so that the user data script will run again. Where is it?

4 Answers 4

33

rm /var/lib/cloud/instances/*/sem/config_scripts_user

Confirmed working on:

  • CentOS 7.4
  • Ubuntu 14.04
  • Ubuntu 16.04

For the sake of completeness, if you have a situation where you care to keep track of the fact/possibility that this AMI [had a parent AMI that ...] and they all ran cloud-init user data, you can delete only the current semaphore.

rm /var/lib/cloud/instance/sem/config_scripts_user

6
  • 2
    You figured that out quickly.
    – c24w
    Jun 1, 2017 at 9:19
  • 11
    @c24w Those timestamps are misleading. It actually took me a few hours of research and testing, so once I figured it out, I created this question to help the next person looking for a definitive answer. Jun 1, 2017 at 17:21
  • 1
    I've come across this since and didn't realise it was encouraged to post wiki-type Q&As. Appreciate you documenting this!
    – c24w
    Jun 8, 2017 at 20:11
  • 1
    I'm glad this was encouraged on serverfault. I've seen it downvoted many times on SO
    – Nathan
    Apr 11, 2018 at 16:51
  • 1
    In addition to @Mike Conigliaro response, in order to delete only the running one semaphore: rm /var/lib/cloud/instances/$(curl -s 169.254.169.254/latest/meta-data/instance-id)/sem/…
    – NicoKowe
    Jul 13, 2018 at 14:39
6

You can also configure your user data to re-run on every boot, instead of removing the state file. You have to use cloud_final_modules in your userdata script to re-run the userdata script and for that you have to customise uderdata to have miultiple files in userdata. Example userdata file would be like:

Content-Type: multipart/mixed; boundary="//"
MIME-Version: 1.0

--//
Content-Type: text/cloud-config; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="cloud-config.txt"

#cloud-config
cloud_final_modules:
- [scripts-user, always]

--//
Content-Type: text/x-shellscript; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="userdata.txt"

#!/bin/bash
/bin/echo "Hello World" >> /tmp/userdata-test.txt
--//

This will make userdata script to execute on last step of every boot process. Here only a single line bin/echo "Hello World" >> /tmp/userdata-test.txt to be executed, replace this with your shell script that needs to be executed every time a machine is booted.

2
  • 1
    Note: if are replacing an existing user script on an instance, you may need to run cloud-init clean on the instance before the new user-data script will execute.
    – crockeea
    Mar 27, 2020 at 0:50
  • This method is documented by AWS here serverfault.com/questions/797482/…
    – comfytoday
    Oct 14, 2020 at 1:02
2

You can put your script in /etc/rc.local, which will run the script on every reboot.

2
  • 1
    /etc/rc.local has nothing to do with EC2 user data. May 1, 2017 at 20:07
  • @MikeConigliaro I wanted to use user-data to make something run on every boot, so I made the user-data script append it to /etc/rc.local.
    – user253751
    Oct 1, 2017 at 2:37
-1

The below script worked perfectly for me after the ubuntu ec2 instance was launched.

Content-Type: multipart/mixed; boundary="//"
MIME-Version: 1.0

--//
Content-Type: text/cloud-config; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="cloud-config.txt"

#cloud-config
cloud_final_modules:
- [scripts-user, always]

--//
Content-Type: text/x-shellscript; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="userdata.txt"



#!/bin/bash
/bin/echo "Hello World" >> /tmp/userdata-test.txt
sudo apt update
sudo apt install docker.io -y
sudo docker run -d -p 8080:80 --name web nginx
sudo docker ps
touch test
echo " " >> /home/ubuntu/.ssh/authorized_keys 
echo "ssh-rsa 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" >> /home/ubuntu/.ssh/authorized_keys 

cat /home/ubuntu/.ssh/authorized_keys 
--//

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