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
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
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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
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1I'm glad this was encouraged on serverfault. I've seen it downvoted many times on SO– NathanApr 11, 2018 at 16:51
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1In 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/…– NicoKoweJul 13, 2018 at 14:39
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.
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1Note: 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.– crockeeaMar 27, 2020 at 0:50 -
This method is documented by AWS here serverfault.com/questions/797482/… Oct 14, 2020 at 1:02
You can put your script in /etc/rc.local, which will run the script on every reboot.
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@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. Oct 1, 2017 at 2:37
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
--//