To run commands on a Linux Container (LXD) instance at provision launch time, you can use the --boot option when creating the instance. The --boot option allows you to specify a list of commands that will be executed when the instance is launched.
Here's an example of how to use the --boot option to run a command on an LXD instance at launch time:
lxc launch ubuntu:16.04 mycontainer --boot "echo 'Hello, world!' > /tmp/hello.txt"
This will create a new LXD instance based on the ubuntu:16.04 image and run the command echo 'Hello, world!' > /tmp/hello.txt when the instance is launched. The command will create a file called hello.txt in the /tmp directory and write the message "Hello, world!" to it.
You can specify multiple commands by separating them with a semicolon (;). For example:
lxc launch ubuntu:16.04 mycontainer --boot "echo 'Hello, world!' > /tmp/hello.txt; apt-get update; apt-get install -y nginx"
This will create a new LXD instance and run the commands echo 'Hello, world!' > /tmp/hello.txt, apt-get update, and apt-get install -y nginx when the instance is launched.
By using the --boot option, you can run commands on an LXD instance at provision launch time and customize the instance to your specific needs. It's always a good idea to carefully review the documentation and use the appropriate options when working with LXD. This will help ensure that your instances are configured and launched correctly and that any problems are detected and addressed.