Infrastructure as Code Cookbook

Running commands during boot using cloud-init

When bootstrapping a new server or instance, the first boot is often very different from all the other boots the instance will experience in its life, and most often we want some commands to be executed very early or very late in the boot process. For example, let's say our cloud instance is launched with an attached block storage. We might want to format this storage space and be sure it's mounted on the host, but while we always want the disk to mount, we probably don't want it to be formatted at each boot! The bootcmd directive is there to handle everything related to commands to be executed very early in the boot process, while the runcmd directive is executed much later in the boot process (and ...