Cloud-init is a widely used tool for the early initialization of cloud instances. It supports various cloud platforms and allows for the automatic configuration of the environment based on user-provided initialization metadata, such as setting hostnames, usernames, and network configurations through user-data scripts or configuration files. This makes it excellent for quickly bootstrapping new virtual machines with the necessary custom settings. Other tools like Puppet and Ansible are also used for automation and configuration management, but they are typically used post-boot for ongoing management, rather than during the initial boot process.