#Concepts

These pages explain one part of a build at a time. Each covers the concept, its visual-editor controls, and the matching YAML.

Sources — Every VM needs one source: the disk image it boots from when the build starts. The editor offers three common options; YAML also supports containerdisk.
Files — files is a named file registry. The virtual floppy, boot-time HTTP directory, and file provisioners reference entries here by name.
Provisioners — Provisioners are build steps that run inside a VM after it boots. They run top to bottom; if one fails, the build fails.
Communicators (SSH) — A communicator lets the build reach a running VM during provisioning. It uploads files and runs scripts inside the guest. SSH is the supported communicator.
Networking — Every module gets an isolated network for its VMs. By default, it has one VPC, one subnet, and internet access. Add more structure only when the module needs it.
Boot Commands — A boot command types keystrokes into the VM's VNC console. Use it for boot loaders, ISO menus, and setup before SSH is available. Once SSH is up, the communicator takes over.
Cloud-init — Cloud images use cloud-init for first-boot setup, including users, SSH keys, packages, and commands. The build uses it to add its SSH key, so cloud-image sources must include a cloudinit block.
Build-only Overrides — Some settings make sense during the build but not in the clones. A build often needs: