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Reference

title: Reference

Reference

The four canonical configuration surfaces that cloud-boot exposes.

  • :material-console-line:{ .lg .middle } Kernel cmdline

    Every cloudboot.* knob: where it lives, what it accepts, and which path it affects. Cross-referenced with the plan HCL and metadata-URL JSON.

  • :material-file-code:{ .lg .middle } Plan HCL schema

    target {} blocks, local.* / self.* scoping, multi-arch OCI indexes, the seven attributes a target carries.

  • :material-link:{ .lg .middle } metadata-URL JSON

    The cloudboot key inside the per-instance metadata response. Overrides cmdline values without rebuilding the boot ISO.

  • :material-restart:{ .lg .middle } NVRAM reset

    How to clear Boot#### + BootOrder after a Path C target has been staged. In-band script and out-of-band libvirt recipe.

Precedence

When the same value appears in multiple places, cloud-boot resolves in this order (later wins):

  1. Kernel cmdline — /proc/cmdline as parsed by the firmware.
  2. HCL plan — values from the resolved target.
  3. metadata-URL JSON — the cloudboot block in the per-instance metadata response.

So a metadata-URL value overrides both the cmdline and the plan, which is what you want for per-instance secrets like LUKS passphrases.