org.osbuild.tree-delta

Compute the delta between an overlay tree and a reference layer

Takes two tree inputs: a 'reference' layer (e.g. a base OS tree) and an 'overlay' layer (e.g. a different tree). Walks the overlay and copies only files that are either absent from or different from the corresponding file in the reference layer, trimming away everything the reference already provides. This is useful for building delta trees that contain only the files not already present in the reference tree.

An optional 'paths' filter restricts which top-level directories are considered (e.g. ["/usr", "/opt"]). Files outside those paths are ignored. An optional 'exclude_paths' filter skips any path that starts with one of the given prefixes (e.g. ["/usr/share/doc"]).

File attributes (permissions, ownership, timestamps, symlinks, extended attributes) are preserved via 'cp -a'.

The comparison is content-based: files are considered identical if they have the same type, permission bits, and content (or symlink target). Metadata-only changes (ownership, timestamps, xattrs) will not cause a file to appear in the delta. Hardlink relationships between files are also not preserved in the output.

Schema 1

{}

Schema 2

{
  "inputs": {
    "additionalProperties": false,
    "properties": {
      "overlay": {
        "additionalProperties": true,
        "type": "object"
      },
      "reference": {
        "additionalProperties": true,
        "type": "object"
      }
    },
    "required": [
      "reference",
      "overlay"
    ],
    "type": "object"
  },
  "options": {
    "additionalProperties": false,
    "properties": {
      "paths": {
        "description": "List of top-level paths to include (e.g. [\"/usr\", \"/opt\"]). If omitted, the entire tree is trimmed.",
        "items": {
          "pattern": "^/",
          "type": "string"
        },
        "type": "array"
      },
      "exclude_paths": {
        "description": "List of canonical paths to exclude. Any path starting with an entry is skipped (e.g. [\"/usr/share/doc\"]).",
        "items": {
          "pattern": "^/",
          "type": "string"
        },
        "type": "array"
      }
    }
  }
}