mesh-controller/internal/catalogue/dir_into.go

package catalogue

import (
	"fmt"
	"regexp"
	"sort"
	"strings"
)

// A directory the mesh places (novox/hq ADR 0112, to-be 27, issue 119).
//
// **A module definition names no host path.** A directory resource may omit `path`; the mesh
// resolves where it lands when the declaration is composed — `<root>/<module>/<id>`, the root a
// node's own setting with /var/lib as the default. From then on the module's own files, mounts
// and environment name the place as `${dir:<id>}`, the same shape as `${bound:…}` and
// `${secret:…}`: a fact the module asks for by name and never states.
//
// **A directory that states a path keeps it, and still answers `${dir:<id>}`.** That is the
// placement for an adopted machine: data that must sit where the predecessor already put it is
// declared with the path as the exception it is, and everything else in the module names it by
// id — so moving it later is one line, not a search.
//
// **Resolved here, not on the machine.** The host receives concrete paths exactly as it always
// has; nothing new reaches it and it learns no field. Which also means a resolved path changing
// is a spec change like any other — and the spec comparison must see it (novox/hq issue 126).

// defaultDataRoot is where module data lands when a node states no root of its own.
const defaultDataRoot = "/var/lib"

// dirRef is how a module names one of its placed directories: ${dir:<id>}.
var dirRef = regexp.MustCompile(`\$\{dir:([a-z0-9][a-z0-9-]*)\}`)

// dataRoot is the root this node keeps placed directories under.
func dataRoot(with Rendering) string {
	if root := strings.TrimRight(strings.TrimSpace(with.DataRoot), "/"); root != "" {
		return root
	}
	return defaultDataRoot
}

// dirsFor is every placed directory of a module, id → the path it resolves to on this node.
func dirsFor(m Manifest, with Rendering) map[string]string {
	dirs := map[string]string{}
	for _, r := range m.Resources {
		if fmt.Sprint(r["type"]) != "directory" {
			continue
		}
		id := fmt.Sprint(r["id"])
		if path, stated := r["path"].(string); stated && path != "" {
			dirs[id] = strings.TrimRight(path, "/")
			continue
		}
		dirs[id] = dataRoot(with) + "/" + m.Module + "/" + id
	}
	return dirs
}

// dirInto places a resource: a pathless directory is given the path the mesh resolved for it,
// and every ${dir:…} the resource carries — in its path, its content, its mounts, its
// environment and its env-files — becomes that path.
//
// A reference naming no directory of this module is refused. Left as written, the literal
// `${dir:x}` would reach the machine as a path, and the runtime would create and mount a
// directory called `${dir:x}` — real, wrong, and named after the mistake.
func dirInto(resource map[string]any, dirs map[string]string, module string) error {
	fill := func(s string) (string, error) {
		var missing error
		out := dirRef.ReplaceAllStringFunc(s, func(ref string) string {
			id := dirRef.FindStringSubmatch(ref)[1]
			path, has := dirs[id]
			if !has {
				missing = fmt.Errorf(
					"%s says ${dir:%s}, and %s declares no directory %q. It declares %s",
					module, id, module, id, orNothing(namesOfDirs(dirs)))
				return ref
			}
			return path
		})
		return out, missing
	}

	if fmt.Sprint(resource["type"]) == "directory" {
		id := fmt.Sprint(resource["id"])
		if path, stated := resource["path"].(string); !stated || path == "" {
			resource["path"] = dirs[id]
		}
	}

	var err error
	if path, ok := resource["path"].(string); ok {
		if resource["path"], err = fill(path); err != nil {
			return err
		}
	}
	if content, ok := resource["content"].(string); ok {
		if resource["content"], err = fill(content); err != nil {
			return err
		}
	}
	// Nested values are rebuilt, never written into: the resource is a shallow copy of the
	// manifest's own map, and the manifest is composed once per node — a fill written in place
	// would leave the first node's paths inside every later composition.
	if volumes, ok := resource["volumes"].([]any); ok {
		filled := make([]any, len(volumes))
		for i, v := range volumes {
			filled[i] = v
			if mount, ok := v.(string); ok {
				if filled[i], err = fill(mount); err != nil {
					return err
				}
			}
		}
		resource["volumes"] = filled
	}
	if env, ok := resource["env"].(map[string]any); ok {
		filled := make(map[string]any, len(env))
		for key, v := range env {
			filled[key] = v
			if value, ok := v.(string); ok {
				if filled[key], err = fill(value); err != nil {
					return err
				}
			}
		}
		resource["env"] = filled
	}
	if files, ok := resource["env-file"].([]any); ok {
		filled := make([]any, len(files))
		for i, v := range files {
			filled[i] = v
			if path, ok := v.(string); ok {
				if filled[i], err = fill(path); err != nil {
					return err
				}
			}
		}
		resource["env-file"] = filled
	}
	return nil
}

// unknownDirRefs is every ${dir:…} in the definition that names no directory the definition
// declares — refused where the author is, not at composition on some later day (the same
// near-versus-far reasoning as the host's strict parse).
func (m Manifest) unknownDirRefs() []string {
	declared := map[string]bool{}
	for _, r := range m.Resources {
		if fmt.Sprint(r["type"]) == "directory" {
			declared[fmt.Sprint(r["id"])] = true
		}
	}
	referenced := func(s string) []string {
		var ids []string
		for _, match := range dirRef.FindAllStringSubmatch(s, -1) {
			ids = append(ids, match[1])
		}
		return ids
	}
	var problems []string
	seen := map[string]bool{}
	refuse := func(id string, where any) {
		if declared[id] || seen[id] {
			return
		}
		seen[id] = true
		problems = append(problems, fmt.Sprintf(
			"%s says ${dir:%s} in %v, and declares no directory %q — a reference the mesh "+
				"cannot place would reach the machine as a literal path",
			m.Module, id, where, id))
	}
	for _, r := range m.Resources {
		for _, field := range []string{"path", "content"} {
			if s, ok := r[field].(string); ok {
				for _, id := range referenced(s) {
					refuse(id, r["id"])
				}
			}
		}
		for _, field := range []string{"volumes", "env-file"} {
			if list, ok := r[field].([]any); ok {
				for _, v := range list {
					if s, ok := v.(string); ok {
						for _, id := range referenced(s) {
							refuse(id, r["id"])
						}
					}
				}
			}
		}
		if env, ok := r["env"].(map[string]any); ok {
			for _, v := range env {
				if s, ok := v.(string); ok {
					for _, id := range referenced(s) {
						refuse(id, r["id"])
					}
				}
			}
		}
	}
	sort.Strings(problems)
	return problems
}

func namesOfDirs(dirs map[string]string) []string {
	var names []string
	for id := range dirs {
		names = append(names, fmt.Sprintf("%q", id))
	}
	sort.Strings(names)
	return names
}