Files
mesh-controller/internal/catalogue/template.go
T

275 lines
10 KiB
Go

package catalogue
import (
"encoding/json"
"errors"
"fmt"
"io/fs"
"os"
"path"
"path/filepath"
"sort"
"strings"
"unicode/utf8"
)
// A file's text kept as a template file in its module's repository (novox/hq ADR 0349 §2, design 57 package T1,
// issue 654).
//
// **Two forms, one composition.** A file resource says its text inline (`content`) or names a template file
// beside its manifest (`"template": "files/<name>"`), never both. The module's build packs `files/` into an
// archive artifact of its own — an `archive` artifact built `from: "files"` — and resolving the build reads each
// template's text back from that packed archive into `content` and drops `template`. So the manifest the mesh
// holds, composition and the node-engine are exactly as they were: a module with its text in `files/` composes
// byte-identically to the same module with it inline. Where there is no build — `module check`, the merge gate,
// `module add` — the text is read from the repository tree beside the manifest (WithTemplatesFrom).
//
// **Read back by the builder, carried in the resolved manifest.** The builder reads each template from the very
// bytes it hashed into the archive's digest, so the text the mesh holds is the archive's. The controller
// registers the resolved manifest as the build result carries it and fetches nothing from the artifact store; a
// manifest that still names a template when it would be held — built by a builder that predates templates — is
// refused at registration (HeldTemplateProblem).
// TemplateField is the key a file resource names its template file by.
const TemplateField = "template"
// TemplatesDir is the module's directory its template files are kept in, and the directory its templates archive
// is built from.
const TemplatesDir = "files"
// Templated is whether any of the manifest's resources names a template.
func (m Manifest) Templated() bool {
for _, r := range m.Resources {
if _, has := r[TemplateField]; has {
return true
}
}
return false
}
// TemplatesArtifact is the name of the archive artifact the module packs its templates into — the one built from
// files/ — or "" when it declares none, or more than one (both refused by templateProblems for a module naming a
// template).
func TemplatesArtifact(m Manifest) string {
found := templatesArtifacts(m)
if len(found) != 1 {
return ""
}
return found[0]
}
func templatesArtifacts(m Manifest) []string {
if m.Build == nil {
return nil
}
var found []string
for _, a := range m.Build.Artifacts {
if a.Kind == ArtifactArchive && a.URL == "" && cleanFrom(a.From) == TemplatesDir {
found = append(found, a.Name)
}
}
return found
}
// cleanFrom is an artifact's directory as one relative path: "./files/" is "files".
func cleanFrom(from string) string {
c := path.Clean(strings.TrimSpace(from))
return strings.TrimPrefix(c, "./")
}
// templateOf is the template a resource names, whether it names one, and what is wrong with it ("" when nothing).
func templateOf(module string, r map[string]any) (string, bool, string) {
raw, has := r[TemplateField]
if !has {
return "", false, ""
}
id := fmt.Sprint(r["id"])
if t := fmt.Sprint(r["type"]); t != "file" {
return "", true, fmt.Sprintf("%s: %s is a %s and names a template; only a file takes its text from one "+
"(novox/hq ADR 0349 §2)", module, id, t)
}
name, ok := raw.(string)
if !ok || strings.TrimSpace(name) == "" {
return "", true, fmt.Sprintf("%s: %s names a template that is not a path: %v; a template is %q",
module, id, raw, TemplatesDir+"/<name>")
}
if _, both := r["content"]; both {
return name, true, fmt.Sprintf("%s: %s names the template %q and says its content too; a file's text is "+
"in one place, the template or the content, never both (novox/hq ADR 0349 §2)", module, id, name)
}
if strings.HasPrefix(name, "/") || path.Clean(name) != name || !strings.HasPrefix(name, TemplatesDir+"/") ||
strings.Contains(name, "\\") {
return name, true, fmt.Sprintf("%s: %s names the template %q, which is not a file under %s/ of its own "+
"repository: a template is %q, a plain relative path, and the build packs only %s/",
module, id, name, TemplatesDir, TemplatesDir+"/<name>", TemplatesDir)
}
return name, true, ""
}
// templateProblems is what is wrong with the manifest's templates, as written: a template on something not a file,
// beside content, outside files/, or a module naming templates whose build packs no archive from files/. Whether
// each template exists is judged where a tree is (ReadTemplates) or the archive's text is (Resolve).
func templateProblems(m Manifest) []string {
var problems []string
templated := false
for _, r := range m.Resources {
_, has, wrong := templateOf(m.Module, r)
templated = templated || has
if wrong != "" {
problems = append(problems, wrong)
}
}
if !templated {
return problems
}
switch found := templatesArtifacts(m); len(found) {
case 0:
problems = append(problems, fmt.Sprintf("%s names templates and its build packs no archive from %s/: "+
"declare an artifact {\"name\": \"files\", \"kind\": \"archive\", \"from\": %q} (novox/hq ADR 0349 §2)",
m.Module, TemplatesDir, TemplatesDir))
case 1:
default:
sort.Strings(found)
problems = append(problems, fmt.Sprintf("%s packs %s/ into %s; its templates are read from one archive",
m.Module, TemplatesDir, strings.Join(found, " and ")))
}
return problems
}
// fillTemplates is resources with each template's text as its content and the template key dropped: text says the
// text of a template by its path ("files/<name>"), and whether it has one. A template it has no text for, or text
// that is not UTF-8, is refused by name. Every resource is copied; the manifest's own are left as they were.
func fillTemplates(module string, resources []map[string]any, text func(string) (string, bool),
where string) ([]map[string]any, error) {
out := make([]map[string]any, 0, len(resources))
var problems []string
for _, r := range resources {
name, has, wrong := templateOf(module, r)
if !has {
out = append(out, r)
continue
}
if wrong != "" {
problems = append(problems, wrong)
continue
}
body, ok := text(name)
if !ok {
problems = append(problems, fmt.Sprintf("%s: %v names the template %q, and %s holds no such file",
module, r["id"], name, where))
continue
}
if !utf8.ValidString(body) {
// A manifest is JSON: text that is not UTF-8 would be changed on the way, silently.
problems = append(problems, fmt.Sprintf("%s: %v names the template %q, which is not UTF-8 text; a "+
"file's text is carried as JSON and would not reach the machine as written", module, r["id"], name))
continue
}
filled := make(map[string]any, len(r))
for k, v := range r {
filled[k] = v
}
delete(filled, TemplateField)
filled["content"] = body
out = append(out, filled)
}
if len(problems) > 0 {
return nil, errors.New(strings.Join(problems, "; "))
}
return out, nil
}
// ReadTemplates is the text of each template the manifest names, read from the module's directory in a repository
// tree, by template path. A missing template, or one that is not a plain file (a symlink is refused by the build's
// packing too), is refused by name.
func ReadTemplates(m Manifest, dir string) (map[string]string, error) {
texts := map[string]string{}
var problems []string
for _, r := range m.Resources {
name, has, wrong := templateOf(m.Module, r)
if !has {
continue
}
if wrong != "" {
problems = append(problems, wrong)
continue
}
if _, read := texts[name]; read {
continue
}
full := filepath.Join(dir, filepath.FromSlash(name))
info, err := os.Lstat(full)
switch {
case errors.Is(err, fs.ErrNotExist):
problems = append(problems, fmt.Sprintf("%s: %v names the template %q, and the module's directory "+
"has no such file", m.Module, r["id"], name))
continue
case err != nil:
problems = append(problems, fmt.Sprintf("%s: %v names the template %q, which cannot be read: %v",
m.Module, r["id"], name, err))
continue
case !info.Mode().IsRegular():
problems = append(problems, fmt.Sprintf("%s: %v names the template %q, which is not a plain file; "+
"the build packs only files", m.Module, r["id"], name))
continue
}
body, err := os.ReadFile(full)
if err != nil {
problems = append(problems, fmt.Sprintf("%s: %v names the template %q, which cannot be read: %v",
m.Module, r["id"], name, err))
continue
}
texts[name] = string(body)
}
if len(problems) > 0 {
return nil, errors.New(strings.Join(problems, "; "))
}
return texts, nil
}
// WithTemplatesFrom is the manifest with each template's text read from the module's directory in a repository
// tree as its content: what `module check`, the merge gate and `module add` judge, where nothing was built. Read
// again strictly afterwards, so every rule about a file's text judges the template's text exactly as it judges
// inline content. A manifest naming no template is returned as it is.
func WithTemplatesFrom(m Manifest, dir string) (Manifest, error) {
if !m.Templated() {
return m, nil
}
texts, err := ReadTemplates(m, dir)
if err != nil {
return Manifest{}, err
}
filled, err := fillTemplates(m.Module, m.Resources, func(name string) (string, bool) {
t, ok := texts[name]
return t, ok
}, "the module's directory")
if err != nil {
return Manifest{}, err
}
out := m
out.Resources = filled
raw, err := json.Marshal(out)
if err != nil {
return Manifest{}, err
}
return ParseManifest(raw)
}
// HeldTemplateProblem is why a manifest cannot be held by the mesh because it still names a template, or "": the
// manifest the mesh holds carries every file's text, which a build reads back from its templates archive. One
// naming a template was resolved by a builder that does not read templates, and would compose files with no text.
func HeldTemplateProblem(m Manifest) string {
var named []string
for _, r := range m.Resources {
if t, has := r[TemplateField]; has {
named = append(named, fmt.Sprintf("%v (%v)", r["id"], t))
}
}
if len(named) == 0 {
return ""
}
return fmt.Sprintf("%s still names the template(s) of %s: the manifest the mesh holds carries each file's "+
"text, read back from the build's templates archive — this one was resolved by a builder that does not "+
"read templates, or not built at all (novox/hq ADR 0349 §2)", m.Module, strings.Join(named, ", "))
}