Add helm local repositories (#140)

In-house charts have nowhere to publish: a helm local stores uploads but serves no index.yaml, and the helm virtual merger drops every chart field except name/version/urls.

- add helm local uploads (`PUT .../files/<name>-<version>.tgz`) recording each Chart.yaml in a new `helm_metadata` table; mismatched filenames stay out of the index
- bound chart parsing (50MiB decompressed, 10k entries, 1MiB Chart.yaml)
- generate a deterministic `index.yaml` with sha256 digests and path-escaped relative urls
- keep all chart fields when merging helm virtual indexes, expanding YAML aliases
- add a real-helm e2e-docker test, UI snippet and README section

Reviewed-on: #140
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

internal/virtual/helm_merger.go

@@ -2,10 +2,14 @@ package virtual
 
 import (
 	"fmt"
+	"log/slog"
+	"maps"
+	"slices"
 	"strings"
 
 	"gopkg.in/yaml.v3"
 
+	"git.unkin.net/unkin/artifactapi/internal/provider"
 	"git.unkin.net/unkin/artifactapi/pkg/models"
 )
 
@@ -16,22 +20,17 @@ func init() {
 type HelmMerger struct{}
 
 type helmIndex struct {
-	APIVersion string                        `yaml:"apiVersion"`
-	Entries    map[string][]helmChartVersion `yaml:"entries"`
-	Generated  string                        `yaml:"generated,omitempty"`
-}
-
-type helmChartVersion struct {
-	Name    string   `yaml:"name"`
-	Version string   `yaml:"version"`
-	URLs    []string `yaml:"urls"`
-	rest    map[string]any
+	APIVersion string                            `yaml:"apiVersion"`
+	Entries    map[string][]map[string]yaml.Node `yaml:"entries"`
+	Generated  string                            `yaml:"generated,omitempty"`
 }
 
+// MergeIndexes keeps each chart version's fields as raw nodes so digest,
+// apiVersion and the rest survive the merge untouched; only urls are rewritten.
 func (m *HelmMerger) MergeIndexes(members []MemberIndex, proxyBaseURL string) ([]byte, error) {
 	merged := &helmIndex{
 		APIVersion: "v1",
-		Entries:    make(map[string][]helmChartVersion),
+		Entries:    make(map[string][]map[string]yaml.Node),
 	}
 
 	seen := map[string]map[string]bool{}
@@ -42,47 +41,38 @@ func (m *HelmMerger) MergeIndexes(members []MemberIndex, proxyBaseURL string) ([
 			continue
 		}
 
-		for chart, versions := range idx.Entries {
+		budget := provider.MaxAliasExpandedNodes
+		for _, chart := range slices.Sorted(maps.Keys(idx.Entries)) {
+			versions := idx.Entries[chart]
 			if seen[chart] == nil {
 				seen[chart] = map[string]bool{}
 			}
-			for _, ver := range versions {
-				key := chart + ":" + ver.Version
-				if seen[chart][ver.Version] {
+			for _, raw := range versions {
+				ver, err := provider.ExpandYAMLAliases(raw, &budget)
+				if err != nil {
+					slog.Warn("helm merge: dropping chart entry", "member", member.RemoteName, "chart", chart, "error", err)
 					continue
 				}
-				seen[chart][ver.Version] = true
+				version := ver["version"].Value
+				if seen[chart][version] {
+					continue
+				}
+				seen[chart][version] = true
 
-				if proxyBaseURL != "" {
-					routePrefix := "remote"
-					if member.RepoType == "local" {
-						routePrefix = "local"
+				if urlsNode, ok := ver["urls"]; ok && proxyBaseURL != "" {
+					var urls []string
+					if err := urlsNode.Decode(&urls); err != nil {
+						continue
 					}
-					baseHost := extractHost(member.BaseURL)
-
-					for i, u := range ver.URLs {
-						if strings.HasPrefix(u, "http://") || strings.HasPrefix(u, "https://") {
-							if baseHost != "" && extractHost(u) != baseHost {
-								continue
-							}
-							relPath := extractPathRelativeToBase(u, member.BaseURL)
-							ver.URLs[i] = fmt.Sprintf("%s/api/v1/%s/%s/%s",
-								strings.TrimRight(proxyBaseURL, "/"),
-								routePrefix,
-								member.RemoteName,
-								relPath)
-						} else {
-							ver.URLs[i] = fmt.Sprintf("%s/api/v1/%s/%s/%s",
-								strings.TrimRight(proxyBaseURL, "/"),
-								routePrefix,
-								member.RemoteName,
-								u)
-						}
+					rewriteHelmURLs(urls, member, proxyBaseURL)
+					var n yaml.Node
+					if err := n.Encode(urls); err != nil {
+						return nil, err
 					}
+					ver["urls"] = n
 				}
 
 				merged.Entries[chart] = append(merged.Entries[chart], ver)
-				_ = key
 			}
 		}
 	}
@@ -90,6 +80,34 @@ func (m *HelmMerger) MergeIndexes(members []MemberIndex, proxyBaseURL string) ([
 	return yaml.Marshal(merged)
 }
 
+func rewriteHelmURLs(urls []string, member MemberIndex, proxyBaseURL string) {
+	routePrefix := "remote"
+	if member.RepoType == "local" {
+		routePrefix = "local"
+	}
+	baseHost := extractHost(member.BaseURL)
+
+	for i, u := range urls {
+		if strings.HasPrefix(u, "http://") || strings.HasPrefix(u, "https://") {
+			if baseHost != "" && extractHost(u) != baseHost {
+				continue
+			}
+			relPath := extractPathRelativeToBase(u, member.BaseURL)
+			urls[i] = fmt.Sprintf("%s/api/v1/%s/%s/%s",
+				strings.TrimRight(proxyBaseURL, "/"),
+				routePrefix,
+				member.RemoteName,
+				relPath)
+		} else {
+			urls[i] = fmt.Sprintf("%s/api/v1/%s/%s/%s",
+				strings.TrimRight(proxyBaseURL, "/"),
+				routePrefix,
+				member.RemoteName,
+				u)
+		}
+	}
+}
+
 func extractHost(rawURL string) string {
 	idx := strings.Index(rawURL, "://")
 	if idx == -1 {

internal/virtual/helm_merger_test.go

@@ -1,9 +1,12 @@
 package virtual_test
 
 import (
+	"fmt"
 	"strings"
 	"testing"
 
+	"gopkg.in/yaml.v3"
+
 	"git.unkin.net/unkin/artifactapi/internal/virtual"
 )
 
@@ -122,3 +125,129 @@ entries:
 		t.Error("expected fallback repo to be excluded for duplicate")
 	}
 }
+
+func TestHelmMerger_PreservesChartFields(t *testing.T) {
+	m := &virtual.HelmMerger{}
+	body := []byte(`apiVersion: v1
+entries:
+  app:
+    - apiVersion: v2
+      name: app
+      version: "1.0"
+      appVersion: "3.1"
+      description: in-house
+      digest: deadbeef
+      urls:
+        - app-1.0.tgz
+`)
+	result, err := m.MergeIndexes([]virtual.MemberIndex{{RemoteName: "charts", RepoType: "local", Body: body}}, "https://proxy.example.com")
+	if err != nil {
+		t.Fatal(err)
+	}
+	out := string(result)
+	for _, want := range []string{
+		"digest: deadbeef",
+		"apiVersion: v2",
+		`appVersion: "3.1"`,
+		"description: in-house",
+		`version: "1.0"`,
+		"https://proxy.example.com/api/v1/local/charts/app-1.0.tgz",
+	} {
+		if !strings.Contains(out, want) {
+			t.Errorf("merged index missing %q:\n%s", want, out)
+		}
+	}
+}
+
+func TestHelmMerger_ExpandsAliasesAcrossDedupe(t *testing.T) {
+	m := &virtual.HelmMerger{}
+	first := []byte(`apiVersion: v1
+entries:
+  app:
+    - version: "1.0"
+      urls: [app-1.0.tgz]
+`)
+	second := []byte(`apiVersion: v1
+entries:
+  app:
+    - version: "1.0"
+      maintainers: &team
+        - name: ops
+      urls: [app-1.0.tgz]
+    - version: "2.0"
+      maintainers: *team
+      urls: [app-2.0.tgz]
+`)
+	result, err := m.MergeIndexes([]virtual.MemberIndex{
+		{RemoteName: "a", RepoType: "local", Body: first},
+		{RemoteName: "b", RepoType: "local", Body: second},
+	}, "https://proxy.example.com")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var idx struct {
+		Entries map[string][]struct {
+			Version     string `yaml:"version"`
+			Maintainers []struct {
+				Name string `yaml:"name"`
+			} `yaml:"maintainers"`
+		} `yaml:"entries"`
+	}
+	if err := yaml.Unmarshal(result, &idx); err != nil {
+		t.Fatalf("merged index does not parse: %v\n%s", err, result)
+	}
+	app := idx.Entries["app"]
+	if len(app) != 2 || app[1].Version != "2.0" || len(app[1].Maintainers) != 1 || app[1].Maintainers[0].Name != "ops" {
+		t.Errorf("alias not expanded: %+v\n%s", app, result)
+	}
+}
+
+func TestHelmMerger_DropsAliasBomb(t *testing.T) {
+	m := &virtual.HelmMerger{}
+	body := []byte(`apiVersion: v1
+entries:
+  app:
+    - version: "1.0"
+      a: &a [x, x, x, x, x, x, x, x, x, x]
+      b: &b [*a, *a, *a, *a, *a, *a, *a, *a, *a, *a]
+      c: &c [*b, *b, *b, *b, *b, *b, *b, *b, *b, *b]
+      d: &d [*c, *c, *c, *c, *c, *c, *c, *c, *c, *c]
+      e: &e [*d, *d, *d, *d, *d, *d, *d, *d, *d, *d]
+      urls: [app-1.0.tgz]
+`)
+	result, err := m.MergeIndexes([]virtual.MemberIndex{{RemoteName: "a", RepoType: "local", Body: body}}, "https://proxy.example.com")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(string(result), "app-1.0.tgz") {
+		t.Errorf("alias bomb entry was kept")
+	}
+}
+
+func TestHelmMerger_LargeIndexWithoutAliasesIsComplete(t *testing.T) {
+	var b strings.Builder
+	b.WriteString("apiVersion: v1\nentries:\n")
+	for c := 0; c < 100; c++ {
+		fmt.Fprintf(&b, "  chart%d:\n", c)
+		for v := 0; v < 100; v++ {
+			fmt.Fprintf(&b, "    - name: chart%d\n      version: \"1.0.%d\"\n      description: d\n      maintainers: [{name: ops, email: ops@example.com}]\n      urls: [chart%d-1.0.%d.tgz]\n", c, v, c, v)
+		}
+	}
+	result, err := (&virtual.HelmMerger{}).MergeIndexes([]virtual.MemberIndex{{RemoteName: "a", RepoType: "local", Body: []byte(b.String())}}, "https://proxy.example.com")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var idx struct {
+		Entries map[string][]map[string]any `yaml:"entries"`
+	}
+	if err := yaml.Unmarshal(result, &idx); err != nil {
+		t.Fatal(err)
+	}
+	total := 0
+	for _, vs := range idx.Entries {
+		total += len(vs)
+	}
+	if len(idx.Entries) != 100 || total != 10000 {
+		t.Errorf("got %d charts, %d versions; want 100, 10000", len(idx.Entries), total)
+	}
+}