feat(domains): 301-Weiterleitung Domain→Domain (redirect_to) — v1.2.108

Neue Domain kann per 301 auf eine andere Domain/URL umgeleitet werden, statt
auf ein Backend zu routen (Use-Case: kvs.netcell-it.de → https://zkm.netcell-it.de,
inkl. HTTPS). Variante (a): immer auf Ziel-Root (`redirect location`), pfad-
unabhängig.

- Migration 0043: domains.redirect_to text NOT NULL DEFAULT ''
- Model + domains-Service (SELECT/INSERT/UPDATE/scan)
- HAProxy-Generator: buildRedirectTo() sanitisiert (nur http(s), kein
  Whitespace/Quotes → sonst kein Redirect statt kaputter Config); Template
  emittiert `http-request redirect location <url> code 301 if hdr(host)`.
  Terminiert vor use_backend → Redirect-Domain routet auf kein Backend.
  http→https läuft über den vorhandenen :80-Redirect (zwei Hops, inkl. TLS).
- UI: Feld „Weiterleitung (301) nach" im Domain-Formular (de/en)
- Tests: Render-Zeile + buildRedirectTo-Sanitisierung

Hinweis: Die Redirect-Domain braucht weiterhin ein eigenes TLS-Zert (ACME).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

VERSION

@@ -1 +1 @@
-1.2.107
+1.2.108

internal/database/migrations/0043_domains_redirect_to.sql

@@ -0,0 +1,8 @@
+-- +goose Up
+-- redirect_to: wenn gesetzt, liefert HAProxy für diese Domain einen 301 auf
+-- die angegebene Ziel-URL (Domain-zu-Domain-Weiterleitung) statt sie auf ein
+-- Backend zu routen. Leerstring = keine Weiterleitung (Normalbetrieb).
+ALTER TABLE domains ADD COLUMN IF NOT EXISTS redirect_to text NOT NULL DEFAULT '';
+
+-- +goose Down
+ALTER TABLE domains DROP COLUMN IF EXISTS redirect_to;

internal/haproxy/haproxy.cfg.tpl

@@ -113,6 +113,11 @@ frontend public_https
     # www-Redirect: {{$d.RedirectFromHost}} → {{$d.Name}}
     http-request redirect prefix https://{{$d.Name}} code 301 if { hdr(host) -i {{$d.RedirectFromHost}} }
     {{- end}}
+    {{- if $d.RedirectTo}}
+    # Domain-Redirect (301): {{$d.Name}} → {{$d.RedirectTo}} (immer auf Ziel-Root,
+    # terminiert vor use_backend → diese Domain routet auf kein Backend).
+    http-request redirect location {{$d.RedirectTo}} code 301 if { hdr(host) -i {{$d.Name}} }
+    {{- end}}
     {{- if $d.MaintenanceMode}}
     # Wartungs-Modus für {{$d.Name}} — alle Requests werden mit 503 beantwortet.
     http-request return status 503 content-type "text/plain; charset=utf-8" string "{{$d.MaintMessage}}" if { hdr(host) -i {{$d.Name}} }

internal/haproxy/haproxy.go

@@ -212,6 +212,11 @@ type DomainView struct {
 	//   to-www    → Name="www.example.com" → "example.com" (strip www.-Prefix)
 	RedirectFromHost string
 
+	// RedirectTo: HAProxy-safe 301-Ziel-URL für eine Domain→Domain-Weiterleitung
+	// (z. B. "https://zkm.netcell-it.de"). Leer = kein Redirect. Schattet das
+	// gleichnamige Feld aus dem eingebetteten models.Domain (sanitisiert).
+	RedirectTo string
+
 	// ResponseHeaders: Custom-Headers die HAProxy auf jede Response für
 	// diese Domain setzt. Werte sind bereits HAProxy-safe escaped
 	// (Quotes → ', Newlines → Space).
@@ -313,6 +318,7 @@ func (g *Generator) loadView(ctx context.Context) (*View, error) {
 			HSTSHeader:       buildHSTSHeader(d),
 			MaintMessage:     buildMaintMessage(d),
 			RedirectFromHost: buildRedirectFromHost(d),
+			RedirectTo:       buildRedirectTo(d),
 			ResponseHeaders:  headersByDomain[d.ID],
 		}
 		if d.MaxBodyKB > 0 {
@@ -429,3 +435,23 @@ func buildRedirectFromHost(d models.Domain) string {
 		return ""
 	}
 }
+
+// buildRedirectTo liefert die 301-Ziel-URL HAProxy-safe, oder "" wenn kein
+// Redirect gesetzt ist bzw. die URL ungültig erscheint. Defensiv: nur
+// http(s)-URLs ohne Whitespace/Steuerzeichen/Quotes — sonst würde die
+// `redirect location <url>`-Zeile die HAProxy-Config sprengen. Im Zweifel
+// lieber KEIN Redirect rendern als eine kaputte Config auszuliefern.
+func buildRedirectTo(d models.Domain) string {
+	u := strings.TrimSpace(d.RedirectTo)
+	if u == "" {
+		return ""
+	}
+	lower := strings.ToLower(u)
+	if !strings.HasPrefix(lower, "http://") && !strings.HasPrefix(lower, "https://") {
+		return ""
+	}
+	if strings.ContainsAny(u, " \t\r\n\"'`\\{}") {
+		return ""
+	}
+	return u
+}

internal/haproxy/haproxy_test.go

@@ -170,6 +170,45 @@ func TestRender_WWWRedirectToWWW(t *testing.T) {
 	}
 }
 
+func TestRender_RedirectTo(t *testing.T) {
+	v := View{
+		Domains: []DomainView{
+			{
+				Domain: models.Domain{
+					ID: 1, Name: "kvs.netcell-it.de", Active: true,
+					RedirectTo: "https://zkm.netcell-it.de",
+				},
+				RedirectTo: "https://zkm.netcell-it.de",
+			},
+		},
+	}
+	out := renderView(t, v)
+	want := `http-request redirect location https://zkm.netcell-it.de code 301 if { hdr(host) -i kvs.netcell-it.de }`
+	if !strings.Contains(out, want) {
+		t.Errorf("missing domain→domain 301 redirect line:\n%s", out)
+	}
+}
+
+func TestBuildRedirectTo(t *testing.T) {
+	cases := []struct{ in, want string }{
+		{"https://zkm.netcell-it.de", "https://zkm.netcell-it.de"},
+		{"  https://zkm.netcell-it.de  ", "https://zkm.netcell-it.de"}, // getrimmt
+		{"http://x.de", "http://x.de"},
+		{"", ""},
+		{"zkm.netcell-it.de", ""},           // kein Schema
+		{"ftp://x.de", ""},                  // falsches Schema
+		{"https://x .de", ""},               // Whitespace → unsafe
+		{"https://x\"de", ""},               // Quote → unsafe
+		{"javascript:alert(1)", ""},         // kein http(s)
+	}
+	for _, c := range cases {
+		got := buildRedirectTo(models.Domain{RedirectTo: c.in})
+		if got != c.want {
+			t.Errorf("buildRedirectTo(%q) = %q, want %q", c.in, got, c.want)
+		}
+	}
+}
+
 func TestBuildHSTSHeader(t *testing.T) {
 	cases := []struct {
 		name string

internal/models/domain.go

@@ -19,6 +19,7 @@ type Domain struct {
 	MaxBodyKB          int       `gorm:"column:max_body_kb"          json:"max_body_kb"`
 	DisableH3          bool      `gorm:"column:disable_h3"           json:"disable_h3"`
 	Notes              *string   `gorm:"column:notes"                json:"notes,omitempty"`
+	RedirectTo         string    `gorm:"column:redirect_to"          json:"redirect_to"` // ""=aus; sonst 301-Ziel-URL (Domain→Domain)
 	CreatedAt          time.Time `gorm:"column:created_at"           json:"created_at"`
 	UpdatedAt          time.Time `gorm:"column:updated_at"           json:"updated_at"`
 }

internal/services/domains/domains.go

@@ -24,7 +24,7 @@ SELECT id, name, active, primary_backend_id, http_to_https,
        hsts_enabled, hsts_max_age, hsts_subdomains, hsts_preload,
        maintenance_mode, maintenance_message, www_redirect,
        rate_limit_rps, max_body_kb, disable_h3,
-       notes, created_at, updated_at
+       notes, redirect_to, created_at, updated_at
 FROM domains
 `
 
@@ -65,17 +65,17 @@ func (r *Repo) Create(ctx context.Context, d models.Domain) (*models.Domain, err
 INSERT INTO domains (name, active, primary_backend_id, http_to_https,
                      hsts_enabled, hsts_max_age, hsts_subdomains, hsts_preload,
                      maintenance_mode, maintenance_message, www_redirect,
-                     rate_limit_rps, max_body_kb, disable_h3, notes)
+                     rate_limit_rps, max_body_kb, disable_h3, notes, redirect_to)
-VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15)
+VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16)
 RETURNING id, name, active, primary_backend_id, http_to_https,
           hsts_enabled, hsts_max_age, hsts_subdomains, hsts_preload,
           maintenance_mode, maintenance_message, www_redirect,
           rate_limit_rps, max_body_kb, disable_h3,
-          notes, created_at, updated_at`,
+          notes, redirect_to, created_at, updated_at`,
 		d.Name, d.Active, d.PrimaryBackendID, d.HTTPToHTTPS,
 		d.HSTSEnabled, d.HSTSMaxAge, d.HSTSSubdomains, d.HSTSPreload,
 		d.MaintenanceMode, d.MaintenanceMessage, d.WWWRedirect,
-		d.RateLimitRPS, d.MaxBodyKB, d.DisableH3, d.Notes)
+		d.RateLimitRPS, d.MaxBodyKB, d.DisableH3, d.Notes, d.RedirectTo)
 	return scanDomain(row)
 }
 
@@ -100,17 +100,18 @@ UPDATE domains SET
    max_body_kb = $13,
    disable_h3 = $14,
    notes = $15,
+   redirect_to = $16,
    updated_at = NOW()
-WHERE id = $16
+WHERE id = $17
 RETURNING id, name, active, primary_backend_id, http_to_https,
           hsts_enabled, hsts_max_age, hsts_subdomains, hsts_preload,
           maintenance_mode, maintenance_message, www_redirect,
           rate_limit_rps, max_body_kb, disable_h3,
-          notes, created_at, updated_at`,
+          notes, redirect_to, created_at, updated_at`,
 		d.Name, d.Active, d.PrimaryBackendID, d.HTTPToHTTPS,
 		d.HSTSEnabled, d.HSTSMaxAge, d.HSTSSubdomains, d.HSTSPreload,
 		d.MaintenanceMode, d.MaintenanceMessage, d.WWWRedirect,
-		d.RateLimitRPS, d.MaxBodyKB, d.DisableH3, d.Notes, id)
+		d.RateLimitRPS, d.MaxBodyKB, d.DisableH3, d.Notes, d.RedirectTo, id)
 	out, err := scanDomain(row)
 	if err != nil {
 		if errors.Is(err, pgx.ErrNoRows) {
@@ -139,7 +140,7 @@ func scanDomain(row interface{ Scan(...any) error }) (*models.Domain, error) {
 		&d.HSTSEnabled, &d.HSTSMaxAge, &d.HSTSSubdomains, &d.HSTSPreload,
 		&d.MaintenanceMode, &d.MaintenanceMessage, &d.WWWRedirect,
 		&d.RateLimitRPS, &d.MaxBodyKB, &d.DisableH3,
-		&d.Notes, &d.CreatedAt, &d.UpdatedAt,
+		&d.Notes, &d.RedirectTo, &d.CreatedAt, &d.UpdatedAt,
 	); err != nil {
 		return nil, err
 	}

management-ui/src/i18n/locales/de/common.json

@@ -533,6 +533,8 @@
     "wwwRedirectNone": "Kein Redirect",
     "wwwRedirectToNaked": "→ naked (ohne www)",
     "wwwRedirectToWWW": "→ www",
+    "redirectTo": "Weiterleitung (301) nach",
+    "redirectToHint": "Leitet ALLE Anfragen dieser Domain per 301 auf die Ziel-URL um (z. B. https://zkm.netcell-it.de) — immer auf die Ziel-Root. Ist es gesetzt, routet die Domain auf kein Backend. Die Domain braucht trotzdem ein eigenes TLS-Zertifikat. Leer = aus.",
     "rateLimit": "Rate-Limit (pro Client-IP)",
     "rateLimitHint": "Max. Requests pro Sekunde je Client-IP. HAProxy zählt über ein 10-Sekunden-Fenster pro Stick-Table (max. 100k IPs). 0 = aus.",
     "maxBody": "Max. Request-Body",

management-ui/src/i18n/locales/en/common.json

@@ -533,6 +533,8 @@
     "wwwRedirectNone": "No redirect",
     "wwwRedirectToNaked": "→ naked (no www)",
     "wwwRedirectToWWW": "→ www",
+    "redirectTo": "Redirect (301) to",
+    "redirectToHint": "Redirects ALL requests for this domain with a 301 to the target URL (e.g. https://zkm.netcell-it.de) — always to the target root. When set, the domain routes to no backend. The domain still needs its own TLS certificate. Empty = off.",
     "rateLimit": "Rate limit (per client IP)",
     "rateLimitHint": "Max requests per second per client IP. HAProxy counts over a 10-second window per stick table (max. 100k IPs). 0 = off.",
     "maxBody": "Max request body",

management-ui/src/pages/Domains/Detail.tsx

@@ -27,6 +27,7 @@ interface Domain {
   hsts_subdomains: boolean; hsts_preload: boolean
   maintenance_mode: boolean; maintenance_message?: string | null
   www_redirect: '' | 'to-naked' | 'to-www'
+  redirect_to: string
   rate_limit_rps: number; max_body_kb: number
   disable_h3: boolean
   notes?: string | null
@@ -40,6 +41,7 @@ interface DomainFormValues {
   hsts_subdomains: boolean; hsts_preload: boolean
   maintenance_mode: boolean; maintenance_message?: string
   www_redirect: '' | 'to-naked' | 'to-www'
+  redirect_to: string
   rate_limit_rps: number; max_body_kb: number
   disable_h3: boolean
   notes?: string
@@ -272,6 +274,7 @@ export default function DomainDetailPage() {
                 maintenance_mode: domain.maintenance_mode,
                 maintenance_message: domain.maintenance_message ?? '',
                 www_redirect: domain.www_redirect ?? '',
+                redirect_to: domain.redirect_to ?? '',
                 rate_limit_rps: domain.rate_limit_rps ?? 0,
                 max_body_kb: domain.max_body_kb ?? 0,
                 disable_h3: domain.disable_h3 ?? false,
@@ -333,6 +336,10 @@ export default function DomainDetailPage() {
                 ]} />
               </Form.Item>
 
+              <Form.Item label={t('domains.redirectTo')} name="redirect_to" extra={t('domains.redirectToHint')}>
+                <Input placeholder="https://ziel-domain.de" allowClear />
+              </Form.Item>
+
               <Form.Item label={t('domains.maintenance')} name="maintenance_mode" valuePropName="checked"
                 extra={t('domains.maintenanceHint')}>
                 <Switch />