fix: move writeLogsToFile doc comment to correct position

The buildRegistryAuths function was inserted between the writeLogsToFile
doc comment and the writeLogsToFile function body, causing Go to treat
the writeLogsToFile comment as part of buildRegistryAuths godoc.

Move the writeLogsToFile comment to sit directly above its function,
and keep only the buildRegistryAuths comment above buildRegistryAuths.

README.md

@@ -9,6 +9,7 @@ A simple self-hosted PaaS that auto-deploys Docker containers from Git repositor
 - Per-app UUID-based webhook URLs for Gitea integration
 - Branch filtering - only deploy on configured branch changes
 - Environment variables, labels, and volume mounts per app
+- Private Docker registry authentication for base images
 - Docker builds via socket access
 - Notifications via ntfy and Slack-compatible webhooks
 - Simple server-rendered UI with Tailwind CSS

internal/database/migrations/007_add_registry_credentials.sql

@@ -0,0 +1,11 @@
+-- Add registry credentials for private Docker registry authentication during builds
+CREATE TABLE registry_credentials (
+    id INTEGER PRIMARY KEY,
+    app_id TEXT NOT NULL REFERENCES apps(id) ON DELETE CASCADE,
+    registry TEXT NOT NULL,
+    username TEXT NOT NULL,
+    password TEXT NOT NULL,
+    UNIQUE(app_id, registry)
+);
+
+CREATE INDEX idx_registry_credentials_app_id ON registry_credentials(app_id);

internal/docker/auth_test.go

@@ -0,0 +1,96 @@
+package docker //nolint:testpackage // tests unexported buildAuthConfigs
+
+import (
+	"testing"
+)
+
+func TestBuildAuthConfigsEmpty(t *testing.T) {
+	t.Parallel()
+
+	result := buildAuthConfigs(nil)
+	if len(result) != 0 {
+		t.Errorf("expected empty map, got %d entries", len(result))
+	}
+}
+
+func TestBuildAuthConfigsSingle(t *testing.T) {
+	t.Parallel()
+
+	auths := []RegistryAuth{
+		{
+			Registry: "registry.example.com",
+			Username: "user",
+			Password: "pass",
+		},
+	}
+
+	result := buildAuthConfigs(auths)
+
+	if len(result) != 1 {
+		t.Fatalf("expected 1 entry, got %d", len(result))
+	}
+
+	cfg, ok := result["registry.example.com"]
+	if !ok {
+		t.Fatal("expected registry.example.com key")
+	}
+
+	if cfg.Username != "user" {
+		t.Errorf("expected username 'user', got %q", cfg.Username)
+	}
+
+	if cfg.Password != "pass" {
+		t.Errorf("expected password 'pass', got %q", cfg.Password)
+	}
+
+	if cfg.ServerAddress != "registry.example.com" {
+		t.Errorf("expected server address 'registry.example.com', got %q", cfg.ServerAddress)
+	}
+}
+
+func TestBuildAuthConfigsMultiple(t *testing.T) {
+	t.Parallel()
+
+	auths := []RegistryAuth{
+		{Registry: "ghcr.io", Username: "ghuser", Password: "ghtoken"},
+		{Registry: "docker.io", Username: "dkuser", Password: "dktoken"},
+	}
+
+	result := buildAuthConfigs(auths)
+
+	if len(result) != 2 {
+		t.Fatalf("expected 2 entries, got %d", len(result))
+	}
+
+	ghcr := result["ghcr.io"]
+	if ghcr.Username != "ghuser" || ghcr.Password != "ghtoken" {
+		t.Errorf("unexpected ghcr.io config: %+v", ghcr)
+	}
+
+	dkr := result["docker.io"]
+	if dkr.Username != "dkuser" || dkr.Password != "dktoken" {
+		t.Errorf("unexpected docker.io config: %+v", dkr)
+	}
+}
+
+func TestRegistryAuthStruct(t *testing.T) {
+	t.Parallel()
+
+	auth := RegistryAuth{
+		Registry: "registry.example.com",
+		Username: "testuser",
+		Password: "testpass",
+	}
+
+	if auth.Registry != "registry.example.com" {
+		t.Errorf("expected registry 'registry.example.com', got %q", auth.Registry)
+	}
+
+	if auth.Username != "testuser" {
+		t.Errorf("expected username 'testuser', got %q", auth.Username)
+	}
+
+	if auth.Password != "testpass" {
+		t.Errorf("expected password 'testpass', got %q", auth.Password)
+	}
+}

internal/docker/client.go

@@ -20,6 +20,7 @@ import (
 	"github.com/docker/docker/api/types/image"
 	"github.com/docker/docker/api/types/mount"
 	"github.com/docker/docker/api/types/network"
+	"github.com/docker/docker/api/types/registry"
 	"github.com/docker/docker/client"
 	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/go-connections/nat"
@@ -105,12 +106,20 @@ func (c *Client) IsConnected() bool {
 	return c.docker != nil
 }
 
+// RegistryAuth contains authentication credentials for a Docker registry.
+type RegistryAuth struct {
+	Registry string
+	Username string
+	Password string //nolint:gosec // credential field required for registry auth
+}
+
 // BuildImageOptions contains options for building an image.
 type BuildImageOptions struct {
 	ContextDir     string
 	DockerfilePath string
 	Tags           []string
-	LogWriter      io.Writer // Optional writer for build output
+	LogWriter      io.Writer      // Optional writer for build output
+	RegistryAuths  []RegistryAuth // Optional registry credentials for pulling private base images
 }
 
 // BuildImage builds a Docker image from a context directory.
@@ -161,6 +170,21 @@ type PortMapping struct {
 	Protocol      string // "tcp" or "udp"
 }
 
+// buildAuthConfigs converts RegistryAuth slices into Docker's AuthConfigs map.
+func buildAuthConfigs(auths []RegistryAuth) map[string]registry.AuthConfig {
+	configs := make(map[string]registry.AuthConfig, len(auths))
+
+	for _, auth := range auths {
+		configs[auth.Registry] = registry.AuthConfig{
+			Username:      auth.Username,
+			Password:      auth.Password,
+			ServerAddress: auth.Registry,
+		}
+	}
+
+	return configs
+}
+
 // buildPortConfig converts port mappings to Docker port configuration.
 func buildPortConfig(ports []PortMapping) (nat.PortSet, nat.PortMap) {
 	exposedPorts := make(nat.PortSet)
@@ -513,12 +537,18 @@ func (c *Client) performBuild(
 	}()
 
 	// Build image
-	resp, err := c.docker.ImageBuild(ctx, tarArchive, dockertypes.ImageBuildOptions{
+	buildOpts := dockertypes.ImageBuildOptions{
 		Dockerfile: opts.DockerfilePath,
 		Tags:       opts.Tags,
 		Remove:     true,
 		NoCache:    false,
-	})
+	}
+
+	if len(opts.RegistryAuths) > 0 {
+		buildOpts.AuthConfigs = buildAuthConfigs(opts.RegistryAuths)
+	}
+
+	resp, err := c.docker.ImageBuild(ctx, tarArchive, buildOpts)
 	if err != nil {
 		return "", fmt.Errorf("failed to build image: %w", err)
 	}

internal/handlers/app.go

@@ -148,6 +148,7 @@ func (h *Handlers) HandleAppDetail() http.HandlerFunc {
 		labels, _ := application.GetLabels(request.Context())
 		volumes, _ := application.GetVolumes(request.Context())
 		ports, _ := application.GetPorts(request.Context())
+		registryCreds, _ := application.GetRegistryCredentials(request.Context())
 		deployments, _ := application.GetDeployments(
 			request.Context(),
 			recentDeploymentsLimit,
@@ -163,16 +164,17 @@ func (h *Handlers) HandleAppDetail() http.HandlerFunc {
 		deployKey := formatDeployKey(application.SSHPublicKey, application.CreatedAt, application.Name)
 
 		data := h.addGlobals(map[string]any{
-			"App":              application,
+			"App":                 application,
-			"EnvVars":          envVars,
+			"EnvVars":             envVars,
-			"Labels":           labels,
+			"Labels":              labels,
-			"Volumes":          volumes,
+			"Volumes":             volumes,
-			"Ports":            ports,
+			"Ports":               ports,
-			"Deployments":      deployments,
+			"RegistryCredentials": registryCreds,
-			"LatestDeployment": latestDeployment,
+			"Deployments":         deployments,
-			"WebhookURL":       webhookURL,
+			"LatestDeployment":    latestDeployment,
-			"DeployKey":        deployKey,
+			"WebhookURL":          webhookURL,
-			"Success":          request.URL.Query().Get("success"),
+			"DeployKey":           deployKey,
+			"Success":             request.URL.Query().Get("success"),
 		}, request)
 
 		h.renderTemplate(writer, tmpl, "app_detail.html", data)
@@ -1382,3 +1384,126 @@ func formatDeployKey(pubKey string, createdAt time.Time, appName string) string
 
 	return parts[0] + " " + parts[1] + " " + comment
 }
+
+// HandleRegistryCredentialAdd handles adding a registry credential.
+func (h *Handlers) HandleRegistryCredentialAdd() http.HandlerFunc {
+	return func(writer http.ResponseWriter, request *http.Request) {
+		appID := chi.URLParam(request, "id")
+
+		application, findErr := models.FindApp(request.Context(), h.db, appID)
+		if findErr != nil || application == nil {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		parseErr := request.ParseForm()
+		if parseErr != nil {
+			http.Error(writer, "Bad Request", http.StatusBadRequest)
+
+			return
+		}
+
+		registryURL := strings.TrimSpace(request.FormValue("registry"))
+		username := strings.TrimSpace(request.FormValue("username"))
+		password := request.FormValue("password")
+
+		if registryURL == "" || username == "" || password == "" {
+			http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+
+			return
+		}
+
+		cred := models.NewRegistryCredential(h.db)
+		cred.AppID = appID
+		cred.Registry = registryURL
+		cred.Username = username
+		cred.Password = password
+
+		saveErr := cred.Save(request.Context())
+		if saveErr != nil {
+			h.log.Error("failed to save registry credential", "error", saveErr)
+		}
+
+		http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+	}
+}
+
+// HandleRegistryCredentialEdit handles editing an existing registry credential.
+func (h *Handlers) HandleRegistryCredentialEdit() http.HandlerFunc {
+	return func(writer http.ResponseWriter, request *http.Request) {
+		appID := chi.URLParam(request, "id")
+		credIDStr := chi.URLParam(request, "credID")
+
+		credID, parseErr := strconv.ParseInt(credIDStr, 10, 64)
+		if parseErr != nil {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		cred, findErr := models.FindRegistryCredential(request.Context(), h.db, credID)
+		if findErr != nil || cred == nil || cred.AppID != appID {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		formErr := request.ParseForm()
+		if formErr != nil {
+			http.Error(writer, "Bad Request", http.StatusBadRequest)
+
+			return
+		}
+
+		registryURL := strings.TrimSpace(request.FormValue("registry"))
+		username := strings.TrimSpace(request.FormValue("username"))
+		password := request.FormValue("password")
+
+		if registryURL == "" || username == "" || password == "" {
+			http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+
+			return
+		}
+
+		cred.Registry = registryURL
+		cred.Username = username
+		cred.Password = password
+
+		saveErr := cred.Save(request.Context())
+		if saveErr != nil {
+			h.log.Error("failed to update registry credential", "error", saveErr)
+		}
+
+		http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+	}
+}
+
+// HandleRegistryCredentialDelete handles deleting a registry credential.
+func (h *Handlers) HandleRegistryCredentialDelete() http.HandlerFunc {
+	return func(writer http.ResponseWriter, request *http.Request) {
+		appID := chi.URLParam(request, "id")
+		credIDStr := chi.URLParam(request, "credID")
+
+		credID, parseErr := strconv.ParseInt(credIDStr, 10, 64)
+		if parseErr != nil {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		cred, findErr := models.FindRegistryCredential(request.Context(), h.db, credID)
+		if findErr != nil || cred == nil || cred.AppID != appID {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		deleteErr := cred.Delete(request.Context())
+		if deleteErr != nil {
+			h.log.Error("failed to delete registry credential", "error", deleteErr)
+		}
+
+		http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+	}
+}

internal/models/app.go

@@ -119,6 +119,11 @@ func (a *App) GetWebhookEvents(
 	return FindWebhookEventsByAppID(ctx, a.db, a.ID, limit)
 }
 
+// GetRegistryCredentials returns all registry credentials for the app.
+func (a *App) GetRegistryCredentials(ctx context.Context) ([]*RegistryCredential, error) {
+	return FindRegistryCredentialsByAppID(ctx, a.db, a.ID)
+}
+
 func (a *App) exists(ctx context.Context) bool {
 	if a.ID == "" {
 		return false

internal/models/models_test.go

@@ -23,6 +23,7 @@ const (
 	testBranch    = "main"
 	testValue     = "value"
 	testEventType = "push"
+	testUser      = "user"
 )
 
 func setupTestDB(t *testing.T) (*database.Database, func()) {
@@ -704,6 +705,127 @@ func TestAppGetWebhookEvents(t *testing.T) {
 	assert.Len(t, events, 1)
 }
 
+// RegistryCredential Tests.
+
+func TestRegistryCredentialCreateAndFind(t *testing.T) {
+	t.Parallel()
+
+	testDB, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	app := createTestApp(t, testDB)
+
+	cred := models.NewRegistryCredential(testDB)
+	cred.AppID = app.ID
+	cred.Registry = "registry.example.com"
+	cred.Username = "myuser"
+	cred.Password = "mypassword"
+
+	err := cred.Save(context.Background())
+	require.NoError(t, err)
+	assert.NotZero(t, cred.ID)
+
+	creds, err := models.FindRegistryCredentialsByAppID(
+		context.Background(), testDB, app.ID,
+	)
+	require.NoError(t, err)
+	require.Len(t, creds, 1)
+	assert.Equal(t, "registry.example.com", creds[0].Registry)
+	assert.Equal(t, "myuser", creds[0].Username)
+	assert.Equal(t, "mypassword", creds[0].Password)
+}
+
+func TestRegistryCredentialUpdate(t *testing.T) {
+	t.Parallel()
+
+	testDB, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	app := createTestApp(t, testDB)
+
+	cred := models.NewRegistryCredential(testDB)
+	cred.AppID = app.ID
+	cred.Registry = "old.registry.com"
+	cred.Username = "olduser"
+	cred.Password = "oldpass"
+
+	err := cred.Save(context.Background())
+	require.NoError(t, err)
+
+	cred.Registry = "new.registry.com"
+	cred.Username = "newuser"
+	cred.Password = "newpass"
+
+	err = cred.Save(context.Background())
+	require.NoError(t, err)
+
+	found, err := models.FindRegistryCredential(context.Background(), testDB, cred.ID)
+	require.NoError(t, err)
+	require.NotNil(t, found)
+	assert.Equal(t, "new.registry.com", found.Registry)
+	assert.Equal(t, "newuser", found.Username)
+	assert.Equal(t, "newpass", found.Password)
+}
+
+func TestRegistryCredentialDelete(t *testing.T) {
+	t.Parallel()
+
+	testDB, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	app := createTestApp(t, testDB)
+
+	cred := models.NewRegistryCredential(testDB)
+	cred.AppID = app.ID
+	cred.Registry = "delete.registry.com"
+	cred.Username = testUser
+	cred.Password = "pass"
+
+	err := cred.Save(context.Background())
+	require.NoError(t, err)
+
+	err = cred.Delete(context.Background())
+	require.NoError(t, err)
+
+	creds, err := models.FindRegistryCredentialsByAppID(
+		context.Background(), testDB, app.ID,
+	)
+	require.NoError(t, err)
+	assert.Empty(t, creds)
+}
+
+func TestRegistryCredentialFindByIDNotFound(t *testing.T) {
+	t.Parallel()
+
+	testDB, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	found, err := models.FindRegistryCredential(context.Background(), testDB, 99999)
+	require.NoError(t, err)
+	assert.Nil(t, found)
+}
+
+func TestAppGetRegistryCredentials(t *testing.T) {
+	t.Parallel()
+
+	testDB, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	app := createTestApp(t, testDB)
+
+	cred := models.NewRegistryCredential(testDB)
+	cred.AppID = app.ID
+	cred.Registry = "ghcr.io"
+	cred.Username = testUser
+	cred.Password = "token"
+	_ = cred.Save(context.Background())
+
+	creds, err := app.GetRegistryCredentials(context.Background())
+	require.NoError(t, err)
+	assert.Len(t, creds, 1)
+	assert.Equal(t, "ghcr.io", creds[0].Registry)
+}
+
 // Cascade Delete Tests.
 
 //nolint:funlen // Test function with many assertions - acceptable for integration tests
@@ -749,6 +871,13 @@ func TestCascadeDelete(t *testing.T) {
 		deploy.Status = models.DeploymentStatusSuccess
 		_ = deploy.Save(context.Background())
 
+		regCred := models.NewRegistryCredential(testDB)
+		regCred.AppID = app.ID
+		regCred.Registry = "registry.example.com"
+		regCred.Username = testUser
+		regCred.Password = "pass"
+		_ = regCred.Save(context.Background())
+
 		// Delete app.
 		err := app.Delete(context.Background())
 		require.NoError(t, err)
@@ -778,6 +907,11 @@ func TestCascadeDelete(t *testing.T) {
 			context.Background(), testDB, app.ID, 10,
 		)
 		assert.Empty(t, deployments)
+
+		regCreds, _ := models.FindRegistryCredentialsByAppID(
+			context.Background(), testDB, app.ID,
+		)
+		assert.Empty(t, regCreds)
 	})
 }
 

internal/models/registry_credential.go

@@ -0,0 +1,130 @@
+package models
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+
+	"sneak.berlin/go/upaas/internal/database"
+)
+
+// RegistryCredential represents authentication credentials for a private Docker registry.
+type RegistryCredential struct {
+	db *database.Database
+
+	ID       int64
+	AppID    string
+	Registry string
+	Username string
+	Password string //nolint:gosec // credential field required for registry auth
+}
+
+// NewRegistryCredential creates a new RegistryCredential with a database reference.
+func NewRegistryCredential(db *database.Database) *RegistryCredential {
+	return &RegistryCredential{db: db}
+}
+
+// Save inserts or updates the registry credential in the database.
+func (r *RegistryCredential) Save(ctx context.Context) error {
+	if r.ID == 0 {
+		return r.insert(ctx)
+	}
+
+	return r.update(ctx)
+}
+
+// Delete removes the registry credential from the database.
+func (r *RegistryCredential) Delete(ctx context.Context) error {
+	_, err := r.db.Exec(ctx, "DELETE FROM registry_credentials WHERE id = ?", r.ID)
+
+	return err
+}
+
+func (r *RegistryCredential) insert(ctx context.Context) error {
+	query := "INSERT INTO registry_credentials (app_id, registry, username, password) VALUES (?, ?, ?, ?)"
+
+	result, err := r.db.Exec(ctx, query, r.AppID, r.Registry, r.Username, r.Password)
+	if err != nil {
+		return err
+	}
+
+	id, err := result.LastInsertId()
+	if err != nil {
+		return err
+	}
+
+	r.ID = id
+
+	return nil
+}
+
+func (r *RegistryCredential) update(ctx context.Context) error {
+	query := "UPDATE registry_credentials SET registry = ?, username = ?, password = ? WHERE id = ?"
+
+	_, err := r.db.Exec(ctx, query, r.Registry, r.Username, r.Password, r.ID)
+
+	return err
+}
+
+// FindRegistryCredential finds a registry credential by ID.
+//
+//nolint:nilnil // returning nil,nil is idiomatic for "not found" in Active Record
+func FindRegistryCredential(
+	ctx context.Context,
+	db *database.Database,
+	id int64,
+) (*RegistryCredential, error) {
+	cred := NewRegistryCredential(db)
+
+	row := db.QueryRow(ctx,
+		"SELECT id, app_id, registry, username, password FROM registry_credentials WHERE id = ?",
+		id,
+	)
+
+	err := row.Scan(&cred.ID, &cred.AppID, &cred.Registry, &cred.Username, &cred.Password)
+	if err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return nil, nil
+		}
+
+		return nil, fmt.Errorf("scanning registry credential: %w", err)
+	}
+
+	return cred, nil
+}
+
+// FindRegistryCredentialsByAppID finds all registry credentials for an app.
+func FindRegistryCredentialsByAppID(
+	ctx context.Context,
+	db *database.Database,
+	appID string,
+) ([]*RegistryCredential, error) {
+	query := `
+		SELECT id, app_id, registry, username, password FROM registry_credentials
+		WHERE app_id = ? ORDER BY registry`
+
+	rows, err := db.Query(ctx, query, appID)
+	if err != nil {
+		return nil, fmt.Errorf("querying registry credentials by app: %w", err)
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	var creds []*RegistryCredential
+
+	for rows.Next() {
+		cred := NewRegistryCredential(db)
+
+		scanErr := rows.Scan(
+			&cred.ID, &cred.AppID, &cred.Registry, &cred.Username, &cred.Password,
+		)
+		if scanErr != nil {
+			return nil, scanErr
+		}
+
+		creds = append(creds, cred)
+	}
+
+	return creds, rows.Err()
+}

internal/server/routes.go

@@ -98,6 +98,11 @@ func (s *Server) SetupRoutes() {
 			// Ports
 			r.Post("/apps/{id}/ports", s.handlers.HandlePortAdd())
 			r.Post("/apps/{id}/ports/{portID}/delete", s.handlers.HandlePortDelete())
+
+			// Registry Credentials
+			r.Post("/apps/{id}/registry-credentials", s.handlers.HandleRegistryCredentialAdd())
+			r.Post("/apps/{id}/registry-credentials/{credID}/edit", s.handlers.HandleRegistryCredentialEdit())
+			r.Post("/apps/{id}/registry-credentials/{credID}/delete", s.handlers.HandleRegistryCredentialDelete())
 		})
 	})
 

internal/service/deploy/deploy.go

@@ -830,6 +830,13 @@ func (svc *Service) buildImage(
 	logWriter := newDeploymentLogWriter(ctx, deployment)
 	defer logWriter.Close()
 
+	// Fetch registry credentials for private base images
+	registryAuths, err := svc.buildRegistryAuths(ctx, app)
+	if err != nil {
+		svc.log.Warn("failed to fetch registry credentials", "error", err, "app", app.Name)
+		// Continue without auth — public images will still work
+	}
+
 	// BuildImage creates a tar archive from the local filesystem,
 	// so it needs the container path where files exist, not the host path.
 	imageID, err := svc.docker.BuildImage(ctx, docker.BuildImageOptions{
@@ -837,6 +844,7 @@ func (svc *Service) buildImage(
 		DockerfilePath: app.DockerfilePath,
 		Tags:           []string{imageTag},
 		LogWriter:      logWriter,
+		RegistryAuths:  registryAuths,
 	})
 	if err != nil {
 		svc.notify.NotifyBuildFailed(ctx, app, deployment, err)
@@ -1227,6 +1235,34 @@ func (svc *Service) failDeployment(
 	_ = app.Save(ctx)
 }
 
+// buildRegistryAuths fetches registry credentials for an app and converts them
+// to Docker RegistryAuth objects for use during image builds.
+func (svc *Service) buildRegistryAuths(
+	ctx context.Context,
+	app *models.App,
+) ([]docker.RegistryAuth, error) {
+	creds, err := app.GetRegistryCredentials(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get registry credentials: %w", err)
+	}
+
+	if len(creds) == 0 {
+		return nil, nil
+	}
+
+	auths := make([]docker.RegistryAuth, 0, len(creds))
+
+	for _, cred := range creds {
+		auths = append(auths, docker.RegistryAuth{
+			Registry: cred.Registry,
+			Username: cred.Username,
+			Password: cred.Password,
+		})
+	}
+
+	return auths, nil
+}
+
 // writeLogsToFile writes the deployment logs to a file on disk.
 // Structure: DataDir/logs/<hostname>/<appname>/<appname>_<sha>_<timestamp>.log.txt
 func (svc *Service) writeLogsToFile(app *models.App, deployment *models.Deployment) {

templates/app_detail.html

@@ -154,6 +154,69 @@
         <div class="hidden">{{ .CSRFField }}</div>
     </div>
 
+    <!-- Registry Credentials -->
+    <div class="card p-6 mb-6">
+        <h2 class="section-title mb-4">Registry Credentials</h2>
+        <p class="text-sm text-gray-500 mb-3">Authenticate to private Docker registries when pulling base images during builds.</p>
+        {{if .RegistryCredentials}}
+        <div class="overflow-x-auto mb-4">
+            <table class="table">
+                <thead class="table-header">
+                    <tr>
+                        <th>Registry</th>
+                        <th>Username</th>
+                        <th>Password</th>
+                        <th class="text-right">Actions</th>
+                    </tr>
+                </thead>
+                <tbody class="table-body">
+                    {{range .RegistryCredentials}}
+                    <tr x-data="{ editing: false }">
+                        <template x-if="!editing">
+                            <td class="font-mono">{{.Registry}}</td>
+                        </template>
+                        <template x-if="!editing">
+                            <td class="font-mono">{{.Username}}</td>
+                        </template>
+                        <template x-if="!editing">
+                            <td class="font-mono text-gray-400">••••••••</td>
+                        </template>
+                        <template x-if="!editing">
+                            <td class="text-right">
+                                <button @click="editing = true" class="text-primary-600 hover:text-primary-800 text-sm mr-2">Edit</button>
+                                <form method="POST" action="/apps/{{$.App.ID}}/registry-credentials/{{.ID}}/delete" class="inline" x-data="confirmAction('Delete this registry credential?')" @submit="confirm($event)">
+                                    {{ $.CSRFField }}
+                                    <button type="submit" class="text-error-500 hover:text-error-700 text-sm">Delete</button>
+                                </form>
+                            </td>
+                        </template>
+                        <template x-if="editing">
+                            <td colspan="4">
+                                <form method="POST" action="/apps/{{$.App.ID}}/registry-credentials/{{.ID}}/edit" class="flex gap-2 items-center">
+                                    {{ $.CSRFField }}
+                                    <input type="text" name="registry" value="{{.Registry}}" required class="input flex-1 font-mono text-sm" placeholder="registry.example.com">
+                                    <input type="text" name="username" value="{{.Username}}" required class="input flex-1 font-mono text-sm" placeholder="username">
+                                    <input type="password" name="password" required class="input flex-1 font-mono text-sm" placeholder="password">
+                                    <button type="submit" class="btn-primary text-sm">Save</button>
+                                    <button type="button" @click="editing = false" class="text-gray-500 hover:text-gray-700 text-sm">Cancel</button>
+                                </form>
+                            </td>
+                        </template>
+                    </tr>
+                    {{end}}
+                </tbody>
+            </table>
+        </div>
+        {{end}}
+        <form method="POST" action="/apps/{{.App.ID}}/registry-credentials" class="flex flex-col sm:flex-row gap-2">
+            {{ .CSRFField }}
+            <input type="text" name="registry" placeholder="registry.example.com" required class="input flex-1 font-mono text-sm">
+            <input type="text" name="username" placeholder="username" required class="input flex-1 font-mono text-sm">
+            <input type="password" name="password" placeholder="password" required class="input flex-1 font-mono text-sm">
+            <button type="submit" class="btn-primary">Add</button>
+        </form>
+    </div>
+
     <!-- Labels -->
     <div class="card p-6 mb-6">
         <h2 class="section-title mb-4">Docker Labels</h2>