feat: external databases — register, probe, encrypted credentials

Databases hosted outside Containr can now be registered alongside
managed ones. The connection is probed before storing (protocol-level
for postgres/redis-family via real drivers, TCP dial for the rest),
credentials are encrypted at rest and never returned, and external rows
skip managed lifecycle actions, backups, and Docker metrics.

- POST /databases/register-external — probe + create
- POST /databases/test-connection — ad-hoc probe (ok/latency_ms/error)
- POST /databases/{id}/test-connection — re-probe stored credentials
- provider/external fields on database services; privileged reads get a
  composed connection URL with loopback hosts rewritten to the caller's
- CLI: databases register + test-connection; MCP: 3 new tools
- UI: managed/external toggle in the create modal, external badge and
  host display, per-row test button, backups section hidden
- Migration widens the plan CHECK to admit 'external'

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/backend/internal/api/databases.go

@@ -4,6 +4,7 @@ import (
 	"archive/tar"
 	"containr/internal/database/sqlcdb"
 	"containr/internal/docker"
+	"containr/internal/secrets"
 	"context"
 	"crypto/rand"
 	"database/sql"
@@ -51,12 +52,30 @@ type DatabaseService struct {
 	Region         string               `json:"region" db:"region"`
 	BackupSchedule string               `json:"backup_schedule,omitempty"`
 	NextBackupAt   *time.Time           `json:"next_backup_at,omitempty"`
+	Provider       string               `json:"provider"`           // managed | external
+	External       *DatabaseExternalRef `json:"external,omitempty"` // connection target for external DBs
 	CreatedAt      time.Time            `json:"created_at" db:"created_at"`
 	UpdatedAt      time.Time            `json:"updated_at" db:"updated_at"`
 	ConnectionURL  string               `json:"connection_url"`
 	Metrics        DatabaseMetrics      `json:"metrics"`
 	Backups        DatabaseBackupConfig `json:"backups"`
 	Settings       DatabaseSettings     `json:"settings"`
+
+	// externalPasswordEnc is the stored ciphertext — needed to compose the
+	// connection URL on privileged reads, never serialized.
+	externalPasswordEnc string `json:"-"`
+}
+
+// DatabaseExternalRef describes a registered external database's connection
+// target. The password is stored encrypted and never returned — has_password
+// signals presence.
+type DatabaseExternalRef struct {
+	Host        string `json:"host"`
+	Port        int    `json:"port"`
+	Database    string `json:"database"`
+	Username    string `json:"username"`
+	HasPassword bool   `json:"has_password"`
+	SSL         bool   `json:"ssl"`
 }
 
 // DatabaseMetrics represents database performance metrics
@@ -467,21 +486,20 @@ func (h *DatabaseHandler) DeleteDatabase(c *gin.Context) {
 	databaseID := c.Param("id")
 	userID = h.effectiveUserID(c, userID, databaseID)
 
-	exists, err := h.queries.DatabaseServiceExistsByIDAndUser(c.Request.Context(), sqlcdb.DatabaseServiceExistsByIDAndUserParams{
+	row, err := h.queries.GetDatabaseServiceByIDAndUser(c.Request.Context(), sqlcdb.GetDatabaseServiceByIDAndUserParams{
 		ID:     databaseID,
 		UserID: userID,
 	})
 	if err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			c.JSON(http.StatusNotFound, gin.H{"error": "Database not found"})
+			return
+		}
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to check database"})
 		return
 	}
 
-	if !exists {
-		c.JSON(http.StatusNotFound, gin.H{"error": "Database not found"})
-		return
-	}
-
-	if h.dockerClient != nil {
+	if row.Provider != "external" && h.dockerClient != nil {
 		if err := h.deleteManagedDatabaseRuntime(databaseID); err != nil {
 			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to delete runtime database"})
 			return
@@ -515,17 +533,24 @@ func (h *DatabaseHandler) PerformDatabaseAction(c *gin.Context) {
 		return
 	}
 
-	exists, err := h.queries.DatabaseServiceExistsByIDAndUser(c.Request.Context(), sqlcdb.DatabaseServiceExistsByIDAndUserParams{
+	row, err := h.queries.GetDatabaseServiceByIDAndUser(c.Request.Context(), sqlcdb.GetDatabaseServiceByIDAndUserParams{
 		ID:     databaseID,
 		UserID: userID,
 	})
 	if err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			c.JSON(http.StatusNotFound, gin.H{"error": "Database not found"})
+			return
+		}
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to check database"})
 		return
 	}
 
-	if !exists {
-		c.JSON(http.StatusNotFound, gin.H{"error": "Database not found"})
+	if row.Provider == "external" {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"error": "Lifecycle actions apply to managed databases only — external databases are run elsewhere",
+			"code":  "VALIDATION",
+		})
 		return
 	}
 
@@ -619,6 +644,13 @@ func (h *DatabaseHandler) CreateBackup(c *gin.Context) {
 		c.JSON(http.StatusConflict, gin.H{"error": "Database is still provisioning"})
 		return
 	}
+	if row.Provider == "external" {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"error": "Backups run against the managed dump pipeline — external database backups are not supported yet",
+			"code":  "VALIDATION",
+		})
+		return
+	}
 
 	backupID := generateDatabaseBackupID(databaseID)
 	archivePath := sanitizeBackupArchivePath(managedDatabaseBackupArchivePath(backupID))
@@ -659,17 +691,23 @@ func (h *DatabaseHandler) RestoreBackup(c *gin.Context) {
 		return
 	}
 
-	exists, err := h.queries.DatabaseServiceExistsByIDAndUser(c.Request.Context(), sqlcdb.DatabaseServiceExistsByIDAndUserParams{
+	dbRow, err := h.queries.GetDatabaseServiceByIDAndUser(c.Request.Context(), sqlcdb.GetDatabaseServiceByIDAndUserParams{
 		ID:     databaseID,
 		UserID: userID,
 	})
 	if err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			c.JSON(http.StatusNotFound, gin.H{"error": "Database not found"})
+			return
+		}
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to check database"})
 		return
 	}
-
-	if !exists {
-		c.JSON(http.StatusNotFound, gin.H{"error": "Database not found"})
+	if dbRow.Provider == "external" {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"error": "Restores run against the managed dump pipeline — external database restores are not supported yet",
+			"code":  "VALIDATION",
+		})
 		return
 	}
 
@@ -787,7 +825,7 @@ func (h *DatabaseHandler) DownloadBackup(c *gin.Context) {
 }
 
 func (h *DatabaseHandler) resolveDatabaseMetrics(ctx context.Context, db DatabaseService) DatabaseMetrics {
-	if h.dockerClient == nil {
+	if h.dockerClient == nil || db.Provider == "external" {
 		return h.generateMockMetrics()
 	}
 
@@ -945,7 +983,11 @@ func (h *DatabaseHandler) generateMockSettings() DatabaseSettings {
 
 // resolveConnectionURL returns the stored connection URL for privileged
 // viewers, or "" when the runtime has not produced one (not provisioned yet).
+// External databases compose it from the registered fields on demand.
 func (h *DatabaseHandler) resolveConnectionURL(db DatabaseService) string {
+	if db.Provider == "external" && db.External != nil {
+		return externalConnectionURL(db.Type, db.External, secrets.Decrypt(db.externalPasswordEnc))
+	}
 	return strings.TrimSpace(db.ConnectionURL)
 }
 
@@ -987,7 +1029,7 @@ func rewriteLoopbackURL(rawURL, host string) string {
 }
 
 func (h *DatabaseHandler) reconcileManagedDatabaseState(ctx context.Context, db DatabaseService) DatabaseService {
-	if h.dockerClient == nil {
+	if h.dockerClient == nil || db.Provider == "external" {
 		return db
 	}
 
@@ -1054,7 +1096,7 @@ func (h *DatabaseHandler) resolveManagedRuntimeStatus(ctx context.Context, db Da
 }
 
 func mapDatabaseServiceRow(row sqlcdb.DatabaseService) DatabaseService {
-	return DatabaseService{
+	svc := DatabaseService{
 		ID:             row.ID,
 		OwnerID:        row.UserID,
 		Name:           row.Name,
@@ -1065,10 +1107,23 @@ func mapDatabaseServiceRow(row sqlcdb.DatabaseService) DatabaseService {
 		Region:         row.Region,
 		BackupSchedule: databaseNullString(row.BackupSchedule),
 		NextBackupAt:   databaseNullTimePtr(row.NextBackupAt),
+		Provider:       row.Provider,
 		ConnectionURL:  databaseNullString(row.ConnectionUrl),
 		CreatedAt:      databaseNullTime(row.CreatedAt),
 		UpdatedAt:      databaseNullTime(row.UpdatedAt),
 	}
+	if svc.Provider == "external" {
+		svc.External = &DatabaseExternalRef{
+			Host:        databaseNullString(row.ExternalHost),
+			Port:        int(row.ExternalPort.Int32),
+			Database:    databaseNullString(row.ExternalName),
+			Username:    databaseNullString(row.ExternalUsername),
+			HasPassword: row.ExternalPassword != "",
+			SSL:         row.ExternalSsl,
+		}
+		svc.externalPasswordEnc = row.ExternalPassword
+	}
+	return svc
 }
 
 func databaseNullTime(value sql.NullTime) time.Time {

app/backend/internal/api/dbexternal.go

@@ -0,0 +1,319 @@
+package api
+
+import (
+	"context"
+	"crypto/tls"
+	"database/sql"
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"containr/internal/database/sqlcdb"
+	"containr/internal/secrets"
+
+	"github.com/gin-gonic/gin"
+	"github.com/go-redis/redis/v8"
+)
+
+// externalDatabaseRequest is the shared payload for registering an external
+// database and for ad-hoc connection tests.
+type externalDatabaseRequest struct {
+	Name     string `json:"name"`
+	Type     string `json:"type" binding:"required"`
+	Host     string `json:"host" binding:"required"`
+	Port     int    `json:"port"`
+	Database string `json:"database"`
+	Username string `json:"username"`
+	Password string `json:"password"`
+	SSL      bool   `json:"ssl"`
+}
+
+var externalDefaultPorts = map[string]int{
+	"postgresql": 5432,
+	"mysql":      3306,
+	"mariadb":    3306,
+	"mongodb":    27017,
+	"redis":      6379,
+	"dragonfly":  6379,
+	"clickhouse": 9000,
+}
+
+// externalConnectionURL composes a DSN for display/bind use. The password is
+// embedded only on privileged reads — the value is decrypted at that point.
+func externalConnectionURL(dbType string, ext *DatabaseExternalRef, password string) string {
+	host := net.JoinHostPort(ext.Host, fmt.Sprintf("%d", ext.Port))
+	creds := ""
+	if ext.Username != "" {
+		creds = url.QueryEscape(ext.Username)
+		if password != "" {
+			creds += ":" + url.QueryEscape(password)
+		}
+		creds += "@"
+	}
+	switch dbType {
+	case "postgresql":
+		u := fmt.Sprintf("postgres://%s%s/%s", creds, host, ext.Database)
+		if ext.SSL {
+			u += "?sslmode=require"
+		}
+		return u
+	case "mysql", "mariadb":
+		return fmt.Sprintf("mysql://%s%s/%s", creds, host, ext.Database)
+	case "mongodb":
+		u := fmt.Sprintf("mongodb://%s%s/%s", creds, host, ext.Database)
+		if ext.SSL {
+			u += "?tls=true"
+		}
+		return u
+	case "redis", "dragonfly":
+		scheme := "redis"
+		if ext.SSL {
+			scheme = "rediss"
+		}
+		// Redis auth is password-only; username support is ACL-era.
+		if password != "" {
+			creds = ":" + url.QueryEscape(password) + "@"
+			if ext.Username != "" {
+				creds = url.QueryEscape(ext.Username) + creds
+			}
+		}
+		return fmt.Sprintf("%s://%s%s", scheme, creds, host)
+	case "clickhouse":
+		return fmt.Sprintf("clickhouse://%s%s/%s", creds, host, ext.Database)
+	}
+	return fmt.Sprintf("%s://%s%s", dbType, creds, host)
+}
+
+// probeExternalDatabase verifies reachability. postgres and redis-family get
+// real protocol checks via the vendored drivers; everything else gets a TCP
+// dial — enough to catch typos and firewall issues without new dependencies.
+func probeExternalDatabase(ctx context.Context, req externalDatabaseRequest) (time.Duration, error) {
+	addr := net.JoinHostPort(req.Host, fmt.Sprintf("%d", req.Port))
+	dialer := &net.Dialer{Timeout: 5 * time.Second}
+	start := time.Now()
+
+	switch req.Type {
+	case "postgresql":
+		sslmode := "disable"
+		if req.SSL {
+			sslmode = "require"
+		}
+		dsn := fmt.Sprintf("postgres://%s:%s@%s/%s?sslmode=%s&connect_timeout=5",
+			url.QueryEscape(req.Username), url.QueryEscape(req.Password), addr,
+			url.QueryEscape(req.Database), sslmode)
+		conn, err := sql.Open("postgres", dsn)
+		if err != nil {
+			return 0, err
+		}
+		defer conn.Close()
+		if err := conn.PingContext(ctx); err != nil {
+			return 0, err
+		}
+	case "redis", "dragonfly":
+		client := redis.NewClient(&redis.Options{
+			Addr:        addr,
+			Username:    req.Username,
+			Password:    req.Password,
+			DialTimeout: 5 * time.Second,
+			ReadTimeout: 5 * time.Second,
+			TLSConfig:   redisTLSConfig(req.SSL, req.Host),
+		})
+		defer client.Close()
+		if err := client.Ping(ctx).Err(); err != nil {
+			return 0, err
+		}
+	default:
+		conn, err := dialer.DialContext(ctx, "tcp", addr)
+		if err != nil {
+			return 0, err
+		}
+		conn.Close()
+	}
+	return time.Since(start), nil
+}
+
+func redisTLSConfig(enabled bool, host string) *tls.Config {
+	if !enabled {
+		return nil
+	}
+	return &tls.Config{ServerName: host, MinVersion: tls.VersionTLS12}
+}
+
+// handleTestDatabaseConnection probes arbitrary connection parameters — used
+// by the register form's "test" button and by agents before registering.
+func (h *DatabaseHandler) TestDatabaseConnection(c *gin.Context) {
+	if _, ok := requireAuthenticatedUserID(c); !ok {
+		return
+	}
+	var req externalDatabaseRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error(), "code": "VALIDATION"})
+		return
+	}
+	if err := normalizeExternalRequest(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error(), "code": "VALIDATION"})
+		return
+	}
+
+	ctx, cancel := context.WithTimeout(c.Request.Context(), 10*time.Second)
+	defer cancel()
+	latency, err := probeExternalDatabase(ctx, req)
+	if err != nil {
+		c.JSON(http.StatusOK, gin.H{"ok": false, "error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"ok": true, "latency_ms": latency.Milliseconds()})
+}
+
+// TestDatabaseConnectionByID re-probes a registered external database using
+// its stored (decrypted) credentials.
+func (h *DatabaseHandler) TestDatabaseConnectionByID(c *gin.Context) {
+	userID, ok := requireAuthenticatedUserID(c)
+	if !ok {
+		return
+	}
+	databaseID := c.Param("id")
+	userID = h.effectiveUserID(c, userID, databaseID)
+
+	row, err := h.queries.GetDatabaseServiceByIDAndUser(c.Request.Context(), sqlcdb.GetDatabaseServiceByIDAndUserParams{
+		ID:     databaseID,
+		UserID: userID,
+	})
+	if err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			c.JSON(http.StatusNotFound, gin.H{"error": "Database not found", "code": "NOT_FOUND"})
+			return
+		}
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to fetch database"})
+		return
+	}
+	if row.Provider != "external" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "test-connection applies to external databases", "code": "VALIDATION"})
+		return
+	}
+
+	req := externalDatabaseRequest{
+		Type:     row.Type,
+		Host:     databaseNullString(row.ExternalHost),
+		Port:     int(row.ExternalPort.Int32),
+		Database: databaseNullString(row.ExternalName),
+		Username: databaseNullString(row.ExternalUsername),
+		Password: secrets.Decrypt(row.ExternalPassword),
+		SSL:      row.ExternalSsl,
+	}
+	ctx, cancel := context.WithTimeout(c.Request.Context(), 10*time.Second)
+	defer cancel()
+	latency, probeErr := probeExternalDatabase(ctx, req)
+	if probeErr != nil {
+		c.JSON(http.StatusOK, gin.H{"ok": false, "error": probeErr.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"ok": true, "latency_ms": latency.Milliseconds()})
+}
+
+func normalizeExternalRequest(req *externalDatabaseRequest) error {
+	req.Type = normalizeDatabaseType(req.Type)
+	if _, ok := supportedDatabaseTypes[req.Type]; !ok {
+		return fmt.Errorf("%w: %s", errUnsupportedDatabaseType, req.Type)
+	}
+	req.Host = strings.TrimSpace(req.Host)
+	if req.Host == "" {
+		return errors.New("host is required")
+	}
+	if req.Port <= 0 {
+		req.Port = externalDefaultPorts[req.Type]
+	}
+	if req.Port <= 0 || req.Port > 65535 {
+		return errors.New("port must be 1-65535")
+	}
+	return nil
+}
+
+// RegisterExternalDatabase records a database hosted elsewhere — same list,
+// same bind surface, no container. The connection is probed first so typos
+// fail at registration, not at the first service bind.
+func (h *DatabaseHandler) RegisterExternalDatabase(c *gin.Context) {
+	userID, ok := requireAuthenticatedUserID(c)
+	if !ok {
+		return
+	}
+	var req externalDatabaseRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error(), "code": "VALIDATION"})
+		return
+	}
+	req.Name = strings.TrimSpace(req.Name)
+	if req.Name == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "name is required", "code": "VALIDATION"})
+		return
+	}
+	if err := normalizeExternalRequest(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error(), "code": "VALIDATION"})
+		return
+	}
+
+	probeCtx, cancel := context.WithTimeout(c.Request.Context(), 10*time.Second)
+	defer cancel()
+	if _, err := probeExternalDatabase(probeCtx, req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"error": fmt.Sprintf("Connection check failed: %v", err),
+			"code":  "DEPENDENCY_UNAVAILABLE",
+		})
+		return
+	}
+
+	count, err := h.queries.CountDatabaseServicesByUserAndName(c.Request.Context(), sqlcdb.CountDatabaseServicesByUserAndNameParams{
+		UserID: userID,
+		Name:   req.Name,
+	})
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to validate database name"})
+		return
+	}
+	if count > 0 {
+		c.JSON(http.StatusConflict, gin.H{"error": "database name already exists", "code": "CONFLICT"})
+		return
+	}
+
+	databaseID := generateDatabaseID(req.Name)
+	now := sql.NullTime{Time: time.Now(), Valid: true}
+	encPassword := ""
+	if req.Password != "" {
+		encPassword = secrets.Encrypt(req.Password)
+	}
+	if err := h.queries.CreateExternalDatabaseService(c.Request.Context(), sqlcdb.CreateExternalDatabaseServiceParams{
+		ID:               databaseID,
+		UserID:           userID,
+		Name:             req.Name,
+		Type:             req.Type,
+		Version:          "",
+		Plan:             "external",
+		Region:           "external",
+		ExternalHost:     sql.NullString{String: req.Host, Valid: true},
+		ExternalPort:     sql.NullInt32{Int32: int32(req.Port), Valid: true},
+		ExternalName:     sql.NullString{String: req.Database, Valid: req.Database != ""},
+		ExternalUsername: sql.NullString{String: req.Username, Valid: req.Username != ""},
+		ExternalPassword: encPassword,
+		ExternalSsl:      req.SSL,
+		CreatedAt:        now,
+		UpdatedAt:        now,
+	}); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to register database"})
+		return
+	}
+
+	LogAudit(userID, "database", databaseID, "register-external", map[string]interface{}{
+		"name": req.Name,
+		"type": req.Type,
+		"host": req.Host,
+	})
+	c.JSON(http.StatusCreated, gin.H{
+		"id":      databaseID,
+		"message": "External database registered",
+		"status":  "running",
+	})
+}

app/backend/internal/api/dbexternal_test.go

@@ -0,0 +1,97 @@
+package api
+
+import (
+	"context"
+	"net"
+	"testing"
+)
+
+func TestNormalizeExternalRequestDefaults(t *testing.T) {
+	req := externalDatabaseRequest{Type: "PostgreSQL", Host: " db.example.com ", Port: 0}
+	if err := normalizeExternalRequest(&req); err != nil {
+		t.Fatalf("normalize failed: %v", err)
+	}
+	if req.Type != "postgresql" {
+		t.Fatalf("type not normalized: %q", req.Type)
+	}
+	if req.Host != "db.example.com" {
+		t.Fatalf("host not trimmed: %q", req.Host)
+	}
+	if req.Port != 5432 {
+		t.Fatalf("default port = %d, want 5432", req.Port)
+	}
+}
+
+func TestNormalizeExternalRequestRejects(t *testing.T) {
+	cases := []externalDatabaseRequest{
+		{Type: "sqlite", Host: "x"},                  // unsupported type
+		{Type: "postgresql", Host: "  "},             // empty host
+		{Type: "postgresql", Host: "h", Port: 70000}, // out of range
+	}
+	for i, req := range cases {
+		if err := normalizeExternalRequest(&req); err == nil {
+			t.Fatalf("case %d: expected error", i)
+		}
+	}
+}
+
+func TestExternalConnectionURLMasking(t *testing.T) {
+	ext := &DatabaseExternalRef{
+		Host:     "db.example.com",
+		Port:     5432,
+		Database: "appdb",
+		Username: "svc",
+		SSL:      true,
+	}
+	u := externalConnectionURL("postgresql", ext, "s3cret")
+	if u != "postgres://svc:[email protected]:5432/appdb?sslmode=require" {
+		t.Fatalf("unexpected pg url: %s", u)
+	}
+	u = externalConnectionURL("postgresql", ext, "")
+	if u != "postgres://[email protected]:5432/appdb?sslmode=require" {
+		t.Fatalf("unexpected passwordless url: %s", u)
+	}
+
+	r := &DatabaseExternalRef{Host: "cache.internal", Port: 6379, SSL: true}
+	u = externalConnectionURL("redis", r, "pw")
+	if u != "rediss://:[email protected]:6379" {
+		t.Fatalf("unexpected redis url: %s", u)
+	}
+}
+
+func TestProbeExternalDatabaseTCP(t *testing.T) {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+	defer ln.Close()
+	port := ln.Addr().(*net.TCPAddr).Port
+
+	// TCP fallback path — mysql uses a plain dial.
+	latency, err := probeExternalDatabase(context.Background(), externalDatabaseRequest{
+		Type: "mysql", Host: "127.0.0.1", Port: port,
+	})
+	if err != nil {
+		t.Fatalf("probe should succeed against open listener: %v", err)
+	}
+	if latency <= 0 {
+		t.Fatalf("latency not recorded")
+	}
+
+	// Closed port must fail fast.
+	if _, err := probeExternalDatabase(context.Background(), externalDatabaseRequest{
+		Type: "mysql", Host: "127.0.0.1", Port: 1,
+	}); err == nil {
+		t.Fatalf("probe should fail against closed port")
+	}
+}
+
+func TestRedisTLSConfig(t *testing.T) {
+	if redisTLSConfig(false, "h") != nil {
+		t.Fatalf("disabled ssl must produce nil tls config")
+	}
+	cfg := redisTLSConfig(true, "db.example.com")
+	if cfg == nil || cfg.ServerName != "db.example.com" {
+		t.Fatalf("expected ServerName passthrough, got %+v", cfg)
+	}
+}

app/backend/internal/api/routes.go

@@ -383,6 +383,9 @@ func SetupRoutes(router *gin.Engine, db *database.DB, redis *database.Redis, cfg
 			authed.POST("/builds/plan", buildHandler.GetBuildPlan)
 
 			authed.POST("/databases", databaseHandler.CreateDatabase)
+			authed.POST("/databases/register-external", databaseHandler.RegisterExternalDatabase)
+			authed.POST("/databases/test-connection", databaseHandler.TestDatabaseConnection)
+			authed.POST("/databases/:id/test-connection", databaseHandler.TestDatabaseConnectionByID)
 			authed.PUT("/databases/:id", databaseHandler.UpdateDatabase)
 			authed.DELETE("/databases/:id", databaseHandler.DeleteDatabase)
 			authed.POST("/databases/:id/action", databaseHandler.PerformDatabaseAction)

app/backend/internal/cli/commands/databases.go

@@ -196,9 +196,96 @@ var dbDownloadCmd = &cobra.Command{
 	},
 }
 
+var dbRegisterCmd = &cobra.Command{
+	Use:   "register <name>",
+	Short: "Register an external database (probes the connection first)",
+	Args:  cobra.ExactArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		c, err := client()
+		if err != nil {
+			return err
+		}
+		body := map[string]interface{}{"name": args[0]}
+		for _, f := range []string{"type", "host", "database", "username", "password"} {
+			if v, _ := cmd.Flags().GetString(f); v != "" {
+				body[f] = v
+			}
+		}
+		if v, _ := cmd.Flags().GetInt("port"); v > 0 {
+			body["port"] = v
+		}
+		if v, _ := cmd.Flags().GetBool("ssl"); v {
+			body["ssl"] = true
+		}
+		data, err := c.Do("POST", "/databases/register-external", body)
+		if err != nil {
+			return err
+		}
+		if JSONMode() {
+			PrintRaw(data)
+			return nil
+		}
+		m, _ := unwrapObject(data)
+		fmt.Printf("Registered external database %s (%s)\n", args[0], str(m, "id"))
+		return nil
+	},
+}
+
+var dbTestConnCmd = &cobra.Command{
+	Use:   "test-connection [<id>]",
+	Short: "Probe a database connection — by id, or with --type/--host flags",
+	Args:  cobra.MaximumNArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		c, err := client()
+		if err != nil {
+			return err
+		}
+		var data []byte
+		if len(args) == 1 {
+			data, err = c.Do("POST", "/databases/"+args[0]+"/test-connection", map[string]interface{}{})
+		} else {
+			body := map[string]interface{}{}
+			for _, f := range []string{"type", "host", "database", "username", "password"} {
+				if v, _ := cmd.Flags().GetString(f); v != "" {
+					body[f] = v
+				}
+			}
+			if v, _ := cmd.Flags().GetInt("port"); v > 0 {
+				body["port"] = v
+			}
+			if v, _ := cmd.Flags().GetBool("ssl"); v {
+				body["ssl"] = true
+			}
+			data, err = c.Do("POST", "/databases/test-connection", body)
+		}
+		if err != nil {
+			return err
+		}
+		m, _ := unwrapObject(data)
+		if str(m, "ok") == "false" {
+			return &APIError{Message: "connection failed: " + str(m, "error"), ExitCode: ExitError}
+		}
+		if JSONMode() {
+			PrintRaw(data)
+			return nil
+		}
+		fmt.Printf("Connection ok (%sms)\n", str(m, "latency_ms"))
+		return nil
+	},
+}
+
 func init() {
 	dbCreateCmd.Flags().String("type", "postgres", "postgres|mysql|mariadb|mongodb|redis|dragonfly|clickhouse")
 	dbCreateCmd.Flags().String("version", "", "engine version tag")
 	dbCreateCmd.Flags().String("storage-size", "", "volume size (e.g. 10Gi)")
-	DatabasesCmd.AddCommand(dbListCmd, dbGetCmd, dbCreateCmd, dbDeleteCmd, dbActionCmd, dbBackupCmd, dbRestoreCmd, dbDownloadCmd)
+	for _, cmd := range []*cobra.Command{dbRegisterCmd, dbTestConnCmd} {
+		cmd.Flags().String("type", "postgres", "postgres|mysql|mariadb|mongodb|redis|dragonfly|clickhouse")
+		cmd.Flags().String("host", "", "database host")
+		cmd.Flags().Int("port", 0, "database port (default per type)")
+		cmd.Flags().String("database", "", "database name")
+		cmd.Flags().String("username", "", "database username")
+		cmd.Flags().String("password", "", "database password (stored encrypted on register)")
+		cmd.Flags().Bool("ssl", false, "require TLS")
+	}
+	DatabasesCmd.AddCommand(dbListCmd, dbGetCmd, dbCreateCmd, dbRegisterCmd, dbTestConnCmd, dbDeleteCmd, dbActionCmd, dbBackupCmd, dbRestoreCmd, dbDownloadCmd)
 }

app/backend/internal/database/sqlcdb/databases.sql.go

@@ -88,6 +88,52 @@ func (q *Queries) CreateDatabaseService(ctx context.Context, arg CreateDatabaseS
 	return err
 }
 
+const createExternalDatabaseService = `-- name: CreateExternalDatabaseService :exec
+INSERT INTO database_services (id, user_id, name, type, status, version, plan, region,
+    provider, external_host, external_port, external_name, external_username, external_password, external_ssl,
+    created_at, updated_at)
+VALUES ($1, $2, $3, $4, 'running', $5, $6, $7, 'external', $8, $9, $10, $11, $12, $13, $14, $15)
+`
+
+type CreateExternalDatabaseServiceParams struct {
+	ID               string         `json:"id"`
+	UserID           string         `json:"user_id"`
+	Name             string         `json:"name"`
+	Type             string         `json:"type"`
+	Version          string         `json:"version"`
+	Plan             string         `json:"plan"`
+	Region           string         `json:"region"`
+	ExternalHost     sql.NullString `json:"external_host"`
+	ExternalPort     sql.NullInt32  `json:"external_port"`
+	ExternalName     sql.NullString `json:"external_name"`
+	ExternalUsername sql.NullString `json:"external_username"`
+	ExternalPassword string         `json:"external_password"`
+	ExternalSsl      bool           `json:"external_ssl"`
+	CreatedAt        sql.NullTime   `json:"created_at"`
+	UpdatedAt        sql.NullTime   `json:"updated_at"`
+}
+
+func (q *Queries) CreateExternalDatabaseService(ctx context.Context, arg CreateExternalDatabaseServiceParams) error {
+	_, err := q.db.ExecContext(ctx, createExternalDatabaseService,
+		arg.ID,
+		arg.UserID,
+		arg.Name,
+		arg.Type,
+		arg.Version,
+		arg.Plan,
+		arg.Region,
+		arg.ExternalHost,
+		arg.ExternalPort,
+		arg.ExternalName,
+		arg.ExternalUsername,
+		arg.ExternalPassword,
+		arg.ExternalSsl,
+		arg.CreatedAt,
+		arg.UpdatedAt,
+	)
+	return err
+}
+
 const databaseServiceExistsByIDAndUser = `-- name: DatabaseServiceExistsByIDAndUser :one
 SELECT EXISTS(
   SELECT 1 FROM database_services WHERE id = $1 AND user_id = $2
@@ -150,7 +196,7 @@ func (q *Queries) GetDatabaseBackupByIDAndDatabaseAndUser(ctx context.Context, a
 }
 
 const getDatabaseServiceByID = `-- name: GetDatabaseServiceByID :one
-SELECT id, user_id, name, type, status, version, plan, region, connection_url, backup_schedule, next_backup_at, created_at, updated_at
+SELECT database_services.id, database_services.user_id, database_services.name, database_services.type, database_services.status, database_services.version, database_services.plan, database_services.region, database_services.connection_url, database_services.backup_schedule, database_services.next_backup_at, database_services.provider, database_services.external_host, database_services.external_port, database_services.external_name, database_services.external_username, database_services.external_password, database_services.external_ssl, database_services.created_at, database_services.updated_at
 FROM database_services
 WHERE id = $1
 `
@@ -170,6 +216,13 @@ func (q *Queries) GetDatabaseServiceByID(ctx context.Context, id string) (Databa
 		&i.ConnectionUrl,
 		&i.BackupSchedule,
 		&i.NextBackupAt,
+		&i.Provider,
+		&i.ExternalHost,
+		&i.ExternalPort,
+		&i.ExternalName,
+		&i.ExternalUsername,
+		&i.ExternalPassword,
+		&i.ExternalSsl,
 		&i.CreatedAt,
 		&i.UpdatedAt,
 	)
@@ -177,7 +230,7 @@ func (q *Queries) GetDatabaseServiceByID(ctx context.Context, id string) (Databa
 }
 
 const getDatabaseServiceByIDAndUser = `-- name: GetDatabaseServiceByIDAndUser :one
-SELECT id, user_id, name, type, status, version, plan, region, connection_url, backup_schedule, next_backup_at, created_at, updated_at
+SELECT database_services.id, database_services.user_id, database_services.name, database_services.type, database_services.status, database_services.version, database_services.plan, database_services.region, database_services.connection_url, database_services.backup_schedule, database_services.next_backup_at, database_services.provider, database_services.external_host, database_services.external_port, database_services.external_name, database_services.external_username, database_services.external_password, database_services.external_ssl, database_services.created_at, database_services.updated_at
 FROM database_services
 WHERE id = $1 AND user_id = $2
 `
@@ -202,6 +255,13 @@ func (q *Queries) GetDatabaseServiceByIDAndUser(ctx context.Context, arg GetData
 		&i.ConnectionUrl,
 		&i.BackupSchedule,
 		&i.NextBackupAt,
+		&i.Provider,
+		&i.ExternalHost,
+		&i.ExternalPort,
+		&i.ExternalName,
+		&i.ExternalUsername,
+		&i.ExternalPassword,
+		&i.ExternalSsl,
 		&i.CreatedAt,
 		&i.UpdatedAt,
 	)
@@ -222,7 +282,7 @@ func (q *Queries) GetDatabaseServiceOwnerID(ctx context.Context, id string) (str
 }
 
 const listAllDatabaseServices = `-- name: ListAllDatabaseServices :many
-SELECT id, user_id, name, type, status, version, plan, region, connection_url, backup_schedule, next_backup_at, created_at, updated_at
+SELECT database_services.id, database_services.user_id, database_services.name, database_services.type, database_services.status, database_services.version, database_services.plan, database_services.region, database_services.connection_url, database_services.backup_schedule, database_services.next_backup_at, database_services.provider, database_services.external_host, database_services.external_port, database_services.external_name, database_services.external_username, database_services.external_password, database_services.external_ssl, database_services.created_at, database_services.updated_at
 FROM database_services
 ORDER BY created_at DESC
 `
@@ -248,6 +308,13 @@ func (q *Queries) ListAllDatabaseServices(ctx context.Context) ([]DatabaseServic
 			&i.ConnectionUrl,
 			&i.BackupSchedule,
 			&i.NextBackupAt,
+			&i.Provider,
+			&i.ExternalHost,
+			&i.ExternalPort,
+			&i.ExternalName,
+			&i.ExternalUsername,
+			&i.ExternalPassword,
+			&i.ExternalSsl,
 			&i.CreatedAt,
 			&i.UpdatedAt,
 		); err != nil {
@@ -311,7 +378,7 @@ func (q *Queries) ListDatabaseBackupsByDatabaseAndUser(ctx context.Context, arg
 }
 
 const listDatabaseServicesByUser = `-- name: ListDatabaseServicesByUser :many
-SELECT id, user_id, name, type, status, version, plan, region, connection_url, backup_schedule, next_backup_at, created_at, updated_at
+SELECT database_services.id, database_services.user_id, database_services.name, database_services.type, database_services.status, database_services.version, database_services.plan, database_services.region, database_services.connection_url, database_services.backup_schedule, database_services.next_backup_at, database_services.provider, database_services.external_host, database_services.external_port, database_services.external_name, database_services.external_username, database_services.external_password, database_services.external_ssl, database_services.created_at, database_services.updated_at
 FROM database_services
 WHERE user_id = $1
 ORDER BY created_at DESC
@@ -338,6 +405,13 @@ func (q *Queries) ListDatabaseServicesByUser(ctx context.Context, userID string)
 			&i.ConnectionUrl,
 			&i.BackupSchedule,
 			&i.NextBackupAt,
+			&i.Provider,
+			&i.ExternalHost,
+			&i.ExternalPort,
+			&i.ExternalName,
+			&i.ExternalUsername,
+			&i.ExternalPassword,
+			&i.ExternalSsl,
 			&i.CreatedAt,
 			&i.UpdatedAt,
 		); err != nil {

app/backend/internal/database/sqlcdb/models.go

@@ -80,19 +80,26 @@ type DatabaseBackup struct {
 }
 
 type DatabaseService struct {
-	ID             string         `json:"id"`
-	UserID         string         `json:"user_id"`
-	Name           string         `json:"name"`
-	Type           string         `json:"type"`
-	Status         string         `json:"status"`
-	Version        string         `json:"version"`
-	Plan           string         `json:"plan"`
-	Region         string         `json:"region"`
-	ConnectionUrl  sql.NullString `json:"connection_url"`
-	BackupSchedule sql.NullString `json:"backup_schedule"`
-	NextBackupAt   sql.NullTime   `json:"next_backup_at"`
-	CreatedAt      sql.NullTime   `json:"created_at"`
-	UpdatedAt      sql.NullTime   `json:"updated_at"`
+	ID               string         `json:"id"`
+	UserID           string         `json:"user_id"`
+	Name             string         `json:"name"`
+	Type             string         `json:"type"`
+	Status           string         `json:"status"`
+	Version          string         `json:"version"`
+	Plan             string         `json:"plan"`
+	Region           string         `json:"region"`
+	ConnectionUrl    sql.NullString `json:"connection_url"`
+	BackupSchedule   sql.NullString `json:"backup_schedule"`
+	NextBackupAt     sql.NullTime   `json:"next_backup_at"`
+	Provider         string         `json:"provider"`
+	ExternalHost     sql.NullString `json:"external_host"`
+	ExternalPort     sql.NullInt32  `json:"external_port"`
+	ExternalName     sql.NullString `json:"external_name"`
+	ExternalUsername sql.NullString `json:"external_username"`
+	ExternalPassword string         `json:"external_password"`
+	ExternalSsl      bool           `json:"external_ssl"`
+	CreatedAt        sql.NullTime   `json:"created_at"`
+	UpdatedAt        sql.NullTime   `json:"updated_at"`
 }
 
 type Deployment struct {
@@ -167,6 +174,17 @@ type ProjectMember struct {
 	CreatedAt sql.NullTime `json:"created_at"`
 }
 
+type Registry struct {
+	ID        uuid.UUID `json:"id"`
+	OwnerID   uuid.UUID `json:"owner_id"`
+	Name      string    `json:"name"`
+	Host      string    `json:"host"`
+	Username  string    `json:"username"`
+	Password  string    `json:"password"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+}
+
 type Service struct {
 	ID              uuid.UUID       `json:"id"`
 	Name            string          `json:"name"`
@@ -204,6 +222,11 @@ type Service struct {
 	Volumes         json.RawMessage `json:"volumes"`
 	MaintenanceMode bool            `json:"maintenance_mode"`
 	BasicAuthUsers  string          `json:"basic_auth_users"`
+	Builder         string          `json:"builder"`
+	CpuReserve      string          `json:"cpu_reserve"`
+	MemoryReserve   string          `json:"memory_reserve"`
+	StaticBuildCmd  string          `json:"static_build_cmd"`
+	StaticDir       string          `json:"static_dir"`
 }
 
 type ServiceDomain struct {

app/backend/internal/database/sqlcdb/querier.go

@@ -22,6 +22,7 @@ type Querier interface {
 	CreateContainer(ctx context.Context, arg CreateContainerParams) (ContainerInstance, error)
 	CreateDatabaseBackup(ctx context.Context, arg CreateDatabaseBackupParams) error
 	CreateDatabaseService(ctx context.Context, arg CreateDatabaseServiceParams) error
+	CreateExternalDatabaseService(ctx context.Context, arg CreateExternalDatabaseServiceParams) error
 	CreateNotification(ctx context.Context, arg CreateNotificationParams) error
 	CreateProject(ctx context.Context, arg CreateProjectParams) (Project, error)
 	CreateServiceFromTemplate(ctx context.Context, arg CreateServiceFromTemplateParams) error

app/backend/internal/mcpserver/server.go

@@ -99,6 +99,9 @@ func init() {
 	register(spec{"containr_databases_list", "List managed databases", "GET", "/databases", nil, nil, false})
 	register(spec{"containr_databases_get", "Get a database (connection URL included)", "GET", "/databases/{id}", []string{"id"}, nil, false})
 	register(spec{"containr_databases_create", "Provision a managed database. Args: name, type (postgres|mysql|mariadb|mongodb|redis|dragonfly|clickhouse).", "POST", "/databases", nil, nil, false})
+	register(spec{"containr_databases_register_external", "Register a database hosted elsewhere — probed first, password stored encrypted. Args: name (required), type (required), host (required), port, database, username, password, ssl.", "POST", "/databases/register-external", nil, []string{"name", "type", "host"}, false})
+	register(spec{"containr_databases_test_connection", "Probe a DB connection ad-hoc. Args: type, host (required), port, database, username, password, ssl.", "POST", "/databases/test-connection", nil, []string{"type", "host"}, false})
+	register(spec{"containr_databases_test_connection_by_id", "Re-probe a registered external database with its stored credentials. Args: id.", "POST", "/databases/{id}/test-connection", []string{"id"}, nil, false})
 	register(spec{"containr_databases_action", "Start/stop/restart a database. Args: id, action.", "POST", "/databases/{id}/action", []string{"id"}, []string{"action"}, false})
 	register(spec{"containr_databases_backup", "Take a manual backup snapshot", "POST", "/databases/{id}/backup", []string{"id"}, nil, false})
 	register(spec{"containr_databases_restore", "Restore a database from a backup — overwrites current data. Requires confirm:true.", "POST", "/databases/{id}/restore", []string{"id"}, []string{"backup_id"}, true})