feat: add custom health check commands per app

Add configurable health check commands per app via a new
'healthcheck_command' field. When set, the command is passed
to Docker as a CMD-SHELL health check on the container.
When empty, the image's default health check is used.

Changes:
- Add migration 007 for healthcheck_command column on apps table
- Add HealthcheckCommand field to App model with full CRUD support
- Add buildHealthcheck() to docker client for CMD-SHELL config
- Pass health check command through CreateContainerOptions
- Add health check command input to app create/edit UI forms
- Extract optionalNullString helper to reduce handler complexity
- Update README features list

closes #81

internal/service/app/app.go

@@ -46,13 +46,14 @@ func New(_ fx.Lifecycle, params ServiceParams) (*Service, error) {
 
 // CreateAppInput contains the input for creating an app.
 type CreateAppInput struct {
-	Name           string
-	RepoURL        string
-	Branch         string
-	DockerfilePath string
-	DockerNetwork  string
-	NtfyTopic      string
-	SlackWebhook   string
+	Name               string
+	RepoURL            string
+	Branch             string
+	DockerfilePath     string
+	DockerNetwork      string
+	NtfyTopic          string
+	SlackWebhook       string
+	HealthcheckCommand string
 }
 
 // CreateApp creates a new application with generated SSH keys and webhook secret.
@@ -100,6 +101,10 @@ func (svc *Service) CreateApp(
 		app.SlackWebhook = sql.NullString{String: input.SlackWebhook, Valid: true}
 	}
 
+	if input.HealthcheckCommand != "" {
+		app.HealthcheckCommand = sql.NullString{String: input.HealthcheckCommand, Valid: true}
+	}
+
 	saveErr := app.Save(ctx)
 	if saveErr != nil {
 		return nil, fmt.Errorf("failed to save app: %w", saveErr)
@@ -112,13 +117,14 @@ func (svc *Service) CreateApp(
 
 // UpdateAppInput contains the input for updating an app.
 type UpdateAppInput struct {
-	Name           string
-	RepoURL        string
-	Branch         string
-	DockerfilePath string
-	DockerNetwork  string
-	NtfyTopic      string
-	SlackWebhook   string
+	Name               string
+	RepoURL            string
+	Branch             string
+	DockerfilePath     string
+	DockerNetwork      string
+	NtfyTopic          string
+	SlackWebhook       string
+	HealthcheckCommand string
 }
 
 // UpdateApp updates an existing application.
@@ -144,6 +150,10 @@ func (svc *Service) UpdateApp(
 		String: input.SlackWebhook,
 		Valid:  input.SlackWebhook != "",
 	}
+	app.HealthcheckCommand = sql.NullString{
+		String: input.HealthcheckCommand,
+		Valid:  input.HealthcheckCommand != "",
+	}
 
 	saveErr := app.Save(ctx)
 	if saveErr != nil {

internal/service/deploy/deploy.go

@@ -1094,14 +1094,20 @@ func (svc *Service) buildContainerOptions(
 		network = app.DockerNetwork.String
 	}
 
+	healthcheckCmd := ""
+	if app.HealthcheckCommand.Valid {
+		healthcheckCmd = app.HealthcheckCommand.String
+	}
+
 	return docker.CreateContainerOptions{
-		Name:    "upaas-" + app.Name,
-		Image:   imageID.String(),
-		Env:     envMap,
-		Labels:  buildLabelMap(app, labels),
-		Volumes: buildVolumeMounts(volumes),
-		Ports:   buildPortMappings(ports),
-		Network: network,
+		Name:               "upaas-" + app.Name,
+		Image:              imageID.String(),
+		Env:                envMap,
+		Labels:             buildLabelMap(app, labels),
+		Volumes:            buildVolumeMounts(volumes),
+		Ports:              buildPortMappings(ports),
+		Network:            network,
+		HealthcheckCommand: healthcheckCmd,
 	}, nil
 }
 

internal/service/deploy/deploy_container_test.go

@@ -2,6 +2,7 @@ package deploy_test
 
 import (
 	"context"
+	"database/sql"
 	"log/slog"
 	"os"
 	"testing"
@@ -43,3 +44,64 @@ func TestBuildContainerOptionsUsesImageID(t *testing.T) {
 		t.Errorf("expected Name=%q, got %q", "upaas-myapp", opts.Name)
 	}
 }
+
+func TestBuildContainerOptionsHealthcheckSet(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDatabase(t)
+
+	app := models.NewApp(db)
+	app.Name = "hc-app"
+	app.HealthcheckCommand = sql.NullString{
+		String: "curl -f http://localhost:8080/healthz || exit 1",
+		Valid:  true,
+	}
+
+	err := app.Save(context.Background())
+	if err != nil {
+		t.Fatalf("failed to save app: %v", err)
+	}
+
+	log := slog.New(slog.NewTextHandler(os.Stderr, nil))
+	svc := deploy.NewTestService(log)
+
+	opts, err := svc.BuildContainerOptionsExported(
+		context.Background(), app, "sha256:test",
+	)
+	if err != nil {
+		t.Fatalf("buildContainerOptions returned error: %v", err)
+	}
+
+	expected := "curl -f http://localhost:8080/healthz || exit 1"
+	if opts.HealthcheckCommand != expected {
+		t.Errorf("expected HealthcheckCommand=%q, got %q", expected, opts.HealthcheckCommand)
+	}
+}
+
+func TestBuildContainerOptionsHealthcheckEmpty(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDatabase(t)
+
+	app := models.NewApp(db)
+	app.Name = "no-hc-app"
+
+	err := app.Save(context.Background())
+	if err != nil {
+		t.Fatalf("failed to save app: %v", err)
+	}
+
+	log := slog.New(slog.NewTextHandler(os.Stderr, nil))
+	svc := deploy.NewTestService(log)
+
+	opts, err := svc.BuildContainerOptionsExported(
+		context.Background(), app, "sha256:test",
+	)
+	if err != nil {
+		t.Fatalf("buildContainerOptions returned error: %v", err)
+	}
+
+	if opts.HealthcheckCommand != "" {
+		t.Errorf("expected empty HealthcheckCommand, got %q", opts.HealthcheckCommand)
+	}
+}