feat(runtime-templates): add support for runtime templates in bind mounts (#412)

internal/machine/docker/server.go

@@ -538,6 +538,15 @@ func (s *Server) CreateServiceContainer(
 		containerName = fmt.Sprintf("%s-%s", spec.Name, suffix)
 	}
 
+	desiredSpec := spec
+	renderedSpec, renderErr := desiredSpec.RenderRuntimeTemplates(api.RuntimeTemplateContext{
+		Container: api.RuntimeTemplateContainerContext{Name: containerName},
+	})
+	if renderErr != nil {
+		return nil, status.Errorf(codes.InvalidArgument, "render runtime templates: %v", renderErr)
+	}
+	spec = renderedSpec
+
 	envVars := maps.Clone(spec.Container.Env)
 	if envVars == nil {
 		envVars = make(api.EnvVars)
@@ -745,7 +754,7 @@ func (s *Server) CreateServiceContainer(
 		_ = s.client.ContainerRemove(ctx, resp.ID, container.RemoveOptions{RemoveVolumes: true})
 	}
 
-	specBytes, err := json.Marshal(spec)
+	specBytes, err := json.Marshal(desiredSpec)
 	if err != nil {
 		removeContainer()
 		return nil, status.Errorf(codes.Internal, "marshal service spec: %v", err)

internal/machine/docker/server_runtime_template_test.go

@@ -0,0 +1,53 @@
+package docker
+
+import (
+	"context"
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"github.com/psviderski/uncloud/api/pb"
+	"github.com/psviderski/uncloud/pkg/api"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+	_ "modernc.org/sqlite"
+)
+
+func TestCreateServiceContainer_RejectsRuntimeTemplateError(t *testing.T) {
+	t.Parallel()
+
+	desiredSpec := api.ServiceSpec{
+		Name: "web",
+		Container: api.ContainerSpec{
+			Image: "busybox:latest",
+			VolumeMounts: []api.VolumeMount{
+				{VolumeName: "data", ContainerPath: "/data"},
+			},
+		},
+		Volumes: []api.VolumeSpec{
+			{
+				Name: "data",
+				Type: api.VolumeTypeBind,
+				BindOptions: &api.BindOptions{
+					// Early validation takes the valid branch. Rendering with the real container name takes the invalid one.
+					HostPath: `/host/{{if eq .Container.Name "web-a1b2"}}{{.Container.ID}}{{else}}valid{{end}}`,
+				},
+			},
+		},
+	}
+	specJSON, err := json.Marshal(desiredSpec)
+	require.NoError(t, err)
+
+	server := &Server{}
+	_, err = server.CreateServiceContainer(context.Background(), &pb.CreateServiceContainerRequest{
+		ServiceId:     strings.Repeat("a", 32),
+		ServiceSpec:   specJSON,
+		ContainerName: "web-a1b2",
+	})
+
+	require.Error(t, err)
+	assert.Equal(t, codes.InvalidArgument, status.Code(err))
+	assert.ErrorContains(t, err, "render runtime template in bind volume 'data' host path")
+}