feat: storage attachments, docker-args triggers, install-time migration

storage:mount and storage:unmount now accept the named-entry form (--container-dir, --phase, --process-type, --volume-subpath, --volume-readonly, --volume-chown), persisting attachments via the property list. The legacy host:container colon form is preserved for back-compat. Storage now emits its own docker-args-deploy and docker-args-run triggers so docker-local apps continue to receive bind mounts even after their data moves out of docker-options. The install trigger walks every app once per upgrade and converts legacy -v lines into legacy-<hash> entries plus attachments, draining the originals from docker-options last so a partial run leaves the old behavior intact. Lifecycle triggers post-delete, post-app-clone-setup, and post-app-rename-setup keep the attachment store in sync with app state.

plugins/storage/triggers.go

@@ -6,11 +6,13 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"strings"
 
 	"github.com/dokku/dokku/plugins/common"
 )
 
-// TriggerInstall sets up the storage plugin on installation
+// TriggerInstall sets up the storage plugin on installation and runs
+// the bulk legacy-mount migration once per upgrade.
 func TriggerInstall() error {
 	storageDir := GetStorageDirectory()
 
@@ -25,6 +27,14 @@ func TriggerInstall() error {
 		return fmt.Errorf("Unable to set storage directory permissions: %s", err.Error())
 	}
 
+	if err := EnsureEntriesDirectory(); err != nil {
+		return err
+	}
+
+	if err := MigrateLegacyMounts(); err != nil {
+		return fmt.Errorf("storage migration failed: %w", err)
+	}
+
 	distro := detectDistro()
 	if distro == "" {
 		return nil
@@ -44,6 +54,44 @@ func TriggerInstall() error {
 	return nil
 }
 
+// TriggerPostDelete clears any attachment list for an app that's being
+// destroyed. Entries are global and survive app deletion.
+func TriggerPostDelete(appName string) error {
+	if appName == "" {
+		return nil
+	}
+	return common.PropertyListWrite(PluginName, appName, AttachmentsProperty, []string{})
+}
+
+// TriggerPostAppCloneSetup copies attachments from the source app to the
+// cloned app. Entries are global so no entry-level work is needed.
+func TriggerPostAppCloneSetup(oldName string, newName string) error {
+	if oldName == "" || newName == "" {
+		return nil
+	}
+	attachments, err := LoadAttachments(oldName)
+	if err != nil {
+		return err
+	}
+	return SaveAttachments(newName, attachments)
+}
+
+// TriggerPostAppRenameSetup moves attachments from the old name to the
+// new name and clears the old.
+func TriggerPostAppRenameSetup(oldName string, newName string) error {
+	if oldName == "" || newName == "" {
+		return nil
+	}
+	attachments, err := LoadAttachments(oldName)
+	if err != nil {
+		return err
+	}
+	if err := SaveAttachments(newName, attachments); err != nil {
+		return err
+	}
+	return common.PropertyListWrite(PluginName, oldName, AttachmentsProperty, []string{})
+}
+
 // detectDistro returns the Linux distribution name
 func detectDistro() string {
 	if runtime.GOOS != "linux" {
@@ -91,3 +139,87 @@ func TriggerStorageList(appName string, phase string, format string) error {
 
 	return nil
 }
+
+// AppMountPair pairs an Attachment with the Entry it references; consumed
+// by scheduler plugins via the storage-app-mounts trigger.
+type AppMountPair struct {
+	Entry      *Entry      `json:"entry"`
+	Attachment *Attachment `json:"attachment"`
+}
+
+// TriggerStorageAppMounts emits the (entry, attachment) pairs an app has
+// for the given phase, in JSON. Schedulers consume this at deploy time.
+func TriggerStorageAppMounts(appName string, phase string) error {
+	if phase == "" {
+		phase = PhaseDeploy
+	}
+	attachments, err := AttachmentsForPhase(appName, phase)
+	if err != nil {
+		return err
+	}
+
+	pairs := []AppMountPair{}
+	for _, attachment := range attachments {
+		entry, err := LoadEntry(attachment.EntryName)
+		if err != nil {
+			return fmt.Errorf("attachment on %q references missing entry %q: %w", appName, attachment.EntryName, err)
+		}
+		pairs = append(pairs, AppMountPair{Entry: entry, Attachment: attachment})
+	}
+
+	output, err := json.Marshal(pairs)
+	if err != nil {
+		return err
+	}
+	fmt.Println(string(output))
+	return nil
+}
+
+// TriggerDockerArgs emits `-v` flags for each docker-local attachment in
+// the requested phase. Plugn concatenates this with docker-options'
+// equivalent trigger output, so docker-local apps continue to receive
+// their bind mounts through the standard pipeline.
+func TriggerDockerArgs(appName string, phase string) error {
+	attachments, err := AttachmentsForPhase(appName, phase)
+	if err != nil {
+		return err
+	}
+
+	for _, attachment := range attachments {
+		entry, err := LoadEntry(attachment.EntryName)
+		if err != nil {
+			return fmt.Errorf("attachment on %q references missing entry %q: %w", appName, attachment.EntryName, err)
+		}
+		if entry.Scheduler != SchedulerDockerLocal {
+			continue
+		}
+		flag := buildDockerVFlag(entry, attachment)
+		if flag == "" {
+			continue
+		}
+		fmt.Printf(" %s", flag)
+	}
+	return nil
+}
+
+// buildDockerVFlag formats the Docker -v argument for a docker-local
+// attachment.
+func buildDockerVFlag(entry *Entry, attachment *Attachment) string {
+	host := entry.HostPath
+	container := attachment.ContainerPath
+	if host == "" || container == "" {
+		return ""
+	}
+	options := []string{}
+	if attachment.Readonly {
+		options = append(options, "ro")
+	}
+	if attachment.VolumeOptions != "" {
+		options = append(options, attachment.VolumeOptions)
+	}
+	flag := fmt.Sprintf("-v %s:%s", host, container)
+	if len(options) > 0 {
+		flag = fmt.Sprintf("%s:%s", flag, strings.Join(options, ","))
+	}
+	return flag
+}