NAS-130339 / 24.10 / Apps filesystem attachment handler (#14113)

* Add filesystem attachment handler for docker service

* Register docker fs attachment delegate

* Add fs attachment delegate for apps

* Be more verbose about the logic where we check if an app is a valid attachment given respective path

src/middlewared/middlewared/plugins/apps/fs_attachments.py

@@ -0,0 +1,61 @@
+from middlewared.common.attachment import FSAttachmentDelegate
+
+
+class AppFSAttachmentDelegate(FSAttachmentDelegate):
+    name = 'apps'
+    title = 'Apps'
+
+    async def query(self, path, enabled, options=None):
+        apps_attached = []
+        for app in await self.middleware.call('app.query'):
+            # We don't want to consider those apps which fit in the following criteria:
+            # - app has no volumes
+            # - app is stopped and we are looking for enabled apps
+            # - app is not stopped and we are looking for disabled apps
+            if not (skip_app := not app['active_workloads']['volumes']):
+                if enabled:
+                    skip_app |= app['state'] == 'STOPPED'
+                else:
+                    skip_app |= app['state'] != 'STOPPED'
+
+            if skip_app:
+                continue
+
+            if await self.middleware.call(
+                'filesystem.is_child', [volume['source'] for volume in app['active_workloads']['volumes']], path
+            ):
+                apps_attached.append({
+                    'id': app['name'],
+                    'name': app['name'],
+                })
+
+        return apps_attached
+
+    async def delete(self, attachments):
+        for attachment in attachments:
+            try:
+                await (await self.middleware.call('app.stop', attachment['id'])).wait(raise_error=True)
+            except Exception:
+                self.middleware.logger.error('Unable to stop %r app', attachment['id'], exc_info=True)
+
+    async def toggle(self, attachments, enabled):
+        # if enabled is true - we are going to ignore that as we don't want to scale up releases
+        # automatically when a path becomes available
+        for attachment in ([] if enabled else attachments):
+            action = 'start' if enabled else 'stop'
+            try:
+                await (await self.middleware.call(f'app.{action}', attachment['id'])).wait(raise_error=True)
+            except Exception:
+                self.middleware.logger.error('Unable to %s %r app', action, attachment['id'], exc_info=True)
+
+    async def stop(self, attachments):
+        await self.toggle(attachments, False)
+
+    async def start(self, attachments):
+        await self.toggle(attachments, True)
+
+
+async def setup(middleware):
+    middleware.create_task(
+        middleware.call('pool.dataset.register_attachment_delegate', AppFSAttachmentDelegate(middleware))
+    )

src/middlewared/middlewared/plugins/docker/attachments.py

@@ -0,0 +1,54 @@
+import os
+
+from middlewared.common.attachment import FSAttachmentDelegate
+
+
+class DockerFSAttachmentDelegate(FSAttachmentDelegate):
+    name = 'docker'
+    title = 'Docker'
+    service = 'docker'
+
+    async def query(self, path, enabled, options=None):
+        results = []
+
+        k8s_config = await self.middleware.call('docker.config')
+        if not k8s_config['pool']:
+            return results
+
+        query_dataset = os.path.relpath(path, '/mnt')
+        if query_dataset in (k8s_config['dataset'], k8s_config['pool']) or query_dataset.startswith(
+            f'{k8s_config["dataset"]}/'
+        ):
+            results.append({'id': k8s_config['pool']})
+
+        return results
+
+    async def get_attachment_name(self, attachment):
+        return attachment['id']
+
+    async def delete(self, attachments):
+        if attachments:
+            await (await self.middleware.call('docker.update', {'pool': None})).wait(raise_error=True)
+
+    async def toggle(self, attachments, enabled):
+        await getattr(self, 'start' if enabled else 'stop')(attachments)
+
+    async def stop(self, attachments):
+        if not attachments:
+            return
+        try:
+            await self.middleware.call('service.stop', self.service)
+        except Exception as e:
+            self.middleware.logger.error('Failed to stop docker: %s', e)
+
+    async def start(self, attachments):
+        if not attachments:
+            return
+        try:
+            await self.middleware.call('docker.state.start_service')
+        except Exception:
+            self.middleware.logger.error('Failed to start docker')
+
+
+async def setup(middleware):
+    await middleware.call('pool.dataset.register_attachment_delegate', DockerFSAttachmentDelegate(middleware))