feat(provisioner): add optional PVC support for sandbox volumes (#2020)

* feat(provisioner): add optional PVC support for sandbox volumes (#1978)

  Add SKILLS_PVC_NAME and USERDATA_PVC_NAME env vars to allow sandbox
  Pods to use PersistentVolumeClaims instead of hostPath volumes. This
  prevents data loss in production when pods are rescheduled across nodes.

  When USERDATA_PVC_NAME is set, a subPath of threads/{thread_id}/user-data
  is used so a single PVC can serve multiple threads. Falls back to hostPath
  when the new env vars are not set, preserving backward compatibility.

* add unit test for provisioner pvc volumes

* refactor: extract shared provisioner_module fixture to conftest.py

Agent-Logs-Url: https://github.com/bytedance/deer-flow/sessions/e7ccf708-c6ba-40e4-844a-b526bdb249dd

Co-authored-by: WillemJiang <219644+WillemJiang@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: JeffJiang <for-eleven@hotmail.com>

backend/tests/conftest.py

@@ -4,10 +4,13 @@ Sets up sys.path and pre-mocks modules that would cause circular import
 issues when unit-testing lightweight config/registry code in isolation.
 """
 
+import importlib.util
 import sys
 from pathlib import Path
 from unittest.mock import MagicMock
 
+import pytest
+
 # Make 'app' and 'deerflow' importable from any working directory
 sys.path.insert(0, str(Path(__file__).parent.parent))
 sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "scripts"))
@@ -32,3 +35,21 @@ _executor_mock.MAX_CONCURRENT_SUBAGENTS = 3
 _executor_mock.get_background_task_result = MagicMock()
 
 sys.modules["deerflow.subagents.executor"] = _executor_mock
+
+
+@pytest.fixture()
+def provisioner_module():
+    """Load docker/provisioner/app.py as an importable test module.
+
+    Shared by test_provisioner_kubeconfig and test_provisioner_pvc_volumes so
+    that any change to the provisioner entry-point path or module name only
+    needs to be updated in one place.
+    """
+    repo_root = Path(__file__).resolve().parents[2]
+    module_path = repo_root / "docker" / "provisioner" / "app.py"
+    spec = importlib.util.spec_from_file_location("provisioner_app_test", module_path)
+    assert spec is not None
+    assert spec.loader is not None
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module

backend/tests/test_provisioner_kubeconfig.py

@@ -2,25 +2,9 @@
 
 from __future__ import annotations
 
-import importlib.util
-from pathlib import Path
 
-
+def test_wait_for_kubeconfig_rejects_directory(tmp_path, provisioner_module):
-def _load_provisioner_module():
-    """Load docker/provisioner/app.py as an importable test module."""
-    repo_root = Path(__file__).resolve().parents[2]
-    module_path = repo_root / "docker" / "provisioner" / "app.py"
-    spec = importlib.util.spec_from_file_location("provisioner_app_test", module_path)
-    assert spec is not None
-    assert spec.loader is not None
-    module = importlib.util.module_from_spec(spec)
-    spec.loader.exec_module(module)
-    return module
-
-
-def test_wait_for_kubeconfig_rejects_directory(tmp_path):
     """Directory mount at kubeconfig path should fail fast with clear error."""
-    provisioner_module = _load_provisioner_module()
     kubeconfig_dir = tmp_path / "config_dir"
     kubeconfig_dir.mkdir()
 
@@ -33,9 +17,8 @@ def test_wait_for_kubeconfig_rejects_directory(tmp_path):
         assert "directory" in str(exc)
 
 
-def test_wait_for_kubeconfig_accepts_file(tmp_path):
+def test_wait_for_kubeconfig_accepts_file(tmp_path, provisioner_module):
     """Regular file mount should pass readiness wait."""
-    provisioner_module = _load_provisioner_module()
     kubeconfig_file = tmp_path / "config"
     kubeconfig_file.write_text("apiVersion: v1\n")
 
@@ -45,9 +28,8 @@ def test_wait_for_kubeconfig_accepts_file(tmp_path):
     provisioner_module._wait_for_kubeconfig(timeout=1)
 
 
-def test_init_k8s_client_rejects_directory_path(tmp_path):
+def test_init_k8s_client_rejects_directory_path(tmp_path, provisioner_module):
     """KUBECONFIG_PATH that resolves to a directory should be rejected."""
-    provisioner_module = _load_provisioner_module()
     kubeconfig_dir = tmp_path / "config_dir"
     kubeconfig_dir.mkdir()
 
@@ -60,9 +42,8 @@ def test_init_k8s_client_rejects_directory_path(tmp_path):
         assert "expected a file" in str(exc)
 
 
-def test_init_k8s_client_uses_file_kubeconfig(tmp_path, monkeypatch):
+def test_init_k8s_client_uses_file_kubeconfig(tmp_path, monkeypatch, provisioner_module):
     """When file exists, provisioner should load kubeconfig file path."""
-    provisioner_module = _load_provisioner_module()
     kubeconfig_file = tmp_path / "config"
     kubeconfig_file.write_text("apiVersion: v1\n")
 
@@ -90,9 +71,8 @@ def test_init_k8s_client_uses_file_kubeconfig(tmp_path, monkeypatch):
     assert result == "core-v1"
 
 
-def test_init_k8s_client_falls_back_to_incluster_when_missing(tmp_path, monkeypatch):
+def test_init_k8s_client_falls_back_to_incluster_when_missing(tmp_path, monkeypatch, provisioner_module):
     """When kubeconfig file is missing, in-cluster config should be attempted."""
-    provisioner_module = _load_provisioner_module()
     missing_path = tmp_path / "missing-config"
 
     calls: dict[str, int] = {"incluster": 0}

backend/tests/test_provisioner_pvc_volumes.py

@@ -0,0 +1,158 @@
+"""Regression tests for provisioner PVC volume support."""
+
+
+# ── _build_volumes ─────────────────────────────────────────────────────
+
+
+class TestBuildVolumes:
+    """Tests for _build_volumes: PVC vs hostPath selection."""
+
+    def test_default_uses_hostpath_for_skills(self, provisioner_module):
+        """When SKILLS_PVC_NAME is empty, skills volume should use hostPath."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        volumes = provisioner_module._build_volumes("thread-1")
+        skills_vol = volumes[0]
+        assert skills_vol.host_path is not None
+        assert skills_vol.host_path.path == provisioner_module.SKILLS_HOST_PATH
+        assert skills_vol.host_path.type == "Directory"
+        assert skills_vol.persistent_volume_claim is None
+
+    def test_default_uses_hostpath_for_userdata(self, provisioner_module):
+        """When USERDATA_PVC_NAME is empty, user-data volume should use hostPath."""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        volumes = provisioner_module._build_volumes("thread-1")
+        userdata_vol = volumes[1]
+        assert userdata_vol.host_path is not None
+        assert userdata_vol.persistent_volume_claim is None
+
+    def test_hostpath_userdata_includes_thread_id(self, provisioner_module):
+        """hostPath user-data path should include thread_id."""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        volumes = provisioner_module._build_volumes("my-thread-42")
+        userdata_vol = volumes[1]
+        path = userdata_vol.host_path.path
+        assert "my-thread-42" in path
+        assert path.endswith("user-data")
+        assert userdata_vol.host_path.type == "DirectoryOrCreate"
+
+    def test_skills_pvc_overrides_hostpath(self, provisioner_module):
+        """When SKILLS_PVC_NAME is set, skills volume should use PVC."""
+        provisioner_module.SKILLS_PVC_NAME = "my-skills-pvc"
+        volumes = provisioner_module._build_volumes("thread-1")
+        skills_vol = volumes[0]
+        assert skills_vol.persistent_volume_claim is not None
+        assert skills_vol.persistent_volume_claim.claim_name == "my-skills-pvc"
+        assert skills_vol.persistent_volume_claim.read_only is True
+        assert skills_vol.host_path is None
+
+    def test_userdata_pvc_overrides_hostpath(self, provisioner_module):
+        """When USERDATA_PVC_NAME is set, user-data volume should use PVC."""
+        provisioner_module.USERDATA_PVC_NAME = "my-userdata-pvc"
+        volumes = provisioner_module._build_volumes("thread-1")
+        userdata_vol = volumes[1]
+        assert userdata_vol.persistent_volume_claim is not None
+        assert userdata_vol.persistent_volume_claim.claim_name == "my-userdata-pvc"
+        assert userdata_vol.host_path is None
+
+    def test_both_pvc_set(self, provisioner_module):
+        """When both PVC names are set, both volumes use PVC."""
+        provisioner_module.SKILLS_PVC_NAME = "skills-pvc"
+        provisioner_module.USERDATA_PVC_NAME = "userdata-pvc"
+        volumes = provisioner_module._build_volumes("thread-1")
+        assert volumes[0].persistent_volume_claim is not None
+        assert volumes[1].persistent_volume_claim is not None
+
+    def test_returns_two_volumes(self, provisioner_module):
+        """Should always return exactly two volumes."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        assert len(provisioner_module._build_volumes("t")) == 2
+
+        provisioner_module.SKILLS_PVC_NAME = "a"
+        provisioner_module.USERDATA_PVC_NAME = "b"
+        assert len(provisioner_module._build_volumes("t")) == 2
+
+    def test_volume_names_are_stable(self, provisioner_module):
+        """Volume names must stay 'skills' and 'user-data'."""
+        volumes = provisioner_module._build_volumes("thread-1")
+        assert volumes[0].name == "skills"
+        assert volumes[1].name == "user-data"
+
+
+# ── _build_volume_mounts ───────────────────────────────────────────────
+
+
+class TestBuildVolumeMounts:
+    """Tests for _build_volume_mounts: mount paths and subPath behavior."""
+
+    def test_default_no_subpath(self, provisioner_module):
+        """hostPath mode should not set sub_path on user-data mount."""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        userdata_mount = mounts[1]
+        assert userdata_mount.sub_path is None
+
+    def test_pvc_sets_subpath(self, provisioner_module):
+        """PVC mode should set sub_path to threads/{thread_id}/user-data."""
+        provisioner_module.USERDATA_PVC_NAME = "my-pvc"
+        mounts = provisioner_module._build_volume_mounts("thread-42")
+        userdata_mount = mounts[1]
+        assert userdata_mount.sub_path == "threads/thread-42/user-data"
+
+    def test_skills_mount_read_only(self, provisioner_module):
+        """Skills mount should always be read-only."""
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        assert mounts[0].read_only is True
+
+    def test_userdata_mount_read_write(self, provisioner_module):
+        """User-data mount should always be read-write."""
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        assert mounts[1].read_only is False
+
+    def test_mount_paths_are_stable(self, provisioner_module):
+        """Mount paths must stay /mnt/skills and /mnt/user-data."""
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        assert mounts[0].mount_path == "/mnt/skills"
+        assert mounts[1].mount_path == "/mnt/user-data"
+
+    def test_mount_names_match_volumes(self, provisioner_module):
+        """Mount names should match the volume names."""
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        assert mounts[0].name == "skills"
+        assert mounts[1].name == "user-data"
+
+    def test_returns_two_mounts(self, provisioner_module):
+        """Should always return exactly two mounts."""
+        assert len(provisioner_module._build_volume_mounts("t")) == 2
+
+
+# ── _build_pod integration ─────────────────────────────────────────────
+
+
+class TestBuildPodVolumes:
+    """Integration: _build_pod should wire volumes and mounts correctly."""
+
+    def test_pod_spec_has_volumes(self, provisioner_module):
+        """Pod spec should contain exactly 2 volumes."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        pod = provisioner_module._build_pod("sandbox-1", "thread-1")
+        assert len(pod.spec.volumes) == 2
+
+    def test_pod_spec_has_volume_mounts(self, provisioner_module):
+        """Container should have exactly 2 volume mounts."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        pod = provisioner_module._build_pod("sandbox-1", "thread-1")
+        assert len(pod.spec.containers[0].volume_mounts) == 2
+
+    def test_pod_pvc_mode(self, provisioner_module):
+        """Pod should use PVC volumes when PVC names are configured."""
+        provisioner_module.SKILLS_PVC_NAME = "skills-pvc"
+        provisioner_module.USERDATA_PVC_NAME = "userdata-pvc"
+        pod = provisioner_module._build_pod("sandbox-1", "thread-1")
+        assert pod.spec.volumes[0].persistent_volume_claim is not None
+        assert pod.spec.volumes[1].persistent_volume_claim is not None
+        # subPath should be set on user-data mount
+        userdata_mount = pod.spec.containers[0].volume_mounts[1]
+        assert userdata_mount.sub_path == "threads/thread-1/user-data"

docker/docker-compose-dev.yaml

@@ -36,6 +36,11 @@ services:
       #   export DEER_FLOW_ROOT=/absolute/path/to/deer-flow
       - SKILLS_HOST_PATH=${DEER_FLOW_ROOT}/skills
       - THREADS_HOST_PATH=${DEER_FLOW_ROOT}/backend/.deer-flow/threads
+      # Production: use PVC instead of hostPath to avoid data loss on node failure.
+      # When set, hostPath vars above are ignored for the corresponding volume.
+      # USERDATA_PVC_NAME uses subPath (threads/{thread_id}/user-data) automatically.
+      # - SKILLS_PVC_NAME=deer-flow-skills-pvc
+      # - USERDATA_PVC_NAME=deer-flow-userdata-pvc
       - KUBECONFIG_PATH=/root/.kube/config
       - NODE_HOST=host.docker.internal
       # Override K8S API server URL since kubeconfig uses 127.0.0.1

docker/provisioner/README.md

@@ -137,6 +137,8 @@ The provisioner is configured via environment variables (set in [docker-compose-
 | `SANDBOX_IMAGE` | `enterprise-public-cn-beijing.cr.volces.com/vefaas-public/all-in-one-sandbox:latest` | Container image for sandbox Pods |
 | `SKILLS_HOST_PATH` | - | **Host machine** path to skills directory (must be absolute) |
 | `THREADS_HOST_PATH` | - | **Host machine** path to threads data directory (must be absolute) |
+| `SKILLS_PVC_NAME` | empty (use hostPath) | PVC name for skills volume; when set, sandbox Pods use PVC instead of hostPath |
+| `USERDATA_PVC_NAME` | empty (use hostPath) | PVC name for user-data volume; when set, uses PVC with `subPath: threads/{thread_id}/user-data` |
 | `KUBECONFIG_PATH` | `/root/.kube/config` | Path to kubeconfig **inside** the provisioner container |
 | `NODE_HOST` | `host.docker.internal` | Hostname that backend containers use to reach host NodePorts |
 | `K8S_API_SERVER` | (from kubeconfig) | Override K8s API server URL (e.g., `https://host.docker.internal:26443`) |
@@ -309,7 +311,7 @@ docker exec deer-flow-gateway curl -s $SANDBOX_URL/v1/sandbox
 
 ## Security Considerations
 
-1. **HostPath Volumes**: The provisioner mounts host directories into sandbox Pods. Ensure these paths contain only trusted data.
+1. **HostPath Volumes**: The provisioner mounts host directories into sandbox Pods by default. Ensure these paths contain only trusted data. For production, prefer PVC-based volumes (set `SKILLS_PVC_NAME` and `USERDATA_PVC_NAME`) to avoid node-specific data loss risks.
 
 2. **Resource Limits**: Each sandbox Pod has CPU, memory, and storage limits to prevent resource exhaustion.
 
@@ -322,7 +324,7 @@ docker exec deer-flow-gateway curl -s $SANDBOX_URL/v1/sandbox
 ## Future Enhancements
 
 - [ ] Support for custom resource requests/limits per sandbox
-- [ ] PersistentVolume support for larger data requirements
+- [x] PersistentVolume support for larger data requirements
 - [ ] Automatic cleanup of stale sandboxes (timeout-based)
 - [ ] Metrics and monitoring (Prometheus integration)
 - [ ] Multi-cluster support (route to different K8s clusters)

docker/provisioner/app.py

@@ -60,6 +60,8 @@ SANDBOX_IMAGE = os.environ.get(
 )
 SKILLS_HOST_PATH = os.environ.get("SKILLS_HOST_PATH", "/skills")
 THREADS_HOST_PATH = os.environ.get("THREADS_HOST_PATH", "/.deer-flow/threads")
+SKILLS_PVC_NAME = os.environ.get("SKILLS_PVC_NAME", "")
+USERDATA_PVC_NAME = os.environ.get("USERDATA_PVC_NAME", "")
 SAFE_THREAD_ID_PATTERN = r"^[A-Za-z0-9_\-]+$"
 
 # Path to the kubeconfig *inside* the provisioner container.
@@ -243,6 +245,64 @@ def _sandbox_url(node_port: int) -> str:
     return f"http://{NODE_HOST}:{node_port}"
 
 
+def _build_volumes(thread_id: str) -> list[k8s_client.V1Volume]:
+    """Build volume list: PVC when configured, otherwise hostPath."""
+    if SKILLS_PVC_NAME:
+        skills_vol = k8s_client.V1Volume(
+            name="skills",
+            persistent_volume_claim=k8s_client.V1PersistentVolumeClaimVolumeSource(
+                claim_name=SKILLS_PVC_NAME,
+                read_only=True,
+            ),
+        )
+    else:
+        skills_vol = k8s_client.V1Volume(
+            name="skills",
+            host_path=k8s_client.V1HostPathVolumeSource(
+                path=SKILLS_HOST_PATH,
+                type="Directory",
+            ),
+        )
+
+    if USERDATA_PVC_NAME:
+        userdata_vol = k8s_client.V1Volume(
+            name="user-data",
+            persistent_volume_claim=k8s_client.V1PersistentVolumeClaimVolumeSource(
+                claim_name=USERDATA_PVC_NAME,
+            ),
+        )
+    else:
+        userdata_vol = k8s_client.V1Volume(
+            name="user-data",
+            host_path=k8s_client.V1HostPathVolumeSource(
+                path=join_host_path(THREADS_HOST_PATH, thread_id, "user-data"),
+                type="DirectoryOrCreate",
+            ),
+        )
+
+    return [skills_vol, userdata_vol]
+
+
+def _build_volume_mounts(thread_id: str) -> list[k8s_client.V1VolumeMount]:
+    """Build volume mount list, using subPath for PVC user-data."""
+    userdata_mount = k8s_client.V1VolumeMount(
+        name="user-data",
+        mount_path="/mnt/user-data",
+        read_only=False,
+    )
+    if USERDATA_PVC_NAME:
+        userdata_mount.sub_path = f"threads/{thread_id}/user-data"
+
+    return [
+        k8s_client.V1VolumeMount(
+            name="skills",
+            mount_path="/mnt/skills",
+            read_only=True,
+        ),
+        userdata_mount,
+    ]
+
+
 def _build_pod(sandbox_id: str, thread_id: str) -> k8s_client.V1Pod:
     """Construct a Pod manifest for a single sandbox."""
     thread_id = _validate_thread_id(thread_id)
@@ -302,40 +362,14 @@ def _build_pod(sandbox_id: str, thread_id: str) -> k8s_client.V1Pod:
                             "ephemeral-storage": "500Mi",
                         },
                     ),
-                    volume_mounts=[
+                    volume_mounts=_build_volume_mounts(thread_id),
-                        k8s_client.V1VolumeMount(
-                            name="skills",
-                            mount_path="/mnt/skills",
-                            read_only=True,
-                        ),
-                        k8s_client.V1VolumeMount(
-                            name="user-data",
-                            mount_path="/mnt/user-data",
-                            read_only=False,
-                        ),
-                    ],
                     security_context=k8s_client.V1SecurityContext(
                         privileged=False,
                         allow_privilege_escalation=True,
                     ),
                 )
             ],
-            volumes=[
+            volumes=_build_volumes(thread_id),
-                k8s_client.V1Volume(
-                    name="skills",
-                    host_path=k8s_client.V1HostPathVolumeSource(
-                        path=SKILLS_HOST_PATH,
-                        type="Directory",
-                    ),
-                ),
-                k8s_client.V1Volume(
-                    name="user-data",
-                    host_path=k8s_client.V1HostPathVolumeSource(
-                        path=join_host_path(THREADS_HOST_PATH, thread_id, "user-data"),
-                        type="DirectoryOrCreate",
-                    ),
-                ),
-            ],
             restart_policy="Always",
         ),
     )