config.example.json

@@ -24,5 +24,9 @@
   "sfm_http_timeout": 60,
   "sfm_state_file": "",
   "sfm_max_forwards_per_pass": 500,
-  "sfm_max_event_age_days": 365
+  "sfm_max_event_age_days": 365,
+
+  "mirror_api_url": "",
+  "mirror_sfm_url": "",
+  "mirror_sfm_state_file": ""
 }

event_forwarder.py

@@ -692,6 +692,74 @@ def forward_pending(
     return counts
 
 
+# ── Mirror (dual-send) ────────────────────────────────────────────────────────
+
+
+def mirror_reachable(base_url: str, timeout: float = 3.0) -> bool:
+    """Quick liveness probe of a mirror SFM base URL.
+
+    Run before a mirror forward pass so an unreachable mirror can't stall
+    the watcher loop on a per-event HTTP timeout for every pending file.
+    Probes ``<base>/health`` (the SFM server exposes it).  ANY HTTP
+    response — even 404/500 — means the server is up, so proceed; only a
+    connection-level failure (refused / timed out / DNS) counts as down.
+    Best-effort: never raises.
+    """
+    if not base_url:
+        return False
+    url = base_url.rstrip("/") + "/health"
+    try:
+        with urllib.request.urlopen(
+            urllib.request.Request(url, method="GET"), timeout=timeout
+        ):
+            return True
+    except urllib.error.HTTPError:
+        return True   # got a status back → server is alive
+    except Exception:
+        return False  # refused / timeout / DNS / socket → down
+
+
+def mirror_forward_pass(
+    watch_dir: str,
+    mirror_url: str,
+    mirror_state: ForwardState,
+    *,
+    reachable_fn=mirror_reachable,
+    reachable_timeout: float = 3.0,
+    **forward_kwargs: Any,
+) -> Optional[Dict[str, int]]:
+    """One best-effort forwarding pass against a *mirror* SFM server.
+
+    The dual-send entry point.  Wraps :func:`forward_pending` with two
+    properties that keep the mirror from ever harming the primary path:
+
+    1. **Fast-fail reachability guard** — probe ``mirror_url`` first; if
+       it's down, return ``None`` immediately rather than let
+       :func:`forward_pending` block on a per-event timeout for every
+       pending file.
+    2. **Total exception isolation** — any error (probe, forward, state
+       I/O) is swallowed and reported as ``None``.  This function NEVER
+       raises, so the caller's already-completed primary forward is
+       untouched.
+
+    The mirror keeps its OWN ``ForwardState`` file, so its idempotency
+    and retry are independent of the primary's.  Nothing is lost while
+    the mirror is down — skipped events stay pending and are delivered
+    on a later pass once it returns.
+
+    Returns the :func:`forward_pending` counts dict on a completed pass,
+    or ``None`` if the mirror was unreachable or the pass raised.
+    """
+    try:
+        if not mirror_url:
+            return None
+        if not reachable_fn(mirror_url, reachable_timeout):
+            return None
+        return forward_pending(watch_dir, mirror_url, mirror_state, **forward_kwargs)
+    except Exception:
+        return None
+
+
 # ── Seed-state mode (skip historical backfill on first deploy) ────────────────
 
 

series4_ingest.py

@@ -69,6 +69,15 @@ def load_config(config_path: str) -> Dict[str, Any]:
         "sfm_state_file":                   "",      # blank → <log_dir>/thor_forwarded.json
         "sfm_max_forwards_per_pass":        500,
         "sfm_max_event_age_days":           365,
+
+        # Mirror (dual-send) — best-effort second destination, default OFF.
+        # See docs/mirror-dual-send-design.md.  Heartbeat-mirror fires iff
+        # api_url AND mirror_api_url are set; event-mirror runs iff SFM
+        # forwarding is on AND mirror_sfm_url is set.  Own state file →
+        # idempotency independent of the primary.
+        "mirror_api_url":         "",
+        "mirror_sfm_url":         "",
+        "mirror_sfm_state_file":  "",   # blank → <log_dir>/thor_forwarded_mirror.json
     }
 
     with open(config_path, "r", encoding="utf-8") as f:
@@ -329,6 +338,12 @@ def run_watcher(state: Dict[str, Any], stop_event: threading.Event) -> None:
     sfm_state_path        = str(cfg.get("sfm_state_file", "")).strip() or \
         os.path.join(state["log_dir"], "thor_forwarded.json")
 
+    # Mirror (dual-send) config
+    MIRROR_API_URL    = str(cfg.get("mirror_api_url", "")).strip()
+    MIRROR_SFM_URL    = str(cfg.get("mirror_sfm_url", "")).strip()
+    mirror_state_path = str(cfg.get("mirror_sfm_state_file", "")).strip() or \
+        os.path.join(state["log_dir"], "thor_forwarded_mirror.json")
+
     log_message(log_file, ENABLE_LOGGING,
         "[cfg] THORDATA_PATH={} SCAN_INTERVAL={}s API_INTERVAL={}s API={} SFM={}".format(
             THORDATA_PATH, SCAN_INTERVAL, API_INTERVAL, bool(API_URL),
@@ -362,6 +377,24 @@ def run_watcher(state: Dict[str, Any], stop_event: threading.Event) -> None:
     else:
         state["sfm_status"] = "disabled"
 
+    # Mirror event-forward state — independent of the primary's.  Created
+    # only when the primary forwarder is on AND a mirror URL is set.
+    mirror_state_obj: Optional[event_forwarder.ForwardState] = None
+    if sfm_state_obj is not None and MIRROR_SFM_URL:
+        try:
+            mirror_state_obj = event_forwarder.ForwardState(mirror_state_path)
+            log_message(log_file, ENABLE_LOGGING,
+                "[mirror] event mirror ready  url={}  state={}  known={}".format(
+                    MIRROR_SFM_URL, mirror_state_path, mirror_state_obj.count()))
+            print("[MIRROR] event mirror ready  url={}".format(MIRROR_SFM_URL))
+        except Exception as exc:
+            log_message(log_file, ENABLE_LOGGING,
+                "[mirror] event mirror init failed: {}".format(exc))
+            mirror_state_obj = None
+    if MIRROR_API_URL:
+        log_message(log_file, ENABLE_LOGGING,
+            "[mirror] heartbeat mirror enabled  url={}".format(MIRROR_API_URL))
+
     state["last_forward"] = None
     state["last_forward_counts"] = None
 
@@ -419,6 +452,13 @@ def run_watcher(state: Dict[str, Any], stop_event: threading.Event) -> None:
                     payload["log_tail"] = _read_log_tail(log_file, 25)
                     response = send_api_payload(payload, API_URL, API_TIMEOUT)
                     last_api_ts = now_ts
+                    # Best-effort heartbeat mirror — never affects primary.
+                    if MIRROR_API_URL:
+                        try:
+                            send_api_payload(payload, MIRROR_API_URL, API_TIMEOUT)
+                        except Exception as exc:
+                            log_message(log_file, ENABLE_LOGGING,
+                                "[mirror] heartbeat post failed: {}".format(exc))
                     if response is not None:
                         state["api_status"] = "ok"
                         if response.get("update_available"):
@@ -459,6 +499,25 @@ def run_watcher(state: Dict[str, Any], stop_event: threading.Event) -> None:
                         print(msg)
                         log_message(log_file, ENABLE_LOGGING, msg)
 
+                    # Best-effort event mirror — own state, fast-fail guard,
+                    # fully isolated.  Runs after the primary each tick.
+                    if mirror_state_obj is not None:
+                        m_counts = event_forwarder.mirror_forward_pass(
+                            THORDATA_PATH, MIRROR_SFM_URL, mirror_state_obj,
+                            max_age_days=SFM_MAX_AGE_DAYS,
+                            quiescence_seconds=SFM_QUIESCENCE,
+                            missing_report_grace_seconds=SFM_GRACE,
+                            timeout=SFM_HTTP_TIMEOUT,
+                            max_per_pass=SFM_MAX_PER_PASS,
+                            logger=lambda m: log_message(log_file, ENABLE_LOGGING, "[mirror] " + m),
+                        )
+                        if m_counts is None:
+                            log_message(log_file, ENABLE_LOGGING,
+                                "[mirror] forward skipped (unreachable/error): {}".format(MIRROR_SFM_URL))
+                        else:
+                            log_message(log_file, ENABLE_LOGGING,
+                                "[mirror] pass forwarded={forwarded} errors={errors}".format(**m_counts))
+
         except Exception as e:
             err = "[loop-error] {}".format(e)
             print(err)

test_event_forwarder.py

@@ -712,5 +712,134 @@ class TestForwardPending(unittest.TestCase):
             self.assertEqual(len(_FakeImportHandler.received), 2)
 
 
+# ── Mirror (dual-send) ───────────────────────────────────────────────────────
+
+
+class TestMirrorReachable(unittest.TestCase):
+
+    def test_empty_url_is_unreachable(self):
+        self.assertFalse(ef.mirror_reachable("", timeout=1.0))
+
+    def test_dead_port_is_unreachable_and_fast(self):
+        # Nothing listens on 127.0.0.1:1 → connection refused → False,
+        # and it must NOT hang (this is the whole point of the guard).
+        t0 = time.time()
+        self.assertFalse(ef.mirror_reachable("http://127.0.0.1:1", timeout=2.0))
+        self.assertLess(time.time() - t0, 2.5)
+
+    def test_any_http_response_counts_as_reachable(self):
+        # The fake server 501s on GET /health, but it's UP — so reachable.
+        server, base = _start_fake_server()
+        try:
+            self.assertTrue(ef.mirror_reachable(base, timeout=2.0))
+        finally:
+            server.shutdown()
+            server.server_close()
+
+
+class TestMirrorForwardPass(unittest.TestCase):
+    """The dual-send entry point: best-effort, isolated, own state."""
+
+    def setUp(self):
+        _FakeImportHandler.received = []
+        self.server, self.base_url = _start_fake_server()
+
+    def tearDown(self):
+        self.server.shutdown()
+        self.server.server_close()
+
+    def _one_event(self, root: Path) -> None:
+        unit = _make_thordata(root, "Project A", "UM11719")
+        _make_event(unit, "UM11719_20231219163444.IDFW", age_seconds=200, content=b"binary")
+        _make_txt(unit, "UM11719_20231219163444.IDFW", age_seconds=100, content=b"report")
+
+    def test_empty_mirror_url_is_noop(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            root = Path(tmp)
+            self._one_event(root)
+            mstate = ef.ForwardState(str(root / "mirror.json"))
+            self.assertIsNone(ef.mirror_forward_pass(str(root), "", mstate, max_age_days=30))
+            self.assertEqual(len(_FakeImportHandler.received), 0)
+
+    def test_skips_when_unreachable_without_posting(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            root = Path(tmp)
+            self._one_event(root)
+            mstate = ef.ForwardState(str(root / "mirror.json"))
+            result = ef.mirror_forward_pass(
+                str(root), self.base_url, mstate,
+                reachable_fn=lambda url, timeout=3.0: False,   # force "down"
+                max_age_days=30, quiescence_seconds=5,
+                missing_report_grace_seconds=60, timeout=5.0,
+            )
+            self.assertIsNone(result)
+            self.assertEqual(mstate.count(), 0)                # nothing forwarded
+            self.assertEqual(len(_FakeImportHandler.received), 0)   # never POSTed
+
+    def test_forwards_when_reachable_using_its_own_state(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            root = Path(tmp)
+            self._one_event(root)
+            mstate = ef.ForwardState(str(root / "mirror.json"))
+            counts = ef.mirror_forward_pass(
+                str(root), self.base_url, mstate,
+                reachable_fn=lambda url, timeout=3.0: True,
+                max_age_days=30, quiescence_seconds=5,
+                missing_report_grace_seconds=60, timeout=5.0,
+            )
+            self.assertIsNotNone(counts)
+            self.assertEqual(counts["forwarded"], 1)
+            self.assertEqual(mstate.count(), 1)
+            self.assertEqual(len(_FakeImportHandler.received), 1)
+
+    def test_never_raises_when_forward_blows_up(self):
+        # Even if forward_pending raises, the mirror swallows it → None.
+        def _boom(*a, **k):
+            raise RuntimeError("boom")
+        with tempfile.TemporaryDirectory() as tmp:
+            root = Path(tmp)
+            self._one_event(root)
+            mstate = ef.ForwardState(str(root / "mirror.json"))
+            orig = ef.forward_pending
+            ef.forward_pending = _boom
+            try:
+                result = ef.mirror_forward_pass(
+                    str(root), self.base_url, mstate,
+                    reachable_fn=lambda url, timeout=3.0: True,
+                    max_age_days=30,
+                )
+            finally:
+                ef.forward_pending = orig
+            self.assertIsNone(result)
+
+    def test_down_mirror_leaves_primary_state_untouched(self):
+        # The invariant: a real down mirror (via the real reachability
+        # probe) is a fast no-op and the primary forward is unaffected.
+        with tempfile.TemporaryDirectory() as tmp:
+            root = Path(tmp)
+            self._one_event(root)
+
+            primary_state = ef.ForwardState(str(root / "primary.json"))
+            pcounts = ef.forward_pending(
+                str(root), self.base_url, primary_state,
+                max_age_days=30, quiescence_seconds=5,
+                missing_report_grace_seconds=60, timeout=5.0,
+            )
+            self.assertEqual(pcounts["forwarded"], 1)
+            primary_snapshot = primary_state.count()
+
+            mstate = ef.ForwardState(str(root / "mirror.json"))
+            t0 = time.time()
+            result = ef.mirror_forward_pass(
+                str(root), "http://127.0.0.1:1", mstate,   # nothing listens
+                max_age_days=30, quiescence_seconds=5,
+                missing_report_grace_seconds=60, timeout=5.0,
+            )
+            self.assertIsNone(result)
+            self.assertLess(time.time() - t0, 3.5)          # fast-failed, didn't hang
+            self.assertEqual(mstate.count(), 0)
+            self.assertEqual(primary_state.count(), primary_snapshot)   # untouched
+
+
 if __name__ == "__main__":
     unittest.main()

thor_settings_dialog.py

@@ -47,6 +47,11 @@ DEFAULTS = {
     "sfm_state_file":                   "",
     "sfm_max_forwards_per_pass":        500,
     "sfm_max_event_age_days":           365,
+
+    # Mirror (dual-send) — best-effort second destination, default OFF.
+    "mirror_api_url":         "",
+    "mirror_sfm_url":         "",
+    "mirror_sfm_state_file":  "",
 }
 
 
@@ -220,6 +225,14 @@ class SettingsDialog:
         self.var_sfm_max_age_days       = tk.StringVar(value=str(v.get("sfm_max_event_age_days", 365)))
         self.var_sfm_state_file         = tk.StringVar(value=str(v.get("sfm_state_file", "")))
 
+        # Mirror (dual-send) — best-effort second destination
+        raw_mirror = str(v.get("mirror_api_url", ""))
+        if raw_mirror.endswith(_suffix):
+            raw_mirror = raw_mirror[:-len(_suffix)]
+        self.var_mirror_api_url        = tk.StringVar(value=raw_mirror)
+        self.var_mirror_sfm_url        = tk.StringVar(value=str(v.get("mirror_sfm_url", "")))
+        self.var_mirror_sfm_state_file = tk.StringVar(value=str(v.get("mirror_sfm_state_file", "")))
+
     # ── UI construction ───────────────────────────────────────────────────────
 
     def _build_ui(self):
@@ -245,6 +258,7 @@ class SettingsDialog:
         self._build_tab_scanning(nb)
         self._build_tab_logging(nb)
         self._build_tab_forwarding(nb)
+        self._build_tab_mirror(nb)
         self._build_tab_updates(nb)
 
         btn_frame = tk.Frame(outer)
@@ -484,6 +498,49 @@ class SettingsDialog:
         finally:
             self._sfm_test_btn.config(state="normal")
 
+    def _build_tab_mirror(self, nb):
+        f = self._tab_frame(nb, "Mirror")
+
+        intro = (
+            "Optional dual-send: post each heartbeat and event to a SECOND\n"
+            "(\"mirror\") server in addition to the primary. Best-effort — the\n"
+            "mirror can never delay or fail the primary. Leave blank to disable."
+        )
+        tk.Label(f, text=intro, justify="left", fg="#1a5276", wraplength=420).grid(
+            row=0, column=0, columnspan=2, sticky="w", padx=(8, 8), pady=(6, 8)
+        )
+
+        _add_label_entry(f, 1, "Mirror Terra-View URL", self.var_mirror_api_url)
+        _add_label_entry(f, 2, "Mirror SFM URL", self.var_mirror_sfm_url)
+
+        def browse_mirror_state():
+            p = filedialog.asksaveasfilename(
+                title="Select Mirror State File",
+                defaultextension=".json",
+                filetypes=[("JSON files", "*.json"), ("All files", "*.*")],
+                initialfile=os.path.basename(
+                    self.var_mirror_sfm_state_file.get() or "thor_forwarded_mirror.json"),
+                initialdir=os.path.dirname(self.var_mirror_sfm_state_file.get() or "C:\\"),
+            )
+            if p:
+                self.var_mirror_sfm_state_file.set(p.replace("/", "\\"))
+
+        _add_label_browse_entry(f, 3, "Mirror State File", self.var_mirror_sfm_state_file,
+                                browse_mirror_state)
+
+        help_text = (
+            "Mirror Terra-View URL → base like http://10.0.0.x:8001 (heartbeats).\n"
+            "Mirror SFM URL → base like http://10.0.0.x:8200 (events).\n"
+            "The event mirror keeps its OWN state file, so nothing is lost while\n"
+            "the mirror is down — pending events are delivered once it returns.\n"
+            "A quick reachability check skips the mirror cleanly when unreachable,\n"
+            "so the primary is never slowed.\n"
+            "State file blank → defaults to <log_dir>\\thor_forwarded_mirror.json."
+        )
+        tk.Label(f, text=help_text, justify="left", fg="#555555", wraplength=420).grid(
+            row=4, column=0, columnspan=2, sticky="w", padx=(8, 8), pady=(8, 4)
+        )
+
     def _build_tab_updates(self, nb):
         f = self._tab_frame(nb, "Updates")
 
@@ -599,6 +656,12 @@ class SettingsDialog:
             sfm_url = ""
         sfm_url = sfm_url.rstrip("/")  # event_forwarder adds the endpoint path
 
+        # Mirror (dual-send) — best-effort second destination.
+        mirror_api_url = self.var_mirror_api_url.get().strip()
+        if mirror_api_url:
+            mirror_api_url = mirror_api_url.rstrip("/") + "/api/series4/heartbeat"
+        mirror_sfm_url = self.var_mirror_sfm_url.get().strip().rstrip("/")
+
         values = {
             "thordata_path":      self.var_thordata_path.get().strip(),
             "scan_interval":      int_values["Scan Interval"],
@@ -623,6 +686,10 @@ class SettingsDialog:
             "sfm_max_forwards_per_pass":        int_values["Max Forwards Per Pass"],
             "sfm_max_event_age_days":           int_values["Max Event Age (days)"],
             "sfm_state_file":                   self.var_sfm_state_file.get().strip(),
+
+            "mirror_api_url":        mirror_api_url,
+            "mirror_sfm_url":         mirror_sfm_url,
+            "mirror_sfm_state_file":  self.var_mirror_sfm_state_file.get().strip(),
         }
 
         try: