From 2fd9d331d69279beee709549f76d4144cf28bb90 Mon Sep 17 00:00:00 2001
From: Bryan Van Deusen <bryan.vandeusen@fabledsword.com>
Date: Tue, 17 Mar 2026 20:23:34 -0400
Subject: [PATCH] feat: add ansible executor with SSE broadcast and DB flush

---
 fablednetmon/ansible/executor.py | 132 +++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 fablednetmon/ansible/executor.py

diff --git a/fablednetmon/ansible/executor.py b/fablednetmon/ansible/executor.py
new file mode 100644
index 0000000..d59dc0a
--- /dev/null
+++ b/fablednetmon/ansible/executor.py
@@ -0,0 +1,132 @@
+# fablednetmon/ansible/executor.py
+from __future__ import annotations
+import asyncio
+import logging
+import time
+from dataclasses import dataclass
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from quart import Quart
+
+logger = logging.getLogger(__name__)
+
+_OUTPUT_CAP_BYTES = 1024 * 1024  # 1 MB DB cap
+_FLUSH_LINES = 50
+_FLUSH_SECS = 5.0
+
+
+@dataclass
+class _Done:
+    status: str
+
+
+# Per-run broadcast state (lives until process restarts)
+_run_lines: dict[str, list[str]] = {}          # all output lines received so far
+_run_done: dict[str, _Done] = {}               # set when run completes
+_run_listeners: dict[str, list[asyncio.Queue]] = {}  # active SSE client queues
+
+
+def register_listener(run_id: str) -> asyncio.Queue:
+    """Create a listener queue for a run. Replays existing lines immediately."""
+    q: asyncio.Queue = asyncio.Queue()
+    for line in _run_lines.get(run_id, []):
+        q.put_nowait(line)
+    done = _run_done.get(run_id)
+    if done:
+        q.put_nowait(done)
+    else:
+        _run_listeners.setdefault(run_id, []).append(q)
+    return q
+
+
+def deregister_listener(run_id: str, q: asyncio.Queue) -> None:
+    listeners = _run_listeners.get(run_id, [])
+    if q in listeners:
+        listeners.remove(q)
+
+
+def _broadcast(run_id: str, item: str | _Done) -> None:
+    if isinstance(item, str):
+        _run_lines.setdefault(run_id, []).append(item)
+    else:
+        _run_done[run_id] = item
+    for q in _run_listeners.get(run_id, []):
+        q.put_nowait(item)
+    if isinstance(item, _Done):
+        _run_listeners.pop(run_id, None)
+
+
+async def start_run(
+    app: "Quart",
+    run_id: str,
+    playbook_path: str,
+    inventory_path: str,
+    source_path: str,
+) -> None:
+    """Execute ansible-playbook as a subprocess and update the DB run row."""
+    _run_lines[run_id] = []
+
+    db_output = ""
+    truncated = False
+    lines_since_flush = 0
+    last_flush_at = time.monotonic()
+
+    async def _flush(final_status: str | None = None) -> None:
+        nonlocal lines_since_flush, last_flush_at
+        from sqlalchemy import update
+        from fablednetmon.models.ansible import AnsibleRun, AnsibleRunStatus
+
+        values: dict = {"output": db_output}
+        if final_status is not None:
+            values["status"] = AnsibleRunStatus(final_status)
+            values["finished_at"] = datetime.now(timezone.utc)
+
+        async with app.db_sessionmaker() as session:
+            async with session.begin():
+                await session.execute(
+                    update(AnsibleRun).where(AnsibleRun.id == run_id).values(**values)
+                )
+        lines_since_flush = 0
+        last_flush_at = time.monotonic()
+
+    cmd = ["ansible-playbook", playbook_path, "-i", inventory_path]
+    cwd = source_path if Path(source_path).exists() else None
+
+    try:
+        proc = await asyncio.create_subprocess_exec(
+            *cmd,
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.STDOUT,
+            cwd=cwd,
+        )
+        assert proc.stdout is not None
+
+        async for raw_line in proc.stdout:
+            line = raw_line.decode(errors="replace").rstrip("\n\r")
+            _broadcast(run_id, line)
+
+            if not truncated:
+                candidate = (db_output + "\n" + line) if db_output else line
+                if len(candidate.encode()) > _OUTPUT_CAP_BYTES:
+                    db_output += "\n[output truncated]"
+                    truncated = True
+                else:
+                    db_output = candidate
+
+            lines_since_flush += 1
+            elapsed = time.monotonic() - last_flush_at
+            if lines_since_flush >= _FLUSH_LINES or elapsed >= _FLUSH_SECS:
+                await _flush()
+
+        await proc.wait()
+        final_status = "success" if proc.returncode == 0 else "failed"
+
+    except Exception:
+        logger.exception("Ansible run %s failed with exception", run_id)
+        final_status = "failed"
+
+    await _flush(final_status)
+    _broadcast(run_id, _Done(status=final_status))