feat(ansible): parameterized runs — extra-vars, limit, tags, dry-run (task 546)

Run form + executor now support optional params, passed as argv (never
shell-interpolated):
- extra_vars: one key=value per line -> repeated -e
- limit -> --limit; tags -> --tags
- dry-run checkbox -> --check --diff

- executor.py: pure build_ansible_command(playbook, inventory, params); start_run
  gains an optional params arg (backward-compatible)
- models/ansible.py + migration 0013: nullable params JSON column
- routes.py: create_run parses + validates (extra-var lines need '='), stores
  params on the run, passes to the executor
- browse.html run form: Extra vars / Limit / Tags / Dry-run fields
- run_detail.html: shows the params used
- tests/test_ansible_command.py: unit coverage of the builder; integration test
  runs a real playbook with extra-var + limit + check and asserts substitution

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

steward/ansible/executor.py

@@ -59,12 +59,37 @@ def _broadcast(run_id: str, item: str | _Done) -> None:
         _run_listeners.pop(run_id, None)
 
 
+def build_ansible_command(
+    playbook_path: str,
+    inventory_path: str,
+    params: dict | None = None,
+) -> list[str]:
+    """Build the ansible-playbook argv from a run's optional params.
+
+    Pure (no IO). Everything is passed as argv — never shell-interpolated — so
+    extra-var values and limits can contain arbitrary characters safely.
+    params keys: extra_vars (list of "key=value"), limit, tags, check (bool).
+    """
+    cmd = ["ansible-playbook", playbook_path, "-i", inventory_path]
+    params = params or {}
+    for ev in params.get("extra_vars") or []:
+        cmd += ["-e", ev]
+    if params.get("limit"):
+        cmd += ["--limit", params["limit"]]
+    if params.get("tags"):
+        cmd += ["--tags", params["tags"]]
+    if params.get("check"):
+        cmd += ["--check", "--diff"]
+    return cmd
+
+
 async def start_run(
     app: "Quart",
     run_id: str,
     playbook_path: str,
     inventory_path: str,
     source_path: str,
+    params: dict | None = None,
 ) -> None:
     """Execute ansible-playbook as a subprocess and update the DB run row."""
     _run_lines[run_id] = []
@@ -92,7 +117,7 @@ async def start_run(
         lines_since_flush = 0
         last_flush_at = time.monotonic()
 
-    cmd = ["ansible-playbook", playbook_path, "-i", inventory_path]
+    cmd = build_ansible_command(playbook_path, inventory_path, params)
     cwd = source_path if Path(source_path).exists() else None
 
     try:

steward/ansible/routes.py

@@ -85,6 +85,30 @@ async def create_run():
     if source is None:
         return "Source not found", 404
 
+    # Optional run parameters (all passed as argv by the executor — no shell).
+    extra_vars: list[str] = []
+    for line in (form.get("extra_vars", "") or "").splitlines():
+        line = line.strip()
+        if not line:
+            continue
+        if "=" not in line:
+            return f"Invalid extra var (expected key=value): {line!r}", 400
+        extra_vars.append(line)
+    limit = (form.get("limit", "") or "").strip()
+    tags = (form.get("tags", "") or "").strip()
+    check = "check" in form
+
+    params: dict = {}
+    if extra_vars:
+        params["extra_vars"] = extra_vars
+    if limit:
+        params["limit"] = limit
+    if tags:
+        params["tags"] = tags
+    if check:
+        params["check"] = True
+    params_or_none = params or None
+
     run_id = str(uuid.uuid4())
     now = datetime.now(timezone.utc)
 
@@ -96,6 +120,7 @@ async def create_run():
         triggered_by=session["user_id"],
         status=AnsibleRunStatus.running,
         started_at=now,
+        params=params_or_none,
     )
     async with current_app.db_sessionmaker() as db:
         async with db.begin():
@@ -108,6 +133,7 @@ async def create_run():
             playbook_path,
             inventory_path,
             source["path"],
+            params_or_none,
         )
     )
     task.add_done_callback(

steward/migrations/versions/0013_ansible_run_params.py

@@ -0,0 +1,22 @@
+"""Add ansible_runs.params (optional run parameters)
+
+Revision ID: 0013_ansible_run_params
+Revises: 0012_ansible_run_nullable
+Create Date: 2026-06-02
+"""
+from typing import Sequence, Union
+from alembic import op
+import sqlalchemy as sa
+
+revision: str = "0013_ansible_run_params"
+down_revision: Union[str, None] = "0012_ansible_run_nullable"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column("ansible_runs", sa.Column("params", sa.JSON(), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("ansible_runs", "params")

steward/models/ansible.py

@@ -2,7 +2,7 @@ from __future__ import annotations
 import enum
 import uuid
 from datetime import datetime, timezone
-from sqlalchemy import DateTime, Enum, ForeignKey, String, Text
+from sqlalchemy import JSON, DateTime, Enum, ForeignKey, String, Text
 from sqlalchemy.orm import Mapped, mapped_column
 from .base import Base
 
@@ -34,3 +34,5 @@ class AnsibleRun(Base):
     )
     finished_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
     output: Mapped[str | None] = mapped_column(Text, nullable=True)
+    # Optional run parameters: {extra_vars: [..], limit: str, tags: str, check: bool}.
+    params: Mapped[dict | None] = mapped_column(JSON, nullable=True)

steward/templates/ansible/browse.html

@@ -83,6 +83,25 @@
                 <label>Or enter inventory path manually</label>
                 <input type="text" id="manual-inv-{{ sd.source.name }}" placeholder="inventories/production/hosts">
             </div>
+            <div class="form-group">
+                <label>Extra vars <span style="color:var(--text-muted);font-weight:normal;">(optional, one key=value per line)</span></label>
+                <textarea name="extra_vars" rows="2" placeholder="version=1.2.3&#10;restart=true"
+                          style="width:100%;font-family:ui-monospace,monospace;font-size:0.85rem;"></textarea>
+            </div>
+            <div class="form-group">
+                <label>Limit to host(s) <span style="color:var(--text-muted);font-weight:normal;">(optional, --limit)</span></label>
+                <input type="text" name="limit" placeholder="web01,db*">
+            </div>
+            <div class="form-group">
+                <label>Tags <span style="color:var(--text-muted);font-weight:normal;">(optional, --tags)</span></label>
+                <input type="text" name="tags" placeholder="deploy,config">
+            </div>
+            <div class="form-group">
+                <label style="display:flex;align-items:center;gap:0.5rem;font-weight:normal;">
+                    <input type="checkbox" name="check">
+                    Dry-run (--check --diff) — preview changes without applying
+                </label>
+            </div>
             <div style="display:flex;gap:0.75rem;align-items:center;">
                 <button type="button" class="btn"
                     onclick="var manual=document.getElementById('manual-inv-{{ sd.source.name }}').value.trim();

steward/templates/ansible/run_detail.html

@@ -19,6 +19,20 @@
         {% if run.finished_at %}
         <span style="color:var(--text-muted);">Finished</span><span style="color:var(--text-dim);">{{ run.finished_at.strftime("%Y-%m-%d %H:%M:%S UTC") }}</span>
         {% endif %}
+        {% if run.params %}
+        {% if run.params.limit %}
+        <span style="color:var(--text-muted);">Limit</span><span style="font-family:ui-monospace,monospace;">{{ run.params.limit }}</span>
+        {% endif %}
+        {% if run.params.tags %}
+        <span style="color:var(--text-muted);">Tags</span><span style="font-family:ui-monospace,monospace;">{{ run.params.tags }}</span>
+        {% endif %}
+        {% if run.params.check %}
+        <span style="color:var(--text-muted);">Mode</span><span style="color:var(--orange);">dry-run (--check --diff)</span>
+        {% endif %}
+        {% if run.params.extra_vars %}
+        <span style="color:var(--text-muted);">Extra vars</span><span style="font-family:ui-monospace,monospace;">{{ run.params.extra_vars | join(", ") }}</span>
+        {% endif %}
+        {% endif %}
     </div>
 </div>