feat(git-gate+orchestrator): slice 13c(v) — provision git-gate into the running gateway

Places a bottle's git-gate credentials + bare repos into the live shared
gateway container when it registers — the execution side of the 13c(i)
provisioning render.

- provision_git_gate(gateway, bottle_id, plan): mkdir the per-bottle creds
  dir, docker cp each upstream's identity key (+ known_hosts when present)
  into /git-gate/creds/<bottle_id>/, then docker exec the namespaced,
  init-only script from git_gate_render_provision. No-op with no upstreams.
- deprovision_git_gate(gateway, bottle_id): rm the bottle's /git/<id> +
  creds on teardown (idempotent).
- bottle_id is validated (shell/path-safe alphabet) BEFORE any docker cp/rm,
  so a traversal id can never reach a path arg — the creds/repo dirs land in
  docker cp/rm arguments. Registry ids are token_hex; defense in depth.

pyright 0 errors; pylint 9.83/10; unit suite green (the 13 test_sidecar_init
/bin/sleep errors are pre-existing NixOS-local noise).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck

bot_bottle/backend/docker/gateway_provision.py

@@ -0,0 +1,94 @@
+"""Provision one bottle's git-gate state into the running shared gateway
+(PRD 0070, docker slice).
+
+The consolidated gateway serves every bottle's repos under `/git/<bottle_id>/`
+with per-repo credentials under `/git-gate/creds/<bottle_id>/`. When a bottle
+is registered the launcher must place *its* deploy keys + known_hosts into
+that per-bottle creds dir and init its bare repos there — so this copies the
+credential files into the live gateway container and runs the (namespaced,
+init-only) provisioning script produced by `git_gate_render_provision`.
+
+Isolating each bottle's creds dir + repo root by id is what keeps one
+bottle's push credentials out of another's repos on the shared gateway.
+"""
+
+from __future__ import annotations
+
+import re
+
+from ...docker_cmd import run_docker
+from ...git_gate import GitGatePlan, git_gate_render_provision
+
+# bottle ids index the gateway's per-bottle repo + creds dirs; they land in
+# `docker cp`/`rm` path arguments, so validate before any path is built (a
+# traversal id like "../etc" must never reach the container). Registry ids are
+# token_hex — this is defense in depth at the docker boundary.
+_SAFE_BOTTLE_ID = re.compile(r"[A-Za-z0-9_-]+")
+
+
+class GatewayProvisionError(RuntimeError):
+    """A git-gate provisioning step against the running gateway failed."""
+
+
+def _require_safe(bottle_id: str) -> None:
+    if not _SAFE_BOTTLE_ID.fullmatch(bottle_id):
+        raise GatewayProvisionError(f"unsafe bottle id {bottle_id!r}")
+
+
+def _creds_dir(bottle_id: str) -> str:
+    return f"/git-gate/creds/{bottle_id}"
+
+
+def _exec(gateway: str, argv: list[str]) -> None:
+    """`docker exec` a command in the gateway, raising on non-zero exit."""
+    proc = run_docker(["docker", "exec", gateway, *argv])
+    if proc.returncode != 0:
+        raise GatewayProvisionError(
+            f"gateway exec {argv!r} failed: {proc.stderr.strip()}"
+        )
+
+
+def _cp_into(gateway: str, src: str, dest: str) -> None:
+    """`docker cp` a host file into the gateway, raising on non-zero exit."""
+    proc = run_docker(["docker", "cp", src, f"{gateway}:{dest}"])
+    if proc.returncode != 0:
+        raise GatewayProvisionError(
+            f"gateway cp {src} -> {dest} failed: {proc.stderr.strip()}"
+        )
+
+
+def provision_git_gate(gateway: str, bottle_id: str, plan: GitGatePlan) -> None:
+    """Place `bottle_id`'s git-gate credentials into the running `gateway`
+    container and init its bare repos under `/git/<bottle_id>/`.
+
+    Copies each upstream's identity key (and known_hosts, when present) into
+    `/git-gate/creds/<bottle_id>/`, then runs the namespaced provisioning
+    script. No-op for a bottle with no git upstreams."""
+    _require_safe(bottle_id)
+    if not plan.upstreams:
+        return
+    creds = _creds_dir(bottle_id)
+    _exec(gateway, ["mkdir", "-p", creds])
+    for u in plan.upstreams:
+        if u.identity_file:
+            _cp_into(gateway, u.identity_file, f"{creds}/{u.name}-key")
+        known_hosts = str(u.known_hosts_file)
+        if known_hosts and known_hosts != ".":
+            _cp_into(gateway, known_hosts, f"{creds}/{u.name}-known_hosts")
+    # Init the bare repos + per-repo credential config for this namespace.
+    script = git_gate_render_provision(bottle_id, plan.upstreams)
+    _exec(gateway, ["sh", "-c", script])
+
+
+def deprovision_git_gate(gateway: str, bottle_id: str) -> None:
+    """Remove a bottle's repos + creds from the gateway on teardown. Idempotent
+    — an already-absent namespace is a clean no-op (best effort; a stray dir
+    can't leak, since attribution is by source IP and the bottle is gone)."""
+    _require_safe(bottle_id)
+    run_docker([
+        "docker", "exec", gateway, "rm", "-rf",
+        f"/git/{bottle_id}", _creds_dir(bottle_id),
+    ])
+
+
+__all__ = ["provision_git_gate", "deprovision_git_gate", "GatewayProvisionError"]