添加嵌套 CI 的 SPIRE JWT broker

.gitea/workflows/spire-identity-smoke.yml

@@ -0,0 +1,33 @@
+name: SPIRE identity smoke
+
+on:
+  workflow_dispatch:
+
+jobs:
+  jwt-svid:
+    runs-on: self-hosted
+    container:
+      volumes:
+        - /run/spire/agent-sockets:/run/spire/agent-sockets:ro
+    steps:
+      - name: Fetch pinned SPIRE CLI
+        shell: bash
+        run: |
+          set -euo pipefail
+          archive=/tmp/spire.tar.gz
+          curl --fail --location --silent --show-error \
+            --output "$archive" \
+            https://github.com/spiffe/spire/releases/download/v1.15.3/spire-1.15.3-linux-amd64-musl.tar.gz
+          printf '%s  %s\n' \
+            ca1a4d1155317bdd2afc7f36663828a10410c7c840e54725b90b4064b0a301c7 \
+            "$archive" | sha256sum --check --status
+          tar -xzf "$archive" -C /tmp spire-1.15.3/bin/spire-agent
+
+      - name: Fetch short-lived zot JWT-SVID
+        shell: bash
+        run: |
+          set -euo pipefail
+          /tmp/spire-1.15.3/bin/spire-agent api fetch jwt \
+            -audience zot \
+            -socketPath /run/spire/agent-sockets/spire-agent.sock \
+            >/dev/null

README.md

@@ -12,6 +12,9 @@
   Cloud Hypervisor，退出后完整清理。
 - `guest-runner`：在 guest 中领取一次性 runner registration token，注册 ephemeral
   runner，执行一个 job 后关机。
+- `jwt-broker`：运行在 Kubernetes runner 外层 Pod 中，以可被 SPIRE attestation
+  的 PID 获取固定 `aud=zot` JWT-SVID；DinD job 通过受限 HTTP endpoint 获取短期
+  token。broker 不记录响应、不缓存 token，也不接受调用方指定 audience。
 
 消息流使用一个 `WorkQueuePolicy` stream。相同 runner label 的所有 worker 共享同一
 durable consumer；扩容只需要增加 worker 或提高单机 capacity。

container/controller.Dockerfile

@@ -1,3 +1,5 @@
+FROM ghcr.io/spiffe/spire-agent:1.15.3@sha256:41b0dcd8b258a69db9e2768292a060766fb76fd866e4bc925849981ea1b825ff AS spire
+
 FROM python:3.12.11-alpine3.22 AS build
 WORKDIR /src
 COPY pyproject.toml README.md ./
@@ -7,6 +9,7 @@ RUN python -m venv /venv && /venv/bin/pip install --no-cache-dir .
 FROM python:3.12.11-alpine3.22
 RUN addgroup -S -g 65532 runner && adduser -S -D -H -u 65532 -G runner runner
 COPY --from=build /venv /venv
+COPY --from=spire /opt/spire/bin/spire-agent /opt/spire/bin/spire-agent
 USER 65532:65532
 EXPOSE 8787
 ENTRYPOINT ["/venv/bin/gitea-microvm-controller"]

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "gitea-microvm-runner"
-version = "0.1.0"
+version = "0.2.0"
 description = "On-demand Cloud Hypervisor runners for Gitea Actions"
 requires-python = ">=3.11"
 dependencies = ["aiohttp==3.12.15", "nats-py==2.11.0"]
@@ -15,6 +15,7 @@ test = ["pytest==8.4.2", "pytest-asyncio==1.2.0"]
 [project.scripts]
 gitea-microvm-controller = "gitea_microvm_runner.controller:main"
 gitea-microvm-worker = "gitea_microvm_runner.worker:cli"
+gitea-spire-jwt-broker = "gitea_microvm_runner.jwt_broker:main"
 
 [tool.pytest.ini_options]
 asyncio_mode = "auto"

src/gitea_microvm_runner/jwt_broker.py

@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+"""Fixed-audience JWT-SVID broker for nested Gitea job containers."""
+
+import asyncio
+import json
+import os
+
+from aiohttp import web
+
+SPIRE_AGENT = os.environ.get("SPIRE_AGENT", "/opt/spire/bin/spire-agent")
+SPIRE_SOCKET = os.environ.get(
+    "SPIRE_SOCKET", "/run/spire/agent-sockets/spire-agent.sock"
+)
+AUDIENCE = os.environ.get("JWT_AUDIENCE", "zot")
+MAX_CONCURRENCY = int(os.environ.get("MAX_CONCURRENCY", "4"))
+semaphore = asyncio.Semaphore(MAX_CONCURRENCY)
+
+
+def extract_svid(document: object) -> str:
+    if not isinstance(document, list):
+        raise ValueError("unexpected SPIRE response")
+    for item in document:
+        if not isinstance(item, dict):
+            continue
+        svids = item.get("svids")
+        if not isinstance(svids, list):
+            continue
+        for svid in svids:
+            if isinstance(svid, dict) and isinstance(svid.get("svid"), str):
+                return svid["svid"]
+    raise ValueError("SPIRE response contains no JWT-SVID")
+
+
+async def fetch_svid() -> str:
+    async with semaphore:
+        process = await asyncio.create_subprocess_exec(
+            SPIRE_AGENT,
+            "api",
+            "fetch",
+            "jwt",
+            "-output",
+            "json",
+            "-audience",
+            AUDIENCE,
+            "-socketPath",
+            SPIRE_SOCKET,
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.PIPE,
+        )
+        stdout, stderr = await asyncio.wait_for(process.communicate(), timeout=10)
+    if process.returncode != 0:
+        message = stderr.decode(errors="replace").strip()
+        raise RuntimeError(f"SPIRE agent failed: {message}")
+    return extract_svid(json.loads(stdout))
+
+
+async def token(_: web.Request) -> web.Response:
+    try:
+        value = await fetch_svid()
+    except (RuntimeError, ValueError, json.JSONDecodeError, asyncio.TimeoutError):
+        raise web.HTTPServiceUnavailable(text="identity unavailable\n")
+    return web.Response(
+        text=f"{value}\n",
+        content_type="text/plain",
+        headers={"Cache-Control": "no-store"},
+    )
+
+
+async def health(_: web.Request) -> web.Response:
+    return web.Response(text="ok\n")
+
+
+def create_app() -> web.Application:
+    app = web.Application(client_max_size=1024)
+    app.router.add_post("/token", token)
+    app.router.add_get("/healthz", health)
+    return app
+
+
+def main() -> None:
+    web.run_app(
+        create_app(),
+        host=os.environ.get("LISTEN", "0.0.0.0"),
+        port=int(os.environ.get("PORT", "8788")),
+        access_log=None,
+    )
+
+
+if __name__ == "__main__":
+    main()

tests/test_jwt_broker.py

@@ -0,0 +1,16 @@
+import pytest
+
+from gitea_microvm_runner.jwt_broker import extract_svid
+
+
+def test_extract_svid_from_spire_json():
+    assert extract_svid([
+        {"svids": [{"hint": "", "spiffe_id": "spiffe://example/ci", "svid": "jwt"}]},
+        {"bundles": {}},
+    ]) == "jwt"
+
+
+@pytest.mark.parametrize("document", [{}, [], [{"bundles": {}}]])
+def test_extract_svid_rejects_unexpected_response(document):
+    with pytest.raises(ValueError):
+        extract_svid(document)