Files
act_runner/internal/app/run/runner_cache_test.go
silverwind 5edc4ba550 Authenticate cache requests via ACTIONS_RUNTIME_TOKEN and scope by repo (#849)
Closes #848. Addresses [GHSA-82g9-637c-2fx2](https://github.com/go-gitea/gitea/security/advisories/GHSA-82g9-637c-2fx2) and the follow-up points raised by @ChristopherHX and @haroutp in that thread.

The change is breaking only for `cache.external_server` which uses auth via a pre-shared secret.

## How auth works now

1. **Runner starts** → opens the embedded cache server on `:port`. Loads / creates a 32-byte HMAC signing key in `<cache-dir>/.secret`.
2. **Runner receives a task** → calls `handler.RegisterJob(ACTIONS_RUNTIME_TOKEN, repository)` before the job runs, defers a revoker that removes the credential on completion. Registrations are reference-counted so a stray re-register cannot revoke a live job.
3. **Job container runs `actions/cache`** → the toolkit sends `Authorization: Bearer $ACTIONS_RUNTIME_TOKEN` on every management call (`reserve`, `upload`, `commit`, `find`, `clean`). The cache server's middleware looks the token up in the registered-jobs map: miss → 401; hit → the job's repository is injected into the request context.
4. **Repository scoping** — every cache entry is stamped with `Repo` on reserve; `find`, `upload`, `commit` all verify the caller's repo matches. A job in repo A cannot see or poison a cache entry owned by repo B, even when both reach the server over the same docker bridge. GC dedup also groups by `(Repo, Key, Version)` so one repo can't age out another.
5. **Archive downloads** — `@actions/cache` does not attach Authorization when downloading `archiveLocation`, so the `find` response is a short-lived HMAC-signed URL: `…/artifacts/:id?exp=<unix>&sig=<hmac>`, 10-minute TTL, signature binds `cacheID:exp`. Tampered, expired, or foreign-secret URLs get 401.
6. **Defence-in-depth** — `ACTIONS_RUNTIME_TOKEN` is added to `task.Secrets` so the runner's log masker scrubs it from step output.

## `cache.external_server` (standalone `act_runner cache-server`)

Operators set `cache.external_secret` to the same value on the runner config and the `act_runner cache-server` config. The `cache-server` then runs with bearer auth on the cache API and exposes a control-plane at `POST /_internal/{register,revoke}` (gated by the shared secret). The runner pre-registers each task's `ACTIONS_RUNTIME_TOKEN` with the remote server before the job runs and revokes it on completion. Same per-job auth + repo scoping as the embedded handler, just over the network.

`cache-server` refuses to start without `cache.external_secret`; runner config load also fails when `cache.external_server` is set without `cache.external_secret`.

## User-facing changes

- **One-time cache miss after upgrade.** Pre-existing entries in `bolt.db` have no `Repo` stamp and won't match any job — they'll be evicted by the normal GC. First job per cache key rebuilds its cache.
- **`cache.external_server` deployments must add `cache.external_secret`.** Breaking change for anyone running a standalone `act_runner cache-server`: set the same `cache.external_secret` in both the runner config and the cache-server config. Without it neither side starts.
- **No config changes required for the default setup.** Runners using the embedded cache server (the common case) keep working without any yaml edits; the auth mechanism is invisible to workflows.

---
This PR was written with the help of Claude Opus 4.7

---------

Co-authored-by: Nicolas <bircni@icloud.com>
Co-authored-by: Christopher Homberger <christopher.homberger@web.de>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/849
Reviewed-by: ChristopherHX <38043+christopherhx@noreply.gitea.com>
2026-04-27 23:59:20 +00:00

240 lines
8.1 KiB
Go

// Copyright 2026 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package run
import (
"bytes"
"encoding/json"
"fmt"
"net/http"
"path/filepath"
"strings"
"testing"
"gitea.com/gitea/act_runner/act/artifactcache"
"gitea.com/gitea/act_runner/internal/pkg/config"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
func emptyCfg() *config.Config { return &config.Config{} }
func TestRunner_registerCacheForTask(t *testing.T) {
dir := filepath.Join(t.TempDir(), "artifactcache")
handler, err := artifactcache.StartHandler(dir, "127.0.0.1", 0, "", nil)
require.NoError(t, err)
defer handler.Close()
r := &Runner{cfg: emptyCfg(), cacheHandler: handler}
token := "run-token-123"
unregister := r.registerCacheForTask(token, "owner/repo", nil)
base := handler.ExternalURL() + "/_apis/artifactcache"
probe := func() int {
req, err := http.NewRequest(http.MethodGet, base+"/cache?keys=x&version=v", nil)
require.NoError(t, err)
req.Header.Set("Authorization", "Bearer "+token)
resp, err := http.DefaultClient.Do(req)
require.NoError(t, err)
resp.Body.Close()
return resp.StatusCode
}
assert.NotEqual(t, http.StatusUnauthorized, probe(),
"token should be accepted while task is registered")
unregister()
assert.Equal(t, http.StatusUnauthorized, probe(),
"token must be rejected after the revoker runs")
}
func TestRunner_registerCacheForTask_NoOps(t *testing.T) {
t.Run("nil cacheHandler", func(t *testing.T) {
r := &Runner{cfg: emptyCfg()}
unregister := r.registerCacheForTask("tok", "owner/repo", nil)
require.NotNil(t, unregister)
unregister()
})
t.Run("empty token", func(t *testing.T) {
dir := filepath.Join(t.TempDir(), "artifactcache")
handler, err := artifactcache.StartHandler(dir, "127.0.0.1", 0, "", nil)
require.NoError(t, err)
defer handler.Close()
r := &Runner{cfg: emptyCfg(), cacheHandler: handler}
unregister := r.registerCacheForTask("", "owner/repo", nil)
require.NotNil(t, unregister)
unregister()
})
}
// Locks in @actions/cache's wire protocol: bearer on reserve/upload/commit
// /find, no auth on the signed archiveLocation download.
func TestRunner_CacheFullFlow_MatchesToolkit(t *testing.T) {
dir := filepath.Join(t.TempDir(), "artifactcache")
handler, err := artifactcache.StartHandler(dir, "127.0.0.1", 0, "", nil)
require.NoError(t, err)
defer handler.Close()
r := &Runner{cfg: emptyCfg(), cacheHandler: handler}
token := "full-flow-token"
unregister := r.registerCacheForTask(token, "owner/repo", nil)
defer unregister()
base := handler.ExternalURL() + "/_apis/artifactcache"
do := func(method, url, contentType, contentRange, body string) *http.Response {
req, err := http.NewRequest(method, url, strings.NewReader(body))
require.NoError(t, err)
req.Header.Set("Authorization", "Bearer "+token)
if contentType != "" {
req.Header.Set("Content-Type", contentType)
}
if contentRange != "" {
req.Header.Set("Content-Range", contentRange)
}
resp, err := http.DefaultClient.Do(req)
require.NoError(t, err)
return resp
}
key := "toolkit-flow"
version := "c19da02a2bd7e77277f1ac29ab45c09b7d46a4ee758284e26bb3045ad11d9d20"
body := `hello-cache-body`
// reserve
resp := do(http.MethodPost, base+"/caches", "application/json", "",
fmt.Sprintf(`{"key":"%s","version":"%s","cacheSize":%d}`, key, version, len(body)))
require.Equal(t, http.StatusOK, resp.StatusCode)
var reserved struct {
CacheID uint64 `json:"cacheId"`
}
require.NoError(t, decodeJSON(resp, &reserved))
require.NotZero(t, reserved.CacheID)
// upload
resp = do(http.MethodPatch, fmt.Sprintf("%s/caches/%d", base, reserved.CacheID),
"application/octet-stream", fmt.Sprintf("bytes 0-%d/*", len(body)-1), body)
require.Equal(t, http.StatusOK, resp.StatusCode)
resp.Body.Close()
// commit
resp = do(http.MethodPost, fmt.Sprintf("%s/caches/%d", base, reserved.CacheID), "", "", "")
require.Equal(t, http.StatusOK, resp.StatusCode)
resp.Body.Close()
// find — @actions/cache always sends comma-separated keys here
resp = do(http.MethodGet,
fmt.Sprintf("%s/cache?keys=%s,fallback&version=%s", base, key, version), "", "", "")
require.Equal(t, http.StatusOK, resp.StatusCode)
var hit struct {
ArchiveLocation string `json:"archiveLocation"`
CacheKey string `json:"cacheKey"`
}
require.NoError(t, decodeJSON(resp, &hit))
require.Equal(t, key, hit.CacheKey)
require.NotEmpty(t, hit.ArchiveLocation)
// download — toolkit does NOT attach Authorization here; the signature
// in the URL must be enough.
dl, err := http.Get(hit.ArchiveLocation)
require.NoError(t, err)
defer dl.Body.Close()
require.Equal(t, http.StatusOK, dl.StatusCode)
got := make([]byte, 64)
n, _ := dl.Body.Read(got)
assert.Equal(t, body, string(got[:n]))
}
func decodeJSON(resp *http.Response, v any) error {
defer resp.Body.Close()
return json.NewDecoder(resp.Body).Decode(v)
}
// End-to-end against a remote cache-server: token unknown → 401, register →
// reserve/upload/commit/find/download all OK, revoke → 401 again.
func TestRunner_ExternalCacheServer_RegisterRevoke(t *testing.T) {
dir := filepath.Join(t.TempDir(), "remote-cache")
const secret = "shared-secret-for-tests"
remote, err := artifactcache.StartHandler(dir, "127.0.0.1", 0, secret, nil)
require.NoError(t, err)
defer remote.Close()
r := &Runner{cfg: &config.Config{Cache: config.Cache{
ExternalServer: remote.ExternalURL(),
ExternalSecret: secret,
}}}
token := "external-task-token"
repo := "owner/repoX"
base := remote.ExternalURL() + "/_apis/artifactcache"
probe := func() int {
req, _ := http.NewRequest(http.MethodGet, base+"/cache?keys=k&version=v", nil)
req.Header.Set("Authorization", "Bearer "+token)
resp, err := http.DefaultClient.Do(req)
require.NoError(t, err)
resp.Body.Close()
return resp.StatusCode
}
require.Equal(t, http.StatusUnauthorized, probe(),
"token must be unknown to the remote server before registration")
unregister := r.registerCacheForTask(token, repo, nil)
require.NotEqual(t, http.StatusUnauthorized, probe(),
"token must be accepted after registerCacheForTask")
// Full reserve→upload→commit→find→download cycle, identical to what
// @actions/cache does, against the remote (external) server.
body := []byte("payload-from-task")
reserveBody, _ := json.Marshal(&artifactcache.Request{Key: "ext-key", Version: "v", Size: int64(len(body))})
req, _ := http.NewRequest(http.MethodPost, base+"/caches", bytes.NewReader(reserveBody))
req.Header.Set("Authorization", "Bearer "+token)
req.Header.Set("Content-Type", "application/json")
resp, err := http.DefaultClient.Do(req)
require.NoError(t, err)
require.Equal(t, http.StatusOK, resp.StatusCode)
var reserved struct {
CacheID uint64 `json:"cacheId"`
}
require.NoError(t, decodeJSON(resp, &reserved))
require.NotZero(t, reserved.CacheID)
req, _ = http.NewRequest(http.MethodPatch, fmt.Sprintf("%s/caches/%d", base, reserved.CacheID), bytes.NewReader(body))
req.Header.Set("Authorization", "Bearer "+token)
req.Header.Set("Content-Range", fmt.Sprintf("bytes 0-%d/*", len(body)-1))
resp, err = http.DefaultClient.Do(req)
require.NoError(t, err)
resp.Body.Close()
require.Equal(t, http.StatusOK, resp.StatusCode)
req, _ = http.NewRequest(http.MethodPost, fmt.Sprintf("%s/caches/%d", base, reserved.CacheID), nil)
req.Header.Set("Authorization", "Bearer "+token)
resp, err = http.DefaultClient.Do(req)
require.NoError(t, err)
resp.Body.Close()
require.Equal(t, http.StatusOK, resp.StatusCode)
req, _ = http.NewRequest(http.MethodGet, base+"/cache?keys=ext-key&version=v", nil)
req.Header.Set("Authorization", "Bearer "+token)
resp, err = http.DefaultClient.Do(req)
require.NoError(t, err)
require.Equal(t, http.StatusOK, resp.StatusCode)
var hit struct {
ArchiveLocation string `json:"archiveLocation"`
}
require.NoError(t, decodeJSON(resp, &hit))
require.NotEmpty(t, hit.ArchiveLocation)
dl, err := http.Get(hit.ArchiveLocation)
require.NoError(t, err)
defer dl.Body.Close()
require.Equal(t, http.StatusOK, dl.StatusCode)
unregister()
assert.Equal(t, http.StatusUnauthorized, probe(),
"token must be rejected after the revoker runs")
}