Files
act_runner/internal/pkg/config/config.example.yaml
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

149 lines
7.8 KiB
YAML

# Example configuration file, it's safe to copy this as the default config file without any modification.
# You don't have to copy this file to your instance,
# just run `./act_runner generate-config > config.yaml` to generate a config file.
log:
# The level of logging, can be trace, debug, info, warn, error, fatal
level: info
runner:
# Where to store the registration result.
file: .runner
# Execute how many tasks concurrently at the same time.
capacity: 1
# Extra environment variables to run jobs.
envs:
A_TEST_ENV_NAME_1: a_test_env_value_1
A_TEST_ENV_NAME_2: a_test_env_value_2
# Extra environment variables to run jobs from a file.
# It will be ignored if it's empty or the file doesn't exist.
env_file: .env
# The timeout for a job to be finished.
# Please note that the Gitea instance also has a timeout (3h by default) for the job.
# So the job could be stopped by the Gitea instance if its timeout is shorter than this.
timeout: 3h
# The timeout for the runner to wait for running jobs to finish when shutting down.
# Any running jobs that haven't finished after this timeout will be cancelled.
shutdown_timeout: 0s
# Whether skip verifying the TLS certificate of the Gitea instance.
insecure: false
# The timeout for fetching the job from the Gitea instance.
fetch_timeout: 5s
# The interval for fetching the job from the Gitea instance.
fetch_interval: 2s
# The maximum interval for fetching the job from the Gitea instance.
# The runner uses exponential backoff when idle, increasing the interval up to this maximum.
# Set to 0 or same as fetch_interval to disable backoff.
fetch_interval_max: 60s
# The base interval for periodic log flush to the Gitea instance.
# Logs may be sent earlier if the buffer reaches log_report_batch_size
# or if log_report_max_latency expires after the first buffered row.
log_report_interval: 5s
# The maximum time a log row can wait before being sent.
# This ensures even a single log line appears on the frontend within this duration.
# Must be less than log_report_interval to have any effect.
log_report_max_latency: 3s
# Flush logs immediately when the buffer reaches this many rows.
# This ensures bursty output (e.g., npm install) is delivered promptly.
log_report_batch_size: 100
# The interval for reporting task state (step status, timing) to the Gitea instance.
# State is also reported immediately on step transitions (start/stop).
state_report_interval: 5s
# The github_mirror of a runner is used to specify the mirror address of the github that pulls the action repository.
# It works when something like `uses: actions/checkout@v4` is used and DEFAULT_ACTIONS_URL is set to github,
# and github_mirror is not empty. In this case,
# it replaces https://github.com with the value here, which is useful for some special network environments.
github_mirror: ''
# The labels of a runner are used to determine which jobs the runner can run, and how to run them.
# Like: "macos-arm64:host" or "ubuntu-latest:docker://docker.gitea.com/runner-images:ubuntu-latest"
# Find more images provided by Gitea at https://gitea.com/gitea/runner-images .
# If it's empty when registering, it will ask for inputting labels.
# If it's empty when execute `daemon`, will use labels in `.runner` file.
labels:
- "ubuntu-latest:docker://docker.gitea.com/runner-images:ubuntu-latest"
- "ubuntu-24.04:docker://docker.gitea.com/runner-images:ubuntu-24.04"
- "ubuntu-22.04:docker://docker.gitea.com/runner-images:ubuntu-22.04"
cache:
# Enable cache server to use actions/cache.
enabled: true
# The directory to store the cache data.
# If it's empty, the cache data will be stored in $HOME/.cache/actcache.
dir: ""
# The host of the cache server.
# It's not for the address to listen, but the address to connect from job containers.
# So 0.0.0.0 is a bad choice, leave it empty to detect automatically.
host: ""
# The port of the cache server.
# 0 means to use a random available port.
port: 0
# The external cache server URL. Valid only when enable is true.
# If it's specified, act_runner will use this URL as the ACTIONS_CACHE_URL rather than start a server by itself.
# The URL should generally end with "/".
# Requires external_secret below to be set to the same value on both this runner and the cache-server.
external_server: ""
# Shared secret between this runner and the external `act_runner cache-server`. Required when external_server
# (or `act_runner cache-server`) is in use: the runner pre-registers each job's ACTIONS_RUNTIME_TOKEN with the
# cache-server, and the cache-server enforces bearer auth + per-repo cache isolation.
external_secret: ""
container:
# Specifies the network to which the container will connect.
# Could be host, bridge or the name of a custom network.
# If it's empty, act_runner will create a network automatically.
network: ""
# Whether to use privileged mode or not when launching task containers (privileged mode is required for Docker-in-Docker).
privileged: false
# Any other options to be used when the container is started (e.g., --add-host=my.gitea.url:host-gateway).
options:
# The parent directory of a job's working directory.
# NOTE: There is no need to add the first '/' of the path as act_runner will add it automatically.
# If the path starts with '/', the '/' will be trimmed.
# For example, if the parent directory is /path/to/my/dir, workdir_parent should be path/to/my/dir
# If it's empty, /workspace will be used.
workdir_parent:
# Volumes (including bind mounts) can be mounted to containers. Glob syntax is supported, see https://github.com/gobwas/glob
# You can specify multiple volumes. If the sequence is empty, no volumes can be mounted.
# For example, if you only allow containers to mount the `data` volume and all the json files in `/src`, you should change the config to:
# valid_volumes:
# - data
# - /src/*.json
# If you want to allow any volume, please use the following configuration:
# valid_volumes:
# - '**'
valid_volumes: []
# Overrides the docker client host with the specified one.
# If it's empty, act_runner will find an available docker host automatically.
# If it's "-", act_runner will find an available docker host automatically, but the docker host won't be mounted to the job containers and service containers.
# If it's not empty or "-", the specified docker host will be used. An error will be returned if it doesn't work.
docker_host: ""
# Pull docker image(s) even if already present
force_pull: true
# Rebuild docker image(s) even if already present
force_rebuild: false
# Always require a reachable docker daemon, even if not required by act_runner
require_docker: false
# Timeout to wait for the docker daemon to be reachable, if docker is required by require_docker or act_runner
docker_timeout: 0s
# Bind the workspace to the host filesystem instead of using Docker volumes.
# This is required for Docker-in-Docker (DinD) setups when jobs use docker compose
# with bind mounts (e.g., ".:/app"), as volume-based workspaces are not accessible
# from the DinD daemon's filesystem. When enabled, ensure the workspace parent
# directory is also mounted into the runner container and listed in valid_volumes.
bind_workdir: false
host:
# The parent directory of a job's working directory.
# If it's empty, $HOME/.cache/act/ will be used.
workdir_parent:
metrics:
# Enable the Prometheus metrics endpoint.
# When enabled, metrics are served at http://<addr>/metrics and a liveness check at /healthz.
enabled: false
# The address for the metrics HTTP server to listen on.
# Defaults to localhost only. Set to ":9101" to allow external access,
# but ensure the port is firewall-protected as there is no authentication.
addr: "127.0.0.1:9101"