enhance: support client certificates for mutual TLS (#1273)

Add `runner.client_cert_file` and `runner.client_key_file` for Gitea instances that require mutual TLS. The runner presents the certificate on its RPCs, job summary uploads, and the action, reusable workflow and `builtin:checkout` clones from the instance. The files are read on use, so renewed certificates apply without a restart. Job steps do not get them. An incomplete or mismatched pair fails startup.

Clones now decide the token, client certificate and `runner.insecure` with one host check, which also gives reusable workflow clones the TLS settings they lacked. `runner.insecure` still only covers the registered address.

Fixes: https://gitea.com/gitea/runner/issues/321
Co-authored-by: silverwind <[email protected]>
Co-authored-by: silverwind <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1273
Reviewed-by: silverwind <[email protected]>
Co-authored-by: bircni <[email protected]>

internal/pkg/client/http.go

@@ -19,20 +19,23 @@ import (
 	"gitea.dev/actionslib/runner/v1/runnerv1connect"
 )
 
-func getHTTPClient(endpoint string, insecure bool, timeout time.Duration, extraHeaders map[string]string) *http.Client {
+func NewTransport(endpoint string, tlsConfig *tls.Config) *http.Transport {
 	transport := &http.Transport{
 		Proxy:               http.ProxyFromEnvironment,
 		MaxIdleConns:        10,
 		MaxIdleConnsPerHost: 10, // All requests go to one host; default is 2 which causes frequent reconnects.
 		IdleConnTimeout:     90 * time.Second,
+		ForceAttemptHTTP2:   true,
 	}
-	if strings.HasPrefix(endpoint, "https://") && insecure {
-		transport.TLSClientConfig = &tls.Config{
-			InsecureSkipVerify: true,
-		}
+	if strings.HasPrefix(endpoint, "https://") {
+		transport.TLSClientConfig = tlsConfig
 	}
+	return transport
+}
+
+func getHTTPClient(endpoint string, tlsConfig *tls.Config, timeout time.Duration, extraHeaders map[string]string) *http.Client {
 	return &http.Client{
-		Transport: transport,
+		Transport: NewTransport(endpoint, tlsConfig),
 		Timeout:   timeout,
 		CheckRedirect: func(req *http.Request, via []*http.Request) error {
 			if len(via) >= 10 { // a custom CheckRedirect replaces net/http's own limit
@@ -54,7 +57,7 @@ func getHTTPClient(endpoint string, insecure bool, timeout time.Duration, extraH
 // New returns a new runner client. timeout bounds every RPC: without it a
 // stalled connection parks the reporter for the whole job context, so logs and
 // heartbeats stop together and the task is reaped as a zombie.
-func New(endpoint string, insecure bool, uuid, token string, timeout time.Duration, extraHeaders map[string]string, opts ...connect.ClientOption) *HTTPClient {
+func New(endpoint string, tlsConfig *tls.Config, uuid, token string, timeout time.Duration, extraHeaders map[string]string, opts ...connect.ClientOption) *HTTPClient {
 	baseURL := strings.TrimRight(endpoint, "/") + "/api/actions"
 
 	opts = append(opts, connect.WithInterceptors(connect.UnaryInterceptorFunc(func(next connect.UnaryFunc) connect.UnaryFunc {
@@ -75,7 +78,7 @@ func New(endpoint string, insecure bool, uuid, token string, timeout time.Durati
 		}
 	})))
 
-	httpClient := getHTTPClient(endpoint, insecure, timeout, extraHeaders)
+	httpClient := getHTTPClient(endpoint, tlsConfig, timeout, extraHeaders)
 	return &HTTPClient{
 		PingServiceClient: pingv1connect.NewPingServiceClient(
 			httpClient,