enhance: bind-mount job paths through the docker proxy (#1226)

Containers a job starts through its Docker socket, for example `docker run -v "$PWD:/src"`, `./data:/data` in docker compose, or actions like dockerfile-roast, can now bind-mount the workspace and other paths the job sees, as on a host, without `bind_workdir`. The per-job Docker proxy rewrites container and volume create requests. A bind source, or the device of a `local` volume with `o: bind`, that lies under one of the job container's mounts is pointed at that mount's path on the daemon, read from inspecting the job container. Paths that already name a daemon path, like `GITEA_DOCKER_WORKSPACE`, and paths outside the job's mounts pass through unchanged. The proxy now also starts when the runner runs in a container given the host's Docker socket, by placing its socket in the runner's working directory, and in rootless dind, by granting the daemon socket's group through an ACL. Fixes https://gitea.com/gitea/runner/issues/1219 Fixes https://gitea.com/gitea/runner/issues/1193 Reviewed-on: https://gitea.com/gitea/runner/pulls/1226 Reviewed-by: bircni <bircni@icloud.com> Co-authored-by: silverwind <2021+silverwind@noreply.gitea.com>
2026-09-21 19:37:07 +02:00 · 2026-09-14 20:21:58 +00:00
parent 19afebc53f
commit 699a97fc8c
13 changed files with 367 additions and 28 deletions
@@ -19,9 +19,11 @@ import (
 	"net/http"
 	"net/http/httputil"
 	"os"
+	"path"
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"slices"
 	"strings"
 	"sync"
 	"time"
@@ -69,13 +71,19 @@ func NewDockerProxy(ctx context.Context, job string) *DockerProxy {
 		common.Logger(ctx).Infof("docker proxy probe failed, jobs get the daemon socket directly: %v", err)
 		return nil
 	}
-	seen, err := daemonSeesDir(probeCtx, cli, dir)
+	daemonDir := dir
+	seen, err := daemonSeesDir(probeCtx, cli, dir, daemonDir)
+	if err == nil && !seen {
+		if dir, daemonDir = runnerContainerWorkdir(probeCtx, cli); daemonDir != "" {
+			seen, err = daemonSeesDir(probeCtx, cli, dir, daemonDir)
+		}
+	}
 	if err != nil {
 		common.Logger(ctx).Infof("docker proxy probe failed, jobs get the daemon socket directly: %v", err)
 		return nil
 	}
 	if !seen {
-		common.Logger(ctx).Infof("the docker daemon cannot reach the runner's temporary filesystem, jobs get the daemon socket directly")
+		common.Logger(ctx).Infof("the docker daemon cannot reach the runner's temporary or working directory, jobs get the daemon socket directly")
 		return nil
 	}
 	if ctx.Err() != nil {
@@ -84,13 +92,35 @@ func NewDockerProxy(ctx context.Context, job string) *DockerProxy {
 	proxy, err := StartDockerProxy(daemonSocket, dir, job)
 	if err != nil {
 		common.Logger(ctx).Warnf("docker proxy not started, the job gets the daemon socket directly: %v", err)
+		return nil
 	}
+	proxy.Socket = daemonDir + strings.TrimPrefix(proxy.Socket, dir)
 	return proxy
 }

-// daemonSeesDir reports whether the daemon opens the files the runner writes in dir,
+// runnerContainerWorkdir looks the runner's container up by hostname to find the daemon's path to its working directory.
+func runnerContainerWorkdir(ctx context.Context, cli client.APIClient) (workdir, daemonDir string) {
+	workdir, err := os.Getwd()
+	hostname, hostnameErr := os.Hostname()
+	if err != nil || hostnameErr != nil {
+		return "", ""
+	}
+	self, err := cli.ContainerInspect(ctx, hostname, client.ContainerInspectOptions{})
+	if err != nil {
+		return "", ""
+	}
+	destination := ""
+	for _, point := range self.Container.Mounts {
+		if rel, err := filepath.Rel(point.Destination, workdir); err == nil && filepath.IsLocal(rel) && len(point.Destination) > len(destination) {
+			destination, daemonDir = point.Destination, filepath.Join(point.Source, rel)
+		}
+	}
+	return workdir, daemonDir
+}
+
+// daemonSeesDir reports whether the daemon opens the files the runner writes in dir by their path in daemonDir,
 // which is what a job's proxy socket mounted from there needs.
-func daemonSeesDir(ctx context.Context, cli client.APIClient, dir string) (bool, error) {
+func daemonSeesDir(ctx context.Context, cli client.APIClient, dir, daemonDir string) (bool, error) {
 	marker, err := os.CreateTemp(dir, "gitea-runner-probe-")
 	if err != nil {
 		return false, err
@@ -113,7 +143,7 @@ func daemonSeesDir(ctx context.Context, cli client.APIClient, dir string) (bool,
 	created, err := cli.ContainerCreate(ctx, client.ContainerCreateOptions{
 		Config: &container.Config{Image: images.Items[0].ID, Cmd: []string{"true"}},
 		HostConfig: &container.HostConfig{Mounts: []mount.Mount{
-			{Type: mount.TypeBind, Source: marker.Name(), Target: "/gitea-runner-probe", ReadOnly: true},
+			{Type: mount.TypeBind, Source: filepath.Join(daemonDir, filepath.Base(marker.Name())), Target: "/gitea-runner-probe", ReadOnly: true},
 		}},
 	})
 	if cerrdefs.IsInvalidArgument(err) {
@@ -151,7 +181,7 @@ func StartDockerProxy(daemonSocket, dir, job string) (*DockerProxy, error) {
 	if err != nil {
 		return nil, errors.Join(err, os.RemoveAll(instance))
 	}
-	if err := copyDockerSocketPermissions(socket, info); err != nil {
+	if err := copyDockerSocketPermissions(daemonSocket, socket, info); err != nil {
 		return nil, errors.Join(err, listener.Close(), os.RemoveAll(instance))
 	}
 	dial := func(ctx context.Context, _, _ string) (net.Conn, error) {
@@ -165,6 +195,7 @@ func StartDockerProxy(daemonSocket, dir, job string) (*DockerProxy, error) {
 		},
 		Transport: transport,
 	}
+	proxy := &DockerProxy{Socket: socket}
 	streams, cancelStreams := context.WithCancel(context.Background())
 	creates, cancelCreates := context.WithCancel(context.Background())
 	var admission sync.Mutex
@@ -200,7 +231,8 @@ func StartDockerProxy(daemonSocket, dir, job string) (*DockerProxy, error) {
 		r = r.WithContext(ctx)
 		if creating {
 			r.Body = http.MaxBytesReader(w, r.Body, maxCreateBody)
-			if err := addLabel(r, job); err != nil {
+			mounts, _ := proxy.mounts.Load().(map[string]string)
+			if err := rewriteCreate(r, job, mounts); err != nil {
 				status := http.StatusBadRequest
 				if _, ok := errors.AsType[*http.MaxBytesError](err); ok {
 					status = http.StatusRequestEntityTooLarge
@@ -219,7 +251,7 @@ func StartDockerProxy(daemonSocket, dir, job string) (*DockerProxy, error) {
 		defer close(served)
 		_ = server.Serve(listener)
 	}()
-	return &DockerProxy{Socket: socket, close: func(ctx context.Context) error {
+	proxy.close = func(ctx context.Context) error {
 		ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
 		defer cancel()
 		admission.Lock()
@@ -233,10 +265,11 @@ func StartDockerProxy(daemonSocket, dir, job string) (*DockerProxy, error) {
 		handlers.Wait()
 		transport.CloseIdleConnections()
 		return errors.Join(ctx.Err(), listenerErr, shutdownErr, serverErr, os.RemoveAll(instance))
-	}}, nil
+	}
+	return proxy, nil
 }

-func addLabel(r *http.Request, job string) error {
+func rewriteCreate(r *http.Request, job string, mounts map[string]string) error {
 	body, err := io.ReadAll(r.Body)
 	if err != nil {
 		return err
@@ -255,6 +288,9 @@ func addLabel(r *http.Request, job string) error {
 	if fields == nil {
 		fields = make(map[string]json.RawMessage)
 	}
+	if len(mounts) > 0 && !hasAmbiguousFields(body) {
+		translateBinds(fields, createPath.FindStringSubmatch(r.URL.Path)[2], mounts)
+	}
 	maps.DeleteFunc(fields, func(name string, _ json.RawMessage) bool {
 		return strings.EqualFold(name, "Labels")
 	})
@@ -274,6 +310,155 @@ func addLabel(r *http.Request, job string) error {
 	return nil
 }

+func translateBinds(fields map[string]json.RawMessage, kind string, mounts map[string]string) {
+	cleanedSource := func(source string) string {
+		cleaned := path.Clean(source)
+		if target := jobMount(cleaned, mounts); mounts[target] != "" {
+			return mounts[target] + cleaned[len(target):]
+		}
+		return source
+	}
+	spelledSource := func(source string) string { // dockerd checks these as spelled
+		target := jobMount(path.Clean(source), mounts)
+		if rest, spelled := strings.CutPrefix(source, target); mounts[target] != "" && spelled && (rest == "" || rest[0] == '/') && filepath.IsLocal("."+rest) {
+			return mounts[target] + rest
+		}
+		return cleanedSource(source)
+	}
+	switch kind {
+	case "volumes":
+		var driver string
+		var options map[string]any
+		decodeField(fields, "Driver", &driver)
+		if key := decodeField(fields, "DriverOpts", &options); options != nil {
+			translateDevice(driver, options, spelledSource)
+			if encoded, err := json.Marshal(options); err == nil {
+				fields[key] = encoded
+			}
+		}
+	case "containers":
+		var hostConfig map[string]any
+		key := decodeField(fields, "HostConfig", &hostConfig)
+		binds, _ := field(hostConfig, "Binds").([]any)
+		for i, bind := range binds {
+			bind, _ := bind.(string)
+			source, target, _ := strings.Cut(bind, ":")
+			if translated := cleanedSource(source); strings.HasPrefix(target, "/") && !strings.Contains(translated, ":") {
+				binds[i] = translated + ":" + target
+			}
+		}
+		specs, _ := field(hostConfig, "Mounts").([]any)
+		for _, spec := range specs {
+			spec, _ := spec.(map[string]any)
+			switch field(spec, "Type") {
+			case "bind":
+				if source, ok := field(spec, "Source").(string); ok {
+					spec["Source"] = spelledSource(source)
+				}
+			case "volume":
+				volumeOptions, _ := field(spec, "VolumeOptions").(map[string]any)
+				driverConfig, _ := field(volumeOptions, "DriverConfig").(map[string]any)
+				translateDevice(field(driverConfig, "Name"), field(driverConfig, "Options"), spelledSource)
+			}
+		}
+		if encoded, err := json.Marshal(hostConfig); err == nil && hostConfig != nil {
+			fields[key] = encoded
+		}
+	}
+}
+
+func decodeField(fields map[string]json.RawMessage, name string, value any) string {
+	for key, raw := range fields {
+		if strings.EqualFold(key, name) {
+			decoder := json.NewDecoder(bytes.NewReader(raw))
+			decoder.UseNumber()
+			_ = decoder.Decode(value) // wrong types stay unset for dockerd to reject
+			return key
+		}
+	}
+	return ""
+}
+
+func translateDevice(driver, options any, translate func(string) string) {
+	optionMap, _ := options.(map[string]any)
+	device, ok := optionMap["device"].(string)
+	flags, _ := optionMap["o"].(string)
+	tokens := strings.Split(flags, ",")
+	local := driver == nil || driver == "" || driver == "local"
+	if ok && local && (slices.Contains(tokens, "bind") || slices.Contains(tokens, "rbind")) && !slices.Contains(tokens, "remount") {
+		optionMap["device"] = translate(device)
+	}
+}
+
+// field also renames the matched key to name.
+func field(object map[string]any, name string) any {
+	for key, value := range object {
+		if strings.EqualFold(key, name) {
+			delete(object, key)
+			object[name] = value
+			return value
+		}
+	}
+	return nil
+}
+
+var (
+	requestFields = []string{"hostconfig", "driver", "driveropts"}
+	asciiFolds    = strings.NewReplacer("ſ", "s", "K", "k") // the non-ASCII runes strings.EqualFold matches to ASCII letters
+)
+
+// dockerd settles repeated names by order, which re-encoding loses.
+func hasAmbiguousFields(body []byte) bool {
+	type frame struct {
+		names     map[string]bool
+		key       string
+		expectKey bool
+		nested    bool
+	}
+	decoder := json.NewDecoder(bytes.NewReader(body))
+	decoder.UseNumber()
+	stack := []*frame{{}}
+	for {
+		token, err := decoder.Token()
+		if err != nil {
+			return !errors.Is(err, io.EOF)
+		}
+		top := stack[len(stack)-1]
+		if name, ok := token.(string); ok && top.expectKey {
+			top.key, top.expectKey = strings.ToLower(asciiFolds.Replace(name)), false
+			if top.names[top.key] && (top.nested || slices.Contains(requestFields, top.key)) {
+				return true
+			}
+			top.names[top.key] = true
+			continue
+		}
+		top.expectKey = top.names != nil
+		nested := top.nested || len(stack) == 2 && slices.Contains(requestFields, top.key)
+		switch token {
+		case json.Delim('{'):
+			stack = append(stack, &frame{names: map[string]bool{}, expectKey: true, nested: nested})
+		case json.Delim('['):
+			stack = append(stack, &frame{nested: nested})
+		case json.Delim('}'), json.Delim(']'):
+			stack = stack[:len(stack)-1]
+		}
+	}
+}
+
+// jobMount returns "" also for a path already naming a daemon source.
+func jobMount(source string, mounts map[string]string) string {
+	target := ""
+	for destination, daemonSource := range mounts {
+		if daemonSource != "" && (source == daemonSource || strings.HasPrefix(source, daemonSource+"/")) {
+			return ""
+		}
+		if len(destination) > len(target) && (source == destination || strings.HasPrefix(source, destination+"/")) {
+			target = destination
+		}
+	}
+	return target
+}
+
 type dockerProxyConnKey struct{}

 type dockerProxyResponse struct {
@@ -380,7 +565,9 @@ func removeLabelled(ctx context.Context, cli client.APIClient, job string) error
 	networks, err := cli.NetworkList(ctx, client.NetworkListOptions{Filters: filters})
 	errs = append(errs, err)
 	for _, n := range networks.Items {
-		if _, err := cli.NetworkRemove(ctx, n.ID, client.NetworkRemoveOptions{}); err != nil && !cerrdefs.IsNotFound(err) {
+		if _, err := cli.NetworkRemove(ctx, n.ID, client.NetworkRemoveOptions{}); n.Scope == "swarm" && cerrdefs.IsInvalidArgument(err) { // swarm refuses while a service or its tasks use it
+			logger.Infof("keeping network %s, a swarm service still uses it", n.Name)
+		} else if err != nil && !cerrdefs.IsNotFound(err) {
 			errs = append(errs, fmt.Errorf("failed to remove network %s: %w", n.Name, err))
 		}
 	}