runservice: implement caching

Add `save_cache` and `restore_cache steps`

internal/config/config.go

@@ -147,7 +147,7 @@ type Value struct {
 	Value string
 }
 
-type SaveToWorkspaceContent struct {
+type SaveContent struct {
 	SourceDir string   `yaml:"source_dir"`
 	DestDir   string   `yaml:"dest_dir"`
 	Paths     []string `yaml:"paths"`
@@ -155,7 +155,7 @@ type SaveToWorkspaceContent struct {
 
 type SaveToWorkspaceStep struct {
 	Step     `yaml:",inline"`
-	Contents []SaveToWorkspaceContent
+	Contents []*SaveContent `yaml:"contents"`
 }
 
 type RestoreWorkspaceStep struct {
@@ -163,6 +163,18 @@ type RestoreWorkspaceStep struct {
 	DestDir string `yaml:"dest_dir"`
 }
 
+type SaveCacheStep struct {
+	Step     `yaml:",inline"`
+	Key      string         `yaml:"key"`
+	Contents []*SaveContent `yaml:"contents"`
+}
+
+type RestoreCacheStep struct {
+	Step    `yaml:",inline"`
+	Keys    []string `yaml:"keys"`
+	DestDir string   `yaml:"dest_dir"`
+}
+
 func (t *Task) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	type task struct {
 		Name        string                   `yaml:"name"`
@@ -198,38 +210,54 @@ func (t *Task) UnmarshalYAML(unmarshal func(interface{}) error) error {
 			}
 			switch stepType {
 			case "clone":
-				var cs CloneStep
-				cs.Type = stepType
-				steps[i] = &cs
+				var s CloneStep
+				s.Type = stepType
+				steps[i] = &s
 
 			case "run":
-				var rs RunStep
+				var s RunStep
 				switch stepSpec.(type) {
 				case string:
-					rs.Command = stepSpec.(string)
+					s.Command = stepSpec.(string)
 				default:
-					if err := yaml.Unmarshal(o, &rs); err != nil {
+					if err := yaml.Unmarshal(o, &s); err != nil {
 						return err
 					}
 				}
-				rs.Type = stepType
-				steps[i] = &rs
+				s.Type = stepType
+				steps[i] = &s
 
 			case "save_to_workspace":
-				var sws SaveToWorkspaceStep
-				if err := yaml.Unmarshal(o, &sws); err != nil {
+				var s SaveToWorkspaceStep
+				if err := yaml.Unmarshal(o, &s); err != nil {
 					return err
 				}
-				sws.Type = stepType
-				steps[i] = &sws
+				s.Type = stepType
+				steps[i] = &s
 
 			case "restore_workspace":
-				var rws RestoreWorkspaceStep
-				if err := yaml.Unmarshal(o, &rws); err != nil {
+				var s RestoreWorkspaceStep
+				if err := yaml.Unmarshal(o, &s); err != nil {
 					return err
 				}
-				rws.Type = stepType
-				steps[i] = &rws
+				s.Type = stepType
+				steps[i] = &s
+
+			case "save_cache":
+				var s SaveCacheStep
+				if err := yaml.Unmarshal(o, &s); err != nil {
+					return err
+				}
+				s.Type = stepType
+				steps[i] = &s
+
+			case "restore_cache":
+				var s RestoreCacheStep
+				if err := yaml.Unmarshal(o, &s); err != nil {
+					return err
+				}
+				s.Type = stepType
+				steps[i] = &s
 			default:
 				return errors.Errorf("unknown step type: %s", stepType)
 			}
@@ -572,6 +600,25 @@ func ParseConfig(configData []byte) (*Config, error) {
 		}
 	}
 
+	// set steps defaults
+	for _, t := range config.Tasks {
+		for _, s := range t.Steps {
+			switch step := s.(type) {
+			// TODO(sgotti) we could use the run step command as step name but when the
+			// command is very long or multi line it doesn't makes sense and will
+			// probably be quite unuseful/confusing from an UI point of view
+			case *SaveCacheStep:
+				for _, content := range step.Contents {
+					if len(content.Paths) == 0 {
+						// default to all files inside the sourceDir
+						content.Paths = []string{"**"}
+					}
+				}
+				log.Infof("s: %s", util.Dump(s))
+			}
+		}
+	}
+
 	return &config, checkConfig(&config)
 }
 

internal/config/config_test.go

@@ -167,6 +167,10 @@ func TestParseOutput(t *testing.T) {
                             ENV01: ENV01
                             ENVFROMVARIABLE01:
                               from_variable: variable01
+                      - save_cache:
+                          key: cache-{{ arch }}
+                          contents:
+                            - source_dir: /go/pkg/mod/cache
 
                 pipelines:
                   pipeline01:
@@ -247,6 +251,11 @@ func TestParseOutput(t *testing.T) {
 									"ENVFROMVARIABLE01": Value{Type: ValueTypeFromVariable, Value: "variable01"},
 								},
 							},
+							&SaveCacheStep{
+								Step:     Step{Type: "save_cache"},
+								Key:      "cache-{{ arch }}",
+								Contents: []*SaveContent{&SaveContent{SourceDir: "/go/pkg/mod/cache", Paths: []string{"**"}}},
+							},
 						},
 					},
 				},

internal/runconfig/runconfig.go

@@ -131,9 +131,9 @@ fi
 		sws.Type = cs.Type
 		sws.Name = cs.Name
 
-		sws.Contents = make([]rstypes.SaveToWorkspaceContent, len(cs.Contents))
+		sws.Contents = make([]rstypes.SaveContent, len(cs.Contents))
 		for i, csc := range cs.Contents {
-			sc := rstypes.SaveToWorkspaceContent{}
+			sc := rstypes.SaveContent{}
 			sc.SourceDir = csc.SourceDir
 			sc.DestDir = csc.DestDir
 			sc.Paths = csc.Paths
@@ -150,6 +150,33 @@ fi
 
 		return rws
 
+	case *config.SaveCacheStep:
+		sws := &rstypes.SaveCacheStep{}
+
+		sws.Type = cs.Type
+		sws.Name = cs.Name
+		sws.Key = cs.Key
+
+		sws.Contents = make([]rstypes.SaveContent, len(cs.Contents))
+		for i, csc := range cs.Contents {
+			sc := rstypes.SaveContent{}
+			sc.SourceDir = csc.SourceDir
+			sc.DestDir = csc.DestDir
+			sc.Paths = csc.Paths
+
+			sws.Contents[i] = sc
+		}
+		return sws
+
+	case *config.RestoreCacheStep:
+		rws := &rstypes.RestoreCacheStep{}
+		rws.Name = cs.Name
+		rws.Type = cs.Type
+		rws.Keys = cs.Keys
+		rws.DestDir = cs.DestDir
+
+		return rws
+
 	default:
 		panic(fmt.Errorf("unknown config step type: %s", util.Dump(cs)))
 	}

internal/services/gateway/api/run.go

@@ -200,6 +200,10 @@ func createRunTaskResponse(rt *rstypes.RunTask, rct *rstypes.RunConfigTask) *Run
 			s.Name = "save to workspace"
 		case *rstypes.RestoreWorkspaceStep:
 			s.Name = "restore workspace"
+		case *rstypes.SaveCacheStep:
+			s.Name = "save cache"
+		case *rstypes.RestoreCacheStep:
+			s.Name = "restore cache"
 		}
 
 		t.Steps[i] = s

internal/services/runservice/executor/executor.go

@@ -253,6 +253,42 @@ func (e *Executor) doSaveToWorkspaceStep(ctx context.Context, s *types.SaveToWor
 	return exitCode, nil
 }
 
+func (e *Executor) template(ctx context.Context, t *types.ExecutorTask, pod driver.Pod, logf io.Writer, key string) (string, error) {
+	cmd := append([]string{toolboxContainerPath, "template"})
+
+	// limit the template answer to max 1MiB
+	stdout := util.NewLimitedBuffer(1024 * 1024)
+
+	execConfig := &driver.ExecConfig{
+		Cmd:        cmd,
+		Env:        t.Environment,
+		WorkingDir: t.WorkingDir,
+		Stdout:     stdout,
+		Stderr:     logf,
+	}
+
+	ce, err := pod.Exec(ctx, execConfig)
+	if err != nil {
+		return "", err
+	}
+
+	stdin := ce.Stdin()
+	go func() {
+		io.WriteString(stdin, key)
+		stdin.Close()
+	}()
+
+	exitCode, err := ce.Wait(ctx)
+	if err != nil {
+		return "", err
+	}
+	if exitCode != 0 {
+		return "", errors.Errorf("template ended with exit code %d", exitCode)
+	}
+
+	return stdout.String(), nil
+}
+
 func (e *Executor) unarchive(ctx context.Context, t *types.ExecutorTask, source io.Reader, pod driver.Pod, logf io.Writer, destDir string, overwrite, removeDestDir bool) error {
 	args := []string{"--destdir", destDir}
 	if overwrite {
@@ -328,6 +364,176 @@ func (e *Executor) doRestoreWorkspaceStep(ctx context.Context, s *types.RestoreW
 	return 0, nil
 }
 
+func (e *Executor) doSaveCacheStep(ctx context.Context, s *types.SaveCacheStep, t *types.ExecutorTask, pod driver.Pod, logPath string, archivePath string) (int, error) {
+	cmd := []string{toolboxContainerPath, "archive"}
+
+	if err := os.MkdirAll(filepath.Dir(logPath), 0770); err != nil {
+		return -1, err
+	}
+	logf, err := os.Create(logPath)
+	if err != nil {
+		return -1, err
+	}
+	defer logf.Close()
+
+	save := false
+
+	// calculate key from template
+	userKey, err := e.template(ctx, t, pod, logf, s.Key)
+	if err != nil {
+		return -1, err
+	}
+	fmt.Fprintf(logf, "cache key %q\n", userKey)
+
+	// append cache prefix
+	key := t.CachePrefix + "-" + userKey
+
+	// check that the cache key doesn't already exists
+	resp, err := e.runserviceClient.CheckCache(ctx, key, false)
+	if err != nil {
+		// ignore 404 errors since they means that the cache key doesn't exists
+		if resp != nil && resp.StatusCode == http.StatusNotFound {
+			fmt.Fprintf(logf, "no cache available for key %q. Saving.\n", userKey)
+			save = true
+		} else {
+			// TODO(sgotti) retry before giving up
+			fmt.Fprintf(logf, "error checking for cache key %q: %v\n", userKey, err)
+			return -1, err
+		}
+	}
+	if !save {
+		fmt.Fprintf(logf, "cache for key %q already exists\n", userKey)
+		return 0, nil
+	}
+
+	fmt.Fprintf(logf, "archiving cache with key %q\n", userKey)
+	if err := os.MkdirAll(filepath.Dir(archivePath), 0770); err != nil {
+		return -1, err
+	}
+	archivef, err := os.Create(archivePath)
+	if err != nil {
+		return -1, err
+	}
+	defer archivef.Close()
+
+	execConfig := &driver.ExecConfig{
+		Cmd:        cmd,
+		Env:        t.Environment,
+		WorkingDir: t.WorkingDir,
+		Stdout:     archivef,
+		Stderr:     logf,
+	}
+
+	ce, err := pod.Exec(ctx, execConfig)
+	if err != nil {
+		return -1, err
+	}
+
+	type ArchiveInfo struct {
+		SourceDir string
+		DestDir   string
+		Paths     []string
+	}
+	type Archive struct {
+		ArchiveInfos []*ArchiveInfo
+		OutFile      string
+	}
+
+	a := &Archive{
+		OutFile:      "", // use stdout
+		ArchiveInfos: make([]*ArchiveInfo, len(s.Contents)),
+	}
+
+	for i, c := range s.Contents {
+		a.ArchiveInfos[i] = &ArchiveInfo{
+			SourceDir: c.SourceDir,
+			DestDir:   c.DestDir,
+			Paths:     c.Paths,
+		}
+
+	}
+
+	stdin := ce.Stdin()
+	enc := json.NewEncoder(stdin)
+
+	go func() {
+		enc.Encode(a)
+		stdin.Close()
+	}()
+
+	exitCode, err := ce.Wait(ctx)
+	if err != nil {
+		return -1, err
+	}
+
+	if exitCode != 0 {
+		return exitCode, errors.Errorf("save cache archiving command ended with exit code %d", exitCode)
+	}
+
+	f, err := os.Open(archivePath)
+	if err != nil {
+		return -1, err
+	}
+
+	// send cache archive to scheduler
+	if resp, err := e.runserviceClient.PutCache(ctx, key, f); err != nil {
+		if resp != nil && resp.StatusCode == http.StatusNotModified {
+			return exitCode, nil
+		}
+		return -1, err
+	}
+
+	return exitCode, nil
+}
+
+func (e *Executor) doRestoreCacheStep(ctx context.Context, s *types.RestoreCacheStep, t *types.ExecutorTask, pod driver.Pod, logPath string) (int, error) {
+	if err := os.MkdirAll(filepath.Dir(logPath), 0770); err != nil {
+		return -1, err
+	}
+	logf, err := os.Create(logPath)
+	if err != nil {
+		return -1, err
+	}
+	defer logf.Close()
+
+	fmt.Fprintf(logf, "restoring cache: %s\n", util.Dump(s))
+	for _, key := range s.Keys {
+		// calculate key from template
+		userKey, err := e.template(ctx, t, pod, logf, key)
+		if err != nil {
+			return -1, err
+		}
+		fmt.Fprintf(logf, "cache key %q\n", userKey)
+
+		// append cache prefix
+		key := t.CachePrefix + "-" + userKey
+
+		resp, err := e.runserviceClient.GetCache(ctx, key, true)
+		if err != nil {
+			// ignore 404 errors since they means that the cache key doesn't exists
+			if resp != nil && resp.StatusCode == http.StatusNotFound {
+				fmt.Fprintf(logf, "no cache available for key %q\n", userKey)
+				continue
+			}
+			// TODO(sgotti) retry before giving up
+			fmt.Fprintf(logf, "error reading cache: %v\n", err)
+			return -1, err
+		}
+		fmt.Fprintf(logf, "restoring cache with key %q\n", userKey)
+		cachef := resp.Body
+		if err := e.unarchive(ctx, t, cachef, pod, logf, s.DestDir, false, false); err != nil {
+			cachef.Close()
+			return -1, err
+		}
+		cachef.Close()
+
+		// stop here
+		break
+	}
+
+	return 0, nil
+}
+
 func (e *Executor) executorIDPath() string {
 	return filepath.Join(e.c.DataDir, "id")
 }
@@ -570,6 +776,17 @@ func (e *Executor) executeTaskInternal(ctx context.Context, et *types.ExecutorTa
 			stepName = s.Name
 			exitCode, err = e.doRestoreWorkspaceStep(ctx, s, et, pod, e.stepLogPath(et.ID, i))
 
+		case *types.SaveCacheStep:
+			log.Debugf("save cache step: %s", util.Dump(s))
+			stepName = s.Name
+			archivePath := e.archivePath(et.ID, i)
+			exitCode, err = e.doSaveCacheStep(ctx, s, et, pod, e.stepLogPath(et.ID, i), archivePath)
+
+		case *types.RestoreCacheStep:
+			log.Debugf("restore cache step: %s", util.Dump(s))
+			stepName = s.Name
+			exitCode, err = e.doRestoreCacheStep(ctx, s, et, pod, e.stepLogPath(et.ID, i))
+
 		default:
 			return i, errors.Errorf("unknown step type: %s", util.Dump(s))
 		}

internal/services/runservice/scheduler/api/client.go

@@ -141,6 +141,26 @@ func (c *Client) GetArchive(ctx context.Context, taskID string, step int) (*http
 	return c.getResponse(ctx, "GET", "/executor/archives", q, nil, nil)
 }
 
+func (c *Client) CheckCache(ctx context.Context, key string, prefix bool) (*http.Response, error) {
+	q := url.Values{}
+	if prefix {
+		q.Add("prefix", "")
+	}
+	return c.getResponse(ctx, "HEAD", fmt.Sprintf("/executor/caches/%s", url.PathEscape(key)), q, nil, nil)
+}
+
+func (c *Client) GetCache(ctx context.Context, key string, prefix bool) (*http.Response, error) {
+	q := url.Values{}
+	if prefix {
+		q.Add("prefix", "")
+	}
+	return c.getResponse(ctx, "GET", fmt.Sprintf("/executor/caches/%s", url.PathEscape(key)), q, nil, nil)
+}
+
+func (c *Client) PutCache(ctx context.Context, key string, r io.Reader) (*http.Response, error) {
+	return c.getResponse(ctx, "POST", fmt.Sprintf("/executor/caches/%s", url.PathEscape(key)), nil, nil, r)
+}
+
 func (c *Client) GetRuns(ctx context.Context, phaseFilter, groups []string, lastRun bool, changeGroups []string, start string, limit int, asc bool) (*GetRunsResponse, *http.Response, error) {
 	q := url.Values{}
 	for _, phase := range phaseFilter {

internal/services/runservice/scheduler/api/executor.go

@@ -19,6 +19,7 @@ import (
 	"encoding/json"
 	"io"
 	"net/http"
+	"net/url"
 	"strconv"
 
 	"github.com/gorilla/mux"
@@ -168,7 +169,7 @@ func NewArchivesHandler(logger *zap.Logger, lts *objectstorage.ObjStorage) *Arch
 }
 
 func (h *ArchivesHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	// TODO(sgotti) Check authorized call from scheduler
+	// TODO(sgotti) Check authorized call from executors
 
 	taskID := r.URL.Query().Get("taskid")
 	if taskID == "" {
@@ -216,6 +217,165 @@ func (h *ArchivesHandler) readArchive(rtID string, step int, w io.Writer) error
 	return err
 }
 
+type CacheHandler struct {
+	log *zap.SugaredLogger
+	lts *objectstorage.ObjStorage
+}
+
+func NewCacheHandler(logger *zap.Logger, lts *objectstorage.ObjStorage) *CacheHandler {
+	return &CacheHandler{
+		log: logger.Sugar(),
+		lts: lts,
+	}
+}
+
+func (h *CacheHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	// TODO(sgotti) Check authorized call from executors
+	key, err := url.PathUnescape(vars["key"])
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	if key == "" {
+		http.Error(w, "empty cache key", http.StatusBadRequest)
+		return
+	}
+	if len(key) > common.MaxCacheKeyLength {
+		http.Error(w, "cache key too long", http.StatusBadRequest)
+		return
+	}
+	query := r.URL.Query()
+	_, prefix := query["prefix"]
+
+	matchedKey, err := matchCache(h.lts, key, prefix)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	if matchedKey == "" {
+		http.Error(w, "", http.StatusNotFound)
+		return
+	}
+
+	if r.Method == "HEAD" {
+		return
+	}
+
+	w.Header().Set("Cache-Control", "no-cache")
+
+	if err := h.readCache(matchedKey, w); err != nil {
+		switch err.(type) {
+		case common.ErrNotExist:
+			http.Error(w, err.Error(), http.StatusNotFound)
+		default:
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+		}
+		return
+	}
+}
+
+func matchCache(lts *objectstorage.ObjStorage, key string, prefix bool) (string, error) {
+	cachePath := store.LTSCachePath(key)
+
+	if prefix {
+		doneCh := make(chan struct{})
+		defer close(doneCh)
+
+		// get the latest modified object
+		var lastObject *objectstorage.ObjectInfo
+		for object := range lts.List(store.LTSCacheDir()+"/"+key, "", false, doneCh) {
+			if object.Err != nil {
+				return "", object.Err
+			}
+
+			if (lastObject == nil) || (lastObject != nil && lastObject.LastModified.Before(object.LastModified)) {
+				lastObject = &object
+			}
+
+		}
+		if lastObject == nil {
+			return "", nil
+
+		}
+		return store.LTSCacheKey(lastObject.Path), nil
+	}
+
+	_, err := lts.Stat(cachePath)
+	if err == objectstorage.ErrNotExist {
+		return "", nil
+	}
+	if err != nil {
+		return "", err
+	}
+	return key, nil
+}
+
+func (h *CacheHandler) readCache(key string, w io.Writer) error {
+	cachePath := store.LTSCachePath(key)
+	f, err := h.lts.ReadObject(cachePath)
+	if err != nil {
+		if err == objectstorage.ErrNotExist {
+			return common.NewErrNotExist(err)
+		}
+		return err
+	}
+	defer f.Close()
+
+	br := bufio.NewReader(f)
+
+	_, err = io.Copy(w, br)
+	return err
+}
+
+type CacheCreateHandler struct {
+	log *zap.SugaredLogger
+	lts *objectstorage.ObjStorage
+}
+
+func NewCacheCreateHandler(logger *zap.Logger, lts *objectstorage.ObjStorage) *CacheCreateHandler {
+	return &CacheCreateHandler{
+		log: logger.Sugar(),
+		lts: lts,
+	}
+}
+
+func (h *CacheCreateHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	// TODO(sgotti) Check authorized call from executors
+	key, err := url.PathUnescape(vars["key"])
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	if key == "" {
+		http.Error(w, "empty cache key", http.StatusBadRequest)
+		return
+	}
+	if len(key) > common.MaxCacheKeyLength {
+		http.Error(w, "cache key too long", http.StatusBadRequest)
+		return
+	}
+
+	w.Header().Set("Cache-Control", "no-cache")
+
+	matchedKey, err := matchCache(h.lts, key, false)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	if matchedKey != "" {
+		http.Error(w, "", http.StatusNotModified)
+		return
+	}
+
+	cachePath := store.LTSCachePath(key)
+	if err := h.lts.WriteObject(cachePath, r.Body); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+}
+
 type ExecutorDeleteHandler struct {
 	log *zap.SugaredLogger
 	ch  *command.CommandHandler
@@ -230,7 +390,6 @@ func NewExecutorDeleteHandler(logger *zap.Logger, ch *command.CommandHandler) *E
 
 func (h *ExecutorDeleteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
-
 	vars := mux.Vars(r)
 
 	// TODO(sgotti) Check authorized call from executors

internal/services/runservice/scheduler/common/common.go

@@ -19,6 +19,10 @@ import (
 	"path"
 )
 
+const (
+	MaxCacheKeyLength = 200
+)
+
 type ErrNotExist struct {
 	err error
 }

internal/services/runservice/scheduler/scheduler.go

@@ -270,6 +270,7 @@ func (s *Scheduler) genExecutorTask(ctx context.Context, r *types.Run, rt *types
 		Shell:       rct.Shell,
 		User:        rct.User,
 		Steps:       rct.Steps,
+		CachePrefix: store.LTSRootGroup(r.Group),
 		Status: types.ExecutorTaskStatus{
 			Phase:      types.ExecutorTaskPhaseNotStarted,
 			Steps:      make([]*types.ExecutorTaskStepStatus, len(rct.Steps)),
@@ -1515,6 +1516,8 @@ func (s *Scheduler) Run(ctx context.Context) error {
 	executorTaskHandler := api.NewExecutorTaskHandler(s.e)
 	executorTasksHandler := api.NewExecutorTasksHandler(s.e)
 	archivesHandler := api.NewArchivesHandler(logger, s.lts)
+	cacheHandler := api.NewCacheHandler(logger, s.lts)
+	cacheCreateHandler := api.NewCacheCreateHandler(logger, s.lts)
 
 	// api from clients
 	executorDeleteHandler := api.NewExecutorDeleteHandler(logger, s.ch)
@@ -1530,6 +1533,8 @@ func (s *Scheduler) Run(ctx context.Context) error {
 
 	router := mux.NewRouter()
 	apirouter := router.PathPrefix("/api/v1alpha").Subrouter()
+
+	// don't return 404 on a call to an undefined handler but 400 to distinguish between a non existent resource and a wrong method
 	apirouter.NotFoundHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { w.WriteHeader(http.StatusBadRequest) })
 
 	apirouter.Handle("/executor/{executorid}", executorStatusHandler).Methods("POST")
@@ -1538,6 +1543,9 @@ func (s *Scheduler) Run(ctx context.Context) error {
 	apirouter.Handle("/executor/{executorid}/tasks/{taskid}", executorTaskHandler).Methods("GET")
 	apirouter.Handle("/executor/{executorid}/tasks/{taskid}", executorTaskStatusHandler).Methods("POST")
 	apirouter.Handle("/executor/archives", archivesHandler).Methods("GET")
+	apirouter.Handle("/executor/caches/{key}", cacheHandler).Methods("HEAD")
+	apirouter.Handle("/executor/caches/{key}", cacheHandler).Methods("GET")
+	apirouter.Handle("/executor/caches/{key}", cacheCreateHandler).Methods("POST")
 
 	apirouter.Handle("/logs", logsHandler).Methods("GET")
 

internal/services/runservice/scheduler/store/store.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"path"
 	"reflect"
+	"strings"
 
 	"github.com/sorintlab/agola/internal/etcd"
 	"github.com/sorintlab/agola/internal/objectstorage"
@@ -42,12 +43,12 @@ func LTSSubGroupsAndGroupTypes(group string) []string {
 }
 
 func LTSRootGroup(group string) string {
-	h := util.PathHierarchy(group)
-	if len(h)%2 != 1 {
-		panic(fmt.Errorf("wrong group path %q", group))
+	pl := util.PathList(group)
+	if len(pl) < 2 {
+		panic(fmt.Errorf("cannot determine root group name, wrong group path %q", group))
 	}
 
-	return h[2]
+	return pl[1]
 }
 
 func LTSSubGroups(group string) []string {
@@ -131,6 +132,19 @@ func LTSRunArchivePath(rtID string, step int) string {
 	return path.Join("workspacearchives", fmt.Sprintf("%s/%d.tar", rtID, step))
 }
 
+func LTSCacheDir() string {
+	return "caches"
+}
+
+func LTSCachePath(key string) string {
+	return path.Join(LTSCacheDir(), fmt.Sprintf("%s.tar", key))
+}
+
+func LTSCacheKey(p string) string {
+	base := path.Base(p)
+	return strings.TrimSuffix(base, path.Ext(base))
+}
+
 func LTSGetRunConfig(wal *wal.WalManager, runConfigID string) (*types.RunConfig, error) {
 	runConfigPath := common.StorageRunConfigFile(runConfigID)
 	rcf, _, err := wal.ReadObject(runConfigPath, nil)

internal/services/runservice/types/types.go

@@ -357,11 +357,11 @@ const (
 )
 
 type RegistryAuth struct {
-	Type RegistryAuthType `yaml:"type"`
+	Type RegistryAuthType `json:"type,omitempty"`
 
 	// default auth
-	Username string `yaml:"username"`
-	Password string `yaml:"password"`
+	Username string `json:"username,omitempty"`
+	Password string `json:"password,omitempty"`
 }
 
 type Runtime struct {
@@ -387,30 +387,42 @@ func (rct *RunConfigTask) UnmarshalJSON(b []byte) error {
 	}
 
 	steps := make([]interface{}, len(st.Steps))
-	for i, s := range st.Steps {
+	for i, step := range st.Steps {
 		var bs Step
-		if err := json.Unmarshal(s, &bs); err != nil {
+		if err := json.Unmarshal(step, &bs); err != nil {
 			return err
 		}
 		switch bs.Type {
 		case "run":
-			var rs RunStep
-			if err := json.Unmarshal(s, &rs); err != nil {
+			var s RunStep
+			if err := json.Unmarshal(step, &s); err != nil {
 				return err
 			}
-			steps[i] = &rs
+			steps[i] = &s
 		case "save_to_workspace":
-			var rs SaveToWorkspaceStep
-			if err := json.Unmarshal(s, &rs); err != nil {
+			var s SaveToWorkspaceStep
+			if err := json.Unmarshal(step, &s); err != nil {
 				return err
 			}
-			steps[i] = &rs
+			steps[i] = &s
 		case "restore_workspace":
-			var rs RestoreWorkspaceStep
-			if err := json.Unmarshal(s, &rs); err != nil {
+			var s RestoreWorkspaceStep
+			if err := json.Unmarshal(step, &s); err != nil {
 				return err
 			}
-			steps[i] = &rs
+			steps[i] = &s
+		case "save_cache":
+			var s SaveCacheStep
+			if err := json.Unmarshal(step, &s); err != nil {
+				return err
+			}
+			steps[i] = &s
+		case "restore_cache":
+			var s RestoreCacheStep
+			if err := json.Unmarshal(step, &s); err != nil {
+				return err
+			}
+			steps[i] = &s
 		}
 	}
 
@@ -433,7 +445,7 @@ type RunStep struct {
 	User        string            `json:"user,omitempty"`
 }
 
-type SaveToWorkspaceContent struct {
+type SaveContent struct {
 	SourceDir string   `json:"source_dir,omitempty"`
 	DestDir   string   `json:"dest_dir,omitempty"`
 	Paths     []string `json:"paths,omitempty"`
@@ -441,7 +453,7 @@ type SaveToWorkspaceContent struct {
 
 type SaveToWorkspaceStep struct {
 	Step
-	Contents []SaveToWorkspaceContent `json:"contents,omitempty"`
+	Contents []SaveContent `json:"contents,omitempty"`
 }
 
 type RestoreWorkspaceStep struct {
@@ -449,6 +461,18 @@ type RestoreWorkspaceStep struct {
 	DestDir string `json:"dest_dir,omitempty"`
 }
 
+type SaveCacheStep struct {
+	Step
+	Key      string        `json:"key,omitempty"`
+	Contents []SaveContent `json:"contents,omitempty"`
+}
+
+type RestoreCacheStep struct {
+	Step
+	Keys    []string `json:"keys,omitempty"`
+	DestDir string   `json:"dest_dir,omitempty"`
+}
+
 type ExecutorTaskPhase string
 
 const (
@@ -474,7 +498,7 @@ type ExecutorTask struct {
 	WorkingDir  string            `json:"working_dir,omitempty"`
 	Shell       string            `json:"shell,omitempty"`
 	User        string            `json:"user,omitempty"`
-	Privileged  bool              `yaml:"privileged"`
+	Privileged  bool              `json:"privileged"`
 
 	Steps []interface{} `json:"steps,omitempty"`
 
@@ -484,6 +508,10 @@ type ExecutorTask struct {
 
 	Workspace Workspace `json:"workspace,omitempty"`
 
+	// Cache prefix to use when asking for a cache key. To isolate caches between
+	// groups (projects)
+	CachePrefix string `json:"cache_prefix,omitempty"`
+
 	// Stop is used to signal from the scheduler when the task must be stopped
 	Stop bool `json:"stop,omitempty"`
 }
@@ -546,30 +574,42 @@ func (et *ExecutorTask) UnmarshalJSON(b []byte) error {
 	}
 
 	steps := make([]interface{}, len(ett.Steps))
-	for i, s := range st.Steps {
+	for i, step := range st.Steps {
 		var bs Step
-		if err := json.Unmarshal(s, &bs); err != nil {
+		if err := json.Unmarshal(step, &bs); err != nil {
 			return err
 		}
 		switch bs.Type {
 		case "run":
-			var rs RunStep
-			if err := json.Unmarshal(s, &rs); err != nil {
+			var s RunStep
+			if err := json.Unmarshal(step, &s); err != nil {
 				return err
 			}
-			steps[i] = &rs
+			steps[i] = &s
 		case "save_to_workspace":
-			var rs SaveToWorkspaceStep
-			if err := json.Unmarshal(s, &rs); err != nil {
+			var s SaveToWorkspaceStep
+			if err := json.Unmarshal(step, &s); err != nil {
 				return err
 			}
-			steps[i] = &rs
+			steps[i] = &s
 		case "restore_workspace":
-			var rs RestoreWorkspaceStep
-			if err := json.Unmarshal(s, &rs); err != nil {
+			var s RestoreWorkspaceStep
+			if err := json.Unmarshal(step, &s); err != nil {
 				return err
 			}
-			steps[i] = &rs
+			steps[i] = &s
+		case "save_cache":
+			var s SaveCacheStep
+			if err := json.Unmarshal(step, &s); err != nil {
+				return err
+			}
+			steps[i] = &s
+		case "restore_cache":
+			var s RestoreCacheStep
+			if err := json.Unmarshal(step, &s); err != nil {
+				return err
+			}
+			steps[i] = &s
 		}
 	}
 

internal/util/buffer.go

@@ -0,0 +1,36 @@
+// Copyright 2019 Sorint.lab
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package util
+
+import (
+	"bytes"
+	"io"
+)
+
+type LimitedBuffer struct {
+	*bytes.Buffer
+	cap int
+}
+
+func (b *LimitedBuffer) Write(p []byte) (n int, err error) {
+	if len(p)+b.Len() > b.cap {
+		return 0, io.EOF
+	}
+	return b.Buffer.Write(p)
+}
+
+func NewLimitedBuffer(cap int) *LimitedBuffer {
+	return &LimitedBuffer{Buffer: &bytes.Buffer{}, cap: cap}
+}