new endpoint: /libpod/containers/stats

Add a new endpoint for container stats allowing for batch operations on
more than one container.  The new endpoint deprecates the
single-container endpoint which will eventually be removed with the next
major release.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

pkg/api/handlers/libpod/containers_stats.go

@@ -0,0 +1,73 @@
+package libpod
+
+import (
+	"encoding/json"
+	"net/http"
+	"time"
+
+	"github.com/containers/podman/v2/libpod"
+	"github.com/containers/podman/v2/pkg/api/handlers/utils"
+	"github.com/containers/podman/v2/pkg/domain/entities"
+	"github.com/containers/podman/v2/pkg/domain/infra/abi"
+	"github.com/gorilla/schema"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+const DefaultStatsPeriod = 5 * time.Second
+
+func StatsContainer(w http.ResponseWriter, r *http.Request) {
+	runtime := r.Context().Value("runtime").(*libpod.Runtime)
+	decoder := r.Context().Value("decoder").(*schema.Decoder)
+
+	query := struct {
+		Containers []string `schema:"containers"`
+		Stream     bool     `schema:"stream"`
+	}{
+		Stream: true,
+	}
+	if err := decoder.Decode(&query, r.URL.Query()); err != nil {
+		utils.Error(w, "Something went wrong.", http.StatusBadRequest, errors.Wrapf(err, "Failed to parse parameters for %s", r.URL.String()))
+		return
+	}
+
+	// Reduce code duplication and use the local/abi implementation of
+	// container stats.
+	containerEngine := abi.ContainerEngine{Libpod: runtime}
+
+	statsOptions := entities.ContainerStatsOptions{
+		All:      len(query.Containers) == 0, // no containers -> query all of them
+		NoStream: !query.Stream,
+	}
+
+	// Stats will stop if the connection is closed.
+	statsChan, err := containerEngine.ContainerStats(r.Context(), query.Containers, statsOptions)
+	if err != nil {
+		utils.InternalServerError(w, err)
+		return
+	}
+
+	// Write header and content type.
+	w.WriteHeader(http.StatusOK)
+	w.Header().Add("Content-Type", "application/json")
+	if flusher, ok := w.(http.Flusher); ok {
+		flusher.Flush()
+	}
+
+	// Setup JSON encoder for streaming.
+	coder := json.NewEncoder(w)
+	coder.SetEscapeHTML(true)
+
+	for stats := range statsChan {
+		if err := coder.Encode(stats); err != nil {
+			// Note: even when streaming, the stats goroutine will
+			// be notified (and stop) as the connection will be
+			// closed.
+			logrus.Errorf("Unable to encode stats: %v", err)
+			return
+		}
+		if flusher, ok := w.(http.Flusher); ok {
+			flusher.Flush()
+		}
+	}
+}

pkg/api/server/register_containers.go

@@ -1013,7 +1013,7 @@ func (s *APIServer) registerContainersHandlers(r *mux.Router) error {
 	// tags:
 	//  - containers
 	// summary: Get stats for a container
-	// description: This returns a live stream of a container’s resource usage statistics.
+	// description: DEPRECATED. This endpoint will be removed with the next major release. Please use /libpod/containers/stats instead.
 	// parameters:
 	//  - in: path
 	//    name: name
@@ -1035,6 +1035,35 @@ func (s *APIServer) registerContainersHandlers(r *mux.Router) error {
 	//   500:
 	//     $ref: "#/responses/InternalError"
 	r.HandleFunc(VersionedPath("/libpod/containers/{name}/stats"), s.APIHandler(compat.StatsContainer)).Methods(http.MethodGet)
+	// swagger:operation GET /libpod/containers/stats libpod libpodStatsContainers
+	// ---
+	// tags:
+	//  - containers
+	// summary: Get stats for one or more containers
+	// description: Return a live stream of resource usage statistics of one or more container. If no container is specified, the statistics of all containers are returned.
+	// parameters:
+	//  - in: query
+	//    name: containers
+	//    description: names or IDs of containers
+	//    type: array
+	//    items:
+	//       type: string
+	//  - in: query
+	//    name: stream
+	//    type: boolean
+	//    default: true
+	//    description: Stream the output
+	// produces:
+	// - application/json
+	// responses:
+	//   200:
+	//     description: no error
+	//   404:
+	//     $ref: "#/responses/NoSuchContainer"
+	//   500:
+	//     $ref: "#/responses/InternalError"
+	r.HandleFunc(VersionedPath("/libpod/containers/stats"), s.APIHandler(libpod.StatsContainer)).Methods(http.MethodGet)
+
 	// swagger:operation GET /libpod/containers/{name}/top libpod libpodTopContainer
 	// ---
 	// tags:

pkg/bindings/containers/containers.go

@@ -197,7 +197,56 @@ func Start(ctx context.Context, nameOrID string, detachKeys *string) error {
 	return response.Process(nil)
 }
 
-func Stats() {}
+func Stats(ctx context.Context, containers []string, stream *bool) (chan entities.ContainerStatsReport, error) {
+	conn, err := bindings.GetClient(ctx)
+	if err != nil {
+		return nil, err
+	}
+	params := url.Values{}
+	if stream != nil {
+		params.Set("stream", strconv.FormatBool(*stream))
+	}
+	for _, c := range containers {
+		params.Add("containers", c)
+	}
+
+	response, err := conn.DoRequest(nil, http.MethodGet, "/containers/stats", params, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	statsChan := make(chan entities.ContainerStatsReport)
+
+	go func() {
+		defer close(statsChan)
+
+		dec := json.NewDecoder(response.Body)
+		doStream := true
+		if stream != nil {
+			doStream = *stream
+		}
+
+	streamLabel: // label to flatten the scope
+		select {
+		case <-response.Request.Context().Done():
+			return // lost connection - maybe the server quit
+		default:
+			// fall through and do some work
+		}
+		var report entities.ContainerStatsReport
+		if err := dec.Decode(&report); err != nil {
+			report = entities.ContainerStatsReport{Error: err}
+		}
+		statsChan <- report
+
+		if report.Error != nil || !doStream {
+			return
+		}
+		goto streamLabel
+	}()
+
+	return statsChan, nil
+}
 
 // Top gathers statistics about the running processes in a container. The nameOrID can be a container name
 // or a partial/full ID.  The descriptors allow for specifying which data to collect from the process.

pkg/domain/infra/abi/containers.go

@@ -1216,7 +1216,7 @@ func (ic *ContainerEngine) ContainerStats(ctx context.Context, namesOrIds []stri
 		report.Stats, report.Error = computeStats()
 		statsChan <- report
 
-		if options.NoStream {
+		if report.Error != nil || options.NoStream {
 			return
 		}
 

pkg/domain/infra/tunnel/containers.go

@@ -683,5 +683,6 @@ func (ic *ContainerEngine) Shutdown(_ context.Context) {
 }
 
 func (ic *ContainerEngine) ContainerStats(ctx context.Context, namesOrIds []string, options entities.ContainerStatsOptions) (statsChan chan entities.ContainerStatsReport, err error) {
-	return nil, errors.New("not implemented")
+	stream := !options.NoStream
+	return containers.Stats(ic.ClientCxt, namesOrIds, &stream)
 }

test/e2e/stats_test.go

@@ -1,4 +1,4 @@
-// +build !remote
+// +build
 
 package integration