implement pod stats

Implement pod stats for the local and remote client. Both code paths end
up in infra/abi to allow for code share.

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

pkg/api/handlers/libpod/pods.go

@@ -11,6 +11,7 @@ import (
 	"github.com/containers/libpod/pkg/api/handlers"
 	"github.com/containers/libpod/pkg/api/handlers/utils"
 	"github.com/containers/libpod/pkg/domain/entities"
+	"github.com/containers/libpod/pkg/domain/infra/abi"
 	"github.com/containers/libpod/pkg/specgen"
 	"github.com/containers/libpod/pkg/specgen/generate"
 	"github.com/containers/libpod/pkg/util"
@@ -419,3 +420,44 @@ func PodExists(w http.ResponseWriter, r *http.Request) {
 	}
 	utils.WriteResponse(w, http.StatusNoContent, "")
 }
+
+func PodStats(w http.ResponseWriter, r *http.Request) {
+	runtime := r.Context().Value("runtime").(*libpod.Runtime)
+	decoder := r.Context().Value("decoder").(*schema.Decoder)
+
+	query := struct {
+		NamesOrIDs []string `schema:"namesOrIDs"`
+		All        bool     `schema:"all"`
+	}{
+		// default would go here
+	}
+	if err := decoder.Decode(&query, r.URL.Query()); err != nil {
+		utils.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest,
+			errors.Wrapf(err, "Failed to parse parameters for %s", r.URL.String()))
+		return
+	}
+
+	// Validate input.
+	options := entities.PodStatsOptions{All: query.All}
+	if err := entities.ValidatePodStatsOptions(query.NamesOrIDs, &options); err != nil {
+		utils.InternalServerError(w, err)
+	}
+
+	// Collect the stats and send them over the wire.
+	containerEngine := abi.ContainerEngine{Libpod: runtime}
+	reports, err := containerEngine.PodStats(r.Context(), query.NamesOrIDs, options)
+
+	// Error checks as documented in swagger.
+	switch errors.Cause(err) {
+	case define.ErrNoSuchPod:
+		utils.Error(w, "one or more pods not found", http.StatusNotFound, err)
+		return
+	case nil:
+		// Nothing to do.
+	default:
+		utils.InternalServerError(w, err)
+		return
+	}
+
+	utils.WriteResponse(w, http.StatusOK, reports)
+}

pkg/api/handlers/swagger/swagger.go

@@ -122,6 +122,13 @@ type swagPodTopResponse struct {
 	}
 }
 
+// List processes in pod
+// swagger:response DocsPodStatsResponse
+type swagPodStatsResponse struct {
+	// in:body
+	Body []*entities.PodStatsReport
+}
+
 // Inspect container
 // swagger:response LibpodInspectContainerResponse
 type swagLibpodInspectContainerResponse struct {

pkg/api/handlers/utils/errors.go

@@ -14,6 +14,9 @@ var (
 	ErrLinkNotSupport = errors.New("Link is not supported")
 )
 
+// TODO: document the exported functions in this file and make them more
+// generic (e.g., not tied to one ctr/pod).
+
 // Error formats an API response to an error
 //
 // apiMessage and code must match the container API, and are sent to client

pkg/api/server/register_pods.go

@@ -286,9 +286,36 @@ func (s *APIServer) registerPodsHandlers(r *mux.Router) error {
 	//   200:
 	//     $ref: "#/responses/DocsPodTopResponse"
 	//   404:
-	//     $ref: "#/responses/NoSuchContainer"
+	//     $ref: "#/responses/NoSuchPod"
 	//   500:
 	//     $ref: "#/responses/InternalError"
 	r.Handle(VersionedPath("/libpod/pods/{name}/top"), s.APIHandler(libpod.PodTop)).Methods(http.MethodGet)
+	// swagger:operation GET /libpod/pods/stats pods statsPod
+	// ---
+	// tags:
+	//  - pods
+	// summary: Get stats for one or more pods
+	// description: Display a live stream of resource usage statistics for the containers in one or more pods
+	// parameters:
+	//  - in: query
+	//    name: all
+	//    description: Provide statistics for all running pods.
+	//    type: boolean
+	//  - in: query
+	//    name: namesOrIDs
+	//    description: Names or IDs of pods.
+	//    type: array
+	//    items:
+	//      type: string
+	// produces:
+	// - application/json
+	// responses:
+	//   200:
+	//     $ref: "#/responses/DocsPodTopResponse"
+	//   404:
+	//     $ref: "#/responses/NoSuchPod"
+	//   500:
+	//     $ref: "#/responses/InternalError"
+	r.Handle(VersionedPath("/libpod/pods/stats"), s.APIHandler(libpod.PodStats)).Methods(http.MethodGet)
 	return nil
 }