stats: add a interval parameter to cli and api stream mode

podman stats polled by default in a 1 sec period.
This can put quite some load on a machine if you run many containers.

The default value is now 5 seconds.
You can change this interval with a new, optional, --interval, -i cli flag.
The api request got also a interval query parameter for the same purpose.

Additionally a unused const was removed.
Api and cli will fail the request if a 0 or negative value is passed in.

Signed-off-by: Thomas Weber <towe75@googlemail.com>

cmd/podman/containers/stats.go

@@ -5,6 +5,7 @@ import (
 	"os"
 
 	tm "github.com/buger/goterm"
+	"github.com/containers/common/pkg/completion"
 	"github.com/containers/common/pkg/report"
 	"github.com/containers/podman/v3/cmd/podman/common"
 	"github.com/containers/podman/v3/cmd/podman/registry"
@@ -55,6 +56,7 @@ type statsOptionsCLI struct {
 	Latest   bool
 	NoReset  bool
 	NoStream bool
+	Interval int
 }
 
 var (
@@ -72,6 +74,9 @@ func statFlags(cmd *cobra.Command) {
 
 	flags.BoolVar(&statsOptions.NoReset, "no-reset", false, "Disable resetting the screen between intervals")
 	flags.BoolVar(&statsOptions.NoStream, "no-stream", false, "Disable streaming stats and only pull the first result, default setting is false")
+	intervalFlagName := "interval"
+	flags.IntVarP(&statsOptions.Interval, intervalFlagName, "i", 5, "Time in seconds between stats reports")
+	_ = cmd.RegisterFlagCompletionFunc(intervalFlagName, completion.AutocompleteNone)
 }
 
 func init() {
@@ -122,8 +127,9 @@ func stats(cmd *cobra.Command, args []string) error {
 	// Convert to the entities options.  We should not leak CLI-only
 	// options into the backend and separate concerns.
 	opts := entities.ContainerStatsOptions{
-		Latest: statsOptions.Latest,
+		Latest:   statsOptions.Latest,
-		Stream: !statsOptions.NoStream,
+		Stream:   !statsOptions.NoStream,
+		Interval: statsOptions.Interval,
 	}
 	statsChan, err := registry.ContainerEngine().ContainerStats(registry.Context(), args, opts)
 	if err != nil {

docs/source/markdown/podman-stats.1.md

@@ -37,6 +37,10 @@ Do not clear the terminal/screen in between reporting intervals
 
 Disable streaming stats and only pull the first result, default setting is false
 
+#### **--interval**=*seconds*, **-i**=*seconds*
+
+Time in seconds between stats reports, defaults to 5 seconds.
+
 #### **--format**=*template*
 
 Pretty-print container statistics to JSON or using a Go template

pkg/api/handlers/libpod/containers_stats.go

@@ -3,7 +3,6 @@ package libpod
 import (
 	"encoding/json"
 	"net/http"
-	"time"
 
 	"github.com/containers/podman/v3/libpod"
 	"github.com/containers/podman/v3/pkg/api/handlers/utils"
@@ -14,8 +13,6 @@ import (
 	"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)
@@ -23,8 +20,10 @@ func StatsContainer(w http.ResponseWriter, r *http.Request) {
 	query := struct {
 		Containers []string `schema:"containers"`
 		Stream     bool     `schema:"stream"`
+		Interval   int      `schema:"interval"`
 	}{
-		Stream: true,
+		Stream:   true,
+		Interval: 5,
 	}
 	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()))
@@ -36,7 +35,8 @@ func StatsContainer(w http.ResponseWriter, r *http.Request) {
 	containerEngine := abi.ContainerEngine{Libpod: runtime}
 
 	statsOptions := entities.ContainerStatsOptions{
-		Stream: query.Stream,
+		Stream:   query.Stream,
+		Interval: query.Interval,
 	}
 
 	// Stats will stop if the connection is closed.

pkg/api/server/register_containers.go

@@ -1106,6 +1106,11 @@ func (s *APIServer) registerContainersHandlers(r *mux.Router) error {
 	//    type: boolean
 	//    default: true
 	//    description: Stream the output
+	//  - in: query
+	//    name: interval
+	//    type: integer
+	//    default: 5
+	//    description: Time in seconds between stats reports
 	// produces:
 	// - application/json
 	// responses:

pkg/bindings/containers/types.go

@@ -165,7 +165,8 @@ type StartOptions struct {
 //go:generate go run ../generator/generator.go StatsOptions
 // StatsOptions are optional options for getting stats on containers
 type StatsOptions struct {
-	Stream *bool
+	Stream   *bool
+	Interval *int
 }
 
 //go:generate go run ../generator/generator.go TopOptions

pkg/bindings/containers/types_stats_options.go

@@ -35,3 +35,19 @@ func (o *StatsOptions) GetStream() bool {
 	}
 	return *o.Stream
 }
+
+// WithInterval
+func (o *StatsOptions) WithInterval(value int) *StatsOptions {
+	v := &value
+	o.Interval = v
+	return o
+}
+
+// GetInterval
+func (o *StatsOptions) GetInterval() int {
+	var interval int
+	if o.Interval == nil {
+		return interval
+	}
+	return *o.Interval
+}

pkg/domain/entities/containers.go

@@ -435,6 +435,8 @@ type ContainerStatsOptions struct {
 	Latest bool
 	// Stream stats.
 	Stream bool
+	// Interval in seconds
+	Interval int
 }
 
 // ContainerStatsReport is used for streaming container stats.

pkg/domain/infra/abi/containers.go

@@ -1281,6 +1281,9 @@ func (ic *ContainerEngine) Shutdown(_ context.Context) {
 }
 
 func (ic *ContainerEngine) ContainerStats(ctx context.Context, namesOrIds []string, options entities.ContainerStatsOptions) (statsChan chan entities.ContainerStatsReport, err error) {
+	if options.Interval < 1 {
+		return nil, errors.New("Invalid interval, must be a positive number greater zero")
+	}
 	statsChan = make(chan entities.ContainerStatsReport, 1)
 
 	containerFunc := ic.Libpod.GetRunningContainers
@@ -1361,7 +1364,7 @@ func (ic *ContainerEngine) ContainerStats(ctx context.Context, namesOrIds []stri
 			return
 		}
 
-		time.Sleep(time.Second)
+		time.Sleep(time.Second * time.Duration(options.Interval))
 		goto stream
 	}()
 

pkg/domain/infra/tunnel/containers.go

@@ -871,7 +871,7 @@ func (ic *ContainerEngine) ContainerStats(ctx context.Context, namesOrIds []stri
 	if options.Latest {
 		return nil, errors.New("latest is not supported for the remote client")
 	}
-	return containers.Stats(ic.ClientCtx, namesOrIds, new(containers.StatsOptions).WithStream(options.Stream))
+	return containers.Stats(ic.ClientCtx, namesOrIds, new(containers.StatsOptions).WithStream(options.Stream).WithInterval(options.Interval))
 }
 
 // ShouldRestart reports back whether the container will restart