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>

1 files changed, 73 insertions, 0 deletions

diff --git a/pkg/api/handlers/libpod/containers_stats.go b/pkg/api/handlers/libpod/containers_stats.go
new file mode 100644
index 000000000..3066d5ebc
--- /dev/null
+++ b/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()
+		}
+	}
+}