Implement top streaming for containers and pods

* Implement API query parameter stream and delay for containers and
  pods top endpoints
* Update swagger with breaking changes
* Add python API tests for endpoints

Fixes #12115

Signed-off-by: Jhon Honce <jhonce@redhat.com>

4 files changed, 148 insertions, 47 deletions

diff --git a/pkg/api/handlers/compat/containers_top.go b/pkg/api/handlers/compat/containers_top.go
index b5debd37d..545320ad9 100644
--- a/pkg/api/handlers/compat/containers_top.go
+++ b/pkg/api/handlers/compat/containers_top.go
@@ -1,8 +1,11 @@
 package compat
 
 import (
+	"encoding/json"
+	"fmt"
 	"net/http"
 	"strings"
+	"time"
 
 	"github.com/containers/podman/v3/libpod"
 	"github.com/containers/podman/v3/pkg/api/handlers"
@@ -10,20 +13,24 @@ import (
 	api "github.com/containers/podman/v3/pkg/api/types"
 	"github.com/gorilla/schema"
 	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
 )
 
 func TopContainer(w http.ResponseWriter, r *http.Request) {
 	runtime := r.Context().Value(api.RuntimeKey).(*libpod.Runtime)
 	decoder := r.Context().Value(api.DecoderKey).(*schema.Decoder)
 
-	defaultValue := "-ef"
+	psArgs := "-ef"
 	if utils.IsLibpodRequest(r) {
-		defaultValue = ""
+		psArgs = ""
 	}
 	query := struct {
+		Delay  int    `schema:"delay"`
 		PsArgs string `schema:"ps_args"`
+		Stream bool   `schema:"stream"`
 	}{
-		PsArgs: defaultValue,
+		Delay:  5,
+		PsArgs: psArgs,
 	}
 	if err := decoder.Decode(&query, r.URL.Query()); err != nil {
 		utils.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest,
@@ -31,6 +38,12 @@ func TopContainer(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if query.Delay < 1 {
+		utils.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest,
+			fmt.Errorf("\"delay\" parameter of value %d < 1", query.Delay))
+		return
+	}
+
 	name := utils.GetName(r)
 	c, err := runtime.LookupContainer(name)
 	if err != nil {
@@ -38,26 +51,56 @@ func TopContainer(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	output, err := c.Top([]string{query.PsArgs})
-	if err != nil {
-		utils.InternalServerError(w, err)
-		return
+	// We are committed now - all errors logged but not reported to client, ship has sailed
+	w.WriteHeader(http.StatusOK)
+	w.Header().Set("Content-Type", "application/json")
+	if f, ok := w.(http.Flusher); ok {
+		f.Flush()
 	}
 
-	var body = handlers.ContainerTopOKBody{}
-	if len(output) > 0 {
-		body.Titles = strings.Split(output[0], "\t")
-		for i := range body.Titles {
-			body.Titles[i] = strings.TrimSpace(body.Titles[i])
-		}
+	encoder := json.NewEncoder(w)
+
+loop: // break out of for/select infinite` loop
+	for {
+		select {
+		case <-r.Context().Done():
+			break loop
+		default:
+			output, err := c.Top([]string{query.PsArgs})
+			if err != nil {
+				logrus.Infof("Error from %s %q : %v", r.Method, r.URL, err)
+				break loop
+			}
+
+			if len(output) > 0 {
+				body := handlers.ContainerTopOKBody{}
+				body.Titles = strings.Split(output[0], "\t")
+				for i := range body.Titles {
+					body.Titles[i] = strings.TrimSpace(body.Titles[i])
+				}
+
+				for _, line := range output[1:] {
+					process := strings.Split(line, "\t")
+					for i := range process {
+						process[i] = strings.TrimSpace(process[i])
+					}
+					body.Processes = append(body.Processes, process)
+				}
+
+				if err := encoder.Encode(body); err != nil {
+					logrus.Infof("Error from %s %q : %v", r.Method, r.URL, err)
+					break loop
+				}
+				if f, ok := w.(http.Flusher); ok {
+					f.Flush()
+				}
+			}
 
-		for _, line := range output[1:] {
-			process := strings.Split(line, "\t")
-			for i := range process {
-				process[i] = strings.TrimSpace(process[i])
+			if query.Stream {
+				time.Sleep(time.Duration(query.Delay) * time.Second)
+			} else {
+				break loop
 			}
-			body.Processes = append(body.Processes, process)
 		}
 	}
-	utils.WriteJSON(w, http.StatusOK, body)
 }
diff --git a/pkg/api/handlers/libpod/pods.go b/pkg/api/handlers/libpod/pods.go
index 1e64de0ee..2ba292579 100644
--- a/pkg/api/handlers/libpod/pods.go
+++ b/pkg/api/handlers/libpod/pods.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net/http"
 	"strings"
+	"time"
 
 	"github.com/containers/common/pkg/config"
 	"github.com/containers/podman/v3/libpod"
@@ -363,10 +364,17 @@ func PodTop(w http.ResponseWriter, r *http.Request) {
 	runtime := r.Context().Value(api.RuntimeKey).(*libpod.Runtime)
 	decoder := r.Context().Value(api.DecoderKey).(*schema.Decoder)
 
+	psArgs := "-ef"
+	if utils.IsLibpodRequest(r) {
+		psArgs = ""
+	}
 	query := struct {
+		Delay  int    `schema:"delay"`
 		PsArgs string `schema:"ps_args"`
+		Stream bool   `schema:"stream"`
 	}{
-		PsArgs: "",
+		Delay:  5,
+		PsArgs: psArgs,
 	}
 	if err := decoder.Decode(&query, r.URL.Query()); err != nil {
 		utils.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest,
@@ -374,31 +382,71 @@ func PodTop(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	name := utils.GetName(r)
-	pod, err := runtime.LookupPod(name)
-	if err != nil {
-		utils.PodNotFound(w, name, err)
+	if query.Delay < 1 {
+		utils.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest,
+			fmt.Errorf("\"delay\" parameter of value %d < 1", query.Delay))
 		return
 	}
 
-	args := []string{}
-	if query.PsArgs != "" {
-		args = append(args, query.PsArgs)
-	}
-	output, err := pod.GetPodPidInformation(args)
+	name := utils.GetName(r)
+	pod, err := runtime.LookupPod(name)
 	if err != nil {
-		utils.InternalServerError(w, err)
+		utils.PodNotFound(w, name, err)
 		return
 	}
 
-	var body = handlers.PodTopOKBody{}
-	if len(output) > 0 {
-		body.Titles = strings.Split(output[0], "\t")
-		for _, line := range output[1:] {
-			body.Processes = append(body.Processes, strings.Split(line, "\t"))
+	// We are committed now - all errors logged but not reported to client, ship has sailed
+	w.WriteHeader(http.StatusOK)
+	w.Header().Set("Content-Type", "application/json")
+	if f, ok := w.(http.Flusher); ok {
+		f.Flush()
+	}
+
+	encoder := json.NewEncoder(w)
+
+loop: // break out of for/select infinite` loop
+	for {
+		select {
+		case <-r.Context().Done():
+			break loop
+		default:
+			output, err := pod.GetPodPidInformation([]string{query.PsArgs})
+			if err != nil {
+				logrus.Infof("Error from %s %q : %v", r.Method, r.URL, err)
+				break loop
+			}
+
+			if len(output) > 0 {
+				var body = handlers.PodTopOKBody{}
+				body.Titles = strings.Split(output[0], "\t")
+				for i := range body.Titles {
+					body.Titles[i] = strings.TrimSpace(body.Titles[i])
+				}
+
+				for _, line := range output[1:] {
+					process := strings.Split(line, "\t")
+					for i := range process {
+						process[i] = strings.TrimSpace(process[i])
+					}
+					body.Processes = append(body.Processes, process)
+				}
+
+				if err := encoder.Encode(body); err != nil {
+					logrus.Infof("Error from %s %q : %v", r.Method, r.URL, err)
+					break loop
+				}
+				if f, ok := w.(http.Flusher); ok {
+					f.Flush()
+				}
+			}
+
+			if query.Stream {
+				time.Sleep(time.Duration(query.Delay) * time.Second)
+			} else {
+				break loop
+			}
 		}
 	}
-	utils.WriteJSON(w, http.StatusOK, body)
 }
 
 func PodKill(w http.ResponseWriter, r *http.Request) {
diff --git a/pkg/api/server/register_containers.go b/pkg/api/server/register_containers.go
index 8dcea1301..c4919182b 100644
--- a/pkg/api/server/register_containers.go
+++ b/pkg/api/server/register_containers.go
@@ -442,6 +442,7 @@ func (s *APIServer) registerContainersHandlers(r *mux.Router) error {
 	//  - in: query
 	//    name: ps_args
 	//    type: string
+	//    default: -ef
 	//    description: arguments to pass to ps such as aux. Requires ps(1) to be installed in the container if no ps(1) compatible AIX descriptors are used.
 	// produces:
 	// - application/json
@@ -1142,19 +1143,23 @@ func (s *APIServer) registerContainersHandlers(r *mux.Router) error {
 	//    name: name
 	//    type: string
 	//    required: true
-	//    description: |
-	//      Name of container to query for processes
-	//      (As of version 1.xx)
+	//    description: Name of container to query for processes (As of version 1.xx)
 	//  - in: query
 	//    name: stream
 	//    type: boolean
-	//    default: true
-	//    description: Stream the output
+	//    description: when true, repeatedly stream the latest output (As of version 4.0)
+	//  - in: query
+	//    name: delay
+	//    type: integer
+	//    description: if streaming, delay in seconds between updates. Must be >1. (As of version 4.0)
+	//    default: 5
 	//  - in: query
 	//    name: ps_args
 	//    type: string
 	//    default: -ef
-	//    description: arguments to pass to ps such as aux. Requires ps(1) to be installed in the container if no ps(1) compatible AIX descriptors are used.
+	//    description: |
+	//      arguments to pass to ps such as aux.
+	//      Requires ps(1) to be installed in the container if no ps(1) compatible AIX descriptors are used.
 	// produces:
 	// - application/json
 	// responses:
diff --git a/pkg/api/server/register_pods.go b/pkg/api/server/register_pods.go
index de3669a0a..16a7bbb4c 100644
--- a/pkg/api/server/register_pods.go
+++ b/pkg/api/server/register_pods.go
@@ -296,18 +296,23 @@ func (s *APIServer) registerPodsHandlers(r *mux.Router) error {
 	//    name: name
 	//    type: string
 	//    required: true
-	//    description: |
-	//      Name of pod to query for processes
+	//    description: Name of pod to query for processes
 	//  - in: query
 	//    name: stream
 	//    type: boolean
-	//    default: true
-	//    description: Stream the output
+	//    description: when true, repeatedly stream the latest output (As of version 4.0)
+	//  - in: query
+	//    name: delay
+	//    type: integer
+	//    description: if streaming, delay in seconds between updates. Must be >1. (As of version 4.0)
+	//    default: 5
 	//  - in: query
 	//    name: ps_args
 	//    type: string
 	//    default: -ef
-	//    description: arguments to pass to ps such as aux. Requires ps(1) to be installed in the container if no ps(1) compatible AIX descriptors are used.
+	//    description: |
+	//      arguments to pass to ps such as aux.
+	//      Requires ps(1) to be installed in the container if no ps(1) compatible AIX descriptors are used.
 	// responses:
 	//   200:
 	//     $ref: "#/responses/DocsPodTopResponse"