Add kubernetes composable inputs provider (#21480)

* Add kubernetes composable inputs provider

x-pack/elastic-agent/CHANGELOG.next.asciidoc

@@ -28,6 +28,7 @@
 - Add support for EQL based condition on inputs {pull}20994[20994]
 - Send `fleet.host.id` to Endpoint Security {pull}21042[21042]
 - Add `install` and `uninstall` subcommands {pull}21206[21206]
+- Add `kubernetes` composable dynamic provider. {pull}21480[21480]
 - Send updating state {pull}21461[21461]
 - Add `elastic.agent.id` and `elastic.agent.version` to published events from filebeat and metricbeat {pull}21543[21543]
 - Add `upgrade` subcommand to perform upgrade of installed Elastic Agent {pull}21425[21425]

x-pack/elastic-agent/pkg/agent/cmd/include.go

@@ -10,6 +10,7 @@ import (
 	_ "github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/composable/providers/docker"
 	_ "github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/composable/providers/env"
 	_ "github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/composable/providers/host"
+	_ "github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/composable/providers/kubernetes"
 	_ "github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/composable/providers/local"
 	_ "github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/composable/providers/localdynamic"
 	_ "github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/composable/providers/path"

x-pack/elastic-agent/pkg/composable/providers/kubernetes/config.go

@@ -0,0 +1,31 @@
+// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+// or more contributor license agreements. Licensed under the Elastic License;
+// you may not use this file except in compliance with the Elastic License.
+
+// TODO review the need for this
+// +build linux darwin windows
+
+package kubernetes
+
+import (
+	"time"
+)
+
+// Config for kubernetes provider
+type Config struct {
+	KubeConfig     string        `config:"kube_config"`
+	SyncPeriod     time.Duration `config:"sync_period"`
+	CleanupTimeout time.Duration `config:"cleanup_timeout" validate:"positive"`
+
+	// Needed when resource is a pod
+	Node string `config:"node"`
+
+	// Scope of the provider (cluster or node)
+	Scope string `config:"scope"`
+}
+
+// InitDefaults initializes the default values for the config.
+func (c *Config) InitDefaults() {
+	c.SyncPeriod = 10 * time.Minute
+	c.CleanupTimeout = 60 * time.Second
+}

x-pack/elastic-agent/pkg/composable/providers/kubernetes/kubernetes.go

@@ -0,0 +1,215 @@
+// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+// or more contributor license agreements. Licensed under the Elastic License;
+// you may not use this file except in compliance with the Elastic License.
+
+package kubernetes
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/elastic/beats/v7/libbeat/common/kubernetes"
+	"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/agent/errors"
+	"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/composable"
+	"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/config"
+	"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/core/logger"
+)
+
+func init() {
+	composable.Providers.AddDynamicProvider("kubernetes", DynamicProviderBuilder)
+}
+
+type dynamicProvider struct {
+	logger *logger.Logger
+	config *Config
+}
+
+type eventWatcher struct {
+	logger         *logger.Logger
+	cleanupTimeout time.Duration
+	comm           composable.DynamicProviderComm
+}
+
+// DynamicProviderBuilder builds the dynamic provider.
+func DynamicProviderBuilder(logger *logger.Logger, c *config.Config) (composable.DynamicProvider, error) {
+	var cfg Config
+	if c == nil {
+		c = config.New()
+	}
+	err := c.Unpack(&cfg)
+	if err != nil {
+		return nil, errors.New(err, "failed to unpack configuration")
+	}
+	return &dynamicProvider{logger, &cfg}, nil
+}
+
+// Run runs the environment context provider.
+func (p *dynamicProvider) Run(comm composable.DynamicProviderComm) error {
+	client, err := kubernetes.GetKubernetesClient(p.config.KubeConfig)
+	if err != nil {
+		// info only; return nil (do nothing)
+		p.logger.Debugf("Kubernetes provider skipped, unable to connect: %s", err)
+		return nil
+	}
+
+	// Ensure that node is set correctly whenever the scope is set to "node". Make sure that node is empty
+	// when cluster scope is enforced.
+	if p.config.Scope == "node" {
+		p.config.Node = kubernetes.DiscoverKubernetesNode(p.logger, p.config.Node, kubernetes.IsInCluster(p.config.KubeConfig), client)
+	} else {
+		p.config.Node = ""
+	}
+	p.logger.Infof("Kubernetes provider started with %s scope", p.config.Scope)
+	p.logger.Debugf("Initializing Kubernetes watcher using node: %v", p.config.Node)
+
+	watcher, err := kubernetes.NewWatcher(client, &kubernetes.Pod{}, kubernetes.WatchOptions{
+		SyncTimeout: p.config.SyncPeriod,
+		Node:        p.config.Node,
+		//Namespace:   p.config.Namespace,
+	}, nil)
+	if err != nil {
+		return errors.New(err, "couldn't create kubernetes watcher")
+	}
+
+	watcher.AddEventHandler(&eventWatcher{p.logger, p.config.CleanupTimeout, comm})
+
+	err = watcher.Start()
+	if err != nil {
+		return errors.New(err, "couldn't start kubernetes watcher")
+	}
+
+	return nil
+}
+
+func (p *eventWatcher) emitRunning(pod *kubernetes.Pod) {
+	mapping := map[string]interface{}{
+		"namespace": pod.GetNamespace(),
+		"pod": map[string]interface{}{
+			"uid":    string(pod.GetUID()),
+			"name":   pod.GetName(),
+			"labels": pod.GetLabels(),
+			"ip":     pod.Status.PodIP,
+		},
+	}
+
+	processors := []map[string]interface{}{
+		{
+			"add_fields": map[string]interface{}{
+				"fields": mapping,
+				"target": "kubernetes",
+			},
+		},
+	}
+
+	// Emit the pod
+	// We emit Pod + containers to ensure that configs matching Pod only
+	// get Pod metadata (not specific to any container)
+	p.comm.AddOrUpdate(string(pod.GetUID()), mapping, processors)
+
+	// Emit all containers in the pod
+	p.emitContainers(pod, pod.Spec.Containers, pod.Status.ContainerStatuses)
+
+	// TODO deal with init containers stopping after initialization
+	p.emitContainers(pod, pod.Spec.InitContainers, pod.Status.InitContainerStatuses)
+}
+
+func (p *eventWatcher) emitContainers(pod *kubernetes.Pod, containers []kubernetes.Container, containerstatuses []kubernetes.PodContainerStatus) {
+	// Collect all runtimes from status information.
+	containerIDs := map[string]string{}
+	runtimes := map[string]string{}
+	for _, c := range containerstatuses {
+		cid, runtime := kubernetes.ContainerIDWithRuntime(c)
+		containerIDs[c.Name] = cid
+		runtimes[c.Name] = runtime
+	}
+
+	for _, c := range containers {
+		// If it doesn't have an ID, container doesn't exist in
+		// the runtime, emit only an event if we are stopping, so
+		// we are sure of cleaning up configurations.
+		cid := containerIDs[c.Name]
+		if cid == "" {
+			continue
+		}
+
+		// ID is the combination of pod UID + container name
+		eventID := fmt.Sprintf("%s.%s", pod.GetObjectMeta().GetUID(), c.Name)
+
+		mapping := map[string]interface{}{
+			"namespace": pod.GetNamespace(),
+			"pod": map[string]interface{}{
+				"uid":    string(pod.GetUID()),
+				"name":   pod.GetName(),
+				"labels": pod.GetLabels(),
+				"ip":     pod.Status.PodIP,
+			},
+			"container": map[string]interface{}{
+				"id":      cid,
+				"name":    c.Name,
+				"image":   c.Image,
+				"runtime": runtimes[c.Name],
+			},
+		}
+
+		processors := []map[string]interface{}{
+			{
+				"add_fields": map[string]interface{}{
+					"fields": mapping,
+					"target": "kubernetes",
+				},
+			},
+		}
+
+		// Emit the container
+		p.comm.AddOrUpdate(eventID, mapping, processors)
+	}
+}
+
+func (p *eventWatcher) emitStopped(pod *kubernetes.Pod) {
+	p.comm.Remove(string(pod.GetUID()))
+
+	for _, c := range pod.Spec.Containers {
+		// ID is the combination of pod UID + container name
+		eventID := fmt.Sprintf("%s.%s", pod.GetObjectMeta().GetUID(), c.Name)
+		p.comm.Remove(eventID)
+	}
+
+	for _, c := range pod.Spec.InitContainers {
+		// ID is the combination of pod UID + container name
+		eventID := fmt.Sprintf("%s.%s", pod.GetObjectMeta().GetUID(), c.Name)
+		p.comm.Remove(eventID)
+	}
+}
+
+// OnAdd ensures processing of pod objects that are newly added
+func (p *eventWatcher) OnAdd(obj interface{}) {
+	p.logger.Debugf("pod add: %+v", obj)
+	p.emitRunning(obj.(*kubernetes.Pod))
+}
+
+// OnUpdate emits events for a given pod depending on the state of the pod,
+// if it is terminating, a stop event is scheduled, if not, a stop and a start
+// events are sent sequentially to recreate the resources assotiated to the pod.
+func (p *eventWatcher) OnUpdate(obj interface{}) {
+	pod := obj.(*kubernetes.Pod)
+
+	p.logger.Debugf("pod update for pod: %+v, status: %+v", pod.Name, pod.Status.Phase)
+	switch pod.Status.Phase {
+	case kubernetes.PodSucceeded, kubernetes.PodFailed:
+		time.AfterFunc(p.cleanupTimeout, func() { p.emitStopped(pod) })
+		return
+	case kubernetes.PodPending:
+		p.logger.Debugf("pod update (pending): don't know what to do with this pod yet, skipping for now: %+v", obj)
+		return
+	}
+
+	p.logger.Debugf("pod update: %+v", obj)
+	p.emitRunning(pod)
+}
+
+// OnDelete stops pod objects that are deleted
+func (p *eventWatcher) OnDelete(obj interface{}) {
+	p.logger.Debugf("pod delete: %+v", obj)
+	pod := obj.(*kubernetes.Pod)
+	time.AfterFunc(p.cleanupTimeout, func() { p.emitStopped(pod) })
+}