x-pack/filebeat/input/{cel,httpjson}: make transport keep-alives configurable

CHANGELOG.next.asciidoc

@@ -183,6 +183,7 @@ https://github.com/elastic/beats/compare/v8.2.0\...main[Check the HEAD diff]
 - Convert UDP input to v2 input. {pull}33930[33930]
 - Improve collection of risk information from Okta debug data. {issue}33677[33677] {pull}34030[34030]
 - Adding filename details from zip to response for httpjson {issue}33952[33952] {pull}34044[34044]
+- Allow user configuration of keep-alive behaviour for HTTPJSON and CEL inputs. {issue}33951[33951] {pull}34014[34014]
 
 *Auditbeat*
 

x-pack/filebeat/docs/inputs/input-cel.asciidoc

@@ -434,6 +434,26 @@ This specifies SSL/TLS configuration. If the ssl section is missing, the host's
 CAs are used for HTTPS connections. See <<configuration-ssl>> for more
 information.
 
+[float]
+==== `resource.keep_alive.disable`
+
+This specifies whether to disable keep-alives for HTTP end-points. Default: `true`.
+
+[float]
+==== `resource.keep_alive.max_idle_connections`
+
+The maximum number of idle connections across all hosts. Zero means no limit. Default: `0`.
+
+[float]
+==== `resource.keep_alive.max_idle_connections_per_host`
+
+The maximum idle connections to keep per-host. If zero, defaults to two. Default: `0`.
+
+[float]
+==== `resource.keep_alive.idle_connection_timeout`
+
+The maximum amount of time an idle connection will remain idle before closing itself. Valid time units are `ns`, `us`, `ms`, `s`, `m`, `h`. Zero means no limit. Default: `0s`.
+
 [float]
 ==== `resource.retry.max_attempts`
 

x-pack/filebeat/docs/inputs/input-httpjson.asciidoc

@@ -456,6 +456,26 @@ filebeat.inputs:
   request.proxy_url: http://proxy.example:8080
 ----
 
+[float]
+==== `request.keep_alive.disable`
+
+This specifies whether to disable keep-alives for HTTP end-points. Default: `true`.
+
+[float]
+==== `request.keep_alive.max_idle_connections`
+
+The maximum number of idle connections across all hosts. Zero means no limit. Default: `0`.
+
+[float]
+==== `request.keep_alive.max_idle_connections_per_host`
+
+The maximum idle connections to keep per-host. If zero, defaults to two. Default: `0`.
+
+[float]
+==== `request.keep_alive.idle_connection_timeout`
+
+The maximum amount of time an idle connection will remain idle before closing itself. Valid time units are `ns`, `us`, `ms`, `s`, `m`, `h`. Zero means no limit. Default: `0s`.
+
 [float]
 ==== `request.retry.max_attempts`
 

x-pack/filebeat/input/cel/config.go

@@ -143,13 +143,46 @@ func (c rateLimitConfig) Validate() error {
 	return nil
 }
 
+type keepAlive struct {
+	Disable             *bool         `config:"disable"`
+	MaxIdleConns        int           `config:"max_idle_connections"`
+	MaxIdleConnsPerHost int           `config:"max_idle_connections_per_host"` // If zero, http.DefaultMaxIdleConnsPerHost is the value used by http.Transport.
+	IdleConnTimeout     time.Duration `config:"idle_connection_timeout"`
+}
+
+func (c keepAlive) Validate() error {
+	if c.Disable == nil || *c.Disable {
+		return nil
+	}
+	if c.MaxIdleConns < 0 {
+		return errors.New("max_idle_connections must not be negative")
+	}
+	if c.MaxIdleConnsPerHost < 0 {
+		return errors.New("max_idle_connections_per_host must not be negative")
+	}
+	if c.IdleConnTimeout < 0 {
+		return errors.New("idle_connection_timeout must not be negative")
+	}
+	return nil
+}
+
+func (c keepAlive) settings() httpcommon.WithKeepaliveSettings {
+	return httpcommon.WithKeepaliveSettings{
+		Disable:             c.Disable == nil || *c.Disable,
+		MaxIdleConns:        c.MaxIdleConns,
+		MaxIdleConnsPerHost: c.MaxIdleConnsPerHost,
+		IdleConnTimeout:     c.IdleConnTimeout,
+	}
+}
+
 type ResourceConfig struct {
 	URL                    *urlConfig       `config:"url" validate:"required"`
 	Retry                  retryConfig      `config:"retry"`
 	RedirectForwardHeaders bool             `config:"redirect.forward_headers"`
 	RedirectHeadersBanList []string         `config:"redirect.headers_ban_list"`
 	RedirectMaxRedirects   int              `config:"redirect.max_redirects"`
 	RateLimit              *rateLimitConfig `config:"rate_limit"`
+	KeepAlive              keepAlive        `config:"keep_alive"`
 
 	Transport httpcommon.HTTPTransportSettings `config:",inline"`
 

x-pack/filebeat/input/cel/config_test.go

@@ -17,6 +17,7 @@ import (
 	"golang.org/x/oauth2/google"
 
 	conf "github.com/elastic/elastic-agent-libs/config"
+	"github.com/elastic/elastic-agent-libs/transport/httpcommon"
 )
 
 func TestProviderCanonical(t *testing.T) {
@@ -466,3 +467,60 @@ func TestConfigOauth2Validation(t *testing.T) {
 		})
 	}
 }
+
+var keepAliveTests = []struct {
+	name    string
+	input   map[string]interface{}
+	want    httpcommon.WithKeepaliveSettings
+	wantErr error
+}{
+	{
+		name:  "keep_alive_none", // Default to the old behaviour of true.
+		input: map[string]interface{}{},
+		want:  httpcommon.WithKeepaliveSettings{Disable: true},
+	},
+	{
+		name: "keep_alive_true",
+		input: map[string]interface{}{
+			"resource.keep_alive.disable": true,
+		},
+		want: httpcommon.WithKeepaliveSettings{Disable: true},
+	},
+	{
+		name: "keep_alive_false",
+		input: map[string]interface{}{
+			"resource.keep_alive.disable": false,
+		},
+		want: httpcommon.WithKeepaliveSettings{Disable: false},
+	},
+	{
+		name: "keep_alive_invalid_max",
+		input: map[string]interface{}{
+			"resource.keep_alive.disable":              false,
+			"resource.keep_alive.max_idle_connections": -1,
+		},
+		wantErr: errors.New("max_idle_connections must not be negative accessing 'resource.keep_alive'"),
+	},
+}
+
+func TestKeepAliveSetting(t *testing.T) {
+	for _, test := range keepAliveTests {
+		t.Run(test.name, func(t *testing.T) {
+			test.input["resource.url"] = "localhost"
+			cfg := conf.MustNewConfigFrom(test.input)
+			conf := defaultConfig()
+			conf.Program = "{}" // Provide an empty program to avoid validation error from that.
+			err := cfg.Unpack(&conf)
+			if fmt.Sprint(err) != fmt.Sprint(test.wantErr) {
+				t.Errorf("unexpected error return from Unpack: got: %v want: %v", err, test.wantErr)
+			}
+			if err != nil {
+				return
+			}
+			got := conf.Resource.KeepAlive.settings()
+			if got != test.want {
+				t.Errorf("unexpected setting for %s: got: %#v\nwant:%#v", test.name, got, test.want)
+			}
+		})
+	}
+}

x-pack/filebeat/input/cel/input.go

@@ -645,7 +645,7 @@ func newClient(ctx context.Context, cfg config, log *logp.Logger) (*http.Client,
 	if !wantClient(cfg) {
 		return nil, nil
 	}
-	c, err := cfg.Resource.Transport.Client(clientOptions(cfg.Resource.URL.URL)...)
+	c, err := cfg.Resource.Transport.Client(clientOptions(cfg.Resource.URL.URL, cfg.Resource.KeepAlive.settings())...)
 	if err != nil {
 		return nil, err
 	}
@@ -696,7 +696,7 @@ func wantClient(cfg config) bool {
 
 // clientOption returns constructed client configuration options, including
 // setting up http+unix and http+npipe transports if requested.
-func clientOptions(u *url.URL) []httpcommon.TransportOption {
+func clientOptions(u *url.URL, keepalive httpcommon.WithKeepaliveSettings) []httpcommon.TransportOption {
 	scheme, trans, ok := strings.Cut(u.Scheme, "+")
 	var dialer transport.Dialer
 	switch {
@@ -705,7 +705,7 @@ func clientOptions(u *url.URL) []httpcommon.TransportOption {
 	case !ok:
 		return []httpcommon.TransportOption{
 			httpcommon.WithAPMHTTPInstrumentation(),
-			httpcommon.WithKeepaliveSettings{Disable: true},
+			keepalive,
 		}
 
 	// We set the host for the unix socket and Windows named
@@ -723,7 +723,7 @@ func clientOptions(u *url.URL) []httpcommon.TransportOption {
 	u.Scheme = scheme
 	return []httpcommon.TransportOption{
 		httpcommon.WithAPMHTTPInstrumentation(),
-		httpcommon.WithKeepaliveSettings{Disable: true},
+		keepalive,
 		httpcommon.WithBaseDialer(dialer),
 	}
 }

x-pack/filebeat/input/httpjson/config_request.go

@@ -74,6 +74,38 @@ func (c rateLimitConfig) Validate() error {
 	return nil
 }
 
+type keepAlive struct {
+	Disable             *bool         `config:"disable"`
+	MaxIdleConns        int           `config:"max_idle_connections"`
+	MaxIdleConnsPerHost int           `config:"max_idle_connections_per_host"` // If zero, http.DefaultMaxIdleConnsPerHost is the value used by http.Transport.
+	IdleConnTimeout     time.Duration `config:"idle_connection_timeout"`
+}
+
+func (c keepAlive) Validate() error {
+	if c.Disable == nil || *c.Disable {
+		return nil
+	}
+	if c.MaxIdleConns < 0 {
+		return errors.New("max_idle_connections must not be negative")
+	}
+	if c.MaxIdleConnsPerHost < 0 {
+		return errors.New("max_idle_connections_per_host must not be negative")
+	}
+	if c.IdleConnTimeout < 0 {
+		return errors.New("idle_connection_timeout must not be negative")
+	}
+	return nil
+}
+
+func (c keepAlive) settings() httpcommon.WithKeepaliveSettings {
+	return httpcommon.WithKeepaliveSettings{
+		Disable:             c.Disable == nil || *c.Disable,
+		MaxIdleConns:        c.MaxIdleConns,
+		MaxIdleConnsPerHost: c.MaxIdleConnsPerHost,
+		IdleConnTimeout:     c.IdleConnTimeout,
+	}
+}
+
 type urlConfig struct {
 	*url.URL
 }
@@ -99,6 +131,7 @@ type requestConfig struct {
 	RedirectHeadersBanList []string         `config:"redirect.headers_ban_list"`
 	RedirectMaxRedirects   int              `config:"redirect.max_redirects"`
 	RateLimit              *rateLimitConfig `config:"rate_limit"`
+	KeepAlive              keepAlive        `config:"keep_alive"`
 	Transforms             transformsConfig `config:"transforms"`
 
 	Transport httpcommon.HTTPTransportSettings `config:",inline"`

x-pack/filebeat/input/httpjson/config_test.go

@@ -7,6 +7,7 @@ package httpjson
 import (
 	"context"
 	"errors"
+	"fmt"
 	"os"
 	"testing"
 
@@ -15,6 +16,7 @@ import (
 	"golang.org/x/oauth2/google"
 
 	conf "github.com/elastic/elastic-agent-libs/config"
+	"github.com/elastic/elastic-agent-libs/transport/httpcommon"
 )
 
 func TestProviderCanonical(t *testing.T) {
@@ -485,3 +487,59 @@ func TestCursorEntryConfig(t *testing.T) {
 	assert.True(t, conf["entry3"].mustIgnoreEmptyValue())
 	assert.True(t, conf["entry4"].mustIgnoreEmptyValue())
 }
+
+var keepAliveTests = []struct {
+	name    string
+	input   map[string]interface{}
+	want    httpcommon.WithKeepaliveSettings
+	wantErr error
+}{
+	{
+		name:  "keep_alive_none", // Default to the old behaviour of true.
+		input: map[string]interface{}{},
+		want:  httpcommon.WithKeepaliveSettings{Disable: true},
+	},
+	{
+		name: "keep_alive_true",
+		input: map[string]interface{}{
+			"request.keep_alive.disable": true,
+		},
+		want: httpcommon.WithKeepaliveSettings{Disable: true},
+	},
+	{
+		name: "keep_alive_false",
+		input: map[string]interface{}{
+			"request.keep_alive.disable": false,
+		},
+		want: httpcommon.WithKeepaliveSettings{Disable: false},
+	},
+	{
+		name: "keep_alive_invalid_max",
+		input: map[string]interface{}{
+			"request.keep_alive.disable":              false,
+			"request.keep_alive.max_idle_connections": -1,
+		},
+		wantErr: errors.New("max_idle_connections must not be negative accessing 'request.keep_alive'"),
+	},
+}
+
+func TestKeepAliveSetting(t *testing.T) {
+	for _, test := range keepAliveTests {
+		t.Run(test.name, func(t *testing.T) {
+			test.input["request.url"] = "localhost"
+			cfg := conf.MustNewConfigFrom(test.input)
+			conf := defaultConfig()
+			err := cfg.Unpack(&conf)
+			if fmt.Sprint(err) != fmt.Sprint(test.wantErr) {
+				t.Errorf("unexpected error return from Unpack: got: %q want: %q", err, test.wantErr)
+			}
+			if err != nil {
+				return
+			}
+			got := conf.Request.KeepAlive.settings()
+			if got != test.want {
+				t.Errorf("unexpected setting for %s: got: %#v\nwant:%#v", test.name, got, test.want)
+			}
+		})
+	}
+}

x-pack/filebeat/input/httpjson/input.go

@@ -157,7 +157,7 @@ func run(
 
 func newHTTPClient(ctx context.Context, config config, log *logp.Logger) (*httpClient, error) {
 	// Make retryable HTTP client
-	netHTTPClient, err := config.Request.Transport.Client(clientOptions(config.Request.URL.URL)...)
+	netHTTPClient, err := config.Request.Transport.Client(clientOptions(config.Request.URL.URL, config.Request.KeepAlive.settings())...)
 	if err != nil {
 		return nil, err
 	}
@@ -201,7 +201,7 @@ func newHTTPClient(ctx context.Context, config config, log *logp.Logger) (*httpC
 
 // clientOption returns constructed client configuration options, including
 // setting up http+unix and http+npipe transports if requested.
-func clientOptions(u *url.URL) []httpcommon.TransportOption {
+func clientOptions(u *url.URL, keepalive httpcommon.WithKeepaliveSettings) []httpcommon.TransportOption {
 	scheme, trans, ok := strings.Cut(u.Scheme, "+")
 	var dialer transport.Dialer
 	switch {
@@ -210,7 +210,7 @@ func clientOptions(u *url.URL) []httpcommon.TransportOption {
 	case !ok:
 		return []httpcommon.TransportOption{
 			httpcommon.WithAPMHTTPInstrumentation(),
-			httpcommon.WithKeepaliveSettings{Disable: true},
+			keepalive,
 		}
 
 	// We set the host for the unix socket and Windows named
@@ -228,7 +228,7 @@ func clientOptions(u *url.URL) []httpcommon.TransportOption {
 	u.Scheme = scheme
 	return []httpcommon.TransportOption{
 		httpcommon.WithAPMHTTPInstrumentation(),
-		httpcommon.WithKeepaliveSettings{Disable: true},
+		keepalive,
 		httpcommon.WithBaseDialer(dialer),
 	}
 }

x-pack/filebeat/input/httpjson/request_chain_helper.go

@@ -32,7 +32,7 @@ const (
 
 func newChainHTTPClient(ctx context.Context, authCfg *authConfig, requestCfg *requestConfig, log *logp.Logger, p ...*Policy) (*httpClient, error) {
 	// Make retryable HTTP client
-	netHTTPClient, err := requestCfg.Transport.Client(clientOptions(requestCfg.URL.URL)...)
+	netHTTPClient, err := requestCfg.Transport.Client(clientOptions(requestCfg.URL.URL, requestCfg.KeepAlive.settings())...)
 	if err != nil {
 		return nil, err
 	}