VAULT-17074: socket sink node (#21865)

* syslog sink added, options + tests added, tweaks to file sink comments

* defaults for syslog options

* lock around Process

* Comment on 'nil' return for Process, remove buffer

internal/observability/event/audit_sink_socket.go

@@ -0,0 +1,196 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package event
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/hashicorp/go-multierror"
+
+	"github.com/hashicorp/eventlogger"
+)
+
+// AuditSocketSink is a sink node which handles writing audit events to socket.
+type AuditSocketSink struct {
+	format      auditFormat
+	address     string
+	socketType  string
+	maxDuration time.Duration
+	socketLock  sync.RWMutex
+	connection  net.Conn
+}
+
+// NewAuditSocketSink should be used to create a new AuditSocketSink.
+// Accepted options: WithMaxDuration and WithSocketType.
+func NewAuditSocketSink(format auditFormat, address string, opt ...Option) (*AuditSocketSink, error) {
+	const op = "event.NewAuditSocketSink"
+
+	opts, err := getOpts(opt...)
+	if err != nil {
+		return nil, fmt.Errorf("%s: error applying options: %w", op, err)
+	}
+
+	sink := &AuditSocketSink{
+		format:      format,
+		address:     address,
+		socketType:  opts.withSocketType,
+		maxDuration: opts.withMaxDuration,
+		socketLock:  sync.RWMutex{},
+		connection:  nil,
+	}
+
+	return sink, nil
+}
+
+// Process handles writing the event to the socket.
+func (s *AuditSocketSink) Process(ctx context.Context, e *eventlogger.Event) (*eventlogger.Event, error) {
+	const op = "event.(AuditSocketSink).Process"
+
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+	}
+
+	s.socketLock.Lock()
+	defer s.socketLock.Unlock()
+
+	if e == nil {
+		return nil, fmt.Errorf("%s: event is nil: %w", op, ErrInvalidParameter)
+	}
+
+	formatted, found := e.Format(s.format.String())
+	if !found {
+		return nil, fmt.Errorf("%s: unable to retrieve event formatted as %q", op, s.format)
+	}
+
+	// Try writing and return early if successful.
+	err := s.write(ctx, formatted)
+	if err == nil {
+		return nil, nil
+	}
+
+	// We will try to reconnect and retry a single write.
+	reconErr := s.reconnect(ctx)
+	switch {
+	case reconErr != nil:
+		// Add the reconnection error to the existing error.
+		err = multierror.Append(err, reconErr)
+	default:
+		err = s.write(ctx, formatted)
+	}
+
+	// Format the error nicely if we need to return one.
+	if err != nil {
+		err = fmt.Errorf("%s: error writing to socket: %w", op, err)
+	}
+
+	// return nil for the event to indicate the pipeline is complete.
+	return nil, err
+}
+
+// Reopen handles reopening the connection for the socket sink.
+func (s *AuditSocketSink) Reopen() error {
+	const op = "event.(AuditSocketSink).Reopen"
+
+	s.socketLock.Lock()
+	defer s.socketLock.Unlock()
+
+	err := s.reconnect(nil)
+	if err != nil {
+		return fmt.Errorf("%s: error reconnecting: %w", op, err)
+	}
+
+	return nil
+}
+
+// Type describes the type of this node (sink).
+func (s *AuditSocketSink) Type() eventlogger.NodeType {
+	return eventlogger.NodeTypeSink
+}
+
+// connect attempts to establish a connection using the socketType and address.
+func (s *AuditSocketSink) connect(ctx context.Context) error {
+	const op = "event.(AuditSocketSink).connect"
+
+	// If we're already connected, we should have disconnected first.
+	if s.connection != nil {
+		return nil
+	}
+
+	timeoutContext, cancel := context.WithTimeout(ctx, s.maxDuration)
+	defer cancel()
+
+	dialer := net.Dialer{}
+	conn, err := dialer.DialContext(timeoutContext, s.socketType, s.address)
+	if err != nil {
+		return fmt.Errorf("%s: error connecting to %q address %q: %w", op, s.socketType, s.address, err)
+	}
+
+	s.connection = conn
+
+	return nil
+}
+
+// disconnect attempts to close and clear an existing connection.
+func (s *AuditSocketSink) disconnect() error {
+	const op = "event.(AuditSocketSink).disconnect"
+
+	// If we're already disconnected, we can return early.
+	if s.connection == nil {
+		return nil
+	}
+
+	err := s.connection.Close()
+	if err != nil {
+		return fmt.Errorf("%s: error closing connection: %w", op, err)
+	}
+	s.connection = nil
+
+	return nil
+}
+
+// reconnect attempts to disconnect and then connect to the configured socketType and address.
+func (s *AuditSocketSink) reconnect(ctx context.Context) error {
+	const op = "event.(AuditSocketSink).reconnect"
+
+	err := s.disconnect()
+	if err != nil {
+		return fmt.Errorf("%s: error disconnecting: %w", op, err)
+	}
+
+	err = s.connect(ctx)
+	if err != nil {
+		return fmt.Errorf("%s: error connecting: %w", op, err)
+	}
+
+	return nil
+}
+
+// write attempts to write the specified data using the established connection.
+func (s *AuditSocketSink) write(ctx context.Context, data []byte) error {
+	const op = "event.(AuditSocketSink).write"
+
+	// Ensure we're connected.
+	err := s.connect(ctx)
+	if err != nil {
+		return fmt.Errorf("%s: connection error: %w", op, err)
+	}
+
+	err = s.connection.SetWriteDeadline(time.Now().Add(s.maxDuration))
+	if err != nil {
+		return fmt.Errorf("%s: unable to set write deadline: %w", op, err)
+	}
+
+	_, err = s.connection.Write(data)
+	if err != nil {
+		return fmt.Errorf("%s: unable to write to socket: %w", op, err)
+	}
+
+	return nil
+}

internal/observability/event/options.go

@@ -11,6 +11,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/hashicorp/go-secure-stdlib/parseutil"
+
 	"github.com/hashicorp/go-uuid"
 )
 
@@ -19,22 +21,26 @@ type Option func(*options) error
 
 // options are used to represent configuration for an Event.
 type options struct {
-	withID       string
-	withNow      time.Time
-	withSubtype  auditSubtype
-	withFormat   auditFormat
-	withFileMode *os.FileMode
-	withPrefix   string
-	withFacility string
-	withTag      string
+	withID          string
+	withNow         time.Time
+	withSubtype     auditSubtype
+	withFormat      auditFormat
+	withFileMode    *os.FileMode
+	withPrefix      string
+	withFacility    string
+	withTag         string
+	withSocketType  string
+	withMaxDuration time.Duration
 }
 
 // getDefaultOptions returns options with their default values.
 func getDefaultOptions() options {
 	return options{
-		withNow:      time.Now(),
-		withFacility: "AUTH",
-		withTag:      "vault",
+		withNow:         time.Now(),
+		withFacility:    "AUTH",
+		withTag:         "vault",
+		withSocketType:  "tcp",
+		withMaxDuration: 2 * time.Second,
 	}
 }
 
@@ -204,3 +210,36 @@ func WithTag(tag string) Option {
 		return nil
 	}
 }
+
+// WithSocketType provides an option to represent the socket type for a socket sink.
+func WithSocketType(socketType string) Option {
+	return func(o *options) error {
+		socketType = strings.TrimSpace(socketType)
+
+		if socketType != "" {
+			o.withSocketType = socketType
+		}
+
+		return nil
+	}
+}
+
+// WithMaxDuration provides an option to represent the max duration for writing to a socket sink.
+func WithMaxDuration(duration string) Option {
+	return func(o *options) error {
+		duration = strings.TrimSpace(duration)
+
+		if duration == "" {
+			return nil
+		}
+
+		parsed, err := parseutil.ParseDurationSecond(duration)
+		if err != nil {
+			return err
+		}
+
+		o.withMaxDuration = parsed
+
+		return nil
+	}
+}

internal/observability/event/options_test.go

@@ -273,6 +273,98 @@ func TestOptions_WithTag(t *testing.T) {
 	}
 }
 
+// TestOptions_WithSocketType exercises WithSocketType option to ensure it performs as expected.
+func TestOptions_WithSocketType(t *testing.T) {
+	tests := map[string]struct {
+		Value         string
+		ExpectedValue string
+	}{
+		"empty": {
+			Value:         "",
+			ExpectedValue: "",
+		},
+		"whitespace": {
+			Value:         "    ",
+			ExpectedValue: "",
+		},
+		"value": {
+			Value:         "juan",
+			ExpectedValue: "juan",
+		},
+		"spacey-value": {
+			Value:         "   juan   ",
+			ExpectedValue: "juan",
+		},
+	}
+
+	for name, tc := range tests {
+		name := name
+		tc := tc
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			options := &options{}
+			applyOption := WithSocketType(tc.Value)
+			err := applyOption(options)
+			require.NoError(t, err)
+			require.Equal(t, tc.ExpectedValue, options.withSocketType)
+		})
+	}
+}
+
+// TestOptions_WithMaxDuration exercises WithMaxDuration option to ensure it performs as expected.
+func TestOptions_WithMaxDuration(t *testing.T) {
+	tests := map[string]struct {
+		Value                string
+		ExpectedValue        time.Duration
+		IsErrorExpected      bool
+		ExpectedErrorMessage string
+	}{
+		"empty-gives-default": {
+			Value: "",
+		},
+		"whitespace-give-default": {
+			Value: "    ",
+		},
+		"bad-value": {
+			Value:                "juan",
+			IsErrorExpected:      true,
+			ExpectedErrorMessage: "time: invalid duration \"juan\"",
+		},
+		"bad-spacey-value": {
+			Value:                "   juan   ",
+			IsErrorExpected:      true,
+			ExpectedErrorMessage: "time: invalid duration \"juan\"",
+		},
+		"duration-2s": {
+			Value:         "2s",
+			ExpectedValue: 2 * time.Second,
+		},
+		"duration-2m": {
+			Value:         "2m",
+			ExpectedValue: 2 * time.Minute,
+		},
+	}
+
+	for name, tc := range tests {
+		name := name
+		tc := tc
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			options := &options{}
+			applyOption := WithMaxDuration(tc.Value)
+			err := applyOption(options)
+			switch {
+			case tc.IsErrorExpected:
+				require.Error(t, err)
+				require.EqualError(t, err, tc.ExpectedErrorMessage)
+			default:
+				require.NoError(t, err)
+				require.Equal(t, tc.ExpectedValue, options.withMaxDuration)
+			}
+		})
+	}
+}
+
 // TestOptions_WithFileMode exercises WithFileMode option to ensure it performs as expected.
 func TestOptions_WithFileMode(t *testing.T) {
 	tests := map[string]struct {
@@ -344,6 +436,7 @@ func TestOptions_Default(t *testing.T) {
 	require.False(t, opts.withNow.IsZero())
 	require.Equal(t, "AUTH", opts.withFacility)
 	require.Equal(t, "vault", opts.withTag)
+	require.Equal(t, 2*time.Second, opts.withMaxDuration)
 }
 
 // TestOptions_Opts exercises getOpts with various Option values.