services/horizon: Allow customization of the Captive Core log file.

ingest/ledgerbackend/captive_core_backend.go

@@ -3,6 +3,7 @@ package ledgerbackend
 import (
 	"context"
 	"encoding/hex"
+	"io/ioutil"
 	"os"
 	"sync"
 
@@ -111,6 +112,8 @@ type CaptiveCoreConfig struct {
 	NetworkPassphrase string
 	// HistoryArchiveURLs are a list of history archive urls
 	HistoryArchiveURLs []string
+	// LogPath is the path in which to store Core logs
+	LogPath string
 
 	// Optional fields
 
@@ -134,11 +137,21 @@ type CaptiveCoreConfig struct {
 func NewCaptive(config CaptiveCoreConfig) (*CaptiveStellarCore, error) {
 	// Here we set defaults in the config. Because config is not a pointer this code should
 	// not mutate the original CaptiveCoreConfig instance which was passed into NewCaptive()
+
+	// Create a default logging instance for Captive Core's output if no other
+	// logging configuration was specified.
 	if config.Log == nil {
 		config.Log = log.New()
-		config.Log.Logger.SetOutput(os.Stdout)
-		config.Log.SetLevel(logrus.InfoLevel)
+		if config.LogPath != "" {
+			// We still create an empty logger instance so there's no nil
+			// pointer floating around beyond this call.
+			config.Log.Logger.SetOutput(ioutil.Discard)
+		} else {
+			config.Log.Logger.SetOutput(os.Stdout)
+			config.Log.SetLevel(logrus.InfoLevel)
+		}
 	}
+
 	parentCtx := config.Context
 	if parentCtx == nil {
 		parentCtx = context.Background()

ingest/ledgerbackend/stellar_core_runner.go

@@ -48,6 +48,7 @@ type pipe struct {
 }
 
 type stellarCoreRunner struct {
+	logPath           string
 	executablePath    string
 	configAppendPath  string
 	networkPassphrase string
@@ -82,6 +83,7 @@ func newStellarCoreRunner(config CaptiveCoreConfig, mode stellarCoreRunnerMode)
 	ctx, cancel := context.WithCancel(config.Context)
 
 	runner := &stellarCoreRunner{
+		logPath:           config.LogPath,
 		executablePath:    config.BinaryPath,
 		configAppendPath:  config.ConfigAppendPath,
 		networkPassphrase: config.NetworkPassphrase,
@@ -116,7 +118,7 @@ func (r *stellarCoreRunner) generateConfig() (string, error) {
 		fmt.Sprintf(`NETWORK_PASSPHRASE="%s"`, r.networkPassphrase),
 		fmt.Sprintf(`BUCKET_DIR_PATH="%s"`, filepath.Join(r.tempDir, "buckets")),
 		fmt.Sprintf(`HTTP_PORT=%d`, r.httpPort),
-		`LOG_FILE_PATH=""`,
+		fmt.Sprintf(`LOG_FILE_PATH="%s"`, r.logPath),
 	}
 
 	if r.mode == stellarCoreRunnerModeOffline {

services/horizon/internal/config.go

@@ -21,6 +21,7 @@ type Config struct {
 	CaptiveCoreConfigAppendPath string
 	RemoteCaptiveCoreURL        string
 	CaptiveCoreHTTPPort         uint
+	CaptiveCoreLogPath          string
 
 	StellarCoreDatabaseURL string
 	StellarCoreURL         string

services/horizon/internal/flags.go

@@ -255,6 +255,12 @@ func Flags() (*Config, support.ConfigOptions) {
 			OptType:   types.String,
 			Usage:     "name of the file where logs will be saved (leave empty to send logs to stdout)",
 		},
+		&support.ConfigOption{
+			Name:      "captive-core-log-path",
+			ConfigKey: &config.CaptiveCoreLogPath,
+			OptType:   types.String,
+			Usage:     "name of the path for Core logs (leave empty to log w/ Horizon)",
+		},
 		&support.ConfigOption{
 			Name:        "max-path-length",
 			ConfigKey:   &config.MaxPathLength,

services/horizon/internal/ingest/main.go

@@ -71,6 +71,7 @@ type Config struct {
 	CaptiveCoreBinaryPath       string
 	CaptiveCoreConfigAppendPath string
 	CaptiveCoreHTTPPort         uint
+	CaptiveCoreLogPath          string
 	RemoteCaptiveCoreURL        string
 	NetworkPassphrase           string
 
@@ -189,16 +190,27 @@ func NewSystem(config Config) (System, error) {
 				return nil, errors.Wrap(err, "error creating captive core backend")
 			}
 		} else {
+			// If the user wants a custom logging location for Captive Core (set
+			// via Core's LOG_FILE_PATH), it takes priority over Horizon's
+			// internal logging.
+			//
+			// https://github.com/stellar/go/issues/3438#issuecomment-797690998
+			var logger *logpkg.Entry = nil
+			if config.CaptiveCoreLogPath == "" {
+				logger = log.WithField("subservice", "stellar-core")
+			}
+
 			ledgerBackend, err = ledgerbackend.NewCaptive(
 				ledgerbackend.CaptiveCoreConfig{
+					LogPath:             config.CaptiveCoreLogPath,
 					BinaryPath:          config.CaptiveCoreBinaryPath,
 					ConfigAppendPath:    config.CaptiveCoreConfigAppendPath,
 					HTTPPort:            config.CaptiveCoreHTTPPort,
 					NetworkPassphrase:   config.NetworkPassphrase,
 					HistoryArchiveURLs:  []string{config.HistoryArchiveURL},
 					CheckpointFrequency: config.CheckpointFrequency,
 					LedgerHashStore:     ledgerbackend.NewHorizonDBLedgerHashStore(config.HistorySession),
-					Log:                 log.WithField("subservice", "stellar-core"),
+					Log:                 logger,
 					Context:             ctx,
 				},
 			)

services/horizon/internal/init.go

@@ -72,6 +72,7 @@ func initIngester(app *App) {
 		CaptiveCoreBinaryPath:       app.config.CaptiveCoreBinaryPath,
 		CaptiveCoreConfigAppendPath: app.config.CaptiveCoreConfigAppendPath,
 		CaptiveCoreHTTPPort:         app.config.CaptiveCoreHTTPPort,
+		CaptiveCoreLogPath:          app.config.CaptiveCoreLogPath,
 		RemoteCaptiveCoreURL:        app.config.RemoteCaptiveCoreURL,
 		EnableCaptiveCore:           app.config.EnableCaptiveCoreIngestion,
 		DisableStateVerification:    app.config.IngestDisableStateVerification,