build: Append commit hash to the main LND context

It can be disabled via the new `logging.no-commit-hash` config option.

build/config.go

@@ -27,6 +27,7 @@ const (
 type LogConfig struct {
 	Console      *consoleLoggerCfg `group:"console" namespace:"console" description:"The logger writing to stdout and stderr."`
 	File         *FileLoggerConfig `group:"file" namespace:"file" description:"The logger writing to LND's standard log file."`
+	NoCommitHash bool              `long:"no-commit-hash" description:"If set, the commit-hash of the current build will not be included in log lines by default."`
 }
 
 // Validate validates the LogConfig struct values.

build/version.go

@@ -6,9 +6,13 @@
 package build
 
 import (
+	"context"
+	"encoding/hex"
 	"fmt"
 	"runtime/debug"
 	"strings"
+
+	"github.com/btcsuite/btclog/v2"
 )
 
 var (
@@ -101,3 +105,28 @@ func Tags() []string {
 
 	return strings.Split(RawTags, ",")
 }
+
+// WithBuildInfo derives a child context with the build information attached as
+// attributes. At the moment, this only includes the current build's commit
+// hash.
+func WithBuildInfo(ctx context.Context, cfg *LogConfig) (context.Context,
+	error) {
+
+	if cfg.NoCommitHash {
+		return ctx, nil
+	}
+
+	// Convert the commit hash to a byte slice.
+	commitHash, err := hex.DecodeString(CommitHash)
+	if err != nil {
+		return nil, fmt.Errorf("unable to decode commit hash: %w", err)
+	}
+
+	// Include the first 3 bytes of the commit hash in the context as an
+	// slog attribute.
+	if len(commitHash) > 3 {
+		commitHash = commitHash[:3]
+	}
+
+	return btclog.WithCtx(ctx, btclog.Hex("rev", commitHash)), nil
+}

lnd.go

@@ -155,6 +155,15 @@ func Main(cfg *Config, lisCfg ListenerCfg, implCfg *ImplementationCfg,
 		}
 	}()
 
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	ctx, err := build.WithBuildInfo(ctx, cfg.LogConfig)
+	if err != nil {
+		return fmt.Errorf("unable to add build info to context: %w",
+			err)
+	}
+
 	mkErr := func(format string, args ...interface{}) error {
 		ltndLog.Errorf("Shutting down because error in main "+
 			"method: "+format, args...)
@@ -188,10 +197,6 @@ func Main(cfg *Config, lisCfg ListenerCfg, implCfg *ImplementationCfg,
 		strings.Title(BitcoinChainName), network,
 	)
 
-	ctx := context.Background()
-	ctx, cancel := context.WithCancel(ctx)
-	defer cancel()
-
 	// Enable http profiling server if requested.
 	if cfg.Pprof.Profile != "" {
 		// Create the http handler.

lntest/node/config.go

@@ -203,6 +203,7 @@ func (cfg *BaseNodeConfig) GenArgs() []string {
 		"--bitcoin.defaultchanconfs=1",
 		"--accept-keysend",
 		"--keep-failed-payment-attempts",
+		"--logging.no-commit-hash",
 		fmt.Sprintf("--db.batch-commit-interval=%v", commitInterval),
 		fmt.Sprintf("--bitcoin.defaultremotedelay=%v", DefaultCSV),
 		fmt.Sprintf("--rpclisten=%v", cfg.RPCAddr()),

sample-lnd.conf

@@ -994,6 +994,11 @@
 
 [logging]
 
+; Whether to exclude the current build's commit hash from log lines. Note that
+; the commit hash will not currently show up in all LND log lines as this new
+; feature will take a few versions to propagate through the codebase.
+; logging.no-commit-hash=false
+
 ; Disable logging to stdout and stderror.
 ; logging.console.disable=false