Responding to comments

contrib/database/sql/internal/dsn.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
+	"gopkg.in/DataDog/dd-trace-go.v1/internal/log"
 )
 
 // ParseDSN parses various supported DSN types into a map of key/value pairs which can be used as valid tags.
@@ -20,26 +21,34 @@ func ParseDSN(driverName, dsn string) (meta map[string]string, err error) {
 	case "mysql":
 		meta, err = parseMySQLDSN(dsn)
 		if err != nil {
+			log.Debug("Error parsing DSN for mysql: %v", err)
 			return
 		}
 	case "postgres", "pgx":
 		meta, err = parsePostgresDSN(dsn)
 		if err != nil {
+			log.Debug("Error parsing DSN for postgres: %v", err)
 			return
 		}
 	case "sqlserver":
 		meta, err = parseSQLServerDSN(dsn)
 		if err != nil {
+			log.Debug("Error parsing DSN for sqlserver: %v", err)
 			return
 		}
 	default:
 		// Try to parse the DSN and see if the scheme contains a known driver name.
-		u, err := url.Parse(dsn)
-		if err != nil {
+		u, e := url.Parse(dsn)
+		if e != nil {
 			// dsn is not a valid URL, so just ignore
-			break
+			log.Debug("Error parsing driver name from DSN: %v", e)
+			return
 		}
 		if driverName != u.Scheme {
+			// In some cases the driver is registered under a non-official name.
+			// For example, "Test" may be the registered name with a DSN of "postgres://postgres:[email protected]:5432/fakepreparedb"
+			// for the purposes of testing/mocking.
+			// In these cases, we try to parse the DSN based upon the DSN itself, instead of the registered driver name
 			return ParseDSN(u.Scheme, dsn)
 		}
 	}

ddtrace/tracer/sqlcomment.go

@@ -57,8 +57,10 @@ const (
 	sqlCommentDBService     = "dddbs"
 	sqlCommentParentVersion = "ddpv"
 	sqlCommentEnv           = "dde"
-	sqlCommentPeerHostname  = "ddh"
-	sqlCommentPeerDBName    = "dddb"
+	// These keys are for the database we are connecting to, instead of the service we are running in.
+	// "Peer" is the OpenTelemetry nomenclature for "thing I am talking to"
+	sqlCommentPeerHostname = "ddh"
+	sqlCommentPeerDBName   = "dddb"
 )
 
 // Current trace context version (see https://www.w3.org/TR/trace-context/#version)