Add code version used to upgrade database in the db_version table (cl…

…oses #445) (#446)

* 1 - add basic test infrastructure to test database upgrades

* 2 - started TestUpgradeScripts with pending TODOs

* 3 - assert schema of db_versions table

* 4 - check entries of db_version table and set code_version_string in db_version

cmd/trade.go

@@ -539,7 +539,7 @@ func runTradeCmd(options inputs) {
 		}
 
 		var e error
-		db, e = database.ConnectInitializedDatabase(botConfig.PostgresDbConfig, upgradeScripts)
+		db, e = database.ConnectInitializedDatabase(botConfig.PostgresDbConfig, upgradeScripts, version)
 		if e != nil {
 			logger.Fatal(l, fmt.Errorf("problem encountered while initializing the db: %s", e))
 		}

support/database/schema.go

@@ -10,6 +10,7 @@ import (
 	tables
 */
 const SqlDbVersionTableCreate = "CREATE TABLE IF NOT EXISTS db_version (version INTEGER NOT NULL, date_completed_utc TIMESTAMP WITHOUT TIME ZONE NOT NULL, num_scripts INTEGER NOT NULL, time_elapsed_millis BIGINT NOT NULL, PRIMARY KEY (version))"
+const SqlDbVersionTableAlter1 = "ALTER TABLE db_version ADD COLUMN code_version_string TEXT"
 
 /*
 	queries

support/database/upgrade.go

@@ -12,7 +12,8 @@ import (
 )
 
 // sqlDbVersionTableInsertTemplate inserts into the db_version table
-const sqlDbVersionTableInsertTemplate = "INSERT INTO db_version (version, date_completed_utc, num_scripts, time_elapsed_millis) VALUES (%d, '%s', %d, %d)"
+const sqlDbVersionTableInsertTemplate1 = "INSERT INTO db_version (version, date_completed_utc, num_scripts, time_elapsed_millis) VALUES (%d, '%s', %d, %d)"
+const sqlDbVersionTableInsertTemplate2 = "INSERT INTO db_version (version, date_completed_utc, num_scripts, time_elapsed_millis, code_version_string) VALUES (%d, '%s', %d, %d, '%s')"
 
 // UpgradeScript encapsulates a script to be run to upgrade the database from one version to the next
 type UpgradeScript struct {
@@ -31,8 +32,13 @@ func MakeUpgradeScript(version uint32, command string, moreCommands ...string) *
 	}
 }
 
+var UpgradeScripts = []*UpgradeScript{
+	MakeUpgradeScript(1, SqlDbVersionTableCreate),
+	MakeUpgradeScript(2, SqlDbVersionTableAlter1),
+}
+
 // ConnectInitializedDatabase creates a database with the required metadata tables
-func ConnectInitializedDatabase(postgresDbConfig *postgresdb.Config, upgradeScripts []*UpgradeScript) (*sql.DB, error) {
+func ConnectInitializedDatabase(postgresDbConfig *postgresdb.Config, upgradeScripts []*UpgradeScript, codeVersionString string) (*sql.DB, error) {
 	dbCreated, e := postgresdb.CreateDatabaseIfNotExists(postgresDbConfig)
 	if e != nil {
 		if strings.Contains(e.Error(), "connect: connection refused") {
@@ -53,7 +59,7 @@ func ConnectInitializedDatabase(postgresDbConfig *postgresdb.Config, upgradeScri
 	// don't defer db.Close() here becuase we want it open for the life of the application for now
 
 	log.Printf("creating db schema and running upgrade scripts ...\n")
-	e = runUpgradeScripts(db, upgradeScripts)
+	e = runUpgradeScripts(db, upgradeScripts, codeVersionString)
 	if e != nil {
 		return nil, fmt.Errorf("could not run upgrade scripts: %s", e)
 	}
@@ -62,16 +68,20 @@ func ConnectInitializedDatabase(postgresDbConfig *postgresdb.Config, upgradeScri
 	return db, nil
 }
 
-func runUpgradeScripts(db *sql.DB, scripts []*UpgradeScript) error {
-	currentDbVersion, e := QueryDbVersion(db)
-	if e != nil {
-		if !strings.Contains(e.Error(), "relation \"db_version\" does not exist") {
-			return fmt.Errorf("could not fetch current db version: %s", e)
-		}
-		currentDbVersion = 0
-	}
+func runUpgradeScripts(db *sql.DB, scripts []*UpgradeScript, codeVersionString string) error {
+	// save feature flags for the db_version table here
+	hasCodeVersionString := false
 
 	for _, script := range scripts {
+		// fetch the db version inside the for loop because it constantly gets updated
+		currentDbVersion, e := QueryDbVersion(db)
+		if e != nil {
+			if !strings.Contains(e.Error(), "relation \"db_version\" does not exist") {
+				return fmt.Errorf("could not fetch current db version: %s", e)
+			}
+			currentDbVersion = 0
+		}
+
 		if script.version <= currentDbVersion {
 			log.Printf("   skipping upgrade script for version %d because current db version (%d) is equal or ahead\n", script.version, currentDbVersion)
 			continue
@@ -95,17 +105,34 @@ func runUpgradeScripts(db *sql.DB, scripts []*UpgradeScript) error {
 		endTimeMillis := time.Now().UnixNano() / int64(time.Millisecond)
 		elapsedMillis := endTimeMillis - startTimeMillis
 
+		// update feature flags here where required after running a script so we don't need to hard-code version numbers which can be different for different consumers of this API
+		for _, command := range script.commands {
+			if command == SqlDbVersionTableAlter1 {
+				// if we have run this alter table command it means the database version has the code_version_string feature
+				hasCodeVersionString = true
+			}
+		}
+
 		// add entry to db_version table
-		sqlInsertDbVersion := fmt.Sprintf(sqlDbVersionTableInsertTemplate,
+		sqlInsertDbVersion := fmt.Sprintf(sqlDbVersionTableInsertTemplate1,
 			script.version,
 			startTime.Format(postgresdb.TimestampFormatString),
 			len(script.commands),
 			elapsedMillis,
 		)
+		if hasCodeVersionString {
+			sqlInsertDbVersion = fmt.Sprintf(sqlDbVersionTableInsertTemplate2,
+				script.version,
+				startTime.Format(postgresdb.TimestampFormatString),
+				len(script.commands),
+				elapsedMillis,
+				codeVersionString,
+			)
+		}
 		_, e = db.Exec(sqlInsertDbVersion)
 		if e != nil {
 			// duplicate insert should return an error
-			return fmt.Errorf("could not execute sql insert values statement in db_version table for db version %d (%s): %s", script.version, sqlInsertDbVersion, e)
+			return fmt.Errorf("could not add an entry to the db_version table for upgrade script (db_version=%d) for current db version %d (%s): %s", script.version, currentDbVersion, sqlInsertDbVersion, e)
 		}
 
 		// commit transaction