Function main

go/cmd/gh-ost/main.go:65–422

main is the application's entry point. It will either spawn a CLI or HTTP interfaces.

()

// main is the application's entry point. It will either spawn a CLI or HTTP interfaces.
func main() {
	migrationContext := base.NewMigrationContext()
	flag.StringVar(&migrationContext.InspectorConnectionConfig.Key.Hostname, "host", "127.0.0.1", "MySQL hostname (preferably a replica, not the master)")
	flag.StringVar(&migrationContext.AssumeMasterHostname, "assume-master-host", "", "(optional) explicitly tell gh-ost the identity of the master. Format: some.host.com[:port] This is useful in master-master setups where you wish to pick an explicit master, or in a tungsten-replicator where gh-ost is unable to determine the master")
	flag.IntVar(&migrationContext.InspectorConnectionConfig.Key.Port, "port", 3306, "MySQL port (preferably a replica, not the master)")
	flag.Float64Var(&migrationContext.InspectorConnectionConfig.Timeout, "mysql-timeout", 0.0, "Connect, read and write timeout for MySQL")
	flag.StringVar(&migrationContext.CliUser, "user", "", "MySQL user")
	flag.StringVar(&migrationContext.CliPassword, "password", "", "MySQL password")
	flag.StringVar(&migrationContext.CliMasterUser, "master-user", "", "MySQL user on master, if different from that on replica. Requires --assume-master-host")
	flag.StringVar(&migrationContext.CliMasterPassword, "master-password", "", "MySQL password on master, if different from that on replica. Requires --assume-master-host")
	flag.StringVar(&migrationContext.ConfigFile, "conf", "", "Config file")
	askPass := flag.Bool("ask-pass", false, "prompt for MySQL password")
	charset := flag.String("charset", "utf8mb4,utf8,latin1", "The default charset for the database connection is utf8mb4, utf8, latin1.")

	flag.BoolVar(&migrationContext.UseTLS, "ssl", false, "Enable SSL encrypted connections to MySQL hosts")
	flag.StringVar(&migrationContext.TLSCACertificate, "ssl-ca", "", "CA certificate in PEM format for TLS connections to MySQL hosts. Requires --ssl")
	flag.StringVar(&migrationContext.TLSCertificate, "ssl-cert", "", "Certificate in PEM format for TLS connections to MySQL hosts. Requires --ssl")
	flag.StringVar(&migrationContext.TLSKey, "ssl-key", "", "Key in PEM format for TLS connections to MySQL hosts. Requires --ssl")
	flag.BoolVar(&migrationContext.TLSAllowInsecure, "ssl-allow-insecure", false, "Skips verification of MySQL hosts' certificate chain and host name. Requires --ssl")

	flag.StringVar(&migrationContext.DatabaseName, "database", "", "database name (mandatory)")
	flag.StringVar(&migrationContext.OriginalTableName, "table", "", "table name (mandatory)")
	flag.StringVar(&migrationContext.AlterStatement, "alter", "", "alter statement (mandatory)")
	flag.BoolVar(&migrationContext.AttemptInstantDDL, "attempt-instant-ddl", false, "Attempt to use instant DDL for this migration first")
	storageEngine := flag.String("storage-engine", "innodb", "Specify table storage engine (default: 'innodb'). When 'rocksdb': the session transaction isolation level is changed from REPEATABLE_READ to READ_COMMITTED.")

	flag.BoolVar(&migrationContext.CountTableRows, "exact-rowcount", false, "actually count table rows as opposed to estimate them (results in more accurate progress estimation)")
	flag.BoolVar(&migrationContext.ConcurrentCountTableRows, "concurrent-rowcount", true, "(with --exact-rowcount), when true (default): count rows after row-copy begins, concurrently, and adjust row estimate later on; when false: first count rows, then start row copy")
	flag.BoolVar(&migrationContext.AllowedRunningOnMaster, "allow-on-master", false, "allow this migration to run directly on master. Preferably it would run on a replica")
	flag.BoolVar(&migrationContext.AllowedMasterMaster, "allow-master-master", false, "explicitly allow running in a master-master setup")
	flag.BoolVar(&migrationContext.NullableUniqueKeyAllowed, "allow-nullable-unique-key", false, "allow gh-ost to migrate based on a unique key with nullable columns. As long as no NULL values exist, this should be OK. If NULL values exist in chosen key, data may be corrupted. Use at your own risk!")
	flag.BoolVar(&migrationContext.ApproveRenamedColumns, "approve-renamed-columns", false, "in case your `ALTER` statement renames columns, gh-ost will note that and offer its interpretation of the rename. By default gh-ost does not proceed to execute. This flag approves that gh-ost's interpretation is correct")
	flag.BoolVar(&migrationContext.SkipRenamedColumns, "skip-renamed-columns", false, "in case your `ALTER` statement renames columns, gh-ost will note that and offer its interpretation of the rename. By default gh-ost does not proceed to execute. This flag tells gh-ost to skip the renamed columns, i.e. to treat what gh-ost thinks are renamed columns as unrelated columns. NOTE: you may lose column data")
	flag.BoolVar(&migrationContext.IsTungsten, "tungsten", false, "explicitly let gh-ost know that you are running on a tungsten-replication based topology (you are likely to also provide --assume-master-host)")
	flag.BoolVar(&migrationContext.DiscardForeignKeys, "discard-foreign-keys", false, "DANGER! This flag will migrate a table that has foreign keys and will NOT create foreign keys on the ghost table, thus your altered table will have NO foreign keys. This is useful for intentional dropping of foreign keys")
	flag.BoolVar(&migrationContext.SkipForeignKeyChecks, "skip-foreign-key-checks", false, "set to 'true' when you know for certain there are no foreign keys on your table, and wish to skip the time it takes for gh-ost to verify that")
	flag.BoolVar(&migrationContext.SkipStrictMode, "skip-strict-mode", false, "explicitly tell gh-ost binlog applier not to enforce strict sql mode")
	flag.BoolVar(&migrationContext.AllowZeroInDate, "allow-zero-in-date", false, "explicitly tell gh-ost binlog applier to ignore NO_ZERO_IN_DATE,NO_ZERO_DATE in sql_mode")
	flag.BoolVar(&migrationContext.AliyunRDS, "aliyun-rds", false, "set to 'true' when you execute on Aliyun RDS.")
	flag.BoolVar(&migrationContext.GoogleCloudPlatform, "gcp", false, "set to 'true' when you execute on a 1st generation Google Cloud Platform (GCP).")
	flag.BoolVar(&migrationContext.AzureMySQL, "azure", false, "set to 'true' when you execute on Azure Database on MySQL.")
	flag.BoolVar(&migrationContext.UseGTIDs, "gtid", false, "(experimental) set to 'true' to use MySQL GTIDs for binlog positioning.")

	executeFlag := flag.Bool("execute", false, "actually execute the alter & migrate the table. Default is noop: do some tests and exit")
	flag.BoolVar(&migrationContext.TestOnReplica, "test-on-replica", false, "Have the migration run on a replica, not on the master. At the end of migration replication is stopped, and tables are swapped and immediately swap-revert. Replication remains stopped and you can compare the two tables for building trust")
	flag.BoolVar(&migrationContext.TestOnReplicaSkipReplicaStop, "test-on-replica-skip-replica-stop", false, "When --test-on-replica is enabled, do not issue commands stop replication (requires --test-on-replica)")
	flag.BoolVar(&migrationContext.MigrateOnReplica, "migrate-on-replica", false, "Have the migration run on a replica, not on the master. This will do the full migration on the replica including cut-over (as opposed to --test-on-replica)")

	flag.BoolVar(&migrationContext.OkToDropTable, "ok-to-drop-table", false, "Shall the tool drop the old table at end of operation. DROPping tables can be a long locking operation, which is why I'm not doing it by default. I'm an online tool, yes?")
	flag.BoolVar(&migrationContext.InitiallyDropOldTable, "initially-drop-old-table", false, "Drop a possibly existing OLD table (remains from a previous run?) before beginning operation. Default is to panic and abort if such table exists")
	flag.BoolVar(&migrationContext.InitiallyDropGhostTable, "initially-drop-ghost-table", false, "Drop a possibly existing Ghost table (remains from a previous run?) before beginning operation. Default is to panic and abort if such table exists")
	flag.BoolVar(&migrationContext.TimestampOldTable, "timestamp-old-table", false, "Use a timestamp in old table name. This makes old table names unique and non conflicting cross migrations")
	cutOver := flag.String("cut-over", "atomic", "choose cut-over type (default|atomic, two-step)")
	flag.BoolVar(&migrationContext.ForceNamedCutOverCommand, "force-named-cut-over", false, "When true, the 'unpostpone|cut-over' interactive command must name the migrated table")
	flag.BoolVar(&migrationContext.ForceNamedPanicCommand, "force-named-panic", false, "When true, the 'panic' interactive command must name the migrated table")

	flag.BoolVar(&migrationContext.SwitchToRowBinlogFormat, "switch-to-rbr", false, "let this tool automatically switch binary log format to 'ROW' on the replica, if needed. The format will NOT be switched back. I'm too scared to do that, and wish to protect you if you happen to execute another migration while this one is running")
	flag.BoolVar(&migrationContext.AssumeRBR, "assume-rbr", false, "set to 'true' when you know for certain your server uses 'ROW' binlog_format. gh-ost is unable to tell, event after reading binlog_format, whether the replication process does indeed use 'ROW', and restarts replication to be certain RBR setting is applied. Such operation requires SUPER privileges which you might not have. Setting this flag avoids restarting replication and you can proceed to use gh-ost without SUPER privileges")