FATAL ERROR 1105 (HY000): Failed to register slave: too long 'report-host'

[ealter]

I have been running into this issue when running gh-ost inside of some of our docker containers. When the hostname of the docker container is at least 61 characters in length, I get the following error when trying to run gh-ost.

$ cat /tmp/ghost_user.cnf
[client]
user = ghost
$ /usr/bin/gh-ost --database yelp_pushplan_execution --table pushplan_run --alter ENGINE=InnoDB --conf /tmp/ghost_user.cnf --host xx.xx.xx.xx --chunk-size 500 --force-table-names 1557255792_pushplan_run --assume-rbr
2019/05/07 20:20:05 binlogsyncer.go:79: [info] create BinlogSyncer with config {99999 mysql 10.121.133.170 3306 ghost   false false <nil>}
2019/05/07 20:20:05 binlogsyncer.go:246: [info] begin to sync binlog from position (mysql-bin.000008, 951800672)
2019/05/07 20:20:05 binlogsyncer.go:139: [info] register slave for master server 10.121.133.170:3306
2019-05-07 20:20:05 FATAL ERROR 1105 (HY000): Failed to register slave: too long 'report-host'

The docker container is running on Ubuntu Bionic.

When I specified --hostname when creating the same docker container to be 61 characters instead, gh-ost ran without any issues.

The error message comes from https://github.com/mysql/mysql-server/blob/124c7ab1d6f914637521fd4463a993aa73403513/sql/rpl_master.cc#L161 and it looks like hostname is chosen from https://github.com/siddontang/go-mysql/blob/master/replication/binlogsyncer.go#L495

Let me know if you need any other information to reproduce this.

It looks like this is an actual limit defined in mysql: https://github.com/mysql/mysql-server/blob/124c7ab1d6f914637521fd4463a993aa73403513/sql/sql_const.h#L59

Would it be possible for go-mysql to allow clients to override the hostname used when setting up replication?

[siddontang]

https://github.com/siddontang/go-mysql/blob/master/replication/binlogsyncer.go#L43

seem we have already had this config, you can use it directly.

[lance6716]

I also met this problem, and seems different version of MySQL has different length limit, it's better let the application of this library to decide the hostname

https://github.com/mysql/mysql-server/blob/1bfe02bdad6604d54913c62614bde57a055c8332/include/my_hostname.h#L33-L42

[ljw7630]

normally, what we do is

canal := NewCanal(cfg)
canal.Run()

there's no way for developers to inject custom binlogsyncer to canal. so event BinlogSyncerConfig itself have a public field call LocalHost, it does not help

[lance6716]

normally, what we do is

canal := NewCanal(cfg) canal.Run()

there's no way for developers to inject custom binlogsyncer to canal. so event BinlogSyncerConfig itself have a public field call LocalHost, it does not help

You can set canal.Config.Localhost

[ljw7630]

normally, what we do is
canal := NewCanal(cfg) canal.Run()
there's no way for developers to inject custom binlogsyncer to canal. so event BinlogSyncerConfig itself have a public field call LocalHost, it does not help

You can set canal.Config.Localhost

oh. cool. our repo is using v1.6.0, so this param is not available. but i check latest version, it has this setting. I think this will do the trick. Thank you.

But it looks like this change is not included in v1.7.0, setting our go module directly depends on latest might bring unexpected result though.

[dveeden]

go-mysql/replication/binlogsyncer.go

Line 577 in 81ff5fd

func (b *BinlogSyncer) localHostname() string {

returns the hostname as set by the OS unless it has been specified in the configuration.

go-mysql/canal/config.go

Lines 108 to 109 in 81ff5fd

	// Set Localhost
	Localhost string

I think the comment for this config setting isn't very clear about what this does.

Looks like the length has to be stored in a uint8, but we don't properly check this or truncate the hostname.

MySQL uses report_host for this.

See also: https://dev.mysql.com/worklog/task/?id=12571

In the code MySQL now sets HOSTNAME_LENGTH to 255. I think this was changed in 8.0.17. Before it was set to 60.