vtgr (experimental)
vtgr
is a stateless orchestration component that integrates Vitess with MySQL group replication: it is responsible to bootstrap MySQL group and reconcile between the group and Vitess. It is available as an experimental feature. It still needs thorough testing, and more features need to be added.
In order to configure vtgr
, you have to make the following changes to vttablet
:
- Add
-db_flavor=MysqlGR
: This will allow vttablet to understand stats in group replication. - Add
-disable_active_reparents=true
: This part will prevent vttablet from fixing replication, and will rely on vtgr instead.
vtgr
requires two config files vtgr_config
and db_config
to be launched:
vtgr_config
: controls desired group parameters. A sample is available here.
BootstrapGroupSize
configs the desired size of group. vtgr
will only bootstrap a mysql group for a shard when it discovers desired number of healthy node from topology.
db_config
: controls connection parameters thatvtgr
uses. As an example:
{
"MySQLTopologyUser": "vtgr_user",
"MySQLTopologyPassword": "vtgr_password",
"MySQLReplicaUser": "vtgr_user",
"MySQLReplicaPassword": "vtgr_password",
}
You can bring vtgr
using the following invocation:
vtgr <topo_flags> \
-log_dir=${VTDATAROOT}/tmp \
-vtgr_config vtgr.json \
-db_config db.json \
-clusters_to_watch ks/0 \
Bringing up vtgr
should immediately cause a primary to be elected among the vttablets that have come up.
You can optionally add a clusters_to_watch
flag that contains a comma separated list of keyspaces or keyspace/shard
values. If specified, vtgr
will manage only those clusters.