2017-09-25 22:31:50 140032029358336 [Note] WSREP: Read nil XID from storage engines, skipping position init
2017-09-25 22:31:50 140032029358336 [Note] WSREP: wsrep_load(): loading provider library '/usr/lib/galera/libgalera_smm.so'
2017-09-25 22:31:50 140032029358336 [Note] WSREP: wsrep_load(): Galera 25.3.20(r3703) by Codership Oy <info@codership.com> loaded successfully.
2017-09-25 22:31:50 140032029358336 [Note] WSREP: CRC-32C: using hardware acceleration.
2017-09-25 22:31:50 140032029358336 [Warning] WSREP: Could not open state file for reading: '/var/lib/mysql//grastate.dat'
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Found saved state: 00000000-0000-0000-0000-000000000000:-1, safe_to_bootsrap: 1
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Passing config to GCS: base_dir = /var/lib/mysql/; base_host = 172.29.238.75; base_port = 4567; cert.log_conflicts = no; debug = no; evs.auto_evict = 0; evs.delay_margin = PT1S; evs.delayed_keep_period = PT30S; evs.inactive_check_period = PT0.5S; evs.inactive_timeout = PT15S; evs.join_retrans_period = PT1S; evs.max_install_timeouts = 3; evs.send_window = 4; evs.stats_report_period = PT1M; evs.suspect_timeout = PT5S; evs.user_send_window = 2; evs.view_forget_timeout = PT24H; gcache.dir = /var/lib/mysql/; gcache.keep_pages_size = 0; gcache.mem_size = 0; gcache.name = /var/lib/mysql//galera.cache; gcache.page_size = 128M; gcache.recover = no; gcache.size = 4M; gcomm.thread_prio = ; gcs.fc_debug = 0; gcs.fc_factor = 1.0; gcs.fc_limit = 16; gcs.fc_master_slave = no; gcs.max_packet_size = 64500; gcs.max_throttle = 0.25; gcs.recv_q_hard_limit = 9223372036854775807; gcs.recv_q_soft_limit = 0.25; gcs.sync_donor = no; gmcast.segment = 0; gmcast.version = 0; pc.announce_timeout = PT3S; pc.checksum = false; pc.ig
2017-09-25 22:31:50 140032029358336 [Note] WSREP: GCache history reset: old(00000000-0000-0000-0000-000000000000:0) -> new(00000000-0000-0000-0000-000000000000:-1)
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Assign initial position for certification: -1, protocol version: -1
2017-09-25 22:31:50 140032029358336 [Note] WSREP: wsrep_sst_grab()
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Start replication
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Setting initial position to 00000000-0000-0000-0000-000000000000:-1
2017-09-25 22:31:50 140032029358336 [Note] WSREP: protonet asio version 0
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Using CRC-32C for message checksums.
2017-09-25 22:31:50 140032029358336 [Note] WSREP: backend: asio
2017-09-25 22:31:50 140032029358336 [Note] WSREP: gcomm thread scheduling priority set to other:0 
2017-09-25 22:31:50 140032029358336 [Warning] WSREP: access file(/var/lib/mysql//gvwstate.dat) failed(No such file or directory)
2017-09-25 22:31:50 140032029358336 [Note] WSREP: restore pc from disk failed
2017-09-25 22:31:50 140032029358336 [Note] WSREP: GMCast version 0
2017-09-25 22:31:50 140032029358336 [Note] WSREP: (531a501a, 'tcp://0.0.0.0:4567') listening at tcp://0.0.0.0:4567
2017-09-25 22:31:50 140032029358336 [Note] WSREP: (531a501a, 'tcp://0.0.0.0:4567') multicast: , ttl: 1
2017-09-25 22:31:50 140032029358336 [Note] WSREP: EVS version 0
2017-09-25 22:31:50 140032029358336 [Note] WSREP: gcomm: connecting to group 'openstack_galera_cluster', peer ''
2017-09-25 22:31:50 140032029358336 [Note] WSREP: start_prim is enabled, turn off pc_recovery
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Node 531a501a state prim
2017-09-25 22:31:50 140032029358336 [Note] WSREP: view(view_id(PRIM,531a501a,1) memb {
	531a501a,0
} joined {
} left {
} partitioned {
})
2017-09-25 22:31:50 140032029358336 [Note] WSREP: save pc into disk
2017-09-25 22:31:50 140032029358336 [Note] WSREP: gcomm: connected
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Changing maximum packet size to 64500, resulting msg size: 32636
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Shifting CLOSED -> OPEN (TO: 0)
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Opened channel 'openstack_galera_cluster'
2017-09-25 22:31:50 140032029358336 [Note] WSREP: Waiting for SST to complete.
2017-09-25 22:31:50 140031876392704 [Note] WSREP: New COMPONENT: primary = yes, bootstrap = no, my_idx = 0, memb_num = 1
2017-09-25 22:31:50 140031876392704 [Note] WSREP: Starting new group from scratch: 531b970c-a241-11e7-baa1-23a41dda7c7c
2017-09-25 22:31:50 140031876392704 [Note] WSREP: STATE_EXCHANGE: sent state UUID: 531ba7c4-a241-11e7-a3eb-4fcfb3ac695b
2017-09-25 22:31:50 140031876392704 [Note] WSREP: STATE EXCHANGE: sent state msg: 531ba7c4-a241-11e7-a3eb-4fcfb3ac695b
2017-09-25 22:31:50 140031876392704 [Note] WSREP: STATE EXCHANGE: got state msg: 531ba7c4-a241-11e7-a3eb-4fcfb3ac695b from 0 (aio1_galera_container-9fad60d2)
2017-09-25 22:31:50 140031876392704 [Note] WSREP: Quorum results:
	version    = 4,
	component  = PRIMARY,
	conf_id    = 0,
	members    = 1/1 (joined/total),
	act_id     = 0,
	last_appl. = -1,
	protocols  = 0/7/3 (gcs/repl/appl),
	group UUID = 531b970c-a241-11e7-baa1-23a41dda7c7c
2017-09-25 22:31:50 140031876392704 [Note] WSREP: Flow-control interval: [16, 16]
2017-09-25 22:31:50 140031876392704 [Note] WSREP: Restored state OPEN -> JOINED (0)
2017-09-25 22:31:50 140031876392704 [Note] WSREP: Member 0.0 (aio1_galera_container-9fad60d2) synced with group.
2017-09-25 22:31:50 140031876392704 [Note] WSREP: Shifting JOINED -> SYNCED (TO: 0)
2017-09-25 22:31:50 140032029043456 [Note] WSREP: New cluster view: global state: 531b970c-a241-11e7-baa1-23a41dda7c7c:0, view# 1: Primary, number of nodes: 1, my index: 0, protocol version 3
2017-09-25 22:31:50 140032029358336 [Note] WSREP: SST complete, seqno: 0
2017-09-25 22:31:50 140032029358336 [Note] InnoDB: innodb_empty_free_list_algorithm has been changed to legacy because of small buffer pool size. In order to use backoff, increase buffer pool at least up to 20MB.

2017-09-25 22:31:51 140032029358336 [Note] InnoDB: Using mutexes to ref count buffer pool pages
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: The InnoDB memory heap is disabled
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: Compressed tables use zlib 1.2.8
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: Using Linux native AIO
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: Using SSE crc32 instructions
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: Initializing buffer pool, size = 16.0M
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: Completed initialization of buffer pool
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: Highest supported file format is Barracuda.
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: 128 rollback segment(s) are active.
2017-09-25 22:31:51 140032029358336 [Note] InnoDB: Waiting for purge to start
2017-09-25 22:31:51 140032029358336 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.36-82.2 started; log sequence number 1617086
2017-09-25 22:31:51 140032029358336 [Note] Plugin 'FEEDBACK' is disabled.
2017-09-25 22:31:51 140031305971456 [Note] InnoDB: Dumping buffer pool(s) not yet started
2017-09-25 22:31:51 140032029358336 [Note] Server socket created on IP: '::'.
2017-09-25 22:31:51 140032029043456 [Note] WSREP: wsrep_notify_cmd is not defined, skipping notification.
2017-09-25 22:31:51 140032029043456 [Note] WSREP: REPL Protocols: 7 (3, 2)
2017-09-25 22:31:51 140032029043456 [Note] WSREP: Assign initial position for certification: 0, protocol version: 3
2017-09-25 22:31:51 140031934347008 [Note] WSREP: Service thread queue flushed.
2017-09-25 22:31:51 140032029043456 [Note] WSREP: GCache history reset: old(00000000-0000-0000-0000-000000000000:0) -> new(531b970c-a241-11e7-baa1-23a41dda7c7c:0)
2017-09-25 22:31:51 140032029043456 [Note] WSREP: Synchronized with group, ready for connections
2017-09-25 22:31:51 140032029043456 [Note] WSREP: wsrep_notify_cmd is not defined, skipping notification.
2017-09-25 22:31:51 140032029358336 [Note] /usr/sbin/mysqld: ready for connections.
Version: '10.1.27-MariaDB-1~xenial'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  mariadb.org binary distribution
2017-09-25 22:31:52 140031949806336 [Warning] IP address '172.29.236.100' could not be resolved: Name or service not known
170925 22:46:38 [ERROR] mysqld got signal 11 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.

To report this bug, see https://mariadb.com/kb/en/reporting-bugs

We will try our best to scrape up some info that will hopefully help
diagnose the problem, but since we have already crashed, 
something is definitely wrong and this may fail.

Server version: 10.1.27-MariaDB-1~xenial
key_buffer_size=134217728
read_buffer_size=131072
max_used_connections=1
max_threads=802
thread_count=10
It is possible that mysqld could use up to 
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 1892744 K  bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x7f5ba0b1a008
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 0x7f5bbaa010b8 thread_stack 0x48400
/usr/sbin/mysqld(my_print_stacktrace+0x2e)[0x5614c7e5f4ae]
/usr/sbin/mysqld(handle_fatal_signal+0x2f5)[0x5614c79a8025]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x11390)[0x7f5bbdc81390]
/usr/sbin/mysqld(wsrep_on+0x18)[0x5614c7941ea8]
/usr/sbin/mysqld(+0x8f2336)[0x5614c7cfa336]
/usr/sbin/mysqld(+0x8f329f)[0x5614c7cfb29f]
/usr/sbin/mysqld(+0x8aa088)[0x5614c7cb2088]
/usr/sbin/mysqld(+0x8aa822)[0x5614c7cb2822]
/usr/sbin/mysqld(+0x9bacf7)[0x5614c7dc2cf7]
/usr/sbin/mysqld(+0x9bb9b6)[0x5614c7dc39b6]
/usr/sbin/mysqld(+0x8338b3)[0x5614c7c3b8b3]
/usr/sbin/mysqld(_Z17mysql_alter_tableP3THDPcS1_P14HA_CREATE_INFOP10TABLE_LISTP10Alter_infojP8st_orderb+0x2dad)[0x5614c78a827d]
/usr/sbin/mysqld(_ZN19Sql_cmd_alter_table7executeEP3THD+0x5bc)[0x5614c78f009c]
/usr/sbin/mysqld(_Z21mysql_execute_commandP3THD+0x165c)[0x5614c7812e6c]
/usr/sbin/mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x311)[0x5614c781ad21]
/usr/sbin/mysqld(+0x413675)[0x5614c781b675]
/usr/sbin/mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x1ea5)[0x5614c781dd75]
/usr/sbin/mysqld(_Z10do_commandP3THD+0x139)[0x5614c781ec49]
/usr/sbin/mysqld(_Z24do_handle_one_connectionP3THD+0x182)[0x5614c78ed442]
/usr/sbin/mysqld(handle_one_connection+0x40)[0x5614c78ed5e0]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x76ba)[0x7f5bbdc776ba]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f5bbd3223dd]

Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0x7f5b8fc21020): ALTER TABLE user ADD CONSTRAINT ixu_user_name_domain_id UNIQUE (domain_id, name)
Connection ID (thread ID): 97
Status: NOT_KILLED

Optimizer switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=off

The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains
information that should help you find out what is causing the crash.