Where are log files for kibana server can be used for tracing?

Hi All

I am running opendistroforelasticsearch-kibana-0.9.0-1 on centos 7. the kibana server failed to run with following status:

systemctl -l status kibana
● kibana.service - Kibana
   Loaded: loaded (/etc/systemd/system/kibana.service; disabled; vendor preset: disabled)
   Active: failed (Result: start-limit) since 一 2019-05-06 12:26:30 CST; 2s ago
  Process: 9983 ExecStart=/usr/share/kibana/bin/kibana -c /etc/kibana/kibana.yml (code=exited, status=1/FAILURE)
 Main PID: 9983 (code=exited, status=1/FAILURE)

5月 06 12:26:30 es1.mylogs.com systemd[1]: kibana.service: main process exited, code=exited, status=1/FAILURE
5月 06 12:26:30 es1.mylogs.com systemd[1]: Unit kibana.service entered failed state.
5月 06 12:26:30 es1.mylogs.com systemd[1]: kibana.service failed.
5月 06 12:26:30 es1.mylogs.com systemd[1]: kibana.service holdoff time over, scheduling restart.
5月 06 12:26:30 es1.mylogs.com systemd[1]: Stopped Kibana.
5月 06 12:26:30 es1.mylogs.com systemd[1]: start request repeated too quickly for kibana.service
5月 06 12:26:30 es1.mylogs.com systemd[1]: Failed to start Kibana.
5月 06 12:26:30 es1.mylogs.com systemd[1]: Unit kibana.service entered failed state.
5月 06 12:26:30 es1.mylogs.com systemd[1]: kibana.service failed.

with following very simple kibana configuration kibana.yml:

elasticsearch.url: https://es1.mylogs.com:9200
elasticsearch.ssl.verificationMode: none
# i have modified the username kibanaserver to kibana on elasticsearch:
elasticsearch.username: kibana
elasticsearch.password: ********
elasticsearch.requestHeadersWhitelist: ["securitytenant","Authorization"]

opendistro_security.multitenancy.enabled: true
opendistro_security.multitenancy.tenants.preferred: ["Private", "Global"]
opendistro_security.readonly_mode.roles: ["kibana_read_only"]

where are log files for kibana server can be used for tracing ?

thanks
–charles