Logstash always restart

logstash version:6.0, jdk version: 1.8.0, but no error log for the logstash service, the /var/log/message log is that:
Sep 16 23:17:20 localhost.localdomain systemd[1]: Started logstash.
Sep 16 23:17:30 localhost.localdomain logstash[5740]: Sending Logstash's logs to /var/log/logstash which is now configured via log4j2.properties
Sep 16 23:17:30 localhost.localdomain systemd[1]: logstash.service: main process exited, code=exited, status=1/FAILURE
Sep 16 23:17:30 localhost.localdomain systemd[1]: Unit logstash.service entered failed state.
Sep 16 23:17:30 localhost.localdomain systemd[1]: logstash.service failed.
Sep 16 23:17:30 localhost.localdomain systemd[1]: logstash.service holdoff time over, scheduling restart.
Sep 16 23:17:30 localhost.localdomain systemd[1]: Stopped logstash.
Sep 16 23:17:30 localhost.localdomain systemd[1]: Started logstash.

Please provide log sample of /var/log/logstash/logstash-plain.log

This is the log:
[2020-09-16T23:37:18,317][INFO ][logstash.modules.scaffold] Initializing module {:module_name=>"fb_apache", :directory=>"/usr/share/logstash/modules/fb_apache/configuration"}
[2020-09-16T23:37:18,320][INFO ][logstash.modules.scaffold] Initializing module {:module_name=>"netflow", :directory=>"/usr/share/logstash/modules/netflow/configuration"}
[2020-09-16T23:37:18,340][FATAL][logstash.runner ] An unexpected error occurred! {:error=>#<ArgumentError: Path "/var/lib/logstash/queue" must be a writable directory. It is not writable.>, :backtrace=>["/usr/share/logstash/logstash-core/lib/logstash/settings.rb:443:in validate'", "/usr/share/logstash/logstash-core/lib/logstash/settings.rb:225:in validate_value'", "/usr/share/logstash/logstash-core/lib/logstash/settings.rb:136:in block in validate_all'", "org/jruby/RubyHash.java:1343:in each'", "/usr/share/logstash/logstash-core/lib/logstash/settings.rb:135:in validate_all'", "/usr/share/logstash/logstash-core/lib/logstash/runner.rb:280:in execute'", "/usr/share/logstash/vendor/bundle/jruby/2.3.0/gems/clamp-0.6.5/lib/clamp/command.rb:67:in run'", "/usr/share/logstash/logstash-core/lib/logstash/runner.rb:232:in run'", "/usr/share/logstash/vendor/bundle/jruby/2.3.0/gems/clamp-0.6.5/lib/clamp/command.rb:132:in run'", "/usr/share/logstash/lib/bootstrap/environment.rb:71:in '"]}

<ArgumentError: Path "/var/lib/logstash/queue" must be a writable directory. It is not writable

You have some permissions error on your configuration.

I have change the owner for the every files in the /var/lib/logstash, but still have the error:
[2020-09-16T23:54:14,165][FATAL][logstash.runner ] An unexpected error occurred! {:error=>#<Errno::EADDRNOTAVAIL: Cannot assign requested address - bind - Cannot assign requested address>, :backtrace=>["org/jruby/ext/socket/RubyTCPServer.java:127:in initialize'", "org/jruby/RubyIO.java:875:in new'", "/usr/share/logstash/vendor/bundle/jruby/2.3.0/gems/puma-2.16.0-java/lib/puma/binder.rb:234:in add_tcp_listener'", "(eval):2:in add_tcp_listener'", "/usr/share/logstash/logstash-core/lib/logstash/webserver.rb:88:in start_webserver'", "/usr/share/logstash/logstash-core/lib/logstash/webserver.rb:44:in block in run'", "org/jruby/RubyRange.java:485:in each'", "org/jruby/RubyEnumerable.java:1067:in each_with_index'", "/usr/share/logstash/logstash-core/lib/logstash/webserver.rb:39:in run'", "/usr/share/logstash/logstash-core/lib/logstash/agent.rb:394:in block in start_webserver'"]}

What's your logstash configuration ?

It seems that your network address is not avaibable probably because the process is stalled or you missconfigured and IP address.

Please ensure logstash is killed cleanly and restart.

My logstash config file is:
input {
syslog {
type => "system-syslog"
port => 10514
}
}
output {
elasticsearch {
hosts => ["192.168.56.21:9200"]
index => "system.sys.%{+YYY.MM}"
}
}
The 192.168.56.21 is the elasticsearch master, and I can telnet the port 9200 from logstash vm.
[root@localhost conf.d]# telnet 192.168.56.21 9200
Trying 192.168.56.21...
Connected to 192.168.56.21.
Escape character is '^]'.

logstash is trying to start the webserver used for monitoring it. What is http.host set to in logstash.yml? That is the IP it will be failing to bind to.