ELK之Logstash启动异常：Logstash could not be started because there is already...

Logstash启动异常： Logstash could not be started because there is already another instance using the configured data directory. If you wish to run multiple instances, you must change the "path.data" setting.
提示我们已经有一个实例在用data目录了，如果需要配置多个实例，则需要显式的配置path.data的值。

[root@nb002 bin]# ./logstash -f ../config/first-pipeline.conf
Using JAVA_HOME defined java: /usr/local/jdk1.8.0_331
WARNING: Using JAVA_HOME while Logstash distribution comes with a bundled JDK.
DEPRECATION: The use of JAVA_HOME is now deprecated and will be removed starting from 8.0. Please configure LS_JAVA_HOME instead.
Sending Logstash logs to /data/logstash-7.17.4/logs which is now configured via log4j2.properties
[2022-06-27T10:40:55,149][INFO ][logstash.runner          ] Log4j configuration path used is: /data/logstash-7.17.4/config/log4j2.properties
[2022-06-27T10:40:55,176][INFO ][logstash.runner          ] Starting Logstash {"logstash.version"=>"7.17.4", "jruby.version"=>"jruby 9.2.20.1 (2.5.8) 2021-11-30 2a2962fbd1 Java HotSpot(TM) 64-Bit Server VM 25.331-b09 on 1.8.0_331-b09 +indy +jit [linux-x86_64]"}
[2022-06-27T10:40:55,178][INFO ][logstash.runner          ] JVM bootstrap flags: [-Xms1g, -Xmx1g, -XX:+UseConcMarkSweepGC, -XX:CMSInitiatingOccupancyFraction=75, -XX:+UseCMSInitiatingOccupancyOnly, -Djava.awt.headless=true, -Dfile.encoding=UTF-8, -Djdk.io.File.enableADS=true, -Djruby.compile.invokedynamic=true, -Djruby.jit.threshold=0, -Djruby.regexp.interruptible=true, -XX:+HeapDumpOnOutOfMemoryError, -Djava.security.egd=file:/dev/urandom, -Dlog4j2.isThreadContextMapInheritable=true]
[2022-06-27T10:40:55,537][WARN ][logstash.config.source.multilocal] Ignoring the 'pipelines.yml' file because modules or command line options are specified
[2022-06-27T10:40:55,552][FATAL][logstash.runner          ] Logstash could not be started because there is already another instance using the configured data directory.  If you wish to run multiple instances, you must change the "path.data" setting.
[2022-06-27T10:40:55,558][FATAL][org.logstash.Logstash    ] Logstash stopped processing because of an error: (SystemExit) exit
org.jruby.exceptions.SystemExit: (SystemExit) exit
        at org.jruby.RubyKernel.exit(org/jruby/RubyKernel.java:747) ~[jruby-complete-9.2.20.1.jar:?]
        at org.jruby.RubyKernel.exit(org/jruby/RubyKernel.java:710) ~[jruby-complete-9.2.20.1.jar:?]
        at data.logstash_minus_7_dot_17_dot_4.lib.bootstrap.environment.<main>(/data/logstash-7.17.4/lib/bootstrap/environment.rb:94) ~[?:?]

当然我们可以显式的配置path.data的值，让他指向一个新的目录。
也可以将data目录下的.lock文件删除，来解决这个问题。

[root@nb002 logstash-7.17.4]# ls
bin  config  CONTRIBUTORS  data  Gemfile  Gemfile.lock  jdk  lib  LICENSE.txt  logs  logstash-core  logstash-core-plugin-api  modules  NOTICE.TXT  tools  vendor  x-pack
[root@nb002 logstash-7.17.4]# cd data/
[root@nb002 data]# ls -alh
总用量 4.0K
drwxr-xr-x  5 root wheel  84 6月  26 08:28 .
drwxr-xr-x 14 root root  278 6月  26 07:58 ..
drwxr-xr-x  2 root root    6 6月  26 07:58 dead_letter_queue
-rw-r--r--  1 root root    0 6月  26 07:58 .lock
drwxr-xr-x  4 root root   35 6月  26 08:57 plugins
drwxr-xr-x  2 root root    6 6月  26 07:58 queue
-rw-r--r--  1 root root   36 6月  26 07:58 uuid
[root@nb002 data]# rm .lock 
rm：是否删除普通空文件 ".lock"？yes

删除.lock文件后，再次启动则OK

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