ElasticSearch之系统关键配置

集群名称

在配置文件$ES_HOME/config/elasticsearch.yml中指定，样例如下：

cluster:name: logging-prod

或者

cluster.name: logging-prod

节点的名称

在配置文件$ES_HOME/config/elasticsearch.yml中指定，样例如下：

node:name: prod-data-2

或者

node.name: prod-data-2

监听IP地址
在配置文件$ES_HOME/config/elasticsearch.yml中指定，样例如下：

network:host: 192.168.1.10

或者

network.host: 192.168.1.10

集群发现的配置

在配置文件$ES_HOME/config/elasticsearch.yml中指定，样例如下：

discovery.seed_hosts:- 192.168.1.10:9300- 192.168.1.11- seeds.mydomain.com- [0:0:0:0:0:ffff:c0a8:10c]:9301
cluster.initial_master_nodes:- master-node-a- master-node-b- master-node-c

支持IPv4、IPv6、域名、主机名，允许同时指定端口。

路径
路径相关的关键配置，包括：

数据的保存路径
日志文件的保存路径

数据的保存路径，在配置文件$ES_HOME/config/elasticsearch.yml中使用配置项path.data指定。
日志文件的保存路径，在配置文件$ES_HOME/config/elasticsearch.yml中使用配置项path.logs指定。

配置样例如下：

path:data: /var/data/elasticsearchlogs: /var/log/elasticsearch

或者

path.data: /var/data/elasticsearch
path.logs: /var/log/elasticsearch

临时目录
默认情况下，ElasticSearch使用/tmp作为临时目录。
可以使用环境变量ES_TMPDIR来指定其它路径，命令样例如下：

export ES_TMPDIR=/path/to/tmp
./bin/elasticsearch

启动elasticsearch时假如遇到了如下报错，需要确认临时目录在挂载时是否指定了noexec选项。

java.lang.UnsatisfiedLinkerError
failed to map segment from shared object
failed to allocate closure

上述报错和JNA和libffi相关，ElasticSearch使用这两个完成一些平台相关的业务逻辑。

假如临时目录所在的分区在挂载时指定了noexec选项，并且出于一些原因，不方便切换新的临时目录。
为使JNA和libffi正常工作，可以指定各自的临时目录，操作命令样例如下：

export LIBFFI_TMPDIR=/path/to/tmp
export ES_JAVA_OPTS="-Djava.io.tmpdir=/path/to/temp/dir"
./bin/elasticsearch

JVM的配置

通过环境变量ES_JAVA_OPTS，可以指定JVM参数，如下是命令样例：

ES_JAVA_OPTS="-Xms2g -Xmx2g" ./bin/elasticsearch

另外一个例子，如下：

ES_JAVA_OPTS="-Xms2g -Xmx2g -Djava.io.tmpdir=/path/to/temp/dir" ./bin/elasticsearch

另外可以通过修改配置文件$ES_HOME/config/jvm.options，增加JVM相关的参数。

当前$ES_HOME/config/jvm.options中默认提供了如下参数。

-XX:+UseG1GC## JVM temporary directory
-Djava.io.tmpdir=${ES_TMPDIR}# Leverages accelerated vector hardware instructions; removing this may
# result in less optimal vector performance
20-:--add-modules=jdk.incubator.vector## heap dumps# generate a heap dump when an allocation from the Java heap fails; heap dumps
# are created in the working directory of the JVM unless an alternative path is
# specified
-XX:+HeapDumpOnOutOfMemoryError# exit right after heap dump on out of memory error
-XX:+ExitOnOutOfMemoryError# specify an alternative path for heap dumps; ensure the directory exists and
# has sufficient space
-XX:HeapDumpPath=data# specify an alternative path for JVM fatal error logs
-XX:ErrorFile=logs/hs_err_pid%p.log## GC logging
-Xlog:gc*,gc+age=trace,safepoint:file=logs/gc.log:utctime,level,pid,tags:filecount=32,filesize=64m

增加堆的参数，样例如下：

-Xms4g
-Xmx4g
-XX:MaxDirectMemorySize=2g

修改参数之后，可以通过日志，观察JVM的参数。

[2023-11-22T00:21:47,743][INFO ][o.a.l.i.v.PanamaVectorizationProvider] [jackie-ubuntu] Java vector incubator API enabled; uses preferredBitSize=256
[2023-11-22T00:21:48,670][INFO ][o.e.n.Node               ] [jackie-ubuntu] version[8.11.1], pid[19483], build[tar/6f9ff581fbcde658e6f69d6ce03050f060d1fd0c/2023-11-11T10:05:59.421038163Z], OS[Linux/5.4.0-166-generic/amd64], JVM[Oracle Corporation/OpenJDK 64-Bit Server VM/21.0.1/21.0.1+12-29]
[2023-11-22T00:21:48,672][INFO ][o.e.n.Node               ] [jackie-ubuntu] JVM home [/home/jackie/software/elasticsearch-8.11.1/jdk], using bundled JDK [true]
[2023-11-22T00:21:48,672][INFO ][o.e.n.Node               ] [jackie-ubuntu] JVM arguments [-Des.networkaddress.cache.ttl=60, -Des.networkaddress.cache.negative.ttl=10, -Djava.security.manager=allow, -XX:+AlwaysPreTouch, -Xss1m, -Djava.awt.headless=true, -Dfile.encoding=UTF-8, -Djna.nosys=true, -XX:-OmitStackTraceInFastThrow, -Dio.netty.noUnsafe=true, -Dio.netty.noKeySetOptimization=true, -Dio.netty.recycler.maxCapacityPerThread=0, -Dlog4j.shutdownHookEnabled=false, -Dlog4j2.disable.jmx=true, -Dlog4j2.formatMsgNoLookups=true, -Djava.locale.providers=SPI,COMPAT, --add-opens=java.base/java.io=org.elasticsearch.preallocate, -XX:+UseG1GC, -Djava.io.tmpdir=/tmp/elasticsearch-18105487545703078353, --add-modules=jdk.incubator.vector, -XX:+HeapDumpOnOutOfMemoryError, -XX:+ExitOnOutOfMemoryError, -XX:HeapDumpPath=data, -XX:ErrorFile=logs/hs_err_pid%p.log, -Xlog:gc*,gc+age=trace,safepoint:file=logs/gc.log:utctime,level,pid,tags:filecount=32,filesize=64m, -Xms1926m, -Xmx1926m, -XX:MaxDirectMemorySize=1009778688, -XX:G1HeapRegionSize=4m, -XX:InitiatingHeapOccupancyPercent=30, -XX:G1ReservePercent=15, -Des.distribution.type=tar, --module-path=/home/jackie/software/elasticsearch-8.11.1/lib, --add-modules=jdk.net, --add-modules=ALL-MODULE-PATH, -Djdk.module.main=org.elasticsearch.server][2023-11-22T00:22:09,195][INFO ][o.e.e.NodeEnvironment    ] [jackie-ubuntu] heap size [1.8gb], compressed ordinary object pointers [true]

也可以通过API，查看JVM的配置。

curl -X GET "https://localhost:9200/_nodes/jvm?pretty" --cacert $ES_HOME/config/certs/http_ca.crt -u "elastic:ohCxPH=QBE+s5=*lo7F9"

执行结果如下：

{"_nodes" : {"total" : 1,"successful" : 1,"failed" : 0},"cluster_name" : "elasticsearch","nodes" : {"aKgBu7LgS9a6iPYH8n2JPw" : {"name" : "jackie-ubuntu","transport_address" : "127.0.0.1:9300","host" : "127.0.0.1","ip" : "127.0.0.1","version" : "8.11.1","transport_version" : 8512001,"index_version" : 8500003,"component_versions" : {"transform_config_version" : 10000099,"ml_config_version" : 11000099},"build_flavor" : "default","build_type" : "tar","build_hash" : "6f9ff581fbcde658e6f69d6ce03050f060d1fd0c","roles" : ["data","data_cold","data_content","data_frozen","data_hot","data_warm","ingest","master","ml","remote_cluster_client","transform"],"attributes" : {"ml.machine_memory" : "4040327168","ml.allocated_processors" : "4","ml.allocated_processors_double" : "4.0","ml.max_jvm_size" : "2021654528","ml.config_version" : "11.0.0","xpack.installed" : "true","transform.config_version" : "10.0.0"},"jvm" : {"pid" : 19483,"version" : "21.0.1","vm_name" : "OpenJDK 64-Bit Server VM","vm_version" : "21.0.1+12-29","vm_vendor" : "Oracle Corporation","using_bundled_jdk" : true,"start_time_in_millis" : 1700583699298,"mem" : {"heap_init_in_bytes" : 2021654528,"heap_max_in_bytes" : 2021654528,"non_heap_init_in_bytes" : 7667712,"non_heap_max_in_bytes" : 0,"direct_max_in_bytes" : 0},"gc_collectors" : ["G1 Young Generation","G1 Concurrent GC","G1 Old Generation"],"memory_pools" : ["CodeHeap 'non-nmethods'","Metaspace","CodeHeap 'profiled nmethods'","Compressed Class Space","G1 Eden Space","G1 Old Gen","G1 Survivor Space","CodeHeap 'non-profiled nmethods'"],"using_compressed_ordinary_object_pointers" : "true","input_arguments" : ["-Des.networkaddress.cache.ttl=60","-Des.networkaddress.cache.negative.ttl=10","-Djava.security.manager=allow","-XX:+AlwaysPreTouch","-Xss1m","-Djava.awt.headless=true","-Dfile.encoding=UTF-8","-Djna.nosys=true","-XX:-OmitStackTraceInFastThrow","-Dio.netty.noUnsafe=true","-Dio.netty.noKeySetOptimization=true","-Dio.netty.recycler.maxCapacityPerThread=0","-Dlog4j.shutdownHookEnabled=false","-Dlog4j2.disable.jmx=true","-Dlog4j2.formatMsgNoLookups=true","-Djava.locale.providers=SPI,COMPAT","--add-opens=java.base/java.io=org.elasticsearch.preallocate","-XX:+UseG1GC","-Djava.io.tmpdir=/tmp/elasticsearch-18105487545703078353","--add-modules=jdk.incubator.vector","-XX:+HeapDumpOnOutOfMemoryError","-XX:+ExitOnOutOfMemoryError","-XX:HeapDumpPath=data","-XX:ErrorFile=logs/hs_err_pid%p.log","-Xlog:gc*,gc+age=trace,safepoint:file=logs/gc.log:utctime,level,pid,tags:filecount=32,filesize=64m","-Xms1926m","-Xmx1926m","-XX:MaxDirectMemorySize=1009778688","-XX:G1HeapRegionSize=4m","-XX:InitiatingHeapOccupancyPercent=30","-XX:G1ReservePercent=15","-Des.distribution.type=tar","--module-path=/home/jackie/software/elasticsearch-8.11.1/lib","--add-modules=jdk.net","--add-modules=ALL-MODULE-PATH","-Djdk.module.main=org.elasticsearch.server"]}}}
}