1.准备
先从github官网上clone elasticsearch源码到本地，选择合适的分支。笔者这里选用的是7.4.0（与笔者工作环境使用的分支一致），此版本编译需要jdk11。
2.编译
Readme 中说明了编译命令
./gradlew assemble
执行此命令，等待1h左右即可，根据机器性能可能会有差异
> Task :x-pack:plugin:sql:qa:compileJava
注: /Users/xxx/IdeaProjects/elasticsearch-my/x-pack/plugin/sql/qa/src/main/java/org/elasticsearch/xpack/sql/qa/jdbc/CsvTestUtils.java使用或覆盖了已过时的 API。
注: 有关详细信息, 请使用 -Xlint:deprecation 重新编译。
BUILD SUCCESSFUL in 52m 0s
947 actionable tasks: 946 executed, 1 up-to-date编译过程中可能会遇到的问题：
FAILURE: Build failed with an exception.
* What went wrong:
a problem occurred running Docker from [/usr/local/bin/docker] yet it is required to run the following tasks:
:distribution:docker:buildDockerImage
:distribution:docker:buildOssDockerImage
the problem is that Docker exited with exit code [1] with standard error output [Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?]
you can address this by attending to the reported issue, removing the offending tasks from being executed, or by passing -Dbuild.docker=false新版本 elasticsearch 编译过程依赖docker，启动docker后台或者注释掉以下代码
文件路径：/distribution/docker/build.gradle
void addBuildDockerImage(final boolean oss) {
// final Task buildDockerImageTask = task(taskName("build", oss, "DockerImage"), type: LoggedExec) {
// dependsOn taskName("copy", oss, "DockerContext")
// List<String> tags
// if (oss) {
// tags = [
// "docker.elastic.co/elasticsearch/elasticsearch-oss:${VersionProperties.elasticsearch}",
// "elasticsearch-oss:test"
// ]
// } else {
// tags = [
// "elasticsearch:${VersionProperties.elasticsearch}",
// "docker.elastic.co/elasticsearch/elasticsearch:${VersionProperties.elasticsearch}",
// "docker.elastic.co/elasticsearch/elasticsearch-full:${VersionProperties.elasticsearch}",
// "elasticsearch:test",
// ]
// }
// executable 'docker'
// final List<String> dockerArgs = ['build', files(oss), '--pull', '--no-cache']
// for (final String tag : tags) {
// dockerArgs.add('--tag')
// dockerArgs.add(tag)
// }
// args dockerArgs.toArray()
// }
// BuildPlugin.requireDocker(buildDockerImageTask)
}
for (final boolean oss : [false, true]) {
addCopyDockerContextTask(oss)
addBuildDockerImage(oss)
}
//assemble.dependsOn "buildOssDockerImage"
//assemble.dependsOn "buildDockerImage"3.启动
启动elasticsearch 服务，启动类是 org.elasticsearch.bootstrap.Elasticsearch
启动过程中可能会出现的问题：
问题1：
the system property [es.path.conf] must be set在vm启动项加入参数：-Des.path.conf=/Users/xxx/IdeaProjects/elasticsearch-my/config，然后将配置文件elasticsearch.yaml ，log4j2.properties, modules 复制到这个目录
项目中有配置文件的例子
笔者是这样配置的
# Use a descriptive name for your cluster:
#
cluster.name: my-application
#
# ------------------------------------ Node ------------------------------------
#
# Use a descriptive name for the node:
#
node.name: tiger
#
# Add custom attributes to the node:
#
#node.attr.rack: r1
#
# ----------------------------------- Paths ------------------------------------
#
# Path to directory where to store the data (separate multiple locations by comma):
#
path.data: /Users/xxx/IdeaProjects/elasticsearch-my/home/data
#
# Path to log files:
#
path.logs: /Users/xxx/IdeaProjects/elasticsearch-my/home/datamodules 包在发行版elasticsearch中可以找到，这里就不自行编译了
问题2：
Exception in thread "main" java.lang.IllegalStateException: path.home is not configured
at org.elasticsearch.env.Environment.<init>(Environment.java:104)
at org.elasticsearch.env.Environment.<init>(Environment.java:95)
at org.elasticsearch.node.InternalSettingsPreparer.prepareEnvironment(InternalSettingsPreparer.java:69)
at org.elasticsearch.cli.EnvironmentAwareCommand.createEnv(EnvironmentAwareCommand.java:95)
at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:86)
at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:125)
at org.elasticsearch.cli.Command.main(Command.java:90)
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:115)
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:92)同样的，在vm参数中设定home地址即可，-Des.path.home=/Users/xxx/IdeaProjects/elasticsearch-my/home
问题3：
no log4j2.properties found; tried [/Users/xxx/IdeaProjects/elasticsearch-my/config] and its subdirectories同问题1，没有复制log4j2.properties引起的问题
问题4：
java.lang.NoClassDefFoundError: org/elasticsearch/plugins/ExtendedPluginsClassLoader找到
compileOnly project(':libs:elasticsearch-plugin-classloader')修改为
compile project(':libs:elasticsearch-plugin-classloader')问题5：
Caused by: org.elasticsearch.ElasticsearchException: Failure running machine learning native code. This could be due to running on an unsupported OS or distribution, missing OS libraries, or a problem with the temp directory. To bypass this problem by running Elasticsearch without machine learning functionality set [xpack.ml.enabled: false].意思是我的机器不支持机器学习，把modules中的插件 x-pack-ml 去掉就行
最后启动完成如下
[2022-12-22T11:19:36,704][INFO ][o.e.p.PluginsService ] [tiger] loaded module [x-pack-sql]
[2022-12-22T11:19:36,705][INFO ][o.e.p.PluginsService ] [tiger] loaded module [x-pack-voting-only-node]
[2022-12-22T11:19:36,705][INFO ][o.e.p.PluginsService ] [tiger] loaded module [x-pack-watcher]
[2022-12-22T11:19:36,706][INFO ][o.e.p.PluginsService ] [tiger] no plugins loaded
[2022-12-22T11:19:37,238][INFO ][i.n.u.i.PlatformDependent] [tiger] Your platform does not provide complete low-level API for accessing direct buffers reliably. Unless explicitly requested, heap buffer will always be preferred to avoid potential system instability.
[2022-12-22T11:19:43,453][DEBUG][o.e.a.ActionModule ] [tiger] Using REST wrapper from plugin org.elasticsearch.xpack.security.Security
[2022-12-22T11:19:43,530][INFO ][i.n.u.i.PlatformDependent] [tiger] Your platform does not provide complete low-level API for accessing direct buffers reliably. Unless explicitly requested, heap buffer will always be preferred to avoid potential system instability.
[2022-12-22T11:19:43,914][INFO ][o.e.d.DiscoveryModule ] [tiger] using discovery type [zen] and seed hosts providers [settings]
[2022-12-22T11:19:45,141][INFO ][o.e.n.Node ] [tiger] initialized
[2022-12-22T11:19:45,142][INFO ][o.e.n.Node ] [tiger] starting ...
[2022-12-22T11:19:45,383][INFO ][o.e.t.TransportService ] [tiger] publish_address {127.0.0.1:9300}, bound_addresses {[::1]:9300}, {127.0.0.1:9300}
[2022-12-22T11:19:45,417][WARN ][o.e.b.BootstrapChecks ] [tiger] initial heap size [268435456] not equal to maximum heap size [4294967296]; this can cause resize pauses and prevents mlockall from locking the entire heap
[2022-12-22T11:19:45,418][WARN ][o.e.b.BootstrapChecks ] [tiger] the default discovery settings are unsuitable for production use; at least one of [discovery.seed_hosts, discovery.seed_providers, cluster.initial_master_nodes] must be configured
[2022-12-22T11:19:45,425][INFO ][o.e.c.c.Coordinator ] [tiger] cluster UUID [hhUOjQTPTxC11orp9ptAoQ]
[2022-12-22T11:19:45,450][INFO ][o.e.c.c.ClusterBootstrapService] [tiger] no discovery configuration found, will perform best-effort cluster bootstrapping after [3s] unless existing master is discovered
[2022-12-22T11:19:45,588][INFO ][o.e.c.s.MasterService ] [tiger] elected-as-master ([1] nodes joined)[{tiger}{alQTCfqOStya2j1epxaskQ}{qDAgKIDeTmCbif0-EDJ0FA}{127.0.0.1}{127.0.0.1:9300}{dim}{xpack.installed=true} elect leader, _BECOME_MASTER_TASK_, _FINISH_ELECTION_], term: 2, version: 18, reason: master node changed {previous [], current [{tiger}{alQTCfqOStya2j1epxaskQ}{qDAgKIDeTmCbif0-EDJ0FA}{127.0.0.1}{127.0.0.1:9300}{dim}{xpack.installed=true}]}
[2022-12-22T11:19:45,733][INFO ][o.e.c.s.ClusterApplierService] [tiger] master node changed {previous [], current [{tiger}{alQTCfqOStya2j1epxaskQ}{qDAgKIDeTmCbif0-EDJ0FA}{127.0.0.1}{127.0.0.1:9300}{dim}{xpack.installed=true}]}, term: 2, version: 18, reason: Publication{term=2, version=18}
[2022-12-22T11:19:45,796][INFO ][o.e.h.AbstractHttpServerTransport] [tiger] publish_address {127.0.0.1:9200}, bound_addresses {[::1]:9200}, {127.0.0.1:9200}
[2022-12-22T11:19:45,797][INFO ][o.e.n.Node ] [tiger] started
[2022-12-22T11:19:46,175][INFO ][o.e.l.LicenseService ] [tiger] license [003ac67e-0dd0-42ee-8b76-59e2c21c444a] mode [basic] - valid
[2022-12-22T11:19:46,175][INFO ][o.e.x.s.s.SecurityStatusChangeListener] [tiger] Active license is now [BASIC]; Security is disabled
[2022-12-22T11:19:46,184][INFO ][o.e.g.GatewayService ] [tiger] recovered [0] indices into cluster_state这里推荐一个chrome下的小插件elaticsearch-head，可视化当前集群的状态
4.参考列表
https://www.cnblogs.com/Jackeyzhe/p/13352543.html