ElasticSearch 5.2.2 集群环境的搭建

在之前 ElasticSearch 搭建好之后，我们通过 elasticsearch-header 插件在查看 ES 服务的时候，发现 cluster-health 显示的是 YELLOW。

Why？

首先，我们需要知道的是：颜色代表集群的健康状态。现在的颜色状态有：

* RED(红): 代表具体的分片还没有在集群中分配好；
* YELLOW(黄): 代表主分片已经分配好，但是副本尚未分配；
* GREEN(绿)：表示所有的分片都已分配好，群集正常运行；

有了以上的简介之后，笔者觉得，单节点导致显示的 YELLOW 还可以完善，所以开始搭建 ** ES Cluster **。

首先，我们需要更新之前的配置。进入之前的解压目录，打开配置文件：

vim elasticsearch.yml

我们需要更新这样几个参数：

• node.name： 指定当前节点的名称。我现在有两台机子，可以设置两个节点，所以，这里一个起名为 master，一个为 node1;
• node.master: 指定主节点。值一个设置为 true，另一个为 false；
• discovery.zen.ping.unicast.hosts：这里设置的是节点的 ip，或者自己配置 hosts 文件，指定 ip映射关系，直接写ip对应的名称；
• discovery.zen.minimum_master_nodes：这里，我的主节点是1个，所以我在这配置的是 1；具体的可以参考discovery.zen.minimum_master_nodes

在主节点配置好后，通过 scp 传输到 node1 节点上面，参数也做相应的改变即可。比如 node.name 更新成 node1， node.master: false。其他的保持一致。

我目前的主节点配置如下：

# ======================== Elasticsearch Configuration =========================
#
# NOTE: Elasticsearch comes with reasonable defaults for most settings.
#       Before you set out to tweak and tune the configuration, make sure you
#       understand what are you trying to accomplish and the consequences.
#
# The primary way of configuring a node is via this file. This template lists
# the most important settings you may want to configure for a production cluster.
#
# Please consult the documentation for further information on configuration options:
# https://www.elastic.co/guide/en/elasticsearch/reference/index.html
#
# ---------------------------------- Cluster -----------------------------------
#
# Use a descriptive name for your cluster:
#
#cluster.name: my-application
cluster.name: es-demo
#
# ------------------------------------ Node ------------------------------------
#
# Use a descriptive name for the node:
#
#node.name: node-1
node.name: master
node.master: true
#
# Add custom attributes to the node:
#
#node.attr.rack: r1
node.attr.rack: r1
#
# ----------------------------------- Paths ------------------------------------
#
# Path to directory where to store the data (separate multiple locations by comma):
#
#path.data: /path/to/data
path.data: /data/elasticsearch
#
# Path to log files:
#
#path.logs: /path/to/logs
path.logs: /data/logs/elasticsearch
#
# ----------------------------------- Memory -----------------------------------
#
# Lock the memory on startup:
#
# bootstrap.memory_lock: true
#
# Make sure that the heap size is set to about half the memory available
# on the system and that the owner of the process is allowed to use this
# limit.
#
# Elasticsearch performs poorly when the system is swapping the memory.
#
# ---------------------------------- Network -----------------------------------
#
# Set the bind address to a specific IP (IPv4 or IPv6):
#
network.host: 192.168.1.58 # 从节点成对应的 ip
#
# Set a custom port for HTTP:
#
http.port: 9200
#
# For more information, consult the network module documentation.
#
# --------------------------------- Discovery ----------------------------------
#
# Pass an initial list of hosts to perform discovery when new node is started:
# The default list of hosts is ["127.0.0.1", "[::1]"]
#
discovery.zen.ping.unicast.hosts: ["192.168.1.58", "192.168.1.54"]
#
# Prevent the "split brain" by configuring the majority of nodes (total number of master-eligible nodes / 2 + 1):
#
discovery.zen.minimum_master_nodes: 1
#
# For more information, consult the zen discovery module documentation.
#
# ---------------------------------- Gateway -----------------------------------
#
# Block initial recovery after a full cluster restart until N nodes are started:
#
#gateway.recover_after_nodes: 3
#
# For more information, consult the gateway module documentation.
#
# ---------------------------------- Various -----------------------------------
#
# Require explicit names when deleting indices:
#
#action.destructive_requires_name: true

# --------------------------------- 其他配置 -----------------------------------
http.cors.enabled: true
http.cors.allow-origin: "*"

更新好配置之后呢，我们开始启动 ElasticSearch 服务。我启动 master 和 node1，发现出现了下面的错误：

max virtual memory areas vm.max_map_count [65530] likely too low, increase to at least [262144]

查询发现，导致这种错误，是因为系统默认的 max_map_count 过低所致，我们需要设置大一点（按报错直接翻译也可知哦⁽）。我们需要设置一下这个参数：

sudo vim /etc/sysctl.conf

在最末尾添加：

vm.max_map_count=262144

两台机子配置好之后，我们重新启动下 elasticsearch。这时候 log 也已经提示了：

Cluster health status changed from [YELLOW] to [GREEN] (reason: [shards started [[movies][0]] ...])

好了。刷新下 elasticsearch-head，发现如下图所示：

至此，集群环境算是配置好了，集群状态也从 YELLOW 转到 GREEN 了。

原文网址 http://www.cnblogs.com/scharfsinnig/p/6759630.html

参考：

discovery.zen.minimum_master_nodes 参数说明

vm_map_count 设置