回顾Nacos

一概述

Nacos是一个易于构建原生应用的动态服务发现，配置管理和服务管理平台，在Dubbo和Spring Cloud里都可以使用Nacos进行注册与发现。

Nacos三大主要功能为：动态配置服务；服务发现与管理；动态DNS服务。

二 Nacos注册中心

Nacos注册中心是Nacos中负责注册，服务发现，健康检查等功能的组件。

服务注册与发现组件

支持使用Java，Go，NodeJs等客户端进行服务的注册与发现
支持Dubbo服务框架，SpringCloud Alibaba服务框架
支持使用DNS协议进行服务的发现

健康检查

支持服务端发送TCP，HTTP，MySQL请求进行服务健康状态的探测
支持客户端心跳上报的健康更新

访问策略

支持基于权重的复杂均衡策略
支持保护阈值，解决服务雪崩的问题
支持服务上下线
支持基于机房等环境信息设置访问策略

三 Nacos作为注册中心的优势

Eureka是SpringCloud中默认的注册中心，Zookeeper是Dubbo中默认的注册中心。

同时支持CP+AP的一致性协议，所以用户可以通过配置的方式或者API参数的方式来选择写入的数据是支持CP一致性还是AP一致性。

当写入数据的成功是由单条数据请求保证的时候应该使用CP的一致性，因为CP的一致性是优先保证保证数据的一致性而牺牲服务整体的可用性。

当单次写请求的成败不是很重要，而是可以通过后续的补偿机制来将数据上报，此时应该是使用AP的一致性，通过AP的一致性来保证数据的一致。

客户端访问策略为将服务的所有实例都下发到客户端，然后再客户端借助第三方的组件来进行服务实例的筛选。

服务端访问策略是通过在Nacos控制台或者通过API来对服务配置特定的访问策略，这样在通过接口进行服务实例查询的时候就会在Nacos的服务端进行服务实例的过滤。因为它不需要客户端的修改，以及运行时可动态的调整，所以服务端的访问策略更加灵活。

Nacos支持单节点，集群，同城双机房或多机房部署以及跨地域多数据中心的部署。

四 Nacos的部署

单机部署

集群部署

1. 先配置Nacos集群列表文件，文件中包含集群中所有地址

#
# Copyright 1999-2018 Alibaba Group Holding Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
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#      http://www.apache.org/licenses/LICENSE-2.0
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# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

#it is ip
#example
192.168.16.101:8847
192.168.16.102
192.168.16.103

2. 检查配置文件application.properties

#
# Copyright 1999-2018 Alibaba Group Holding Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

#*************** Spring Boot Related Configurations ***************#
### Default web context path:
server.servlet.contextPath=/nacos
### Default web server port:
server.port=8848

#*************** Network Related Configurations ***************#
### If prefer hostname over ip for Nacos server addresses in cluster.conf:
# nacos.inetutils.prefer-hostname-over-ip=false

### Specify local server's IP:
# nacos.inetutils.ip-address=


#*************** Config Module Related Configurations ***************#
### If use MySQL as datasource:
# spring.datasource.platform=mysql

### Count of DB:
# db.num=1

### Connect URL of DB:
# db.url.0=jdbc:mysql://127.0.0.1:3306/nacos?characterEncoding=utf8&connectTimeout=1000&socketTimeout=3000&autoReconnect=true&useUnicode=true&useSSL=false&serverTimezone=UTC
# db.user.0=nacos
# db.password.0=nacos

### Connection pool configuration: hikariCP
db.pool.config.connectionTimeout=30000
db.pool.config.validationTimeout=10000
db.pool.config.maximumPoolSize=20
db.pool.config.minimumIdle=2

#*************** Naming Module Related Configurations ***************#
### Data dispatch task execution period in milliseconds:
# nacos.naming.distro.taskDispatchPeriod=200

### Data count of batch sync task:
# nacos.naming.distro.batchSyncKeyCount=1000

### Retry delay in milliseconds if sync task failed:
# nacos.naming.distro.syncRetryDelay=5000

### If enable data warmup. If set to false, the server would accept request without local data preparation:
# nacos.naming.data.warmup=true

### If enable the instance auto expiration, kind like of health check of instance:
# nacos.naming.expireInstance=true

nacos.naming.empty-service.auto-clean=true
nacos.naming.empty-service.clean.initial-delay-ms=50000
nacos.naming.empty-service.clean.period-time-ms=30000


#*************** CMDB Module Related Configurations ***************#
### The interval to dump external CMDB in seconds:
# nacos.cmdb.dumpTaskInterval=3600

### The interval of polling data change event in seconds:
# nacos.cmdb.eventTaskInterval=10

### The interval of loading labels in seconds:
# nacos.cmdb.labelTaskInterval=300

### If turn on data loading task:
# nacos.cmdb.loadDataAtStart=false


#*************** Metrics Related Configurations ***************#
### Metrics for prometheus
#management.endpoints.web.exposure.include=*

### Metrics for elastic search
management.metrics.export.elastic.enabled=false
#management.metrics.export.elastic.host=http://localhost:9200

### Metrics for influx
management.metrics.export.influx.enabled=false
#management.metrics.export.influx.db=springboot
#management.metrics.export.influx.uri=http://localhost:8086
#management.metrics.export.influx.auto-create-db=true
#management.metrics.export.influx.consistency=one
#management.metrics.export.influx.compressed=true


#*************** Access Log Related Configurations ***************#
### If turn on the access log:
server.tomcat.accesslog.enabled=true

### The access log pattern:
server.tomcat.accesslog.pattern=%h %l %u %t "%r" %s %b %D %{User-Agent}i %{Request-Source}i

### The directory of access log:
server.tomcat.basedir=


#*************** Access Control Related Configurations ***************#
### If enable spring security, this option is deprecated in 1.2.0:
#spring.security.enabled=false

### The ignore urls of auth, is deprecated in 1.2.0:
nacos.security.ignore.urls=/,/error,/**/*.css,/**/*.js,/**/*.html,/**/*.map,/**/*.svg,/**/*.png,/**/*.ico,/console-ui/public/**,/v1/auth/**,/v1/console/health/**,/actuator/**,/v1/console/server/**

### The auth system to use, currently only 'nacos' is supported:
nacos.core.auth.system.type=nacos

### If turn on auth system:
nacos.core.auth.enabled=false

### The token expiration in seconds:
nacos.core.auth.default.token.expire.seconds=18000

### The default token:
nacos.core.auth.default.token.secret.key=SecretKey012345678901234567890123456789012345678901234567890123456789

### Turn on/off caching of auth information. By turning on this switch, the update of auth information would have a 15 seconds delay.
nacos.core.auth.caching.enabled=true

### Since 1.4.1, Turn on/off white auth for user-agent: nacos-server, only for upgrade from old version.
nacos.core.auth.enable.userAgentAuthWhite=true

### Since 1.4.1, worked when nacos.core.auth.enabled=true and nacos.core.auth.enable.userAgentAuthWhite=false.
### The two properties is the white list for auth and used by identity the request from other server.
nacos.core.auth.server.identity.key=
nacos.core.auth.server.identity.value=

#*************** Istio Related Configurations ***************#
### If turn on the MCP server:
nacos.istio.mcp.server.enabled=false



###*************** Add from 1.3.0 ***************###


#*************** Core Related Configurations ***************#

### set the WorkerID manually
# nacos.core.snowflake.worker-id=

### Member-MetaData
# nacos.core.member.meta.site=
# nacos.core.member.meta.adweight=
# nacos.core.member.meta.weight=

### MemberLookup
### Addressing pattern category, If set, the priority is highest
# nacos.core.member.lookup.type=[file,address-server]
## Set the cluster list with a configuration file or command-line argument
# nacos.member.list=192.168.16.101:8847?raft_port=8807,192.168.16.101?raft_port=8808,192.168.16.101:8849?raft_port=8809
## for AddressServerMemberLookup
# Maximum number of retries to query the address server upon initialization
# nacos.core.address-server.retry=5
## Server domain name address of [address-server] mode
# address.server.domain=jmenv.tbsite.net
## Server port of [address-server] mode
# address.server.port=8080
## Request address of [address-server] mode
# address.server.url=/nacos/serverlist

#*************** JRaft Related Configurations ***************#

### Sets the Raft cluster election timeout, default value is 5 second
# nacos.core.protocol.raft.data.election_timeout_ms=5000
### Sets the amount of time the Raft snapshot will execute periodically, default is 30 minute
# nacos.core.protocol.raft.data.snapshot_interval_secs=30
### raft internal worker threads
# nacos.core.protocol.raft.data.core_thread_num=8
### Number of threads required for raft business request processing
# nacos.core.protocol.raft.data.cli_service_thread_num=4
### raft linear read strategy. Safe linear reads are used by default, that is, the Leader tenure is confirmed by heartbeat
# nacos.core.protocol.raft.data.read_index_type=ReadOnlySafe
### rpc request timeout, default 5 seconds
# nacos.core.protocol.raft.data.rpc_request_timeout_ms=5000