Eureka

Consul

Nacos

Zookeeper

Etcd

Eureka

架构图 architecture diagram

master-slave

peer-to-peer replication

服务注册 registry

Why Is It so Slow to Register a Service?

服务续约 renew heartbeat

服务下线 cancel

服务失效剔除 Eviction

自我保护机制 self-protection mode

机房 Zones

高可用 High Availability, Zones and Regions

测试

Zookeeper

服务注册 registry

心跳检测 heartbeat

Watch机制

Zookeeper是否用作注册中心？

所以 3.2版本之后，读写性能增大了2倍，Leader宕机之后也能很快的完成选举，可以考虑用做注册中心。

Nacos

Introduce

●Service Discovery And Service Health Check Nacos supports both DNS-based and RPC-based (Dubbo/gRPC) service discovery. After a service provider registers a service with native, OpenAPI, or a dedicated agent, a consumer can discover the service with either DNS or HTTP.Nacos provides real-time health check to prevent services from sending requests to unhealthy hosts or service instances. Nacos supports both transport layer (PING or TCP) health check and application layer (such as HTTP, Redis, MySQL, and user-defined protocol) health check. For the health check of complex clouds and network topologies(such as VPC, Edge Service etc), Nacos provides both agent mode and server mode health check. Nacos also provide a unity service health dashboard to help you manage the availability and traffic of services.

●Dynamic configuration management Dynamic configuration service allows you to manage the configuration of all applications and services in a centralized, externalized and dynamic manner across all environments.Dynamic configuration eliminates the need to redeploy applications and services when configurations are updated.Centralized management of configuration makes it more convenient for you to achieve stateless services and elastic expansion of service instances on-demand.Nacos provides an easy-to-use UI (DEMO) to help you manage all of your application or services's configurations. It provides some out-of-box features including configuration version tracking, canary/beta release, configuration rollback, and client configuration update status tracking to ensure the safety and control the risk of configuration change.

●Dynamic DNS service Dynamic DNS service which supports weighted routing makes it easier for you to implement mid-tier load balancing, flexible routing policies, traffic control, and simple DNS resolution services in your production environment within your data center. Dynamic DNS service makes it easier for you to implement DNS-based Service discovery.Nacos provides some simple DNS APIs TODO for you to manage your DNS domain names and IPs.

●Service governance and metadata management Nacos allows you to manage all of your services and metadata from the perspective of a microservices platform builder. This includes managing service description, life cycle, service static dependencies analysis, service health status, service traffic management，routing and security rules, service SLA, and first line metrics.

Domain Model

Data Model

Service Entity Relationship Model

Config Entity Relationship Model

Artifacts, Deployment, and Start Mode

Two Artifacts

Two Start Modes

Nacos service discovery performance test report

Nacos 2.0 的性能测试报告

腾讯云对Nacos 2.0 的性能测试报告

Consul

What is Consul?

Hands-on: Complete the Getting Started tutorials to learn how to deploy Consul:

How does Consul work?

Consul provides a control plane that enables you to register, query, and secure services deployed across your network. The control plane is the part of the network infrastructure that maintains a central registry to track services and their respective IP addresses. It is a distributed system that runs on clusters of nodes, such as physical servers, cloud instances, virtual machines, or containers.

Consul interacts with the data plane through proxies. The data plane is the part of the network infrastructure that processes data requests. Refer to Consul Architecture for details.

●Register: Teams add services to the Consul catalog, which is a central registry that lets services automatically discover each other without requiring a human operator to modify application code, deploy additional load balancers, or hardcode IP addresses. It is the runtime source of truth for all services and their addresses. Teams can manually define and register services using the CLI or the API, or you can automate the process in Kubernetes with service sync. Services can also include health checks so that Consul can monitor for unhealthy services.

●Query: Consul’s identity-based DNS lets you find healthy services in the Consul catalog. Services registered with Consul provide health information, access points, and other data that help you control the flow of data through your network. Your services only access other services through their local proxy according to the identity-based policies you define.

●Secure: After services locate upstreams, Consul ensures that service-to-service communication is authenticated, authorized, and encrypted. Consul service mesh secures microservice architectures with mTLS and can allow or restrict access based on service identities, regardless of differences in compute environments and runtimes.

What is service discovery?

Service discovery helps you discover, track, and monitor the health of services within a network. Service discovery registers and maintains a record of all your services in a service catalog. This service catalog acts as a single source of truth that allows your services to query and communicate with each other.

Benefits of service discovery

How does service discovery work?

What is service discovery in microservices?

What are the two main types of service discovery?

There are two main service?discovery patterns: client-side discovery and server-side discovery.

Service discovery vs load balancing

How do you implement service discovery?

Recommended Architecture

Failure tolerance characteristics

Node failure

Availability zone failure

Etcd

Simple interface

{JSON

HTTP

Key-value storage

Watch for changes

PPP1

/CONFIG

APP2

Kubernetes

Compared

	Consul	Nacos	Zookeeper	Etcd	Kubernetes(Etcd)	Eureka
Conpany	HashiCorp	Alibaba	Apache	CoreOS	Google	Netflix
Language	Go	Java	Java	Go	Go	Java
GitHub	//github.com/hashicorp/consul(25.9K Star)	//github.com/alibaba/nacos(25.2K Star)	//github.com/apache/zookeeper(11K Star)	//github.com/etcd-io/etcd(42.3K Star)	//github.com/kubernetes/kubernetes(95.2K Star)	//github.com/Netflix/eureka(11.6K Star)
GitHub Solve Issue	??(May be Stablize)	???	??(May be Stablize)	???	???
LICENSE	MPL-2.0 license	Apache-2.0 license	Apache-2.0 license	Apache-2.0 license	Apache-2.0 license	Apache-2.0 license
Web Tools	Consul	Nacos	ZKUI	etcd-browser、etcdkeeper	cloud platform	Eureka
Cloud Products	? Aliyun? AWS ? Tencent Cloud TSE Consul	? Aliyun MSE Nacos? AWS ? Tencent Cloud TSE Nacos	? Aliyun MSE Zookeeper? AWS EMR ZooKeeper ? Tencent Cloud TSE Zookeeper	? Aliyun ACK(kubernetes)? AWS EKS(kubernetes) ? Tencent Cloud TKE / Cloud Service for etcd(cetcd)	? Aliyun ACK(kubernetes)? AWS EKS(kubernetes)? Tencent Cloud TKE
Performance	??	Nacos2.0的服务发现了功效检测报告范文??Configuration center: a single machine, 8C 16G, write TPS reaches 2500, with an average of about 10ms. Read TPS 14000, an average of 40ms.Registration center: 3 clusters, 8C 16G, the service and instance capacity reached one million levels during the stress test, the cluster operation continued to be stable, the registration/deregistration instance TPS reached more than 26,000, and the average time-consuming was 3.6ms, and the query instance TPS could reach more than 30,000. Average time spent 3.12ms	ZooKeeper: Because Coordinating Distributed Systems is a Zoo ???	Performance ????	????	?
Performance Bottleneck	Consul's write capability is limited by disk I/O, and its read capability is limited by CPU. Memory requirements will depend on the total size of KV pairs stored and should be sized based on that data (as should hard disk storage). The value of the key (Value) size limit is 512KB.		●In order to ensure strong consistency, in the same zk cluster, only one leader can perform write operations, and the write operation must be completed after more than half of the node machines are synchronized before acking the client.●When there are hundreds of thousands of machines in this cluster system to continuously use zk for distributed lock operations or other operations, zk will inevitably become a performance bottleneck (cannot be scaled horizontally)●ZooKeeper does not support cross-computer room routing. Unlike eureka, which has the concept of zone, local routing is preferred. When the local computer room is routed, when there is a problem in the local computer room, it can be routed to another computer room.●When there are too many ZooKeeper nodes, if there is a service node change and the machine needs to be notified at the same time, then the network card will be fully loaded in an instant, and it is easy to repeat the notification			When the scale of Eureka's service instances is around 5000, the problem of service unavailability has already occurred. Even in the process of stress testing, if the number of concurrent threads is too high, Eureka will crash.
CAP	CP	CP：Config CenterAP：Registry Center	CP	CP		AP
Consistency Algorithm	Raft	Raft	ZAB	Raft		-
Service Health Check	TCP/HTTP/GRPC/CMD	TCP/HTTP/MySQL/Custom	Keep Alive	Heart Beat		Client Beat
Load Balance	Fabio	Weight/Metadata/Selector	-			Ribbon
Avalanche Protection	?	?	?	?		?
Multi Data Center	??（natural support）	?	?	?		?
Sync Across Registry Center	?	?	?	?		?
KV Storage Service	?	?	?	?	?After purchase, test whether it is convenient to change the configuration, whether it supports dynamic configuration, and whether it is convenient to authorize permissions	?
Service Auto Remove	?	?	?	?		?
Watch	?	?	? Pros： Real-time perception of service on-line and off-line configuration hot deployment in distributed systems distributed locks Cons： ZooKeeper opens a new socket connection per each new watch request we make. This has made ZooKeepers like more complex since it has to manage a lot of open socket connections in real time, also affects performance The callback mechanism is limited. The watch on the Znode only supports triggering a callback once, and does not support timed expiration.	?? Pros： There is no need to make a socket connection for each watch like zookeeper, it can be reused Zookeeper can only receive one event notification per watch, etcd can continuously monitor, and there is no need to set a watch again after a watch is triggered Zookeeper will discard events, etcd3 holds an event window, and will not lose all events after the client disconnects		?
Access Agreement	HTTP/DNS	HTTP/DNS/UDP	TCP	HTTP/gRPC		HTTP
Self-monitoring	Metrics	Metrics	?	Metrics Relying on the Watch function, when a node disappears or changes, Watcher will discover and notify the user as soon as possible; A node can set a TTL key, such as sending a heartbeat signal to etcd every 30s, to represent that the node is still alive, otherwise it means that the node has disappeared;		Metrics
Access Control	ACL	RBAC	ACL	RBAC	RBAC	?
SRE Authorization Convenient?	??	??	?	??	test after purchase
Dubbo	?	?	?	?		?
K8S	?	?	?	?		?
Spring Cloud	?	?	?	?		?
Pros	● Compared with other distributed service registration and discovery solutions, Consul's solution is more "one-stop", with built-in service registration and discovery framework, distributed consistency protocol implementation, health check, Key/Value storage, and multi-data center solutions , no longer need to rely on other tools (such as ZooKeeper, etc.). It is also relatively simple to use. Consul is written in the Go language, so it is naturally portable; the installation package contains only one executable file, which is easy to deploy and works seamlessly with lightweight containers such as Docker. ● At the same time, Consul is more famous in the world, the official documents are very complete, the recommended deployment architecture, the number of nodes, and the stability of multiple data centers are very clear	● The configuration center uses CP, and the registration center uses AP, which not only ensures the consistency of configuration, but also ensures the high availability of services.	● Non-blocking full snapshots (to make eventually consistent).● Efficient memory management.● Reliable (has been around for a long time).● A simplified API.● Automatic ZooKeeper connection management with retries.● Complete, well-tested implementations of ZooKeeper recipes.● A framework that makes writing new ZooKeeper recipes much easier.● Event support through ZooKeeper watches.● In a network partition, both minority and majority partitions will start a leader election. Therefore, the minority partition will stop operations. You can read more about this here.	● Incremental snapshots avoid pauses when creating snapshots, which is a problem in ZooKeeper.● No garbage collection pauses due to off-heap storage.● Watchers are redesigned, replacing the older event model with one that streams and multiplexes events over key intervals. Therefore, there's no socket connection per watch. Instead, it multiplexes events on the same connection. ● Unlike ZooKeeper, etcd can continuously watch from the current revision. There's no need to place another watch once a watch is triggered.● Etcd3 holds a sliding window to keep old events so that disconnecting will not cause all events to be lost.
Cons	● Service registration will be slower, because Consul's Raft protocol requires more than half of the nodes to write successfully to register successfully.● When the Leader hangs up, the entire Consul is unavailable during the re-election period, ensuring strong consistency but sacrificing availability.	● Nacos is not well-known internationally, and there are relatively few English documents● This is not friendly to foreign SRE and development students, especially SRE, because Nacos needs to ensure high availability and no problems.	● Since ZooKeeper is written in Java, it inherits few drawbacks of Java (i.e. garbage collection pauses).● When creating snapshots (where the data is written to disks), ZooKeeper read/write operations are halted temporarily. This only happens if we have enabled snapshots. If not, ZooKeeper operates as an in-memory distributed storage.● ZooKeeper opens a new socket connection per each new watch request we make. This has made ZooKeepers like more complex since it has to manage a lot of open socket connections in real time.●The callback mechanism is limited. The watch on the Znode only supports triggering a callback once, and does not support timed expiration.●Insufficient scalability, ZK cluster does not support online dynamic addition or replacement of machines：Because there is only one Leader, horizontal expansion cannot significantly improve performance. Because there is only one Leader, the more zk machine nodes, it will lead to longer communication and synchronization time, and performance may deteriorate.●Zab protocol, the protocol has room for optimization in the election and sending links：The design of zab is extremely sensitive to the network. If you manage a dual-computer room (network jitter in a dual-computer room is normal), the single-computer room will be unavailable due to jitter (because there is only one Leader), even in a computer room (often in the computer room. Routing adjustment), jitter will also lead to leader re-election, the actual leader election is usually tens of seconds to a few minutes, which will seriously amplify the network jitter that was originally only in seconds	● Note that the client may be uncertain about the status of an operation if it times out or if there's a network disruption between the client and the etcd member. etcd may also abort operations when there is a leader election. etcd does not send abort responses to clients’ outstanding requests in this event.● Serialized read requests will continue to be served in a network split where the minority partition is the leader at the time of the split.		1Eureka currently does not support the watch function, and can only update the service status through rotation training. If there are many services, the pressure on the server will be relatively high, and the relative performance will be relatively poor. However, the number of our services is currently within 100, so performance is not the main problem

● Zookeeper's write performance can reach tens of thousands of TPS, and its capacity can reach millions in terms of the number of storage nodes. However, the Paxos protocol limits the size of the Zookeeper cluster (3, 5 nodes). When a large number of instances go offline, the performance of Zookeeper is not stable. At the same time, the defect in the push mechanism will cause the resource usage of the client to increase, resulting in a sharp drop in performance, so we will discard it.

● Etcd is developed based on Zookeeper and written in Go, so there will be no Java GC problems. At the same time, it also optimizes Watch. Etcd is a durable and stable watch rather than a simple single-trigger watch. Zookeeper's single-trigger watch means that after monitoring an event, the client needs to re-initiate the monitoring, so that the zookeeper server cannot obtain the events before receiving the client's monitoring request; and at the time of the two monitoring requests The client cannot perceive the events that occur within the interval. The persistent monitoring of etcd is triggered continuously whenever an event occurs, and the client does not need to re-initiate the monitoring. Although etcd is relatively new, it has a strong background of Kubernetes, an active community, and a bright future, so it can still be considered.

● Nacos /nɑ:k??s/ is the acronym for 'Dynamic Naming and Configuration Service'，an easy-to-use dynamic service discovery, configuration and service management platform for building cloud native applications，It is easy to use and has high performance(Doubtful). The community in China is very active and used a lot. However, for foreign colleagues, especially SRE, Nacos is not well-known internationally, and there are relatively few English documents. The cluster deployment in the official document Documentation is also relatively simple, so we will discard it.

● Compared with other distributed service registration and discovery solutions, Consul's solution is more "one-stop", with built-in service registration and discovery framework, distributed consistency protocol implementation, health check, Key/Value storage, and multi-data center solutions , no longer need to rely on other tools (such as ZooKeeper, etc.). It is also relatively simple to use. Consul is written in the Go language, so it is naturally portable; the installation package contains only one executable file, which is easy to deploy and works seamlessly with lightweight containers such as Docker, so it can still be considered.

● Kubernetes has some built-in components(Etcd), which allow him to have functions such as service discovery, configuration management, which are fully functional and make our distributed applications more elastic and free, so it can still be considered.

Reference Documents

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SpringCloudConsul