ServiceCenter Syncer

中文简介

1. What is ServiceCenter Syncer

Syncer is a multiple servicecenters synchronization tool designed for large microservice architectures,supporting differ-structure servicecenters. The project adheres to the following beliefst:

• Transparent to the application. Regardless of whether the tool is running or not, it should not affect the original microservices.
• Provide peer-to-peer networks for multiple service-centers. Syncers are loosely coupled and members can join and quit freely.
• Support for different service-centers. Plug-in form, users can easily implement plug-ins for different service-centers.

Glossary

• Gossip - Syncer uses a gossip protocol by serf for inter-cluster broadcasts. The Gossip protocol uses UDP to indirectly force random propagation between cluster nodes, which is a viral propagation protocol.
• Serf - An implementation of the Gossip protocol, a tool for cluster member management, fault detection, and orchestration, which is distributed, fault tolerant and highly available.
• service center - It can be a single microservice discovery and registration center or a cluster of microservice discovery and registration centers. We define a service center to be a network area with unified instances data.

2. ServiceCenter Syncer Architecture

Syncer's runtime architecture diagram is as follows,
There are three service-centers, labeled “A” and “B” and “C”.

• Within each service center, a service registry (ServiceCenter, Eurake, or other) cluster is deployed that manages all microservice instances of the service center to which it belongs, and the service centers are isolated from each other. At the same time, a Syner cluster is deployed in each service center, which is responsible for discovering instances from the registry and registering instance information from other service centers to its own service centers.
• Between multiple service centers, multiple Syncers form a peer-to-peer network that maintains a Gossip pool. The use of the Gossip protocol mainly brings the following conveniences,
  • Syncer only needs any pool member information to join the network, and the discovery of other member information is done automatically.
  • The fault detection of members is distributed, and multiple members in the pool cooperate with each other, which is more accurate and perfect than simple heartbeat.
  • Provides cluster messaging, mainly for event notification of instances data.
• Syncer provides RPC service for transmitting microservice instances information. When a Syncer receives event notifications from other members or queries across service centers, the data can be synchronized through the Pull and Push interfaces provided by the RPC service.

3. Quick Start

3.1 Getting & Running Service center

Take Service-center as an example, reference to ServiceCenter Quick Start

3.2 Building Service-Center Syncer from Source

Requirements, Golang version 1.11+

# Get Service-center Syncer source code from github
$ git clone https://github.com/apache/servicecomb-service-center.git $GOPATH/src/github.com/apache/servicecomb-service-center
$cd $GOPATH/src/github.com/apache/servicecomb-service-center

# Set "go mod" compile env
$ GO111MODULE=on go mod download
$ GO111MODULE=on go mod vendor

# Build it
$ cd syncer
$ go build

3.3 Running ServiceCenter Syncer

Parameter Description

• dc-addr

  Service center address, which is the service registry address. Cluster mode is supported, and multiple addresses are separated by commas.
  Example --dc-addr http://10.0.0.10:30100,http://10.0.0.11:30100

• bind

  P2P address of Syncer for communication with other Syner members in P2P networks by Gossip.
  Example --bind 10.0.0.10:30190

• rpc-addr

  Address of Syncer for data transmission, used to synchronize microservices data between Syncers.
  Example --rpc-addr 10.0.0.10:30191

• join

  The address of any member of the P2P network, to enable itself join the specified P2P network, ignore this parameter when starting the first syncer on a P2P network.
  Example --join 10.0.0.10:30191

Suppose there are 2 Service centers, each of them with a Service-center cluster for microservices discovery and registry, as following,

Start Service-center Syncer to enable communication between 2 service centers,

Start the ServiceCenter Syner by executing the following command on the 10.0.0.10 machine

$ ./syncer daemon --dc-addr http://10.0.0.10:30100 --bind 10.0.0.10:30190 --rpc-addr 10.0.0.10:30191

Start the ServiceCenter Syncer by executing the following command on the 10.0.0.10 machine and join the 10.0.0.10 gossip pool

$ ./syncer daemon --dc-addr http://10.0.0.11:30100 --bind 10.0.0.11:30190 --rpc-addr 10.0.0.11:30191 --join 10.0.0.10:30191

Verification
30 seconds after registering a microservice to one of the Service-centers, the information about it can be get from the other one.