Yorkie

Self-Hosted Server

Sometimes you may want to run your own Yorkie Server. This page explains how to run a Yorkie Server.

To run a Yorkie Server, you need to install the CLI. If you haven't installed it yet, please refer to CLI.

Running a Server via CLI

Let's start a Server with the CLI. You can start a Server with the following command:

```bash
$ yorkie server

backend created: id: c6ljcdl94818baveba8g, rpc: localhost:11101: db: memory
serving admin on 11103
serving RPC on 11101
serving profiling on 11102

The Server handles administrative requests such as project maintenance, and it continues to run until it's told to quit with termination commands such as Ctrl+C. The Server stores its data using an in-memory DB, which does not provide durability by default.

Persistence

If you start the Server with a MongoDB address, you can permanently save the data stored by Yorkie.

Then, start a Yorkie Server with --mongo-connection-uri flag to connect the MongoDB.

$ yorkie server --mongo-connection-uri mongodb://localhost:27017

MongoDB connected, URI: mongodb://localhost:27017, DB: yorkie-meta
backend created: id: c6ljibt948102kkt9neg, rpc: localhost:11101: db: mongodb://localhost:27017
serving profiling on 11102
serving RPC on 11101

Server for Web

Server uses gRPC to provide an API that Clients can connect to. Since it is currently impossible to implement the HTTP/2 gRPC in some browsers, Envoy is required for web. For more details: gRPC-web

This page shows how to start the Server for web. Overall structure is as follows:

Browser            Envoy                  Server
┌────────┐         ┌──────────────┐       ┌───────────┐
│gRPC-web├─HTTP1.1─┤gRPC-web Proxy├─HTTP2─┤gRPC Server│
└────────┘         └──────────────┘       └───────────┘

Configuring Envoy by hand with its config file is cumbersome, but using Docker Compose makes it easy.

First, download all manifests files from docker folder. Then, execute the following command in the folder containing the downloaded file.

$ docker-compose up --build -d

Starting yorkie ... done
Starting envoy  ... done

This will launch Yorkie(Server) and envoy containers on your environment.

$ docker ps

IMAGE                      COMMAND                  PORTS                                  NAMES
grpcweb:envoy              "/usr/local/bin/envo…"   0.0.0.0:8080->9090/tcp                 envoy
yorkieteam/yorkie:latest   "yorkie server --ena…"   0.0.0.0:11101-11103->11101-11103/tcp   yorkie

Then, the ports of the services are bound to the host environment.

• 8080: gRPC-web port for SDK
• 9090: gRPC-web port for Admin Server is used by Dashboard(Dashboard) or CLI
• 11101: gRPC port for SDK
• 11102: HTML port for Profiling Server
• 11103: gRPC port for Admin Server

Now, let's create a Client with address https://api.yorkie.dev.

1const client = new yorkie.Client('https://api.yorkie.dev');
2await client.activate();

Next, let's take a look at the JS SDK.

Monitoring

Server exports metrics under the /metrics path on its profiling port. The metrics can be fetched with curl:

$ curl http://localhost:11102/metrics

yorkie_server_version{server_version="{{site.version}}"} 1
# HELP yorkie_pushpull_received_changes_total The total count of changes included
# TYPE yorkie_pushpull_received_changes_total counter
yorkie_pushpull_received_changes_total 6
...

This metrics can be collected from Prometheus.

Running Prometheus and Grafana is the easiest way to monitor Server's metrics.

First, download all manifests files from docker folder. Then, start the applications with docker-compose:

$ docker-compose -f docker-compose-monitoring.yml up --build -d

Creating prometheus ... done
Creating grafana    ... done

Now, Prometheus will collect Server metrics every 10 seconds.

Grafana has a built-in Prometheus support; just add a Prometheus data source:

Name:   prometheus
Type:   Prometheus
Url:    http://localhost:9090
Access: proxy

Then, import the default Yorkie dashboard template and customize it. For instance, if Prometheus data source name is my-prometheus, the datasource field values in JSON also need to be my-prometheus.

Sample dashboard:

Cluster Mode

In a production environment, it is generally expected that more than one server handles requests. Even if a Server goes down, the other Servers must be able to handle the request. We can achieve that by setting up Servers with Cluster-Mode.

This page describes how to set up a cluster of Servers. An example of the cluster is as follows:

┌───────────┐
                        │  ┌──────┐ │
                      ┌─┼─►│Server│ │    ┌───────┐
                      │ │  └──▲───┘ │ ┌─►│MongoDB│
┌──────┐  ┌────────┐  │ │     │     │ │  └───────┘
│Client├─►│Load    ├──┤ │ Broadcast ├─┤
└──────┘  │Balancer│  │ │ DocEvents │ │  ┌────┐
          └────────┘  │ │     │     │ └─►│etcd│
                      │ │  ┌──▼───┐ │    └────┘
                      └─┼─►│Server│ │
                        │  └──────┘ │
                        └───────────┘

• Load Balancer: It is responsible for distributing the load of the requests to the Servers.
• Broadcast Channel: It is responsible for broadcasting the events to all Servers.
• MongoDB: It stores the data of Yorkie.
• etcd: It is used to store the state of the cluster such as MemberMap, SubscriptionMap, etc.

First, we need components such as etcd, MongoDB, and Load Balancer in order to set up the cluster.

Various types of load balancer can be used for the cluster. For CodePair, We have configured the cluster on AWS, so we use ALB as Load Balancer.

If etcd and MongoDB are ready, we can run Servers in cluster mode. In the terminal, run the Server with flags for MongoDB and etcd.

$ yorkie server --mongodb-uri mongodb://localhost:27017 --etcd-endpoints http://localhost:2379

MongoDB connected, URI: mongodb://localhost:27017, DB: yorkie-meta
etcd connected, URI: [http://localhost:2379]
backend created: id: c6n20nnblaroaopqdbp0, rpc: localhost:11101: db: mongodb://localhost:27017
serving profiling on 11102
serving RPC on 11101

Open a new terminal and run the Server by using xxx-port flags to avoid ports conflicts.

$ yorkie server --rpc-port 21101 --profiling-port 21102 --mongo-connection-uri mongodb://localhost:27017 --etcd-endpoints http://localhost:2379

MongoDB connected, URI: mongodb://localhost:27017, DB: yorkie-meta
etcd connected, URI: [http://localhost:2379]
backend created: id: c6n25o7blarohq3ve250, rpc: localhost:21101: db: mongodb://localhost:27017
serving profiling on 21102
serving RPC on 21101

Now both Servers are ready to receive requests from Clients.