微軟的分佈式應用框架 Dapr Helloworld

Dapr HelloWorld

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Dapr

Distributed Application Runtime. An event-driven, portable runtime for building microservices on cloud and edge.

分佈式應用運行時、事件驅動、爲雲和邊緣構建微服務提供便攜化運行時。

我如今也不是很懂。

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dapr/dapr

GitHub

Dapr is a portable, serverless, event-driven runtime that makes it easy for developers to build resilient, stateless and stateful microservices that run on the cloud and edge and embraces the diversity of languages and developer frameworks.

Dapr codifies the best practices for building microservice applications into open, independent, building blocks that enable you to build portable applications with the language and framework of your choice. Each building block is independent and you can use one, some, or all of them in your application.

比上面的介紹多了 stateless or stateful 的標籤。學《計算理論》的時候接觸過一些狀態機。

」狀態時萬惡之源「 

注意提到了多語言和多開發者框架，我認爲這是他選擇的經過通訊共享信息，即 HTTP 和 GRPC 支持多語言等特性。微軟想經過這個設定一個構建微服務應用的規則。從根本上確立你開發的每個應用的獨立性。

下面進行一個 QuickStart

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環境

1. Install Docker（微服務已經離不開容器化了）
2. Install Dapr
3. Node.js version 8 or greater（這個 Helloworld 是 node 應用）

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On MacOS

Install the latest darwin Dapr CLI to /usr/local/bin

curl -fsSL https://raw.githubusercontent.com/dapr/cli/master/install/install.sh | /bin/bash

有條件能夠加速

執行初始化（會啓動 docker 容器）

$ dapr init
⌛  Making the jump to hyperspace...
Downloading binaries and setting up components
✅  Success! Dapr is up and running

$ docker ps
CONTAINER ID        IMAGE                COMMAND                  CREATED             STATUS              PORTS                        NAMES
b3a5600e672f        redis                "docker-entrypoint.s…"   44 hours ago        Up 44 hours         0.0.0.0:6379->6379/tcp       xenodochial_hofstadter
e5010ba0c33f        daprio/dapr          "./placement"            44 hours ago        Up 44 hours         0.0.0.0:50005->50005/tcp     dapr_placement

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HelloWorld

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Application Architecture

<br />可以看到暴露兩個 endpoint 是 HTTP 訪問，一個建立一個查詢。

主要看咱們使用 Dapr 的交互。在圖中它做爲 Runtime 

• 提供 Dapr API 給多語言調用。
• 提供 狀態管理 By state stores

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Download Code

下載並進入相應文件夾

git clone https://github.com/dapr/samples.git
cd samples/1.hello-world

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Cat app.js

// $ cat app.js 
// ------------------------------------------------------------
// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
// ------------------------------------------------------------

const express = require('express');
const bodyParser = require('body-parser');
require('isomorphic-fetch');

const app = express();
app.use(bodyParser.json());

const daprPort = process.env.DAPR_HTTP_PORT || 3500;
const stateUrl = `http://localhost:${daprPort}/v1.0/state`;
const port = 3000;

app.get('/order', (_req, res) => {
    fetch(`${stateUrl}/order`)
        .then((response) => {
            return response.json();
        }).then((orders) => {
            res.send(orders);
        });
});

app.post('/neworder', (req, res) => {
    const data = req.body.data;
    const orderId = data.orderId;
    console.log("Got a new order! Order ID: " + orderId);

    const state = [{
        key: "order",
        value: data
    }];

    fetch(stateUrl, {
        method: "POST",
        body: JSON.stringify(state),
        headers: {
            "Content-Type": "application/json"
        }
    }).then((response) => {
        console.log((response.ok) ? "Successfully persisted state" : "Failed to persist state");
    });

    res.status(200).send();
});

app.listen(port, () => console.log(`Node App listening on port ${port}!`));

這是一些路由和 handlers

注意 14-16 行

const daprPort = process.env.DAPR_HTTP_PORT || 3500;
const stateUrl = `http://localhost:${daprPort}/v1.0/state`;
const port = 3000;

3500 是 Dapr 的環境端口，若是你安裝時有改動，須要考慮。<br />stateurl 就是 Dapr 提供的 URL 了

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Handlers

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/neworder

app.post('/neworder', (req, res) => {
    const data = req.body.data;
    const orderId = data.orderId;
    console.log("Got a new order! Order ID: " + orderId);

    const state = [{
        key: "order",
        value: data
    }];

    fetch(stateUrl, {
        method: "POST",
        body: JSON.stringify(state),
        headers: {
            "Content-Type": "application/json"
        }
    }).then((response) => {
        console.log((response.ok) ? "Successfully persisted state" : "Failed to persist state");
    });

    res.status(200).send();
});

這裏重點是狀態存儲，即將 state 經過 stateurl 存儲在 Dapr 中。

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/order

咱們並非直接經過 res.json 做爲 Response 來進行已經持久化的數據的使用，而是經過暴露一個 GET endpoint 經過訪問它來驗證持久化是否成功。

app.get('/order', (_req, res) => {
    fetch(`${stateUrl}/order`)
        .then((response) => {
            return response.json();
        }).then((orders) => {
            res.send(orders);
        });
});

如今咱們經過狀態轉移在 Dapr 裏實現了 stateless，一樣咱們也能夠在加上一個 local cache 並經過一個新的 endpoint 訪問來使 Node application 變成 stateful

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Dapr Run Node.js App

1. npm install ：經過當前目錄下的 package.json , 會安裝 express 和 body-parser ，在 app.js 7-8行咱們能夠看到這兩項。
2. dapr run --app-id mynode --app-port 3000 --port 3500 node app.js

$ dapr run --app-id mynode --app-port 3000 --port 3500 node app.js
ℹ️  Starting Dapr with id mynode. HTTP Port: 3500. gRPC Port: 55099
✅  You're up and running! Both Dapr and your app logs will appear here.

應該是有後臺運行的 CLI 命令，這裏是前臺打印的日誌

== DAPR == time="2019-11-06T10:37:41+08:00" level=info msg="starting Dapr Runtime -- version 0.1.0 -- commit 4358565-dirty"
== DAPR == time="2019-11-06T10:37:41+08:00" level=info msg="log level set to: info"
== DAPR == time="2019-11-06T10:37:41+08:00" level=info msg="standalone mode configured"
== DAPR == time="2019-11-06T10:37:41+08:00" level=info msg="dapr id: mynode"
== DAPR == time="2019-11-06T10:37:41+08:00" level=info msg="loaded component messagebus (pubsub.redis)"
== DAPR == time="2019-11-06T10:37:41+08:00" level=info msg="loaded component statestore (state.redis)"
== DAPR == time="2019-11-06T10:37:41+08:00" level=info msg="application protocol: http. waiting on port 3000"
== APP == Node App listening on port 3000!
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="application discovered on port 3000"
== DAPR == 2019/11/06 10:37:42 redis: connecting to localhost:6379
== DAPR == 2019/11/06 10:37:42 redis: connected to localhost:6379 (localAddr: [::1]:55130, remAddr: [::1]:6379)
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="actor runtime started. actor idle timeout: 1h0m0s. actor scan interval: 30s"
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="actors: starting connection attempt to placement service at localhost:50005"
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="http server is running on port 3500"
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="gRPC server is running on port 55099"
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="local service entry announced"
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="dapr initialized. Status: Running. Init Elapsed 945.8297490000001ms"
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="actors: established connection to placement service at localhost:50005"
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="actors: placement order received: lock"
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="actors: placement order received: update"
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="actors: placement tables updated"
== DAPR == time="2019-11-06T10:37:42+08:00" level=info msg="actors: placement order received: unlock"

⚠️：注意到 Node App 在指定的 3000 端口運行，同時還有狀態存儲的 redis 在 6379 端口運行

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Post and Get

接下來注意，文中的端口是 app.js 裏默認的 3500 <a name="B0eiO"></a>

Post

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Curl

curl -XPOST -d @sample.json http://localhost:3500/v1.0/invoke/mynode/method/neworder

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Vscode

若是你用 vscode ，使用這個插件 Rest Client Plugin<br />而後打開目錄下的 sample.http , 能夠看到 send request 的選項<br />sample.http 

POST http://localhost:3500/v1.0/invoke/mynode/method/neworder
{
  "data": {
    "orderId": "42"
  } 
}

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Postman

如圖： http://localhost:3500/v1.0/invoke/mynode/method/neworder 

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Result Update

你能夠在你啓動的終端中看到新的日誌

== APP == Got a new order! Order ID: 42
== APP == Successfully persisted state

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Get

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Curl

curl http://localhost:3500/v1.0/invoke/mynode/method/order

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Vscode

sample.http

GET http://localhost:3500/v1.0/invoke/mynode/method/order

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Postman

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Terminate

ctrl + c 或者 dapr stop --app-id mynode

^C
ℹ️  terminated signal received: shutting down
✅  Exited Dapr successfully
✅  Exited App successfully

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Feature

• 具備可插入提供程序和至少一次語義的事件驅動的Pub-Sub系統
• 使用可插入提供程序的輸入和輸出綁定
• 具備可插拔數據存儲的狀態管理
• 一致的服務到服務發現和調用
• 選擇加入狀態模型：強大/最終一致性，首次寫入/最後寫入獲勝
• 跨平臺虛擬演員
• 限速
• 使用OpenTelemetry的內置分佈式跟蹤
• 使用專用的Operator和CRD在Kubernetes上本地運行
• 經過HTTP和gRPC支持全部編程語言
• 來自Azure，AWS，GCP的多雲，開放式組件（綁定，發佈-訂閱，狀態）
• 做爲過程或容器化在任何地方運行
• 輕量級（58MB二進制，4MB物理內存）
• 做爲輔助工具運行-無需特殊的SDK或庫
• 專用的CLI-易於調試的開發人員友好體驗
• Java，Dotnet，Go，Javascript和Python的客戶端

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Refer

• https://github.com/dapr/dapr
• https://github.com/dapr/docs/blob/master/getting-started/environment-setup.md#environment-setup
• https://github.com/dapr/docs/tree/master/howto
• https://github.com/dapr/samples
• https://github.com/dapr/samples/tree/master/1.hello-world