从 App Engine 柔性环境应用连接到 Redis 实例

App Engine 应用必须与 Redis 实例位于同一区域和同一网络才可获得授权来访问此 Redis 实例。

设置

如果您已安装 Cloud SDK 且已创建 Redis 实例,则可跳过这些步骤。

  1. 安装 Cloud SDK 并进行初始化:

    gcloud init
    
  2. 按照快速入门指南创建一个 Redis 实例。记下该 Redis 实例的地区、IP 地址和端口。

示例应用

此示例 HTTP 服务器应用建立从 App Engine 柔性环境实例到 Redis 实例的连接。

克隆您所需编程语言的代码库,并转到包含示例代码的文件夹:

Go

git clone https://github.com/GoogleCloudPlatform/golang-samples
cd golang-samples/memorystore/redis

Java

git clone https://github.com/GoogleCloudPlatform/java-docs-samples
cd java-docs-samples/memorystore/redis

Node.js

git clone https://github.com/GoogleCloudPlatform/nodejs-docs-samples
cd nodejs-docs-samples/memorystore/redis

Python

git clone https://github.com/GoogleCloudPlatform/python-docs-samples
cd python-docs-samples/memorystore/redis

每次访问 / 端点时,此示例应用都会增加一个 Redis 计数器。

Go

此应用使用 github.com/gomodule/redigo/redis 客户端。通过运行以下命令进行安装:

go get github.com/gomodule/redigo/redis

// Command redis is a basic app that connects to a managed Redis instance.
package main

import (
	"fmt"
	"log"
	"net/http"
	"os"

	"github.com/gomodule/redigo/redis"
)

var redisPool *redis.Pool

func incrementHandler(w http.ResponseWriter, r *http.Request) {
	conn := redisPool.Get()
	defer conn.Close()

	counter, err := redis.Int(conn.Do("INCR", "visits"))
	if err != nil {
		http.Error(w, "Error incrementing visitor counter", http.StatusInternalServerError)
		return
	}
	fmt.Fprintf(w, "Visitor number: %d", counter)
}

func main() {
	redisHost := os.Getenv("REDISHOST")
	redisPort := os.Getenv("REDISPORT")
	redisAddr := fmt.Sprintf("%s:%s", redisHost, redisPort)

	const maxConnections = 10
	redisPool = redis.NewPool(func() (redis.Conn, error) {
		return redis.Dial("tcp", redisAddr)
	}, maxConnections)

	http.HandleFunc("/", incrementHandler)

	port := os.Getenv("PORT")
	if port == "" {
		port = "8080"
	}
	log.Printf("Listening on port %s", port)
	if err := http.ListenAndServe(":"+port, nil); err != nil {
		log.Fatal(err)
	}
}

Java

此应用基于 Jetty 3.1 servlet。

它使用 Jedis 库:

<dependency>
  <groupId>redis.clients</groupId>
  <artifactId>jedis</artifactId>
  <version>3.3.0</version>
</dependency>

AppServletContextListener 类用于创建长效 Redis 连接池:


package com.example.redis;

import java.io.IOException;
import java.util.Properties;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;

@WebListener
public class AppServletContextListener implements ServletContextListener {

  private Properties config = new Properties();

  private JedisPool createJedisPool() throws IOException {
    String host;
    Integer port;
    config.load(
        Thread.currentThread()
            .getContextClassLoader()
            .getResourceAsStream("application.properties"));
    host = config.getProperty("redis.host");
    port = Integer.valueOf(config.getProperty("redis.port", "6379"));

    JedisPoolConfig poolConfig = new JedisPoolConfig();
    // Default : 8, consider how many concurrent connections into Redis you will need under load
    poolConfig.setMaxTotal(128);

    return new JedisPool(poolConfig, host, port);
  }

  @Override
  public void contextDestroyed(ServletContextEvent event) {
    JedisPool jedisPool = (JedisPool) event.getServletContext().getAttribute("jedisPool");
    if (jedisPool != null) {
      jedisPool.destroy();
      event.getServletContext().setAttribute("jedisPool", null);
    }
  }

  // Run this before web application is started
  @Override
  public void contextInitialized(ServletContextEvent event) {
    JedisPool jedisPool = (JedisPool) event.getServletContext().getAttribute("jedisPool");
    if (jedisPool == null) {
      try {
        jedisPool = createJedisPool();
        event.getServletContext().setAttribute("jedisPool", jedisPool);
      } catch (IOException e) {
        // handle exception
      }
    }
  }
}

VisitCounterServlet 类是一个网络 Servlet,用于增加 Redis 计数器。


package com.example.redis;

import java.io.IOException;
import java.net.SocketException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;

@WebServlet(name = "Track visits", value = "")
public class VisitCounterServlet extends HttpServlet {

  @Override
  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    try {
      JedisPool jedisPool = (JedisPool) req.getServletContext().getAttribute("jedisPool");

      if (jedisPool == null) {
        throw new SocketException("Error connecting to Jedis pool");
      }
      Long visits;

      try (Jedis jedis = jedisPool.getResource()) {
        visits = jedis.incr("visits");
      }

      resp.setStatus(HttpServletResponse.SC_OK);
      resp.getWriter().println("Visitor counter: " + String.valueOf(visits));
    } catch (Exception e) {
      resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e.getMessage());
    }
  }
}

Node.js

此应用使用 redis 模块。

{
  "name": "memorystore-redis",
  "description": "An example of using Memorystore(Redis) with Node.js",
  "version": "0.0.1",
  "private": true,
  "license": "Apache Version 2.0",
  "author": "Google Inc.",
  "engines": {
    "node": ">=8.0.0"
  },
  "dependencies": {
    "redis": "^3.0.0"
  }
}

'use strict';
const http = require('http');
const redis = require('redis');

const REDISHOST = process.env.REDISHOST || 'localhost';
const REDISPORT = process.env.REDISPORT || 6379;

const client = redis.createClient(REDISPORT, REDISHOST);
client.on('error', (err) => console.error('ERR:REDIS:', err));

// create a server
http
  .createServer((req, res) => {
    // increment the visit counter
    client.incr('visits', (err, reply) => {
      if (err) {
        console.log(err);
        res.status(500).send(err.message);
        return;
      }
      res.writeHead(200, {'Content-Type': 'text/plain'});
      res.end(`Visitor number: ${reply}\n`);
    });
  })
  .listen(8080);

Python

此应用使用 Flask 进行网络服务,并使用 redis-py 软件包与 Redis 实例进行通信。

Flask==1.1.2
gunicorn==20.0.4
redis==3.5.3
import logging
import os

from flask import Flask
import redis

app = Flask(__name__)

redis_host = os.environ.get('REDISHOST', 'localhost')
redis_port = int(os.environ.get('REDISPORT', 6379))
redis_client = redis.StrictRedis(host=redis_host, port=redis_port)

@app.route('/')
def index():
    value = redis_client.incr('counter', 1)
    return 'Visitor number: {}'.format(value)

@app.errorhandler(500)
def server_error(e):
    logging.exception('An error occurred during a request.')
    return """
    An internal error occurred: <pre>{}</pre>
    See logs for full stacktrace.
    """.format(e), 500

if __name__ == '__main__':
    # This is used when running locally. Gunicorn is used to run the
    # application on Google App Engine and Cloud Run.
    # See entrypoint in app.yaml or Dockerfile.
    app.run(host='127.0.0.1', port=8080, debug=True)

准备应用进行部署

要访问 Redis 实例,App Engine 实例必须与 Redis 实例部署在相同的网络上,并且您必须提供 Redis 实例的连接详细信息。您可以通过运行以下命令找到 Redis 实例的已授权网络、IP 地址和端口:

 gcloud redis instances describe [INSTANCE_ID] --region [REGION]
  1. 在 Redis 实例所在的区域中创建 App Engine 应用

  2. 更新应用的配置以指定 Redis 实例的 IP 地址、端口和网络:

    Go

    更新 gae_flex_deployment/app.yaml 文件:

    runtime: go
    env: flex
    
    # Update with Redis instance details
    env_variables:
      REDISHOST: '<REDIS_IP>'
      REDISPORT: '6379'
    
    # Update with Redis instance network name
    network:
      name: default

    如需了解详情,请参阅使用 app.yaml 配置应用

    Java

    更新 gae_flex_deployment/app.yaml 文件以指定 Redis 实例的网络:

    runtime: java
    env: flex
    
    # Update with Redis instance network name
    network:
      name: default

    并使用 Redis 实例的 IP 地址和端口更新 src/main/resources/application.properties 文件:

    redis.host=REDIS_HOST_IP
    redis.port=6379

    如需详细了解如何配置应用,请参阅使用 app.yaml 配置应用

    Node.js

    更新 gae_flex_deployment/app.yaml 文件:

    runtime: nodejs
    env: flex
    
    # Update with Redis instance details
    env_variables:
      REDISHOST: '<REDIS_IP>'
      REDISPORT: '6379'
    
    # Update with Redis instance network name
    network:
      name: default

    如需了解详情,请参阅使用 app.yaml 配置应用

    Python

    更新 gae_flex_deployment/app.yaml 文件:

    runtime: python
    env: flex
    entrypoint: gunicorn -b :$PORT main:app
    
    runtime_config:
      python_version: 3
    
    # Update with Redis instance IP and port
    env_variables:
      REDISHOST: '<REDIS_IP>'
      REDISPORT: '6379'
    
    # Update with Redis instance network name
    network:
      name: default

    如需了解详情,请参阅使用 app.yaml 配置应用

将应用部署到 App Engine 柔性环境

如需部署应用,请执行以下操作:

  1. 将必要的配置文件复制到来源目录中:

    Go

    app.yaml 文件复制到来源目录中:

    cp gae_flex_deployment/app.yaml .
    

    Java

    app.yaml 文件复制到来源目录中:

    mkdir -p src/main/appengine
    cp gae_flex_deployment/app.yaml src/main/appengine/
    

    Node.js

    app.yaml 文件复制到来源目录中:

    cp gae_flex_deployment/app.yaml .
    

    Python

    app.yaml 文件复制到来源目录中:

    cp gae_flex_deployment/app.yaml .
    
  2. 运行 deploy 命令:

    Go

    gcloud app deploy
    

    这可能需要几分钟时间。

    Java

    mvn appengine:deploy
    

    这可能需要几分钟时间。

    Node.js

    gcloud app deploy
    

    这可能需要几分钟时间。

    Python

    gcloud app deploy
    

    这可能需要几分钟时间。

部署完成后,通过以下网址访问应用,将 [PROJECT_ID] 替换为 Google Cloud 项目 ID:

https://[PROJECT_ID].appspot.com

每次访问应用时,Redis 实例上的计数都会增加。