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从 App Engine 柔性环境应用连接到 Redis 实例

App Engine 应用必须与 Redis 实例位于同一已获授权的网络上才能访问此 Redis 实例。

设置

如果您已安装 Google Cloud CLI 且已创建 Redis 实例，则可以跳过这些步骤。

安装 gcloud CLI 并初始化：
```
gcloud init
```
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.Pool{
		MaxIdle: maxConnections,
		Dial:    func() (redis.Conn, error) { return redis.Dial("tcp", redisAddr) },
	}

	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>5.1.0</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": ">=16.0.0"
  },
  "dependencies": {
    "redis": "^4.0.0"
  }
}

'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==3.0.3
gunicorn==22.0.0
redis==5.0.1
Werkzeug==3.0.3

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 f"Visitor number: {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 实例部署在相同的授权网络上，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]

创建 App Engine 应用。

注意：您还可以使用现有的 App Engine 应用。

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：

将必要的配置文件复制到来源目录中：
Go
将 app.yaml 文件复制到来源目录中：
```
cp gae_flex_deployment/app.yaml .
```
Java
将 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
将 app.yaml 文件复制到来源目录中：
```
cp gae_flex_deployment/app.yaml .
```
Python
将 app.yaml 文件复制到来源目录中：
```
cp gae_flex_deployment/app.yaml .
```
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。