Docker多容器连接实例（link方式 Nginx+3*Nod

有一个node应用，部署在多个容器中，需要用到redis存储，同时我想要将node应用和redis独立开来，然后用Nginx在最前端负载均衡这些应用。
所以需要

• 1 Redis container
• 3 Node container

• 1 Nginx container
  可以得到如下架构图：

  
  Nginx+Node+Redis架构.png

有两种方法可以构建该连接，一：从空白的操作镜像（如：Ubuntu、Debian等）开始构建；二：从一个预先构建好的镜像；这里选择使用一个Redis镜像、一个Nginx镜像和一个基于Ubuntu的node镜像

Redis container
从官方Docker Hub中下载Redis镜像，构建一个Redis容器，端口默认6379

docker run -d --name redis -p 6379:6379 redis

***Dockerfile ***：

# Set the base image to Ubuntu
FROM        ubuntu

# File Author / Maintainer
MAINTAINER InfiniteRain

# Update the repository and install Redis Server
RUN         apt-get update && apt-get install -y redis-server

# Expose Redis port 6379
EXPOSE      6379

# Run Redis Server
ENTRYPOINT  ["/usr/bin/redis-server"]

---

Node container
从Node镜像中生成一个node容器，同时在应用中指定6379端口为redis侦听的端口。
index.js

var express = require('express'),
    http = require('http'),
    redis = require('redis');

var app = express();

console.log(process.env.REDIS_PORT_6379_TCP_ADDR + ':' + process.env.REDIS_PORT_6379_TCP_PORT);

var client = redis.createClient('6379', 'redis');

app.get('/', function(req, res, next) {
  client.incr('counter', function(err, counter) {
    if(err) return next(err);
    res.send('This page has been viewed ' + counter + ' times!, HOSTNAME:' + process.env.HOSTNAME);
  });
});

http.createServer(app).listen(process.env.PORT || 8080, function() {
  console.log('Listening on port ' + (process.env.PORT || 8080));
});

***Dockerfile ***：

# Set the base image to Ubuntu
FROM    ubuntu

# File Author / Maintainer
MAINTAINER InfiniteRain

# Install Node.js and other dependencies
RUN apt-get update && \
    apt-get -y install curl && \
    curl -sL https://deb.nodesource.com/setup_8.x | sudo bash - && \
    apt-get -y install python build-essential nodejs

# Install nodemon
RUN npm install -g nodemon

# Provides cached layer for node_modules
ADD package.json /tmp/package.json
RUN cd /tmp && npm install
RUN mkdir -p /src && cp -a /tmp/node_modules /src/

# Define working directory
WORKDIR /src
ADD . /src

# Expose port
EXPOSE  8080

# Run app using nodemon
CMD ["nodemon", "/src/index.js"]

使用Dockerfile构建一个镜像

docker build -t infinite/node .

创建一个Node容器，指定8080端口，并且连接redis容器

docker run -d --name node -p 8080 --link redis:redis infinite/node

依照上述方法创建三个相同的容器 node1、node2、node3

Nginx container
同样从Docker Hub中拉取镜像，并生成一个名为infinite/nginx的容器
Nginx中关于负载均衡的配置
nginx.conf

worker_processes 4;

events { worker_connections 1024; }

http {

        upstream node-app {
              least_conn;
              server node1:8080 weight=10 max_fails=3 fail_timeout=30s;
              server node2:8080 weight=10 max_fails=3 fail_timeout=30s;
              server node3:8080 weight=10 max_fails=3 fail_timeout=30s;
        }
         
        server {
              listen 80;
         
              location / {
                proxy_pass http://node-app;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection 'upgrade';
                proxy_set_header Host $host;
                proxy_cache_bypass $http_upgrade;
              }
        }
}

Dockerfile

# Set nginx base image
FROM nginx

# File Author / Maintainer
MAINTAINER InfiniteRain

# Copy custom configuration file from the current directory
COPY nginx.conf /etc/nginx/nginx.conf

docker build -t infinite/nginx .
docker run -d --name nginx -p 80:80 --link node:node infinite/nginx

---

使用Docker Compose组合应用程序
docker-compose.yml

nginx:
    build: ./nginx
    links:
        - node1:node1
        - node2:node2
        - node3:node3
    ports:
        - "80:80"
node1:
    build: ./node
    links:
        - redis
    ports:
        - "8080"
node2:
    build: ./node
    links:
        - redis
    ports:
        - "8080"
node3:
    build: ./node
    links:
        - redis
    ports:
        - "8080"
redis:
    image: redis
    ports:
        - "6379"

上述YAML文件为各个容器定义了名称，指定了Dockerfile文件，同时还包括了容器之间的连接关系。只需要一个命令docker-compose up就可以建好这五个容器了。最后文件结构如图：

docker-compose-tree.png