5.8 KiB
使用docker快速组成样品机
在写前，我们将看看 Node.js 样机 ** 找寻树莓派 PI Zero ** 的供应在英国三个主要销售.
我写的代码，黑客部署到 Azure Ubuntu 虚拟机一个晚上就可以到位。Docker 和 docker-compose 工具做出调配和更新过程非常快。
建立链接？
如果您已经通过 [动手 Docker 教程指南] 1 那么你已有在命令行建立 Docker 容器的经验。链接一个Redis 服务器计数器节点在命令行上可能是这样：
$ docker run -d -P --name redis1
$ docker run -d hit_counter -p 3000:3000 --link redis1:redis
现在，假设应用程序中有三个等级
- Web 前端
- 批次层处理长时间运行的任务
- Redis 或 MongoDB 数据库
通过 --link 管理几个容器，但可能失效，可以添加多层级或容器到应用程序。
键入 docker 撰写
Docker 撰写图标
docker-compose 工具是标准的 docker工具箱的一部分，也可以单独下载。它提供了丰富功能，通过一个纯文本YAML文件配置所有应用程序组件。
上述提供了一个例子：
version: "2.0"
services:
redis1:
image: redis
hit_counter:
build: ./hit_counter
ports:
- 3000:3000
从Docker 1.10起，我们可以充分利用网络来帮助我们在多个主机进行扩展覆盖。在此之前，仅通过单个主机工作。“docker-compose scale” 命令可用于更多计算能力有需要时。
参考docker.com上关于"docker-compose"
真实例子：树莓派 PI 到货通知
新版树莓派 PI Zero V1.3 图片提供来自Pimoroni
树莓派 PI Zero - 巨大的轰动一个微型计算机具有一个1GHz 处理器 和 512MB 内存能够运行完整 Linux，Docker，Node.js，Ruby 和许多流行的开源工具。一个关于 PI Zero 的好消息是，成本只有5美元。这也意味着，存量迅速抢购一空。
如果您想尝试Docker 或集群在PI看看下面的教程。
Original site: whereismypizero.com
I found a webpage which used screen scraping to find whether 4-5 of the most popular outlets had stock.
- The site contained a static HTML page
- Issued one XMLHttpRequest per outlet accessing /public/api/
- The server issued the HTTP request to each shop and performed the scraping
Every call to /public/api/ took 3 seconds to execute and using Apache Bench (ab) I was only able to get through 0.25 requests per second.
Reinventing the wheel
The retailers didn't seem to mind whereismypizero.com scraping their sites for stock, so I set about writing a similar tool from the ground up. I had the intention of handing a much higher amount of requests per second through caching and de-coupling the scrape from the web tier. Redis was the perfect tool for the job. It allowed me to set an automatically expiring key/value pair (i.e. a simple cache) and also to transmit messages between Node processes through pub/sub.
Fork or star the code on Github: alexellis/pi_zero_stock
If you've worked with Node.js before then you will know it is single-threaded and that any CPU intensive tasks such as parsing HTML or JSON could lead to a slow-down. One way to mitigate that is to use a second worker process and a Redis messaging channel as connective tissue between this and the web tier.
- Web tier -Gives 200 for cache hit (Redis key exists for store) -Gives 202 for cache miss (Redis key doesn't exist, so issues message) -Since we are only ever reading a Redis key the response time is very quick.
- Stock Fetcher -Performs HTTP request -Scrapes for different types of web stores -Updates a Redis key with a cache expire of 60 seconds -Also locks a Redis key to prevent too many in-flight HTTP requests to the web stores.
version: "2.0"
services:
web:
build: ./web/
ports:
- "3000:3000"
stock_fetch:
build: ./stock_fetch/
redis:
image: redis
The docker-compose.yml file from the example.
Once I had this working locally deploying to an Ubuntu 16.04 image in the cloud (Azure) took less than 5 minutes. I logged in, cloned the repository and typed in docker compose up -d. That was all it took - rapid prototyping a whole system doesn't get much better. Anyone (including the owner of whereismypizero.com) can deploy the new solution with just two lines:
$ git clone https://github.com/alexellis/pi_zero_stock
$ docker-compose up -d
Updating the site is easy and just involves a git pull followed by a docker-compose up -d with the --build argument passed along.
If you are still linking your Docker containers manually, try Docker Compose for yourself or my code below:
Fork or star the code on Github: alexellis/pi_zero_stock
Check out the test site
The test site is currently deployed now using docker-compose.
Preview as of 16th of May 2016
via: http://blog.alexellis.io/rapid-prototype-docker-compose/
作者：Alex Ellis 译者：erlinux 校对：校对者ID