利用Docker、Kubernetes和ECS轻松部署Rails应用

需积分: 9 119 浏览量更新于2024-07-20 收藏 1.42MB PDF 举报

《利用Docker、Kubernetes和ECS部署Rails应用》是由Pablo Acuña撰写的一本教程，旨在帮助读者深入了解如何借助Docker和Kubernetes的强大功能，轻松高效地部署Rails应用程序。随着Docker和Kubernetes在IT领域的日益普及，本书为那些希望将这些技术应用于Rails项目的开发者提供了实用指南。本书主要分为五个章节： 1. **开发**：从零开始，作者会指导读者如何使用Rails 5和PostgreSQL创建一个API应用，并逐步将其Docker化，确保应用程序在容器化环境中的稳定运行。 2. **设置生产环境工具**：这部分会介绍必要的生产环境配置，包括选择合适的工具和框架，如如何管理和优化Docker镜像，以及设置基础架构以便与Kubernetes集成。 3. **Kubernetes**：深入讲解Kubernetes的工作原理和概念，包括如何编写和测试模板，以实现应用程序在Kubernetes集群中的自动化部署和管理。读者将学习如何创建和维护一个高效、可扩展的容器化部署环境。 4. **Amazon EC2 Container Service (ECS)**：书中会详细介绍如何利用AWS的ECS服务来部署Dockerized Rails应用，包括如何在ECS上创建任务定义、服务和任务集，以及如何通过ECS进行自动扩缩容。 5. **持续集成**：探讨如何结合Jenkins等工具，实现整个部署过程的自动化，确保代码质量并简化运维流程。读者将了解到如何进行版本控制、构建、测试和部署的无缝集成。本书适合那些已经熟悉Rails且对Docker和Kubernetes有一定了解的开发者阅读，无论是初学者还是经验丰富的开发者，都能从中受益匪浅。通过学习本书，读者不仅能掌握最新的云计算部署技术，还能提升自己的DevOps技能，为Rails项目带来更高的可靠性和可扩展性。

CHAPTER 1 ■ DEVELOPMENT

Dockerizing Rails

With all the Docker images available these days, it’s pretty easy to dockerize any type of

application. In our case we only going to need something for the Rails app and something

for PostgreSQL. For Rails you have practically the same options you have when you don’t

use containers for deployments (Unicorn, Puma, Passenger, etc). And for PostgreSQL we

can use the official image from DockerHub.

If you explore DockerHub, you can find almost any image you need. And if you don’t,

you can always use a base image, and build a new one by adding the dependencies you

need on top of it.

For Ruby/Rails I strongly recommend that you use the phusion passenger-docker

(https://github.com/phusion/passenger-docker) image. It has a lot of features and

a very nice documentation. You can have a solid production application server out of

the box with that image, so we will use it throughout this book. Keep in mind that if you

choose another application server like unicorn or puma, the setup is going to be quite

different.

First we are going to create a development environment with Docker Compose.

This environment is going to be just for development. For production we want to use

a more robust tool with cluster management support like Kubernetes or ECS.

Even though we don’t want to use Docker Compose for production, it’s a very

realistic scenario to see that our containers are interacting with each other and if you

have a working environment with Docker Compose, it’s going to be much easier to have a

working production environment. That’s the beauty of containers.

The application needs to be built using the phusion passenger-docker as the base

image. So we need a Dockerfile. This Dockerfile is also going to add the application

source code along with other configuration files to the container.

The typical configuration files that you need for this image are the Nginx Virtual Host

for your application and a file to declare the environmental variables you may need to

pass to the application. First, let’s create a file for the virtual host configuration. You can

create all of these files in the root of the webapp application:

$ touch webapp.conf

And add the following to that file:

server {

listen 80;

server_name _;

root /home/app/webapp/public;

passenger_enabled on;

passenger_user app;

passenger_ruby /usr/bin/ruby2.3;

}

CHAPTER 1 ■ DEVELOPMENT

# In case we need some environmental variables in Nginx. Make sure

# the file is in the correct path

ADD rails-env.conf /etc/nginx/main.d/rails-env.conf

# Install gems: it's better to build an independent layer for the gems

# so they are cached during builds unless Gemfile changes WORKDIR /tmp

ADD Gemfile /tmp/

ADD Gemfile.lock /tmp/

RUN bundle install

# Copy application into the container and use right permissions: passenger

# uses the app user for running the application RUN mkdir /home/app/webapp

COPY . /home/app/webapp

RUN usermod -u 1000 app

RUN chown -R app:app /home/app/webapp

WORKDIR /home/app/webapp

# Clean up APT when done.

RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

EXPOSE 80

This Dockerfile should do the trick for our Rails application. It might seem a little

bit complicated at first, but trust me, you’ll get used to it after building a couple of Rails

services.

The cool thing about this setup, is that you’ll be using the same server for

development and production, so you’ll have a lot less work to do once you ship the

application to production. This image in particular uses the PASSENGER_APP_ENV variable

to set the environment. So, for example, in Rails, that variable also controls the RAILS_ENV

variable value.

Now that we have the Dockerfile to build our application, we need a Docker

Compose file so we can run the database and then test these containers to see if

everything works well.

We’ll need to declare three services in our Docker Compose file: one for our web

application, one for the PostgreSQL database, and one setup container for running

initialization commands. This setup container will be run before the actual application,

and it’s going to migrate our database.

■ Tip It’s good practice to run tasks in separate containers. In a production scenario you

may want to run several containers for your web application, and if you run initialization

commands in that same container (such as migrations), you’ll have collisions, since all the

containers will be running those commands before the main container starts.

CHAPTER 1 ■ DEVELOPMENT

Setup Container

As I mentioned previously, we need a mechanism to run initialization commands. In a Rails

application, these are typically rails db:create, rails db:migrate. With the exception

of the rails assets:precompile command, we can’t run those commands in the same

container that we’re running our web application. That would work well if you’re deploying

only one container, but suppose you want to scale your application and you want to run ten

containers; then every one of those containers will try to execute those commands during

startup time and things can get ugly. With that said, it’s always better to separate concerns

and to use an independent container to run tasks and then just remove it once it finishes.

This setup container has to use the same Dockerfile that we just created since it

needs access to the whole application environment. The only part we need to overwrite is

the entry point.

Right now we don’t have an entry point for our container since we want to use the

one the same image is providing for us. But since this setup container doesn’t need to run

as a web application, we can just overwrite it with our own initialization commands. Let’s

create this new entry point script in our root path.

$ touch setup.sh

And add the following:

#!/bin/sh

echo "Waiting PostgreSQL to start on 5432..."

while ! nc -z postgres 5432; do

sleep 0.1

done

echo "PostgreSQL started"

bin/rails db:migrate

The whole purpose of this script is to run the possible new migrations our

application may have. But, what if the database is not yet available for the command?

That would generate an error and the whole run would crash. That’s why we use a while

expression that’s going to loop until the connection is alive. We are using the netcat

package for this and also we’re assuming that the PostgreSQL service end point will be

reachable by using the postgres alias. Finally, when the connection is alive, we can run

the latest migrations.

Let’s also add the proper execution permissions for this file.

$ chmod +x setup.sh

This type of script is very typical when you need to orchestrate different services that

are constantly being shut down and turned on. So you’d better get used to getting your

hands dirty with some bash when you run containers.

剩余137页未读，继续阅读

ramissue

粉丝: 354
资源: 1487

利用Docker、Kubernetes和ECS轻松部署Rails应用

rails-k8s-demoapp：与Kubernetes和Helm一起部署的示例Rails应用程序

Pragmatic.Bookshelf.Deploying.Rails.Applications.May.2008

IDEA 2022.2

kubernetes service

openstack docker

docker-compose platform

编辑Jenkinsfile文件，定义流水线的各个阶段和任务。可以使用Jenkins中提供的语法和函数来定义流水线。例如，可以使用stage函数定义流水线的各个阶段，使用sh函数执行Shell命令，使用git函数从Git仓库拉取代码等具体细节步骤

jenkins pipline docker

docker service

"provisioning docker wsl distros: deploying \"docker-desktop"

最新资源