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張 旭

Break Deep Associations - 0 views

ingramchen.io/...break-deep-associations.html

database development test programming table architecture

shared by 張 旭 on 08 May 15 - No Cached
  • 常寫單元測試的開發者，多半已經養成遇到難測的元件時，就替該元件抽一個 interface 隔離
  • 部署的時候再藉由 Dependency Injection 注入真正的實作
  • 將它們隔離。這跟 class 抽 interface 其實很像的，都讓耦合下降，提高模組化
  • ...1 more annotation...
  • 如果測試很難寫，那八成設計有問題
張 旭

Getting Started with Docker - Servers for Hackers - 0 views

serversforhackers.com/getting-started-with-docker

docker system virtualization

shared by 張 旭 on 30 Apr 15 - No Cached
  • Docker is an isolated portion of the host computer, sharing the host kernel (OS) and even its bin/libraries if appropriate.
  • the Docker Container contains the parts that make Ubuntu different from CoreOS.
  • A Docker container only stays alive as long as there is an active process being run in it.
  • ...10 more annotations...
  • Allocate a (pseudo) tty
  • Keep stdin open (so we can interact with it)
  • Docker allows us make changes to an image, commit those changes, and then push those changes out somehwere.
  • Docker tracks any changes we make to a container
  • The Dockerfile provides a set of instructions for Docker to run on a container.
  • what image (and tag in this case) to base this off of
  • run the given command (as user "root")
  • copy a file from the host machine into the container
  • expose a port to the host machine. You can expose multiple ports
  • run a command
張 旭

David Verhasselt - Different Ways to Set Attributes in ActiveRecord - 0 views

www.davidverhasselt.com/set-attributes-in-activerecord

rails model ORM

shared by 張 旭 on 18 Mar 15 - No Cached
  • update
  • attribute will be marked as dirty and the change will not be sent to the database yet
  • will change the attribute in the model and pass it straight to the database, without running any validations
  • ...9 more annotations...
  • end up with invalid data
  • Any other changed attributes are also saved
  • set all the attributes you pass it. The changes are not saved to the database. Any attributes you don’t pass will be left unchanged
  • also saves other changed attributes to the database
  • executes a direct SQL UPDATE query and bypasses any validations or callbacks.
  • finds the object with the specified ID and updates it’s attributes with the passed in hash
  • pass in an array of ID’s and parameters
  • runs an SQL UPDATE query that updates the attributes of all objects without running any validations or callbacks
  • call this method on a scoped relation
張 旭

Asset Pipeline - Ruby on Rails 指南 - 0 views

guides.ruby-china.org/asset_pipeline.html

shared by 張 旭 on 30 Jan 15 - No Cached
  • 清单文件或帮助方法
    • 張 旭
      張 旭 on 30 Jan 15
       
      清單文件是指：application.css 跟 application.js
  • Sprockets 会按照搜索路径中各路径出现的顺序进行搜索。默认情况下，这意味着 app/assets 文件夹中的静态资源优先级较高，会遮盖 lib 和 vendor 文件夹中的相应文件
  • 如果静态资源不会在清单文件中引入，就要添加到预编译的文件列表中，否则在生产环境中就无法访问文件。
  • ...36 more annotations...
  • 程序中使用了 jQuery 代码库和许多模块，都保存在 lib/assets/javascripts/library_name 文件夹中，那么 lib/assets/javascripts/library_name/index.js 文件的作用就是这个代码库的清单。清单文件中可以按顺序列出所需的文件，或者干脆使用 require_tree 指令。
  • 如果使用 Turbolinks（Rails 4 默认启用），加上 data-turbolinks-track 选项后，Turbolinks 会检查静态资源是否有更新，如果更新了就会将其载入页面
  • config.assets.paths 包含标准路径和其他 Rails 引擎添加的路径。
  • 链接不存在的资源（也包括链接到空字符串的情况）会在调用页面抛出异常。
  • 关闭标签不能使用 -%> 形式
  • Sprockets 通过清单文件决定要引入和伺服哪些静态资源
  • 在 JavaScript 文件中，Sprockets 的指令以 //= 开头。在上面的文件中，用到了 require 和 the require_tree 指令。
  • app/assets/javascripts/application.js
  • require_tree 指令告知 Sprockets 递归引入指定文件夹中的所有 JavaScript 文件。文件夹的路径必须相对于清单文件。也可使用 require_directory 指令加载指定文件夹中的所有 JavaScript 文件，但不会递归。
  • Sprockets 会按照从上至下的顺序处理指令，但 require_tree 引入的文件顺序是不可预期的，不要设想能得到一个期望的顺序。
  • app/assets/stylesheets/application.css
  • 不管创建新程序时有没有指定 --skip-sprockets 选项，Rails 4 都会生成 app/assets/javascripts/application.js 和 app/assets/stylesheets/application.css
  • 如果多次调用 require_self，只有最后一次调用有效
  • 如果想使用多个 Sass 文件，应该使用 Sass 中的 @import 规则，不要使用 Sprockets 指令。
  • 清单文件可以有多个。
  • 如果使用默认的 gem，生成控制器或脚手架时，会生成 CoffeeScript 和 SCSS 文件，而不是普通的 JavaScript 和 CSS 文件。
  • 在开发环境中，或者禁用 Asset Pipeline 时，这些文件会使用 coffee-script 和 sass 提供的预处理器处理，然后再发给浏览器
  • 启用 Asset Pipeline 时，这些文件会先使用预处理器处理，然后保存到 public/assets 文件夹中，再由 Rails 程序或网页服务器伺服
  • 添加额外的扩展名可以增加预处理次数，预处理程序会按照扩展名从右至左的顺序处理文件内容。所以，扩展名的顺序要和处理的顺序一致
  • 预处理器的执行顺序很重要
  • 在开发环境中也可启用压缩功能，检查是否能正常运行。需要调试时再禁用压缩即可。
  • 默认情况下，Rails 认为静态资源已经事先编译好了，直接由网页服务器伺服。
  • 般情况下，请勿修改 config.assets.digest 的默认值
  • 可在部署时编译静态资源
  • 在多次部署之间共用这个文件夹是十分重要的，这样只要缓存的页面可用，其中引用的编译后的静态资源就能正常使用。
  • 默认编译的文件包括 application.js、application.css 以及 gem 中 app/assets 文件夹中的所有非 JS/CSS 文件（会自动加载所有图片）
  • 如果想编译其他清单，或者单独的样式表和 JavaScript，可以添加到 config/application.rb 文件中的 precompile 选项
  • 设置编译所有静态资源
  • manifest-md5hash.json 的文件，列出所有静态资源和对应的指纹
  • 把 Expires 报头设置为很久以后
  • 在本地预编译后，可以把编译好的文件纳入版本控制系统，再按照常规的方式部署
  • 实时编译消耗的内存更多，比默认的编译方式性能更低，因此不推荐使用
  • 如果用 CDN 分发静态资源，要确保文件不会被缓存，因为缓存会导致问题。如果设置了 config.action_controller.perform_caching = true，Rack::Cache 会使用 Rails.cache 存储静态文件，很快缓存空间就会用完。
  • Sprockets 默认使用的公开路径是 /assets
  • X-Sendfile 报头的作用是让服务器忽略程序的响应，直接从硬盘上伺服指定的文件
  • 为 Rails 提供标准 JavaScript 代码库的 jquery-rails gem 是个很好的例子。这个 gem 中有个引擎类，继承自 Rails::Engine。添加这层继承关系后，Rails 就知道这个 gem 中可能包含静态资源文件，会把这个引擎中的 app/assets、lib/assets 和 vendor/assets 三个文件夹加入 Sprockets 的搜索路径中。
張 旭

Embracing REST with mind, body and soul « Plataformatec Blog - 0 views

blog.plataformatec.com.br/...g-rest-with-mind-body-and-soul

rails REST MVC controller

shared by 張 旭 on 30 Dec 14 - No Cached
  • gain with respond_with introduction is more obvious if you compare index, new and show actions
    • 張 旭
      張 旭 on 30 Dec 14
       
      看起來 respond_with 會根據 request 型態自動回覆對應型態的 response
  • you can define supported formats at the class level and tell in the instance the resource to be represented by those formats.
  • when a request comes, for example with format xml, it will first search for a template at users/index.xml. If the template is not available, it tries to render the resource given (in this case, @users) by calling :to_xml on it
  • ...6 more annotations...
  • how to render our resources depending on the format AND HTTP verb
  • By default, ActionController::Responder holds all formats behavior in a method called to_format.
  • Suddenly we realized that respond_with is useful just for GET requests
  • it renders the resource based on the HTTP verb and whether it has errors or not
  • Your controller code just have to send the resource using respond_with(@resource) and respond_with will call ActionController::Responder which will know what to do.
    • 張 旭
      張 旭 on 30 Dec 14
       
      簡單說，就是只要寫 respond_with 就好了，其它都不用管了。Responder 會幫你判斷 HTTP 的動作。
  • Anything that responds to :call can be a responder, so you can create your custom classes or even give procs, fibers and so on.
張 旭

The Asset Pipeline - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/asset_pipeline.html

rails image javascript font CSS file

shared by 張 旭 on 29 Dec 14 - No Cached
  • provides a framework to concatenate and minify or compress JavaScript and CSS assets
  • adds the ability to write these assets in other languages and pre-processors such as CoffeeScript, Sass and ERB
  • invalidate the cache by altering this fingerprint
  • ...80 more annotations...
  • Rails 4 automatically adds the sass-rails, coffee-rails and uglifier gems to your Gemfile
  • reduce the number of requests that a browser makes to render a web page
  • Starting with version 3.1, Rails defaults to concatenating all JavaScript files into one master .js file and all CSS files into one master .css file
  • In production, Rails inserts an MD5 fingerprint into each filename so that the file is cached by the web browser
  • The technique sprockets uses for fingerprinting is to insert a hash of the content into the name, usually at the end.
  • asset minification or compression
  • The sass-rails gem is automatically used for CSS compression if included in Gemfile and no config.assets.css_compressor option is set.
  • Supported languages include Sass for CSS, CoffeeScript for JavaScript, and ERB for both by default.
  • When a filename is unique and based on its content, HTTP headers can be set to encourage caches everywhere (whether at CDNs, at ISPs, in networking equipment, or in web browsers) to keep their own copy of the content
  • asset pipeline is technically no longer a core feature of Rails 4
  • Rails uses for fingerprinting is to insert a hash of the content into the name, usually at the end
  • With the asset pipeline, the preferred location for these assets is now the app/assets directory.
  • Fingerprinting is enabled by default for production and disabled for all other environments
  • The files in app/assets are never served directly in production.
  • Paths are traversed in the order that they occur in the search path
  • You should use app/assets for files that must undergo some pre-processing before they are served.
  • By default .coffee and .scss files will not be precompiled on their own
  • app/assets is for assets that are owned by the application, such as custom images, JavaScript files or stylesheets.
  • lib/assets is for your own libraries' code that doesn't really fit into the scope of the application or those libraries which are shared across applications.
  • vendor/assets is for assets that are owned by outside entities, such as code for JavaScript plugins and CSS frameworks.
  • Any path under assets/* will be searched
  • By default these files will be ready to use by your application immediately using the require_tree directive.
  • By default, this means the files in app/assets take precedence, and will mask corresponding paths in lib and vendor
  • Sprockets uses files named index (with the relevant extensions) for a special purpose
  • Rails.application.config.assets.paths
  • causes turbolinks to check if an asset has been updated and if so loads it into the page
  • if you add an erb extension to a CSS asset (for example, application.css.erb), then helpers like asset_path are available in your CSS rules
  • If you add an erb extension to a JavaScript asset, making it something such as application.js.erb, then you can use the asset_path helper in your JavaScript code
  • The asset pipeline automatically evaluates ERB
  • data URI — a method of embedding the image data directly into the CSS file — you can use the asset_data_uri helper.
  • Sprockets will also look through the paths specified in config.assets.paths, which includes the standard application paths and any paths added by Rails engines.
  • image_tag
  • the closing tag cannot be of the style -%>
  • asset_data_uri
  • app/assets/javascripts/application.js
  • sass-rails provides -url and -path helpers (hyphenated in Sass, underscored in Ruby) for the following asset classes: image, font, video, audio, JavaScript and stylesheet.
  • Rails.application.config.assets.compress
  • In JavaScript files, the directives begin with //=
  • The require_tree directive tells Sprockets to recursively include all JavaScript files in the specified directory into the output.
  • manifest files contain directives — instructions that tell Sprockets which files to require in order to build a single CSS or JavaScript file.
  • You should not rely on any particular order among those
  • Sprockets uses manifest files to determine which assets to include and serve.
  • the family of require directives prevents files from being included twice in the output
  • which files to require in order to build a single CSS or JavaScript file
  • Directives are processed top to bottom, but the order in which files are included by require_tree is unspecified.
  • In JavaScript files, Sprockets directives begin with //=
  • If require_self is called more than once, only the last call is respected.
  • require directive is used to tell Sprockets the files you wish to require.
  • You need not supply the extensions explicitly. Sprockets assumes you are requiring a .js file when done from within a .js file
  • paths must be specified relative to the manifest file
  • require_directory
  • Rails 4 creates both app/assets/javascripts/application.js and app/assets/stylesheets/application.css regardless of whether the --skip-sprockets option is used when creating a new rails application.
  • The file extensions used on an asset determine what preprocessing is applied.
  • app/assets/stylesheets/application.css
  • Additional layers of preprocessing can be requested by adding other extensions, where each extension is processed in a right-to-left manner
  • require_self
  • use the Sass @import rule instead of these Sprockets directives.
  • Keep in mind that the order of these preprocessors is important
  • In development mode, assets are served as separate files in the order they are specified in the manifest file.
  • when these files are requested they are processed by the processors provided by the coffee-script and sass gems and then sent back to the browser as JavaScript and CSS respectively.
  • css.scss.erb
  • js.coffee.erb
  • Keep in mind the order of these preprocessors is important.
  • By default Rails assumes that assets have been precompiled and will be served as static assets by your web server
  • with the Asset Pipeline the :cache and :concat options aren't used anymore
  • Assets are compiled and cached on the first request after the server is started
  • RAILS_ENV=production bundle exec rake assets:precompile
  • Debug mode can also be enabled in Rails helper methods
  • If you set config.assets.initialize_on_precompile to false, be sure to test rake assets:precompile locally before deploying
  • By default Rails assumes assets have been precompiled and will be served as static assets by your web server.
  • a rake task to compile the asset manifests and other files in the pipeline
  • RAILS_ENV=production bin/rake assets:precompile
  • a recipe to handle this in deployment
  • links the folder specified in config.assets.prefix to shared/assets
  • config/initializers/assets.rb
  • The initialize_on_precompile change tells the precompile task to run without invoking Rails
  • The X-Sendfile header is a directive to the web server to ignore the response from the application, and instead serve a specified file from disk
  • the jquery-rails gem which comes with Rails as the standard JavaScript library gem.
  • Possible options for JavaScript compression are :closure, :uglifier and :yui
  • concatenate assets
張 旭

The Flatiron School | Why You Don't Need Has_and_belongs_to_many... - 0 views

blog.flatironschool.com/...t-need-has-and-belongs-to-many

rails model database

shared by 張 旭 on 14 Dec 14 - No Cached
  • When creating associations between models, you almost never know how this relationship will blossom as your application grows.
  • setup a solid has_many :through relationship with an associated join table, you provide yourself with a huge amount of flexibility down the road.
  • A has_many :through association is used to setup a many to many relationship with another model
  • ...2 more annotations...
  • This relationship now allows for extending the association within the join table.
  • You should use has_many :through if you need validations, callbacks, or extra attributes on the join model
張 旭

How to Report Bugs Effectively - 0 views

www.chiark.greenend.org.uk/...bugs-tw.html

bug debug

shared by 張 旭 on 04 Dec 14 - Cached
  • 有個理由可以解釋為什麼技術支援工作這麼難做, 原因就是這些亂七八糟的錯誤報告
  • 希望全世界的人在報告任何錯誤前都能讀讀這篇短文
  • 錯誤報告的目的是要讓程式師能親眼目睹程式出錯
  • ...26 more annotations...
  • 如果他們無法重現問題, 就只能要你幫他們收集資訊
  • 必須要把真實發生的事實(我在電腦前看到這個狀況)和臆測(我認為問題可能是)很明顯的區分開來. 必要時可以把臆測略過不提, 不過事實絕對不能漏.
  • 資訊過多往往好過資訊不足
  • 報告錯誤的最佳方法之一就是直接示範給程式師看. 讓他們站到你的電腦前面, 執行他們的軟體, 然後指出問題所在
  • 可能會要你說明整個操作過程, 以便他們能自己重複重現問題
  • 也可能會改變操作過程多試幾次, 看看問題只在某一種狀況發生, 還是在相關的多種狀況下都有出現
  • 可能得坐下來花上幾個小時拿出整組開發工具真正深入調查
  • 最重要的還是讓程式師看到電腦出錯. 只要他們能看到問題發生, 通常都可以由此開始嘗試修正問題
  • 向一個不可能到你身旁的程式師報告錯誤, 首要目標是讓他們能重現問題. 希望讓程式師執行自己的那份程式, 進行相同的操作, 然後以相同的方式出錯.
  • 如果這是個有圖形介面的程式, 告訴他們你按了哪些按鈕以及按各按鈕的次序.
  • 如果是輸入命令執行的程式, 就要精確地告知你所輸入的命令
  • 在目前這個階段, 程式師只是想找出問題所在, 並不會嘗試去修正問題. 他們必須知道什麼地方出錯, 而那些錯誤訊息正是電腦對問題的最佳敘述
  • 不過如果不能同時報告錯誤訊息的內容, 光說程式出錯是沒有意義的
  • 程式師喜歡那些能重複產生的問題. 這時候快樂的程式師能更快更有效率地修正問題.
  • 並不是程式師以外的人才會寫出爛錯誤報告
  • 對程式師也一樣. 提供你自己的診斷有時可能有幫助, 不過一定要先敘述症狀. 診斷是可有可無的, 絕不能取代症狀敘述
  • 用你的聰明智慧幫助程式師是很好. 即使你的推論不對, 程式師也應該心存感謝, 因為至少你已經試著讓他們更好過. 不過記得要報告症狀, 否則你可能會讓他們過得更痛苦
  • 程式師要確認他們處理的是真正的偶發性問題還是與機器相關的錯誤. 他們會要知道很多有關你的電腦的細節
  • 很多報告來自非英語系地區, 而且很多人為英文寫得不好致歉. 通常有為英文不好而致歉的錯誤報告實際上都非常清楚有用
  • 寧願多給資訊而不要少給
  • 閱讀你寫的東西
  • 自己把報告重新讀一遍, 看看有是否夠清楚. 如果你有寫出了重現問題的步驟列表, 試著照做一遍確定沒有漏掉任何步驟.
    • 張 旭
      張 旭 on 04 Dec 14
       
      自己的報告自己看
  • 一份錯誤報告的首要目標是要讓程式師親眼看到問題
  • 如果你不能到他們面前把問題顯示出來, 就得提供詳細的指示讓他們能自己做出來
  • 如果你自認能力夠的話可以儘量嘗試自己診斷問題, 不過即使你做了診斷, 還是應該報告問題的症狀
張 旭

The Rails Command Line - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/command_line.html

rails console command

shared by 張 旭 on 28 Nov 14 - Cached
  • rake --tasks
  • Think of destroy as the opposite of generate.
  • runner runs Ruby code in the context of Rails non-interactively
  • ...28 more annotations...
  • rails dbconsole figures out which database you're using and drops you into whichever command line interface you would use with it
  • The console command lets you interact with your Rails application from the command line. On the underside, rails console uses IRB
  • rake about gives information about version numbers for Ruby, RubyGems, Rails, the Rails subcomponents, your application's folder, the current Rails environment name, your app's database adapter, and schema version
  • You can precompile the assets in app/assets using rake assets:precompile and remove those compiled assets using rake assets:clean.
  • rake db:version is useful when troubleshooting
  • The doc: namespace has the tools to generate documentation for your app, API documentation, guides.
  • rake notes will search through your code for comments beginning with FIXME, OPTIMIZE or TODO.
  • You can also use custom annotations in your code and list them using rake notes:custom by specifying the annotation using an environment variable ANNOTATION.
  • rake routes will list all of your defined routes, which is useful for tracking down routing problems in your app, or giving you a good overview of the URLs in an app you're trying to get familiar with.
  • rake secret will give you a pseudo-random key to use for your session secret.
  • Custom rake tasks have a .rake extension and are placed in Rails.root/lib/tasks.
  • rails new . --git --database=postgresql
  • All commands can run with -h or --help to list more information
  • The rails server command launches a small web server named WEBrick which comes bundled with Ruby
  • rails server -e production -p 4000
  • You can run a server as a daemon by passing a -d option
  • The rails generate command uses templates to create a whole lot of things.
  • Using generators will save you a large amount of time by writing boilerplate code, code that is necessary for the app to work.
  • All Rails console utilities have help text.
  • generate controller ControllerName action1 action2.
  • With a normal, plain-old Rails application, your URLs will generally follow the pattern of http://(host)/(controller)/(action), and a URL like http://(host)/(controller) will hit the index action of that controller.
  • A scaffold in Rails is a full set of model, database migration for that model, controller to manipulate it, views to view and manipulate the data, and a test suite for each of the above.
  • Unit tests are code that tests and makes assertions about code.
  • Unit tests are your friend.
  • rails console --sandbox
  • rails db
  • Each task has a description, and should help you find the thing you need.
  • rake tmp:clear clears all the three: cache, sessions and sockets.
張 旭

Authentication, Permissions and Roles in Rails with Devise, CanCan and Role Model | Phase2 - 0 views

www.phase2technology.com/...h-devise-cancan-and-role-model

rails devise cancan login authentication

shared by 張 旭 on 02 Nov 14 - No Cached
  • Devise is a modular user authentication system
  • just gradually investigating the components you need for your app and configuring them as you need
  • define permissions
張 旭

PsySH - 0 views

psysh.org

php debug toolkit

shared by 張 旭 on 30 Oct 14 - No Cached
張 旭

Baseimage-docker: A minimal Ubuntu base image modified for Docker-friendliness - 0 views

phusion.github.io/baseimage-docker

docker base system linux

shared by 張 旭 on 29 Oct 14 - No Cached
  • We encourage you to use multiple processes.
  • Baseimage-docker is a special Docker image that is configured for correct use within Docker containers.
  • A proper Unix system should run all kinds of important system services.
  • ...16 more annotations...
  • You're not running them, you're only running your app.
  • You have Ubuntu installed in Docker. The files are there. But that doesn't mean Ubuntu's running as it should.
  • The only processes that will be running inside the container is the CMD command, and all processes that it spawns.
  • When your Docker container starts, only the CMD command is run.
  • Ubuntu is not designed to be run inside Docker
  • When a system is started, the first process in the system is called the init process, with PID 1. The system halts when this processs halts.
  • If your init process is your app, then it'll probably only shut down itself, not all the other processes in the container.
  • Docker runs fine with multiple processes in a container.
  • Baseimage-docker encourages you to run multiple processes through the use of runit.
  • Runit (written in C) is much lighter weight than supervisord (written in Python).
  • a Docker container, which is a locked down environment with e.g. no direct access to many kernel resources.
  • Used for service supervision and management.
  • A custom tool for running a command as another user.
  • add additional daemons (e.g. your own app) to the image by creating runit entries.
  • write a small shell script which runs your daemon, and runit will keep it up and running for you, restarting it when it crashes, etc.
  • the shell script must run the daemon without letting it daemonize/fork it.
張 旭

Run Reference - Docker Documentation - 0 views

docs.docker.com/run

docker system deploy

shared by 張 旭 on 29 Oct 14 - No Cached
  • In detached mode (-d=true or just -d), all I/O should be done through network connections or shared volumes because the container is no longer listening to the command line where you executed docker run.
  • start the process in the container and attach the console to the process's standard input, output, and standard error. It can even pretend to be a TTY (this is what most command line executables expect) and pass along signals.
  • For interactive processes (like a shell) you will typically want a tty as well as persistent standard input (STDIN), so you'll use -i -t together in most interactive cases.
張 旭

How To Install and Use Docker: Getting Started | DigitalOcean - 0 views

www.digitalocean.com/...and-use-docker-getting-started

docker system deploy

shared by 張 旭 on 26 Oct 14 - No Cached
  • docker as a project offers you the complete set of higher-level tools to carry everything that forms an application across systems and machines - virtual or physical - and brings along loads more of great benefits with it
  • docker daemon: used to manage docker (LXC) containers on the host it runs
  • docker CLI: used to command and communicate with the docker daemon
  • ...20 more annotations...
  • containers: directories containing everything-your-application
  • images: snapshots of containers or base OS (e.g. Ubuntu) images
  • Dockerfiles: scripts automating the building process of images
  • Docker containers are basically directories which can be packed (e.g. tar-archived) like any other, then shared and run across various different machines and platforms (hosts).
  • Linux Containers can be defined as a combination various kernel-level features (i.e. things that Linux-kernel can do) which allow management of applications (and resources they use) contained within their own environment
  • Each container is layered like an onion and each action taken within a container consists of putting another block (which actually translates to a simple change within the file system) on top of the previous one.
  • Each docker container starts from a docker image which forms the base for other applications and layers to come.
  • Docker images constitute the base of docker containers from which everything starts to form
  • a solid, consistent and dependable base with everything that is needed to run the applications
  • As more layers (tools, applications etc.) are added on top of the base, new images can be formed by committing these changes.
  • a Dockerfile for automated image building
  • Dockerfiles are scripts containing a successive series of instructions, directions, and commands which are to be executed to form a new docker image.
  • As you work with a container and continue to perform actions on it (e.g. download and install software, configure files etc.), to have it keep its state, you need to “commit”.
  • Please remember to “commit” all your changes.
  • When you "run" any process using an image, in return, you will have a container.
  • When the process is not actively running, this container will be a non-running container. Nonetheless, all of them will reside on your system until you remove them via rm command.
  • To create a new container, you need to use a base image and specify a command to run.
  • you can not change the command you run after having created a container (hence specifying one during "creation")
  • If you would like to save the progress and changes you made with a container, you can use “commit”
  • turns your container to an image
張 旭

How to Use Docker on OS X: The Missing Guide | Viget - 0 views

viget.com/...cker-on-os-x-the-missing-guide

docker mac system deploy

shared by 張 旭 on 25 Oct 14 - No Cached
  • Docker is a client-server application.
  • The Docker server is a daemon that does all the heavy lifting: building and downloading images, starting and stopping containers, and the like. It exposes a REST API for remote management.
  • The Docker client is a command line program that communicates with the Docker server using the REST API.
  • ...9 more annotations...
  • interact with Docker by using the client to send commands to the server.
  • The machine running the Docker server is called the Docker host
  • Docker uses features only available to Linux, that machine must be running Linux (more specifically, the Linux kernel).
  • boot2docker is a “lightweight Linux distribution made specifically to run Docker containers.”
  • Docker server will run inside our boot2docker VM
  • boot2docker, not OS X, is the Docker host, not OS X.
  • Docker mounts volumes from the boot2docker VM, not from OS X
  • initialize boot2docker (we only have to do this once):
  • The Docker client assumes the Docker host is the current machine. We need to tell it to use our boot2docker VM by setting the DOCKER_HOST environment variable
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