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Contents contributed and discussions participated by 張 旭

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張 旭

Working with JavaScript in Rails - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/_with_javascript_in_rails.html

rails javascript ajax

shared by 張 旭 on 28 Oct 16 - No Cached
  • JavaScript can also make requests to the server, and parse the response
  • Rails uses a technique called "Unobtrusive JavaScript" to handle attaching JavaScript to the DOM.
  • We call this 'unobtrusive' JavaScript because we're no longer mixing our JavaScript into our HTML.
  • ...2 more annotations...
  • the data-remote="true". Now, the form will be submitted by Ajax rather than by the browser's normal submit mechanism.
  • the format.js in the respond_to block; that allows the controller to respond to your Ajax request.
張 旭

Ask HN: What are the best practises for using SSH keys? | Hacker News - 0 views

news.ycombinator.com/item

security ssh key server

shared by 張 旭 on 14 Oct 16 - No Cached
  • Make sure you use full disk encryption and never stand up from your machine without locking it, and make sure you keep your local machine patched.
  • I'm more focused on just stealing your keys from you regardless of length
  • attacks that aren't after your keys specifically, e.g. your home directory gets stolen.
  • ...19 more annotations...
  • ED25519 is more vulnerable to quantum computation than is RSA
  • best practice to be using a hardware token
  • to use a yubikey via gpg: with this method you use your gpg subkey as an ssh key
  • sit down and spend an hour thinking about your backup and recovery strategy first
  • never share a private keys between physical devices
  • allows you to revoke a single credential if you lose (control over) that device
  • If a private key ever turns up on the wrong machine, you *know* the key and both source and destination machines have been compromised.
  • centralized management of authentication/authorization
  • I have setup a VPS, disabled passwords, and setup a key with a passphrase to gain access. At this point my greatest worry is losing this private key, as that means I can't access the server.What is a reasonable way to backup my private key?
  • a mountable disk image that's encrypted
  • a system that can update/rotate your keys across all of your servers on the fly in case one is compromised or assumed to be compromised.
  • different keys for different purposes per client device
  • fall back to password plus OTP
  • relying completely on the security of your disk, against either physical or cyber.
  • It is better to use a different passphrase for each key but it is also less convenient unless you're using a password manager (personally, I'm using KeePass)
  • - RSA is pretty standard, and generally speaking is fairly secure for key lengths >=2048. RSA-2048 is the default for ssh-keygen, and is compatible with just about everything.
  • public-key authentication has somewhat unexpected side effect of preventing MITM per this security consulting firm
  • Disable passwords and only allow keys even for root with PermitRootLogin without-password
  • You should definitely use a different passphrase for keys stored on separate computers,
  • 張 旭 on 14 Oct 16
     
    "Make sure you use full disk encryption and never stand up from your machine without locking it, and make sure you keep your local machine patched"
張 旭

A Tour of Rails' jQuery UJS - 0 views

robots.thoughtbot.com/a-tour-of-rails-jquery-ujs

rails jquery javascript frontend helper

shared by 張 旭 on 03 Oct 16 - No Cached
  • “I should really figure out what that does someday.”
  • today is that day
  • jquery-ujs wires event handlers to eligible DOM elements to provide enhanced functionality.
  • ...11 more annotations...
  • In most cases, the eligible DOM elements are identified by HTML5 data attributes.
  • using JavaScript to progressively enhance the user experience for capable browsers without negatively impacting clients that do not support or do not enable JavaScript.
    • 張 旭
      張 旭 on 03 Oct 16
       
      讓 user 有更好體驗，但是也不影響到那些沒有 JS 支援的 user
  • jquery-ujs attaches a handler to links with the data-method attribute
  • When the link is clicked, the handler constructs an HTML form along with a hidden input that sets the _method parameter to the requested HTTP verb
  • jquery-ujs attaches a handler to links or forms with the data-confirm attribute that displays a JavaScript confirmation dialog
  • Users double click links and buttons all the time.
  • Links and buttons that have a data-disable-with attribute get a click handler that disables the element and updates the text of the button to that which was provided in the data attribute and disables the button.
    • 張 旭
      張 旭 on 03 Oct 16
       
      優雅地處理了使用者重複點擊傳送按鈕的問題。
  • If the action is performed via AJAX, the handler will re-enable the button and reset the text when the request completes.
  • Thanks to jquery-ujs and Rails’ respond_with, setting remote: true is likely the quickest way to get your Rails application making AJAX requests.
  • support both AJAX and standard requests at the same time.
  • Cross-Site Request Forgery (CSRF) is an attack wherein the attacker tricks the user into submitting a request to an application the user is likely already authenticated to.
張 旭

Handlebars.js: Minimal Templating on Steroids - 0 views

handlebarsjs.com

javascript mustache jquery template library

shared by 張 旭 on 26 Sep 16 - No Cached
  • Handlebars templates look like regular HTML, with embedded handlebars expressions.
  • don't want Handlebars to escape a value, use the "triple-stash", {{{.
  • Handlebars will not escape a Handlebars.SafeString
  • ...13 more annotations...
  • block helpers are identified by a # preceeding the helper name and require a matching closing mustache, /, of the same name.
  • use Handlebars templates with more raw JSON objects.
  • Nested handlebars paths can also include ../ segments, which evaluate their paths against a parent context.
  • The exact value that ../ will resolve to varies based on the helper that is calling the block.
  • reference the same permalink value even though they are located within different blocks.
  • name conflict resolution between helpers and data fields via a this reference
  • comments will not be in the resulting output.
  • register a helper with the Handlebars.registerHelper method.
  • Helpers receive the current context as the this context of the function.
  • returns HTML that you do not want escaped, make sure to return a new Handlebars.SafeString
  • literal values passed to them either as parameter arguments or hash arguments
  • Handlebars partials allow for code reuse by creating shared templates
  • Handlebars.registerPartial
張 旭

http - nginx upload client_max_body_size issue - Stack Overflow - 0 views

stackoverflow.com/...oad-client-max-body-size-issue

nginx upload file http server

shared by 張 旭 on 26 Sep 16 - No Cached
  • nginx "fails fast" when the client informs it that it's going to send a body larger than the client_max_body_size by sending a 413 response and closing the connection.
  • Because nginx closes the connection, the client sends data to the closed socket, causing a TCP RST.
  • Most clients don't read responses until the entire request body is sent.
  • ...2 more annotations...
  • Client body and buffers are key because nginx must buffer incoming data.
  • The clean setting frees up memory and consumption limits by instructing nginx to store incoming buffer in a file and then clean this file later from disk by deleting it.
張 旭

Larry Cai - Travis CI会替代Jenkins吗？ - 0 views

www.larrycaiyu.com/...travis-ci-is-evolution.html

travis jenkins system CI test

shared by 張 旭 on 06 Sep 16 - No Cached
  • Jenkins能够让通过主从模式（master/slave）多台机器一起构建。
  • 一切都可以在Web界面中运行。
  • 当然你可有使用虚拟机的技术vagrant/virtualbox，参见使用vagrant+jenkins来管理虚拟机的技巧。可以工作，不太优雅。因为它不是原生的，有点复杂。
    • 張 旭
      張 旭 on 06 Sep 16
       
      現在應該有 Docker Container 跑測試的整合了。
  • ...5 more annotations...
  • 在CI服务器创建任务（记住：这些配置文件不是有版本控制的）
  • 构建的配置文件直接就和源码放在一起，而且配置文件使用DSL写的，可读性更高。
  • 要求在两个Ruby环境中运行，它就帮我做到了，我并不关心它是怎么切换的
  • Travis CI使用的Ruby语言，一开始考虑的就是分布式构建
  • 它的虚拟机部分只是Vagrant/Virtualbox，但是这一块是很容易迁移到其他的技术的。
    • 張 旭
      張 旭 on 06 Sep 16
       
      Docker! Docker! Docker!
張 旭

plataformatec/simple_form - 0 views

github.com/...simple_form

rails gem form html

shared by 張 旭 on 29 Aug 16 - No Cached
  • The basic goal of Simple Form is to not touch your way of defining the layout
  • by default contains label, hints, errors and the input itself
  • Simple Form acts as a DSL and just maps your input type (retrieved from the column definition in the database) to a specific helper method.
  • ...68 more annotations...
  • can overwrite the default label by passing it to the input method
  • configure the html of any of them
  • disable labels, hints or error
  • add a hint, an error, or even a placeholder
  • add an inline label
  • pass any html attribute straight to the input, by using the :input_html option
  • use the :defaults option in simple_form_fo
  • Simple Form generates a wrapper div around your label and input by default, you can pass any html attribute to that wrapper as well using the :wrapper_html option,
  • By default all inputs are required
  • the required property of any input can be overwritten
  • Simple Form will look at the column type in the database and use an appropriate input for the column
  • lets you overwrite the default input type it creates
  • can also render boolean attributes using as: :select to show a dropdown.
  • give the :disabled option to Simple Form, and it'll automatically mark the wrapper as disabled with a CSS class
  • Simple Form accepts same options as their corresponding input type helper in Rails
  • Any extra option passed to these methods will be rendered as html option.
  • use label, hint, input_field, error and full_error helpers
  • to strip away all the div wrappers around the <input> field
  • is to use f.input_field
  • changing boolean_style from default value :nested to :inline
  • overriding the :collection option
  • Collections can be arrays or ranges, and when a :collection is given the :select input will be rendered by default
  • Other types of collection are :radio_buttons and :check_boxes
  • label_method
  • value_method
  • Both of these options also accept lambda/procs
  • define a to_label method on your model as Simple Form will search for and use :to_label as a :label_method first if it is found
  • create grouped collection selects, that will use the html optgroup tags
  • Grouped collection inputs accept the same :label_method and :value_method options
  • group_method
  • group_label_method
  • configured with a default value to be used on the site through the SimpleForm.country_priority and SimpleForm.time_zone_priority helpers.
  • association
  • association
  • render a :select input for choosing the :company, and another :select input with :multiple option for the :roles
  • all options available to :select, :radio_buttons and :check_boxes are also available to association
  • declare different labels and values
  • the association helper is currently only tested with Active Record
  • f.input
  • f.select
  • create a <button> element
  • simple_fields_for
  • Creates a collection of radio inputs with labels associated
  • Creates a collection of checkboxes with labels associated
  • collection_radio_buttons
  • collection_check_boxes
  • associations in your model
  • Role.all
  • the html element you will get for each attribute according to its database definition
  • redefine existing Simple Form inputs by creating a new class with the same name
  • Simple Form uses all power of I18n API to lookup labels, hints, prompts and placeholders
  • specify defaults for all models under the 'defaults' key
  • Simple Form will always look for a default attribute translation under the "defaults" key if no specific is found inside the model key
  • Simple Form will fallback to default human_attribute_name from Rails when no other translation is found for labels.
  • Simple Form will only do the lookup for options if you give a collection composed of symbols only.
  • "Add %{model}"
  • translations for labels, hints and placeholders for a namespaced model, e.g. Admin::User, should be placed under admin_user, not under admin/user
  • This difference exists because Simple Form relies on object_name provided by Rails' FormBuilder to determine the translation path for a given object instead of i18n_key from the object itself.
  • configure how your components will be rendered using the wrappers API
  • optional
  • unless_blank
  • By default, Simple Form will generate input field types and attributes that are supported in HTML5
  • The HTML5 extensions include the new field types such as email, number, search, url, tel, and the new attributes such as required, autofocus, maxlength, min, max, step.
  • If you want to have all other HTML 5 features, such as the new field types, you can disable only the browser validation
  • add novalidate to a specific form by setting the option on the form itself
  • the Simple Form configuration file
  • passing the html5 option
  • as: :date, html5: true
張 旭

elabs/pundit: Minimal authorization through OO design and pure Ruby classes - 0 views

github.com/pundit

authorization rails ruby gem library

shared by 張 旭 on 20 Mar 16 - No Cached
  • The class implements some kind of query method
  • Pundit will call the current_user method to retrieve what to send into this argumen
  • put these classes in app/policies
  • ...49 more annotations...
  • in leveraging regular Ruby classes and object oriented design patterns to build a simple, robust and scaleable authorization system
  • map to the name of a particular controller action
  • In the generated ApplicationPolicy, the model object is called record.
  • record
  • authorize
  • authorize would have done something like this: raise "not authorized" unless PostPolicy.new(current_user, @post).update?
  • pass a second argument to authorize if the name of the permission you want to check doesn't match the action name.
  • you can chain it
  • authorize returns the object passed to it
  • the policy method in both the view and controller.
  • have some kind of view listing records which a particular user has access to
  • ActiveRecord::Relation
  • Instances of this class respond to the method resolve, which should return some kind of result which can be iterated over.
  • scope.where(published: true)
    • 張 旭
      張 旭 on 29 Aug 16
       
      我想大概的意思就是：如果是 admin 可以看到全部 post，如果不是只能看到 published = true 的 post
  • use this class from your controller via the policy_scope method:
  • PostPolicy::Scope.new(current_user, Post).resolve
  • policy_scope(@user.posts).each
  • This method will raise an exception if authorize has not yet been called.
  • verify_policy_scoped to your controller. This will raise an exception in the vein of verify_authorized. However, it tracks if policy_scope is used instead of authorize
  • need to conditionally bypass verification, you can use skip_authorization
  • skip_policy_scope
  • Having a mechanism that ensures authorization happens allows developers to thoroughly test authorization scenarios as units on the policy objects themselves.
  • Pundit doesn't do anything you couldn't have easily done yourself. It's a very small library, it just provides a few neat helpers.
  • all of the policy and scope classes are just plain Ruby classes
  • rails g pundit:policy post
  • define a filter that redirects unauthenticated users to the login page
  • fail more gracefully
  • raise Pundit::NotAuthorizedError, "must be logged in" unless user
  • having rails handle them as a 403 error and serving a 403 error page.
  • config.action_dispatch.rescue_responses["Pundit::NotAuthorizedError"] = :forbidden
  • with I18n to generate error messages
  • retrieve a policy for a record outside the controller or view
  • define a method in your controller called pundit_user
  • Pundit strongly encourages you to model your application in such a way that the only context you need for authorization is a user object and a domain model that you want to check authorization for.
  • Pundit does not allow you to pass additional arguments to policies
  • authorization is dependent on IP address in addition to the authenticated user
  • create a special class which wraps up both user and IP and passes it to the policy.
  • set up a permitted_attributes method in your policy
  • policy(@post).permitted_attributes
  • permitted_attributes(@post)
  • Pundit provides a convenient helper method
  • permit different attributes based on the current action,
  • If you have defined an action-specific method on your policy for the current action, the permitted_attributes helper will call it instead of calling permitted_attributes on your controller
  • If you don't have an instance for the first argument to authorize, then you can pass the class
  • restart the Rails server
  • Given there is a policy without a corresponding model / ruby class, you can retrieve it by passing a symbol
  • after_action :verify_authorized
  • It is not some kind of failsafe mechanism or authorization mechanism.
  • Pundit will work just fine without using verify_authorized and verify_policy_scoped
張 旭

Kubernetes 架构浅析 - 0 views

jolestar.com/kubernetes-architecture

docker kubernetes google system development

shared by 張 旭 on 08 Aug 16 - No Cached
  • 将Loadbalancer改造成Smart Loadbalancer，通过服务发现机制，应用实例启动或者销毁时自动注册到一个配置中心（etcd/zookeeper），Loadbalancer监听应用配置的变化自动修改自己的配置。
  • Mysql计划该成域名访问方式，而不是ip。为了避免dns变更时的延迟问题，需要在内网架设私有dns。
  • 配合服务发现机制自动修改dns
  • ...23 more annotations...
  • 通过增加一层代理的机制实现
  • 操作系统和基础库的依赖允许应用自定义
  • 对磁盘路径以及端口的依赖通过Docker运行参数动态注入
  • Docker的自定义变量以及参数，需要提供标准化的配置文件
  • 每个服务器节点上要有个agent来执行具体的操作，监控该节点上的应用
  • 还要提供接口以及工具去操作。
  • 应用进程和资源（包括 cpu，内存，磁盘，网络）的解耦
  • 服务依赖关系的解耦
  • scheduler在Kubernetes中是一个plugin，可以用其他的实现替换（比如mesos）
  • 大多数接口都是直接读写etcd中的数据。
  • etcd 作为配置中心和存储服务
  • kubelet 主要包含容器管理，镜像管理，Volume管理等。同时kubelet也是一个rest服务，和pod相关的命令操作都是通过调用接口实现的。
  • kube-proxy 主要用于实现Kubernetes的service机制。提供一部分SDN功能以及集群内部的智能LoadBalancer。
  • Pods Kubernetes将应用的具体实例抽象为pod。每个pod首先会启动一个google_containers/pause docker容器，然后再启动应用真正的docker容器。这样做的目的是为了可以将多个docker容器封装到一个pod中，共享网络地址。
  • Replication Controller 控制pod的副本数量
  • Services service是对一组pods的抽象，通过kube-proxy的智能LoadBalancer机制，pods的销毁迁移不会影响services的功能以及上层的调用方。
  • Namespace Kubernetes中的namespace主要用来避免pod，service的名称冲突。同一个namespace内的pod，service的名称必须是唯一的。
  • Kubernetes的理念里，pod之间是可以直接通讯的
  • 需要用户自己选择解决方案: Flannel,OpenVSwitch,Weave 等。
  • Hypernetes就是一个实现了多租户的Kubernetes版本。
  • 如果运维系统跟不上，服务拆太细，很容易出现某个服务器的角落里部署着一个很古老的不常更新的服务，后来大家竟然忘记了，最后服务器迁移的时候给丢了，用户投诉才发现。
  • 在Kubernetes上的微服务治理框架可以一揽子解决微服务的rpc，监控，容灾问题
  • 同一个pod的多个容器定义中没有优先级，启动顺序不能保证
張 旭

Specification - Swagger - 0 views

swagger.io/specification

shared by 張 旭 on 29 Jul 16 - No Cached
  • A list of parameters that are applicable for all the operations described under this path.
  • MUST NOT include duplicated parameters
  • this field SHOULD be less than 120 characters.
  • ...33 more annotations...
  • Unique string used to identify the operation.
  • The id MUST be unique among all operations described in the API.
  • A list of MIME types the operation can consume.
  • A list of MIME types the operation can produce
  • A unique parameter is defined by a combination of a name and location.
  • There can be one "body" parameter at most.
  • Required. The list of possible responses as they are returned from executing this operation.
  • The transfer protocol for the operation. Values MUST be from the list: "http", "https", "ws", "wss".
  • Declares this operation to be deprecated. Usage of the declared operation should be refrained. Default value is
  • A declaration of which security schemes are applied for this operation.
  • A unique parameter is defined by a combination of a name and location.
  • Path
  • Query
  • Header
  • Body
  • Form
  • Required. The location of the parameter. Possible values are "query", "header", "path", "formData" or "body".
  • the parameter value is actually part of the operation's URL
  • Parameters that are appended to the URL
  • The payload that's appended to the HTTP request.
  • Since there can only be one payload, there can only be one body parameter.
  • The name of the body parameter has no effect on the parameter itself and is used for documentation purposes only
  • body and form parameters cannot exist together for the same operation
  • This is the only parameter type that can be used to send files, thus supporting the file type.
  • If the parameter is in "path", this property is required and its value MUST be true.
  • default value is false.
  • The schema defining the type used for the body parameter.
  • The value MUST be one of "string", "number", "integer", "boolean", "array" or "file"
  • Default value is false
  • Required if type is "array". Describes the type of items in the array.
  • Determines the format of the array if type array is used
  • enum
  • pattern
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