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張 旭

Ruby and AOP: Decouple your code even more - Arkency Blog - 0 views

blog.arkency.com/...p-decouple-your-code-even-more

ruby aop programming algorithm pattern code

shared by 張 旭 on 03 Jun 17 - No Cached
  • Dark Parts in our apps - persistence, networking, logging, notifications… these parts are scattered in our code
  • aspect-oriented programming!
  • components are parts we can easily encapsulate into some kind of code abstraction - a methods, objects or procedures.
  • ...16 more annotations...
  • application’s logic is a great example of a component
  • Aspects cross-cut our application - when we use some kind of persistence (e.g. a database) or network communication (such as ZMQ sockets) our components need to know about it.
  • Aspect-oriented programming aims to get rid of cross-cuts by separating aspect code from component code using injections of our aspects in certain join points in our component code.
  • It’s responsible for pushing snippets scenario
  • SRP-conformant object
  • the join points in Ruby
  • advice
    • 張 旭
      張 旭 on 03 Jun 17
       
      AOP 裡面的術語
  • In most cases after and before advice are sufficient.
  • what does it mean to “evaluate code around” something? In our case it means: Don’t run this method. Take it and push to my advice as an argument and evaluate this advice
  • to provide a join point
  • You’ll often see empty methods in code written in AOP paradigm
  • provide aspect code to link with our use case
  • use case is a pure domain object, without even knowing it’s connected with some kind of persistence and logging layer.
  • Aspect-oriented programming is fixing the problem with polluting pure logic objects with technical context of our applications.
  • we treat our glues as a configuration part, not the logic part of our apps.
  • Glues should not contain any logic at all
張 旭

Deploying Rails Apps, Part 6: Writing Capistrano Tasks - Vladi Gleba - 0 views

vladigleba.com/...art-6-writing-capistrano-tasks

rails capistrano deploy ruby docker devops

shared by 張 旭 on 23 Aug 17 - No Cached
  • we can write our own tasks to help us automate various things.
  • organizing all of the tasks here under a namespace
  • upload a file from our local computer.
  • ...27 more annotations...
  • learn about is SSHKit and the various methods it provides
  • SSHKit was actually developed and released with Capistrano 3, and it’s basically a lower-level tool that provides methods for connecting and interacting with remote servers
  • on(): specifies the server to run on
  • within(): specifies the directory path to run in
  • with(): specifies the environment variables to run with
  • run on the application server
  • within the path specified
  • with certain environment variables set
  • execute(): the workhorse that runs the commands on your server
  • upload(): uploads a file from your local computer to your remote server
  • capture(): executes a command and returns its output as a string
    • 張 旭
      張 旭 on 23 Aug 17
       
      capture 是跑在遠端伺服器上
  • upload() has the bang symbol (!) because that’s how it’s defined in SSHKit, and it’s just a convention letting us know that the method will block until it finishes.
  • But in order to ensure rake runs with the proper environment variables set, we have to use rake as a symbol and pass db:seed as a string
  • This format will also be necessary whenever you’re running any other Rails-specific commands that rely on certain environment variables being set
  • I recommend you take a look at SSHKit’s example page to learn more
  • make sure we pushed all our local changes to the remote master branch
  • run this task before Capistrano runs its own deploy task
  • actually creates three separate tasks
  • I created a namespace called deploy to contain these tasks since that’s what they’re related to.
  • we’re using the callbacks inside a namespace to make sure Capistrano knows which tasks the callbacks are referencing.
  • custom recipe (a Capistrano term meaning a series of tasks)
  • /shared: holds files and directories that persist throughout deploys
  • When you run cap production deploy, you’re actually calling a Capistrano task called deploy, which then sequentially invokes other tasks
  • your favorite browser (I hope it’s not Internet Explorer)
  • Deployment is hard and takes a while to sink in.
  • the most important thing is to not get discouraged
  • I didn’t want other people going through the same thing
張 旭

Best practices for building Kubernetes Operators and stateful apps | Google Cloud Blog - 0 views

cloud.google.com/...es-operators-and-stateful-apps

kubernetes system operator

shared by 張 旭 on 17 May 21 - No Cached
  • use the StatefulSet workload controller to maintain identity for each of the pods, and to use Persistent Volumes to persist data so it can survive a service restart.
  • a way to extend Kubernetes functionality with application specific logic using custom resources and custom controllers.
  • An Operator can automate various features of an application, but it should be specific to a single application
  • ...12 more annotations...
  • Kubebuilder is a comprehensive development kit for building and publishing Kubernetes APIs and Controllers using CRDs
  • Design declarative APIs for operators, not imperative APIs. This aligns well with Kubernetes APIs that are declarative in nature.
  • With declarative APIs, users only need to express their desired cluster state, while letting the operator perform all necessary steps to achieve it.
  • scaling, backup, restore, and monitoring. An operator should be made up of multiple controllers that specifically handle each of the those features.
  • the operator can have a main controller to spawn and manage application instances, a backup controller to handle backup operations, and a restore controller to handle restore operations.
  • each controller should correspond to a specific CRD so that the domain of each controller's responsibility is clear.
  • If you keep a log for every container, you will likely end up with unmanageable amount of logs.
  • integrate application-specific details to the log messages such as adding a prefix for the application name.
  • you may have to use external logging tools such as Google Stackdriver, Elasticsearch, Fluentd, or Kibana to perform the aggregations.
  • adding labels to metrics to facilitate aggregation and analysis by monitoring systems.
  • a more viable option is for application pods to expose a metrics HTTP endpoint for monitoring tools to scrape.
  • A good way to achieve this is to use open-source application-specific exporters for exposing Prometheus-style metrics.
張 旭

Kubernetes Deployments: The Ultimate Guide - Semaphore - 1 views

semaphoreci.com/...kubernetes-deployment

docker kubernetes devops system

shared by 張 旭 on 21 Oct 19 - No Cached
  • Continuous integration gives you confidence in your code. To extend that confidence to the release process, your deployment operations need to come with a safety belt.
  • these Kubernetes objects ensure that you can progressively deploy, roll back and scale your applications without downtime.
  • A pod is just a group of containers (it can be a group of one container) that run on the same machine, and share a few things together.
  • ...34 more annotations...
  • the containers within a pod can communicate with each other over localhost
  • From a network perspective, all the processes in these containers are local.
  • we can never create a standalone container: the closest we can do is create a pod, with a single container in it.
  • Kubernetes is a declarative system (by opposition to imperative systems).
  • All we can do, is describe what we want to have, and wait for Kubernetes to take action to reconcile what we have, with what we want to have.
  • In other words, we can say, “I would like a 40-feet long blue container with yellow doors“, and Kubernetes will find such a container for us. If it doesn’t exist, it will build it; if there is already one but it’s green with red doors, it will paint it for us; if there is already a container of the right size and color, Kubernetes will do nothing, since what we have already matches what we want.
  • The specification of a replica set looks very much like the specification of a pod, except that it carries a number, indicating how many replicas
  • What happens if we change that definition? Suddenly, there are zero pods matching the new specification.
  • the creation of new pods could happen in a more gradual manner.
  • the specification for a deployment looks very much like the one for a replica set: it features a pod specification, and a number of replicas.
  • Deployments, however, don’t create or delete pods directly.
  • When we update a deployment and adjust the number of replicas, it passes that update down to the replica set.
  • When we update the pod specification, the deployment creates a new replica set with the updated pod specification. That replica set has an initial size of zero. Then, the size of that replica set is progressively increased, while decreasing the size of the other replica set.
  • we are going to fade in (turn up the volume) on the new replica set, while we fade out (turn down the volume) on the old one.
  • During the whole process, requests are sent to pods of both the old and new replica sets, without any downtime for our users.
  • A readiness probe is a test that we add to a container specification.
  • Kubernetes supports three ways of implementing readiness probes:Running a command inside a container;Making an HTTP(S) request against a container; orOpening a TCP socket against a container.
  • When we roll out a new version, Kubernetes will wait for the new pod to mark itself as “ready” before moving on to the next one.
  • If there is no readiness probe, then the container is considered as ready, as long as it could be started.
  • MaxSurge indicates how many extra pods we are willing to run during a rolling update, while MaxUnavailable indicates how many pods we can lose during the rolling update.
  • Setting MaxUnavailable to 0 means, “do not shutdown any old pod before a new one is up and ready to serve traffic“.
  • Setting MaxSurge to 100% means, “immediately start all the new pods“, implying that we have enough spare capacity on our cluster, and that we want to go as fast as possible.
  • kubectl rollout undo deployment web
  • the replica set doesn’t look at the pods’ specifications, but only at their labels.
  • A replica set contains a selector, which is a logical expression that “selects” (just like a SELECT query in SQL) a number of pods.
  • it is absolutely possible to manually create pods with these labels, but running a different image (or with different settings), and fool our replica set.
  • Selectors are also used by services, which act as the load balancers for Kubernetes traffic, internal and external.
  • internal IP address (denoted by the name ClusterIP)
  • during a rollout, the deployment doesn’t reconfigure or inform the load balancer that pods are started and stopped. It happens automatically through the selector of the service associated to the load balancer.
  • a pod is added as a valid endpoint for a service only if all its containers pass their readiness check. In other words, a pod starts receiving traffic only once it’s actually ready for it.
  • In blue/green deployment, we want to instantly switch over all the traffic from the old version to the new, instead of doing it progressively
  • We can achieve blue/green deployment by creating multiple deployments (in the Kubernetes sense), and then switching from one to another by changing the selector of our service
  • kubectl label pods -l app=blue,version=v1.5 status=enabled
  • kubectl label pods -l app=blue,version=v1.4 status-
  • 張 旭 on 21 Oct 19
     
    "Continuous integration gives you confidence in your code. To extend that confidence to the release process, your deployment operations need to come with a safety belt."
張 旭

APP_KEY And You | Tighten - 0 views

tighten.co/app-key-and-you

php laravel

shared by 張 旭 on 21 Jan 22 - No Cached
  • The application key is a random, 32-character string stored in the APP_KEY key in your .env file.
  • Once your app is running, there's one place it uses the APP_KEY: cookies.
  • Laravel uses the key for all encrypted cookies, including the session cookie, before handing them off to the user's browser, and it uses it to decrypt cookies read from the browser.
  • ...16 more annotations...
  • Encrypted cookies are an important security feature in Laravel.
  • All of this encryption and decryption is handled in Laravel by the Encrypter using PHP's built-in security tools, including OpenSSL.
  • Passwords are not encrypted, they are hashed.
  • Laravel's passwords are hashed using Hash::make() or bcrypt(), neither of which use APP_KEY.
  • Crypt (symmetric encryption) and Hash (one-way cryptographic hashing).
  • Laravel uses this same method for cookies, both the sender and receiver, using APP_KEY as the encryption key.
  • something like user passwords, you should never have a way to decrypt them. Ever.
  • Unique: The collision rate (different inputs hashing to the same output) should be very small
  • Laravel hashing implements the native PHP password_hash() function, defaulting to a hashing algorithm called bcrypt.
  • a one-way hash, we cannot decrypt it. All that we can do is test against it.
  • When the user with this password attempts to log in, Laravel hashes their password input and uses PHP’s password_verify() function to compare the new hash with the database hash
  • User password storage should never be reversible, and therefore doesn’t need APP_KEY at all.
  • Any good credential management strategy should include rotation: changing keys and passwords on a regular basis
  • update the key on each server.
  • their sessions invalidated as soon as you change your APP_KEY.
  • make and test a plan to decrypt that data with your old key and re-encrypt it with the new key.
crazylion lee

Origami Studio - Design Prototyping - 0 views

origami.design

prototyping design facebook ux app

shared by crazylion lee on 31 Oct 16 - No Cached
  • crazylion lee on 31 Oct 16
     
    "Explore, iterate, and test your ideas. A new tool for designing modern interfaces, built and used by designers at Facebook. Get started today for free."
crazylion lee

jiahaog/nativefier: Make any web page a desktop application - 0 views

github.com/nativefier

desktop electron javascript app

shared by crazylion lee on 31 Oct 16 - No Cached
  • crazylion lee on 31 Oct 16
     
    "Make any web page a desktop application"
crazylion lee

Hyper.app - 0 views

hyper.is

terminal javascript html

shared by crazylion lee on 16 Nov 16 - No Cached
  • crazylion lee on 16 Nov 16
     
    "JS/HTML/CSS Terminal"
張 旭

Slimming Down Your Models and Controllers with Concerns, Service Objects, and Tableless... - 1 views

www.viget.com/...wn-your-models-and-controllers

rails development model pattern controller

shared by 張 旭 on 29 Nov 16 - No Cached
  • The single responsibility principle asserts that every class should have exactly one responsibility. In other words, each class should be concerned about one unique nugget of functionality
  • fat models are a little better than fat controllers
  • when every bit of functionality has been encapsulated into its own object, you find yourself repeating code a lot less.
  • ...2 more annotations...
  • objects with a single responsibility can easily be unit tested
  • a vanilla Rails 4 app directory contains models, views, controllers, and helpers does not mean you are restricted to those four domains.
crazylion lee

Phoenix - 0 views

www.phoenixframework.org

elixir framework Web erlang HTML5 apps

shared by crazylion lee on 17 Apr 16 - No Cached
  • crazylion lee on 17 Apr 16
     
    "A productive web framework that does not compromise speed and maintainability."
張 旭

OmniAuth: Overview · plataformatec/devise Wiki - 0 views

github.com/...OmniAuth%3A-Overview

rails framework development login auth oauth facebook

shared by 張 旭 on 12 Feb 14 - No Cached
  • omniauth-provider
  • add the columns "provider" and "uid" to your User model
  • declare the provider in your config/initializers/devise.rb and require it
  • ...17 more annotations...
  • set it explicitly with the :strategy_class option
  • explicitly tell OmniAuth where to locate your ca_certificates file
  • make your model (e.g. app/models/user.rb) omniauthable
  • devise_for :users was already added to your config/routes.rb
  • user_omniauth_authorize_path(provider) user_omniauth_callback_path(provider)
  • devise does not create *_url methods
  • The symbol passed to the user_omniauth_authorize_path method matches the symbol of the provider passed to Devise's config block
  • After inserting their credentials, they will be redirected back to your application's callback method
  • tell Devise in which controller we will implement Omniauth callbacks
  • find_for_facebook_oauth
  • implement the method below in your model
  • All information retrieved from Facebook by OmniAuth is available as a hash at request.env["omniauth.auth"]
  • Devise removes all the data starting with "devise." from the session whenever a user signs in, so we get automatic session clean up
  • We pass the :event => :authentication to the sign_in_and_redirect method to force all authentication callbacks to be called
  • tries to find an existing user by provider and uid or create one with a random password otherwise.
  • Devise's RegistrationsController by default calls "User.new_with_session" before building a resource
  • if we need to copy data from session whenever a user is initialized before sign up, we just need to implement new_with_session in our model
張 旭

The Rubyist's Guide to Environment Variables - Honeybadger.io Blog - 0 views

blog.honeybadger.io/by-guide-environment-variables

ruby environment development shell

shared by 張 旭 on 12 Jun 15 - No Cached
  • If you want to be able to effectively manage web apps in development and in production, you have to understand environment variables.
  • Every program you run on your server has at least one process. That process gets its own set of environment variables.
  • Once it has them, nothing outside of that process can change them.
  • ...9 more annotations...
  • Every program you run on your server gets its own set of environment variables at the moment you launch it.
  • Environment variables die with their process
  • Every process has a parent. That’s because every program has to be started by some other program.
  • Child processes inherit env vars from their parent
  • By default a child will get copies of every environment variable that its parent has. But the parent has control over this.
  • Changes to the environment don’t sync between running processes
  • shells do provide their own “local” shell variable systems
  • Environment variables are NOT the same as shell variables
  • use the export command to convert the local variable into an environment variable.
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

Getting Started with Rails - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/getting_started.html

shared by 張 旭 on 22 Jan 14 - Cached
  • A controller's purpose is to receive specific requests for the application.
  • Routing decides which controller receives which requests
  • The view should just display that information
  • ...55 more annotations...
  • view templates are written in a language called ERB (Embedded Ruby) which is converted by the request cycle in Rails before being sent to the user.
  • Each action's purpose is to collect information to provide it to a view.
  • A view's purpose is to display this information in a human readable format.
  • routing file which holds entries in a special DSL (domain-specific language) that tells Rails how to connect incoming requests to controllers and actions.
  • You can create, read, update and destroy items for a resource and these operations are referred to as CRUD operations
  • A controller is simply a class that is defined to inherit from ApplicationController.
  • If not found, then it will attempt to load a template called application/new. It looks for one here because the PostsController inherits from ApplicationController
  • :formats specifies the format of template to be served in response. The default format is :html, and so Rails is looking for an HTML template.
  • :handlers, is telling us what template handlers could be used to render our template.
  • When you call form_for, you pass it an identifying object for this form. In this case, it's the symbol :post. This tells the form_for helper what this form is for.
  • that the action attribute for the form is pointing at /posts/new
  • When a form is submitted, the fields of the form are sent to Rails as parameters.
  • parameters can then be referenced inside the controller actions, typically to perform a particular task
  • params method is the object which represents the parameters (or fields) coming in from the form.
  • Active Record is smart enough to automatically map column names to model attributes,
  • Rails uses rake commands to run migrations, and it's possible to undo a migration after it's been applied to your database
  • every Rails model can be initialized with its respective attributes, which are automatically mapped to the respective database columns.
  • migration creates a method named change which will be called when you run this migration.
  • The action defined in this method is also reversible, which means Rails knows how to reverse the change made by this migration, in case you want to reverse it later
  • Migration filenames include a timestamp to ensure that they're processed in the order that they were created.
  • @post.save returns a boolean indicating whether the model was saved or not.
  • prevents an attacker from setting the model's attributes by manipulating the hash passed to the model.
  • If you want to link to an action in the same controller, you don't need to specify the :controller option, as Rails will use the current controller by default.
  • inherits from ActiveRecord::Base
  • Active Record supplies a great deal of functionality to your Rails models for free, including basic database CRUD (Create, Read, Update, Destroy) operations, data validation, as well as sophisticated search support and the ability to relate multiple models to one another.
  • Rails includes methods to help you validate the data that you send to models
  • Rails can validate a variety of conditions in a model, including the presence or uniqueness of columns, their format, and the existence of associated objects.
  • redirect_to will tell the browser to issue another request.
  • rendering is done within the same request as the form submission
  • Each request for a comment has to keep track of the post to which the comment is attached, thus the initial call to the find method of the Post model to get the post in question.
  • pluralize is a rails helper that takes a number and a string as its arguments. If the number is greater than one, the string will be automatically pluralized.
  • The render method is used so that the @post object is passed back to the new template when it is rendered.
  • The method: :patch option tells Rails that we want this form to be submitted via the PATCH HTTP method which is the HTTP method you're expected to use to update resources according to the REST protocol.
  • it accepts a hash containing the attributes that you want to update.
  • field_with_errors. You can define a css rule to make them standout
  • belongs_to :post, which sets up an Active Record association
  • creates comments as a nested resource within posts
  • call destroy on Active Record objects when you want to delete them from the database.
  • Rails allows you to use the dependent option of an association to achieve this.
  • store all external data as UTF-8
  • you're better off ensuring that all external data is UTF-8
  • use UTF-8 as the internal storage of your database
  • Rails defaults to converting data from your database into UTF-8 at the boundary.
  • :patch
  • By default forms built with the form_for helper are sent via POST
  • The :method and :'data-confirm' options are used as HTML5 attributes so that when the link is clicked, Rails will first show a confirm dialog to the user, and then submit the link with method delete. This is done via the JavaScript file jquery_ujs which is automatically included into your application's layout (app/views/layouts/application.html.erb) when you generated the application.
  • Without this file, the confirmation dialog box wouldn't appear.
  • just defines the partial template we want to render
  • As the render method iterates over the @post.comments collection, it assigns each comment to
  • a local variable named the same as the partial
  • use the authentication system
  • require and permit
  • the method is often made private to make sure it can't be called outside its intended context.
  • standard CRUD actions in each controller in the following order: index, show, new, edit, create, update and destroy.
  • must be placed before any private or protected method in the controller in order to work
張 旭

我所认为的RESTful API最佳实践 · ScienJus's Blog - 0 views

www.scienjus.com/my-restful-api-best-practices

api REST

shared by 張 旭 on 29 Oct 18 - No Cached
  • 最好将过滤、分页和排序的相关信息全权交给客户端，包括过滤条件、页数或是游标、每页的数量、排序方式、升降序等，这样可以使 API 更加灵活。
  • 过度纠结如何遵守规范只是徒增烦恼
  • API 的版本号和客户端 APP 的版本号是毫无关系的
  • ...13 more annotations...
  • 除了 POST 其他三种请求都具备幂等性（多次请求的效果相同）
  • PUT 也可以用于创建操作，只要在创建前就可以确定资源的 id。
  • 永远去使用可以指向资源的的最短 URL 路径
  • RESTful 中不建议出现动词
  • 这里我选择了 PUT 而不是 POST，因为我觉得点赞这种行为应该是幂等的，多次操作的结果应该相同。
  • Token 的状态保持一般有两种方式实现：一种是在用户每次操作都会延长或重置 TOKEN 的生存时间（类似于缓存的机制），另一种是 Token 的生存时间固定不变，但是同时返回一个刷新用的 Token，当 Token 过期时可以将其刷新而不是重新登录。
  • 一般客户端会把请求参数拼接后并加密作为 Sign 传给服务端，这样即使被抓包了，对方只修改参数而无法生成对应的 Sign 也会被服务端识破。
  • 尽量使用 HTTP 状态码
  • data是真正需要返回的数据，并且只会在请求成功时才存在，msg只用在开发环境，并且只为了开发人员识别。客户端逻辑只允许识别code，并且不允许直接将msg的内容展示给用户。
  • JSON 比 XML 可视化更好，也更加节约流量，所以尽量不要使用 XML。
  • 创建和修改操作成功后，需要返回该资源的全部信息。
  • 即使客户端一个页面需要展示多个资源，也不要在一个接口中全部返回，而是让客户端分别请求多个接口。
  • 推荐使用游标分页
張 旭

Setup ProxySQL for High Availability (not a Single Point of Failure) - Percona Database... - 0 views

www.percona.com/...ility-not-single-point-failure

mysql database cluster mariadb proxy

shared by 張 旭 on 18 Nov 18 - No Cached
  • ProxySQL doesn’t natively support any high availability solution
  • most common solution is setting up ProxySQL as part of a tile architecture, where Application/ProxySQL are deployed together.
    • 張 旭
      張 旭 on 18 Nov 18
       
      直接把 ProxySQL 跟 App 捆綁發佈
  • If we have 400 instances of ProxySQL, we end up keeping our databases busy just performing the checks.
  • ...5 more annotations...
  • Another possible approach is to have two layers of ProxySQL, one close to the application and another in the middle to connect to the database.
  • creates additional complexity in the management of the platform, and it adds network hops.
  • combining existing solutions and existing blocks: KeepAlived + ProxySQl + MySQL.
  • Keepalived implements a set of checkers to dynamically and adaptively maintain and manage load-balanced server pool according to their health.
  • Keepalived implements a set of hooks to the VRRP finite state machine providing low-level and high-speed protocol interactions.
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