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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
crazylion lee

BearSSL - 0 views

bearssl.org

openssl ssl tls

shared by crazylion lee on 11 Nov 16 - No Cached
  • crazylion lee on 11 Nov 16
     
    "BearSSL is an implementation of the SSL/TLS protocol (RFC 5246) written in C. It aims at offering the following features: Be correct and secure. In particular, insecure protocol versions and choices of algorithms are not supported, by design; cryptographic algorithm implementations are constant-time by default. Be small, both in RAM and code footprint. For instance, a minimal server implementation may fit in about 20 kilobytes of compiled code and 25 kilobytes of RAM. Be highly portable. BearSSL targets not only "big" operating systems like Linux and Windows, but also small embedded systems and even special contexts like bootstrap code. Be feature-rich and extensible. SSL/TLS has many defined cipher suites and extensions; BearSSL should implement most of them, and allow extra algorithm implementations to be added afterwards, possibly from third parties."
張 旭

Operator pattern - Kubernetes - 1 views

kubernetes.io/...operator

kubernetes system

shared by 張 旭 on 31 Oct 19 - No Cached
  • The Operator pattern aims to capture the key aim of a human operator who is managing a service or set of services
  • Operators are software extensions to Kubernetes that make use of custom resources to manage applications and their components
  • The Operator pattern captures how you can write code to automate a task beyond what Kubernetes itself provides.
  • ...7 more annotations...
  • Operators are clients of the Kubernetes API that act as controllers for a Custom Resource.
  • choosing a leader for a distributed application without an internal member election process
  • publishing a Service to applications that don't support Kubernetes APIs to discover them
  • The core of the Operator is code to tell the API server how to make reality match the configured resources.
  • If you add a new SampleDB, the operator sets up PersistentVolumeClaims to provide durable database storage, a StatefulSet to run SampleDB and a Job to handle initial configuration.If you delete it, the Operator takes a snapshot, then makes sure that the StatefulSet and Volumes are also removed.
  • to deploy an Operator is to add the Custom Resource Definition and its associated Controller to your cluster.
  • Once you have an Operator deployed, you'd use it by adding, modifying or deleting the kind of resource that the Operator uses.
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.
crazylion lee

Hammerspoon - 0 views

www.hammerspoon.org

automation lua osx mac

shared by crazylion lee on 24 Nov 16 - No Cached
  • crazylion lee on 24 Nov 16
     
    "This is a tool for powerful automation of OS X. At its core, Hammerspoon is just a bridge between the operating system and a Lua scripting engine. What gives Hammerspoon its power is a set of extensions that expose specific pieces of system functionality, to the user."
張 旭

Active Record Associations - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/association_basics.html

rails database ruby relation

shared by 張 旭 on 12 Apr 16 - Cached
  • With Active Record associations, we can streamline these - and other - operations by declaratively telling Rails that there is a connection between the two models.
  • belongs_to has_one has_many has_many :through has_one :through has_and_belongs_to_many
  • an association is a connection between two Active Record models
  • ...195 more annotations...
  • Associations are implemented using macro-style calls, so that you can declaratively add features to your models
  • A belongs_to association sets up a one-to-one connection with another model, such that each instance of the declaring model "belongs to" one instance of the other model.
  • belongs_to associations must use the singular term.
  • belongs_to
  • A has_one association also sets up a one-to-one connection with another model, but with somewhat different semantics (and consequences).
  • This association indicates that each instance of a model contains or possesses one instance of another model
  • belongs_to
  • A has_many association indicates a one-to-many connection with another model.
  • This association indicates that each instance of the model has zero or more instances of another model.
  • belongs_to
  • A has_many :through association is often used to set up a many-to-many connection with another model
  • This association indicates that the declaring model can be matched with zero or more instances of another model by proceeding through a third model.
  • through:
  • through:
  • The collection of join models can be managed via the API
  • new join models are created for newly associated objects, and if some are gone their rows are deleted.
  • The has_many :through association is also useful for setting up "shortcuts" through nested has_many associations
  • A has_one :through association sets up a one-to-one connection with another model. This association indicates that the declaring model can be matched with one instance of another model by proceeding through a third model.
  • A has_and_belongs_to_many association creates a direct many-to-many connection with another model, with no intervening model.
  • id: false
  • The has_one relationship says that one of something is yours
  • using t.references :supplier instead.
  • declare a many-to-many relationship is to use has_many :through. This makes the association indirectly, through a join model
  • set up a has_many :through relationship if you need to work with the relationship model as an independent entity
  • set up a has_and_belongs_to_many relationship (though you'll need to remember to create the joining table in the database).
  • use has_many :through if you need validations, callbacks, or extra attributes on the join model
  • With polymorphic associations, a model can belong to more than one other model, on a single association.
  • belongs_to :imageable, polymorphic: true
  • a polymorphic belongs_to declaration as setting up an interface that any other model can use.
    • 張 旭
      張 旭 on 13 Apr 16
       
      _id 記錄的是不同類型的外連鍵 id；_type 記錄的是不同類型的表格名稱。
  • In designing a data model, you will sometimes find a model that should have a relation to itself
  • add a references column to the model itself
  • Controlling caching Avoiding name collisions Updating the schema Controlling association scope Bi-directional associations
  • All of the association methods are built around caching, which keeps the result of the most recent query available for further operations.
  • it is a bad idea to give an association a name that is already used for an instance method of ActiveRecord::Base. The association method would override the base method and break things.
  • You are responsible for maintaining your database schema to match your associations.
  • belongs_to associations you need to create foreign keys
  • has_and_belongs_to_many associations you need to create the appropriate join table
  • If you create an association some time after you build the underlying model, you need to remember to create an add_column migration to provide the necessary foreign key.
  • Active Record creates the name by using the lexical order of the class names
  • So a join between customer and order models will give the default join table name of "customers_orders" because "c" outranks "o" in lexical ordering.
  • For example, one would expect the tables "paper_boxes" and "papers" to generate a join table name of "papers_paper_boxes" because of the length of the name "paper_boxes", but it in fact generates a join table name of "paper_boxes_papers" (because the underscore '' is lexicographically _less than 's' in common encodings).
  • id: false
  • pass id: false to create_table because that table does not represent a model
  • By default, associations look for objects only within the current module's scope.
  • will work fine, because both the Supplier and the Account class are defined within the same scope.
  • To associate a model with a model in a different namespace, you must specify the complete class name in your association declaration:
  • class_name
  • class_name
  • Active Record provides the :inverse_of option
    • 張 旭
      張 旭 on 13 Apr 16
       
      意思是說第一次比較兩者的 first_name 是相同的；但透過 c 實體修改 first_name 之後，再次比較就不相同了，因為兩個是記憶體裡面兩個不同的物件。
  • preventing inconsistencies and making your application more efficient
  • Every association will attempt to automatically find the inverse association and set the :inverse_of option heuristically (based on the association name)
  • In database terms, this association says that this class contains the foreign key.
  • In all of these methods, association is replaced with the symbol passed as the first argument to belongs_to.
  • (force_reload = false)
  • The association method returns the associated object, if any. If no associated object is found, it returns nil.
  • the cached version will be returned.
  • The association= method assigns an associated object to this object.
  • Behind the scenes, this means extracting the primary key from the associate object and setting this object's foreign key to the same value.
  • The build_association method returns a new object of the associated type
  • but the associated object will not yet be saved.
  • The create_association method returns a new object of the associated type
  • once it passes all of the validations specified on the associated model, the associated object will be saved
  • raises ActiveRecord::RecordInvalid if the record is invalid.
  • dependent
  • counter_cache
  • :autosave :class_name :counter_cache :dependent :foreign_key :inverse_of :polymorphic :touch :validate
  • finding the number of belonging objects more efficient.
  • Although the :counter_cache option is specified on the model that includes the belongs_to declaration, the actual column must be added to the associated model.
  • add a column named orders_count to the Customer model.
  • :destroy, when the object is destroyed, destroy will be called on its associated objects.
  • deleted directly from the database without calling their destroy method.
  • Rails will not create foreign key columns for you
  • The :inverse_of option specifies the name of the has_many or has_one association that is the inverse of this association
  • set the :touch option to :true, then the updated_at or updated_on timestamp on the associated object will be set to the current time whenever this object is saved or destroyed
  • specify a particular timestamp attribute to update
  • If you set the :validate option to true, then associated objects will be validated whenever you save this object
  • By default, this is false: associated objects will not be validated when this object is saved.
  • where includes readonly select
  • make your code somewhat more efficient
  • no need to use includes for immediate associations
  • will be read-only when retrieved via the association
  • The select method lets you override the SQL SELECT clause that is used to retrieve data about the associated object
  • using the association.nil?
  • Assigning an object to a belongs_to association does not automatically save the object. It does not save the associated object either.
  • In database terms, this association says that the other class contains the foreign key.
  • the cached version will be returned.
  • :as :autosave :class_name :dependent :foreign_key :inverse_of :primary_key :source :source_type :through :validate
  • Setting the :as option indicates that this is a polymorphic association
  • :nullify causes the foreign key to be set to NULL. Callbacks are not executed.
  • It's necessary not to set or leave :nullify option for those associations that have NOT NULL database constraints.
  • The :source_type option specifies the source association type for a has_one :through association that proceeds through a polymorphic association.
  • The :source option specifies the source association name for a has_one :through association.
  • The :through option specifies a join model through which to perform the query
  • more efficient by including representatives in the association from suppliers to accounts
  • When you assign an object to a has_one association, that object is automatically saved (in order to update its foreign key).
  • If either of these saves fails due to validation errors, then the assignment statement returns false and the assignment itself is cancelled.
  • If the parent object (the one declaring the has_one association) is unsaved (that is, new_record? returns true) then the child objects are not saved.
  • If you want to assign an object to a has_one association without saving the object, use the association.build method
  • collection(force_reload = false) collection<<(object, ...) collection.delete(object, ...) collection.destroy(object, ...) collection=(objects) collection_singular_ids collection_singular_ids=(ids) collection.clear collection.empty? collection.size collection.find(...) collection.where(...) collection.exists?(...) collection.build(attributes = {}, ...) collection.create(attributes = {}) collection.create!(attributes = {})
  • In all of these methods, collection is replaced with the symbol passed as the first argument to has_many, and collection_singular is replaced with the singularized version of that symbol.
  • The collection<< method adds one or more objects to the collection by setting their foreign keys to the primary key of the calling model
  • The collection.delete method removes one or more objects from the collection by setting their foreign keys to NULL.
  • objects will be destroyed if they're associated with dependent: :destroy, and deleted if they're associated with dependent: :delete_all
  • The collection.destroy method removes one or more objects from the collection by running destroy on each object.
  • The collection_singular_ids method returns an array of the ids of the objects in the collection.
  • The collection_singular_ids= method makes the collection contain only the objects identified by the supplied primary key values, by adding and deleting as appropriate
  • The default strategy for has_many :through associations is delete_all, and for has_many associations is to set the foreign keys to NULL.
  • The collection.clear method removes all objects from the collection according to the strategy specified by the dependent option
  • uses the same syntax and options as ActiveRecord::Base.find
  • The collection.where method finds objects within the collection based on the conditions supplied but the objects are loaded lazily meaning that the database is queried only when the object(s) are accessed.
  • The collection.build method returns one or more new objects of the associated type. These objects will be instantiated from the passed attributes, and the link through their foreign key will be created, but the associated objects will not yet be saved.
  • The collection.create method returns a new object of the associated type. This object will be instantiated from the passed attributes, the link through its foreign key will be created, and, once it passes all of the validations specified on the associated model, the associated object will be saved.
  • :as :autosave :class_name :dependent :foreign_key :inverse_of :primary_key :source :source_type :through :validate
  • :delete_all causes all the associated objects to be deleted directly from the database (so callbacks will not execute)
  • :nullify causes the foreign keys to be set to NULL. Callbacks are not executed.
  • where includes readonly select
  • :conditions :through :polymorphic :foreign_key
  • By convention, Rails assumes that the column used to hold the primary key of the association is id. You can override this and explicitly specify the primary key with the :primary_key option.
  • The :source option specifies the source association name for a has_many :through association.
  • You only need to use this option if the name of the source association cannot be automatically inferred from the association name.
  • The :source_type option specifies the source association type for a has_many :through association that proceeds through a polymorphic association.
  • The :through option specifies a join model through which to perform the query.
  • has_many :through associations provide a way to implement many-to-many relationships,
  • By default, this is true: associated objects will be validated when this object is saved.
  • where extending group includes limit offset order readonly select uniq
  • If you use a hash-style where option, then record creation via this association will be automatically scoped using the hash
  • The extending method specifies a named module to extend the association proxy.
  • Association extensions
  • The group method supplies an attribute name to group the result set by, using a GROUP BY clause in the finder SQL.
  • has_many :line_items, -> { group 'orders.id' },                        through: :orders
  • more efficient by including line items in the association from customers to orders
  • The limit method lets you restrict the total number of objects that will be fetched through an association.
  • The offset method lets you specify the starting offset for fetching objects via an association
  • The order method dictates the order in which associated objects will be received (in the syntax used by an SQL ORDER BY clause).
  • Use the distinct method to keep the collection free of duplicates.
  • mostly useful together with the :through option
  • -> { distinct }
  • .all.inspect
  • If you want to make sure that, upon insertion, all of the records in the persisted association are distinct (so that you can be sure that when you inspect the association that you will never find duplicate records), you should add a unique index on the table itself
  • unique: true
  • Do not attempt to use include? to enforce distinctness in an association.
  • multiple users could be attempting this at the same time
  • checking for uniqueness using something like include? is subject to race conditions
  • When you assign an object to a has_many association, that object is automatically saved (in order to update its foreign key).
  • If any of these saves fails due to validation errors, then the assignment statement returns false and the assignment itself is cancelled.
  • If the parent object (the one declaring the has_many association) is unsaved (that is, new_record? returns true) then the child objects are not saved when they are added
  • All unsaved members of the association will automatically be saved when the parent is saved.
  • assign an object to a has_many association without saving the object, use the collection.build method
  • collection(force_reload = false) collection<<(object, ...) collection.delete(object, ...) collection.destroy(object, ...) collection=(objects) collection_singular_ids collection_singular_ids=(ids) collection.clear collection.empty? collection.size collection.find(...) collection.where(...) collection.exists?(...) collection.build(attributes = {}) collection.create(attributes = {}) collection.create!(attributes = {})
  • If the join table for a has_and_belongs_to_many association has additional columns beyond the two foreign keys, these columns will be added as attributes to records retrieved via that association.
  • Records returned with additional attributes will always be read-only
  • If you require this sort of complex behavior on the table that joins two models in a many-to-many relationship, you should use a has_many :through association instead of has_and_belongs_to_many.
  • aliased as collection.concat and collection.push.
  • The collection.delete method removes one or more objects from the collection by deleting records in the join table
  • not destroy the objects
  • The collection.destroy method removes one or more objects from the collection by running destroy on each record in the join table, including running callbacks.
  • not destroy the objects.
  • The collection.clear method removes every object from the collection by deleting the rows from the joining table.
  • not destroy the associated objects.
  • The collection.find method finds objects within the collection. It uses the same syntax and options as ActiveRecord::Base.find.
  • The collection.where method finds objects within the collection based on the conditions supplied but the objects are loaded lazily meaning that the database is queried only when the object(s) are accessed.
  • The collection.exists? method checks whether an object meeting the supplied conditions exists in the collection.
  • The collection.build method returns a new object of the associated type.
  • the associated object will not yet be saved.
  • the associated object will be saved.
  • The collection.create method returns a new object of the associated type.
  • it passes all of the validations specified on the associated model
  • :association_foreign_key :autosave :class_name :foreign_key :join_table :validate
  • The :foreign_key and :association_foreign_key options are useful when setting up a many-to-many self-join.
  • Rails assumes that the column in the join table used to hold the foreign key pointing to the other model is the name of that model with the suffix _id added.
  • If you set the :autosave option to true, Rails will save any loaded members and destroy members that are marked for destruction whenever you save the parent object.
  • By convention, Rails assumes that the column in the join table used to hold the foreign key pointing to this model is the name of this model with the suffix _id added.
  • By default, this is true: associated objects will be validated when this object is saved.
  • where extending group includes limit offset order readonly select uniq
  • set conditions via a hash
  • In this case, using @parts.assemblies.create or @parts.assemblies.build will create orders where the factory column has the value "Seattle"
  • If you use a hash-style where, then record creation via this association will be automatically scoped using the hash
  • using a GROUP BY clause in the finder SQL.
  • Use the uniq method to remove duplicates from the collection.
  • assign an object to a has_and_belongs_to_many association, that object is automatically saved (in order to update the join table).
  • If any of these saves fails due to validation errors, then the assignment statement returns false and the assignment itself is cancelled.
  • If the parent object (the one declaring the has_and_belongs_to_many association) is unsaved (that is, new_record? returns true) then the child objects are not saved when they are added.
  • If you want to assign an object to a has_and_belongs_to_many association without saving the object, use the collection.build method.
  • Normal callbacks hook into the life cycle of Active Record objects, allowing you to work with those objects at various points
  • define association callbacks by adding options to the association declaration
  • Rails passes the object being added or removed to the callback.
  • stack callbacks on a single event by passing them as an array
  • If a before_add callback throws an exception, the object does not get added to the collection.
  • if a before_remove callback throws an exception, the object does not get removed from the collection
  • extend these objects through anonymous modules, adding new finders, creators, or other methods.
  • order_number
  • use a named extension module
  • proxy_association.owner returns the object that the association is a part of.
crazylion lee

coreos/torus: Torus Distributed Storage - 1 views

github.com/torus

distributed storage

shared by crazylion lee on 06 Jun 16 - No Cached
  • crazylion lee on 06 Jun 16
     
    "Torus is an open source project for distributed storage coordinated through etcd. Torus provides a resource pool and basic file primitives from a set of daemons running atop multiple nodes. These primitives are made consistent by being append-only and coordinated by etcd. From these primitives, a Torus server can support multiple types of volumes, the semantics of which can be broken into subprojects. It ships with a simple block-device volume plugin, but is extensible to more."
crazylion lee

GNU Octave - 0 views

www.gnu.org/octave

matlab opensource math

shared by crazylion lee on 10 Jun 16 - No Cached
  • crazylion lee on 10 Jun 16
     
    "GNU Octave is a high-level interpreted language, primarily intended for numerical computations. It provides capabilities for the numerical solution of linear and nonlinear problems, and for performing other numerical experiments. It also provides extensive graphics capabilities for data visualization and manipulation. Octave is normally used through its interactive command line interface, but it can also be used to write non-interactive programs. The Octave language is quite similar to Matlab so that most programs are easily portable."
張 旭

certificate - What is a Pem file and how does it differ from other OpenSSL Generated Ke... - 0 views

serverfault.com/...her-openssl-generated-key-file

https security server apache nginx system

shared by 張 旭 on 22 Feb 17 - No Cached
  • Certificate Signing Request.
  • Some applications can generate these for submission to certificate-authorities
  • These get signed by the CA and a certificate is returned
  • ...15 more annotations...
  • The returned certificate is the public certificate (which includes the public key but not the private key), which itself can be in a couple of formats.
  • this is a container format that may include just the public certificate (such as with Apache installs, and CA certificate files /etc/ssl/certs), or may include an entire certificate chain including public key, private key, and root certificates
  • Privacy Enhanced Mail (PEM), a failed method for secure email but the container format it used lives on
  • This is a PEM formatted file containing just the private-key of a specific certificate and is merely a conventional name and not a standardized one.
  • The rights on these files are very important
  • /etc/ssl/private
  • OpenSSL can convert these to .pem
  • .cert .cer .crt A .pem (or rarely .der) formatted file with a different extension
  • there are four different ways to present certificates and their components
  • used preferentially by open-source software
  • It can have a variety of extensions (.pem, .key, .cer, .cert, more)
  • The parent format of PEM
  • a binary version of the base64-encoded PEM file.
  • PEM on it's own isn't a certificate, it's just a way of encoding data
  • X.509 certificates are one type of data that is commonly encoded using PEM.
crazylion lee

Hjson, a user interface for JSON - 0 views

hjson.org

json

shared by crazylion lee on 04 Apr 17 - No Cached
  • crazylion lee on 04 Apr 17
     
    "JSON is easy for humans to read and write... in theory. In practice JSON gives us plenty of opportunities to make mistakes without even realizing it. Hjson is a syntax extension to JSON. It's NOT a proposal to replace JSON or to incorporate it into the JSON spec itself. It's intended to be used like a user interface for humans, to read and edit before passing the JSON data to the machine."
crazylion lee

jkbrzt/httpie - 0 views

github.com/httpie

curl

shared by crazylion lee on 08 Aug 15 - No Cached
  • crazylion lee on 08 Aug 15
     
    "CLI HTTP client; user-friendly cURL replacement featuring intuitive UI, JSON support, syntax highlighting, wget-like downloads, extensions, etc. http://httpie.org"
crazylion lee

Scrapy | A Fast and Powerful Scraping and Web Crawling Framework - 0 views

scrapy.org

Python Crawler web framework

shared by crazylion lee on 15 Oct 15 - Cached
  • crazylion lee on 15 Oct 15
     
    "An open source and collaborative framework for extracting the data you need from websites. In a fast, simple, yet extensible way."
張 旭

Secrets Management with Terraform - 0 views

www.linode.com/...rets-management-with-terraform

terraform config devops security

shared by 張 旭 on 12 Apr 19 - No Cached
  • Terraform is an Infrastructure as Code (IaC) tool that allows you to write declarative code to manage your infrastructure.
  • Keeping Secrets Out of .tf Files
  • .tf files contain the declarative code used to create, manage, and destroy infrastructure.
  • ...17 more annotations...
  • .tf files can accept values from input variables.
  • variable definitions can have default values assigned to them.
  • values are stored in separate files with the .tfvars extension.
  • looks through the working directory for a file named terraform.tfvars, or for files with the .auto.tfvars extension.
  • add the terraform.tfvars file to your .gitignore file and keep it out of version control.
  • include an example terraform.tfvars.example in your Git repository with all of the variable names recorded (but none of the values entered).
  • terraform apply -var-file=myvars.tfvars
  • Terraform allows you to keep input variable values in environment variables.
  • the prefix TF_VAR_
  • If Terraform does not find a default value for a defined variable; or a value from a .tfvars file, environment variable, or CLI flag; it will prompt you for a value before running an action
  • state file contains a JSON object that holds your managed infrastructure’s current state
  • state is a snapshot of the various attributes of your infrastructure at the time it was last modified
  • sensitive information used to generate your Terraform state can be stored as plain text in the terraform.tfstate file.
  • Avoid checking your terraform.tfstate file into your version control repository.
  • Some backends, like Consul, also allow for state locking. If one user is applying a state, another user will be unable to make any changes.
  • Terraform backends allow the user to securely store their state in a remote location, such as a key/value store like Consul, or an S3 compatible bucket storage like Minio.
  • at minimum the repository should be private.
張 旭

Warnings, Notes, & Tips - 0 views

clouddocs.f5.com/...tips-warnings.html

terraform networking network firewall bigip

shared by 張 旭 on 04 May 20 - No Cached
  • AS3 manages topology records globally in /Common, it is required that records only be managed through AS3, as it will treat the records declaratively.
  • If a record is added outside of AS3, it will be removed if it is not included in the next AS3 declaration for topology records (AS3 completely overwrites non-AS3 topologies when a declaration is submitted).
  • using AS3 to delete a tenant (for example, sending DELETE to the /declare/<TENANT> endpoint) that contains GSLB topologies will completely remove ALL GSLB topologies from the BIG-IP.
  • ...12 more annotations...
  • When posting a large declaration (hundreds of application services in a single declaration), you may experience a 500 error stating that the save sys config operation failed.
  • Even if you have asynchronous mode set to false, after 45 seconds AS3 sets asynchronous mode to true (API swap), and returns an async response.
  • When creating a new tenant using AS3, it must not use the same name as a partition you separately create on the target BIG-IP system.
  • If you use the same name and then post the declaration, AS3 overwrites (or removes) the existing partition completely, including all configuration objects in that partition.
  • use AS3 to create a tenant (which creates a BIG-IP partition), manually adding configuration objects to the partition created by AS3 can have unexpected results
  • When you delete the Tenant using AS3, the system deletes both virtual servers.
  • if a Firewall_Address_List contains zero addresses, a dummy IPv6 address of ::1:5ee:bad:c0de is added in order to maintain a valid Firewall_Address_List. If an address is added to the list, the dummy address is removed.
  • use /mgmt/shared/appsvcs/declare?async=true if you have a particularly large declaration which will take a long time to process.
  • reviewing the Sizing BIG-IP Virtual Editions section (page 7) of Deploying BIG-IP VEs in a Hyper-Converged Infrastructure
  • To test whether your system has AS3 installed or not, use GET with the /mgmt/shared/appsvcs/info URI.
  • You may find it more convenient to put multi-line texts such as iRules into AS3 declarations by first encoding them in Base64.
  • no matter your BIG-IP user account name, audit logs show all messages from admin and not the specific user name.
crazylion lee

Cello * High Level C - 0 views

libcello.org

c library high level

shared by crazylion lee on 16 Apr 17 - No Cached
  • crazylion lee on 16 Apr 17
     
    "Cello is a library that brings higher level programming to C. By acting as a modern, powerful runtime system Cello makes many things easy that were previously impractical or awkward in C such as: Generic Data Structures Polymorphic Functions Interfaces / Type Classes Constructors / Destructors Optional Garbage Collection Exceptions Reflection And because Cello works seamlessly alongside standard C you get all the other benefits such as great performance, powerful tooling, and extensive libraries."
張 旭

Custom Resources | Kubernetes - 0 views

kubernetes.io/...custom-resources

kubernetes

shared by 張 旭 on 11 May 21 - No Cached
  • Custom resources are extensions of the Kubernetes API
  • A resource is an endpoint in the Kubernetes API that stores a collection of API objects of a certain kind
  • Custom resources can appear and disappear in a running cluster through dynamic registration
  • ...30 more annotations...
  • Once a custom resource is installed, users can create and access its objects using kubectl
  • When you combine a custom resource with a custom controller, custom resources provide a true declarative API.
  • A declarative API allows you to declare or specify the desired state of your resource and tries to keep the current state of Kubernetes objects in sync with the desired state.
  • Custom controllers can work with any kind of resource, but they are especially effective when combined with custom resources.
  • The Operator pattern combines custom resources and custom controllers.
  • the API represents a desired state, not an exact state.
  • define configuration of applications or infrastructure.
  • The main operations on the objects are CRUD-y (creating, reading, updating and deleting).
  • The client says "do this", and then gets an operation ID back, and has to check a separate Operation object to determine completion of the request.
  • The natural operations on the objects are not CRUD-y.
  • High bandwidth access (10s of requests per second sustained) needed.
  • Use a ConfigMap if any of the following apply
  • You want to put the entire config file into one key of a configMap.
  • You want to perform rolling updates via Deployment, etc., when the file is updated.
  • Use a secret for sensitive data, which is similar to a configMap but more secure.
  • You want to build new automation that watches for updates on the new object, and then CRUD other objects, or vice versa.
  • You want the object to be an abstraction over a collection of controlled resources, or a summarization of other resources.
  • CRDs are simple and can be created without any programming.
  • Aggregated APIs are subordinate API servers that sit behind the primary API server
  • CRDs allow users to create new types of resources without adding another API server
  • Defining a CRD object creates a new custom resource with a name and schema that you specify.
  • The name of a CRD object must be a valid DNS subdomain name
  • each resource in the Kubernetes API requires code that handles REST requests and manages persistent storage of objects.
  • The main API server delegates requests to you for the custom resources that you handle, making them available to all of its clients.
  • The new endpoints support CRUD basic operations via HTTP and kubectl
  • Custom resources consume storage space in the same way that ConfigMaps do.
  • Aggregated API servers may use the same storage as the main API server
  • CRDs always use the same authentication, authorization, and audit logging as the built-in resources of your API server.
  • most RBAC roles will not grant access to the new resources (except the cluster-admin role or any role created with wildcard rules).
  • CRDs and Aggregated APIs often come bundled with new role definitions for the types they add.
張 旭

javascript - How do I "think in AngularJS" if I have a jQuery background? - Stack Overflow - 0 views

stackoverflow.com/...-if-i-have-a-jquery-background

jquery javascript angular programming architecture development google angularjs web

shared by 張 旭 on 02 Oct 13 - No Cached
  • in AngularJS, we have a separate model layer that we can manage in any way we want, completely independently from the view.
  • keep your concerns separate
  • do DOM manipulation and augment your view with directives
  • ...34 more annotations...
  • DI means that you can declare components very freely and then from any other component, just ask for an instance of it and it will be granted
  • do test-driven development iteratively in AngularJS!
  • only do DOM manipulation in a directive
  • with ngClass we can dynamically update the class;
  • ngBind allows two-way data binding;
  • ngShow and ngHide programmatically show or hide an element;
  • The less DOM manipulation, the easier directives are to test, the easier they are to style, the easier they are to change in the future, and the more re-usable and distributable they are.
  • still wrong.
  • Before doing DOM manipulation anywhere in your application, ask yourself if you really need to.
  • a few things wrong with this
  • jQuery was never necessary
  • use angular.element and our component will still work when dropped into a project that doesn't have jQuery.
  • just use angular.element
  • the element that is passed to the link function would already be a jQuery element!
  • directives aren't just collections of jQuery-like functions
  • Directives are actually extensions of HTML
  • If HTML doesn't do something you need it to do, you write a directive to do it for you, and then use it just as if it was part of HTML.
  • think how the team would accomplish it to fit right in with ngClick, ngClass, et al.
  • Don't even use jQuery. Don't even include it.
  • ry to think about how to do it within the confines the AngularJS.
  • In jQuery, selectors are used to find DOM elements and then bind/register event handlers to them.
  • Views are (declarative) HTML that contain AngularJS directives
  • Directives set up the event handlers behind the scenes for us and give us dynamic databinding.
  • Views are tied to models (via scopes). Views are a projection of the model
  • In AngularJS, think about models, rather than jQuery-selected DOM elements that hold your data.
  • AngularJS uses controllers and directives (each of which can have their own controller, and/or compile and linking functions) to remove behavior from the view/structure (HTML). Angular also has services and filters to help separate/organize your application.
  • Think about your models
  • Think about how you want to present your models -- your views.
  • using the necessary directives to get dynamic databinding.
  • Attach a controller to each view (using ng-view and routing, or ng-controller)
  • Make controllers as thin as possible.
  • You can do a lot with jQuery without knowing about how JavaScript prototypal inheritance works.
  • jQuery is a library
  • AngularJS is a beautiful client-side framework
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.
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