Skip to main content

Home/ Larvata/ Group items tagged reference

Rss Feed Group items tagged

Filter: All | Bookmarks | Topics Simple Middle
張 旭

Keycloak and FreeIPA Intro - scott poore's blog - 0 views

spoore.wordpress.com/...keycloak-and-freeipa-intro

authorization authentication oauth system security freeipa user ldap

shared by 張 旭 on 12 Jul 19 - No Cached
  • Keycloak is an “Open source identity and access management” solution.
  • setup a central Identity Provider (IdP) that applications acting as Service Providers (SP) use to authenticate or authorize user access.
  • FreeIPA does a LOT more than just provide user info though.  It can manage user groups, service lists, hosts, DNS, certificates, and much, much, more.
  • ...5 more annotations...
  • IPA – refers to the FreeIPA Master Server.
  • IdP – as mentioned earlier, IdP stands for Identity Provider.
  • SP – stands for Service Provider.   This can be a java application, jboss, etc.  It can also be a simple Apache web server
  • SAML – stands for Security Assertion Markup Language and refers to mod_auth_mellon here.  This provides the SSO functionality.
  • Openidc – stands for OpenID Connect.
張 旭

MongoDB Performance Tuning: Everything You Need to Know - Stackify - 0 views

stackify.com/mongodb-performance-tuning

database mongodb

shared by 張 旭 on 15 Apr 21 - No Cached
  • db.serverStatus().globalLock
  • db.serverStatus().locks
  • globalLock.currentQueue.total: This number can indicate a possible concurrency issue if it’s consistently high. This can happen if a lot of requests are waiting for a lock to be released.
  • ...35 more annotations...
  • globalLock.totalTime: If this is higher than the total database uptime, the database has been in a lock state for too long.
  • Unlike relational databases such as MySQL or PostgreSQL, MongoDB uses JSON-like documents for storing data.
  • Databases operate in an environment that consists of numerous reads, writes, and updates.
  • When a lock occurs, no other operation can read or modify the data until the operation that initiated the lock is finished.
  • locks.deadlockCount: Number of times the lock acquisitions have encountered deadlocks
  • Is the database frequently locking from queries? This might indicate issues with the schema design, query structure, or system architecture.
  • For version 3.2 on, WiredTiger is the default.
  • MMAPv1 locks whole collections, not individual documents.
  • WiredTiger performs locking at the document level.
  • When the MMAPv1 storage engine is in use, MongoDB will use memory-mapped files to store data.
  • All available memory will be allocated for this usage if the data set is large enough.
  • db.serverStatus().mem
  • mem.resident: Roughly equivalent to the amount of RAM in megabytes that the database process uses
  • If mem.resident exceeds the value of system memory and there’s a large amount of unmapped data on disk, we’ve most likely exceeded system capacity.
  • If the value of mem.mapped is greater than the amount of system memory, some operations will experience page faults.
  • The WiredTiger storage engine is a significant improvement over MMAPv1 in performance and concurrency.
  • By default, MongoDB will reserve 50 percent of the available memory for the WiredTiger data cache.
  • wiredTiger.cache.bytes currently in the cache – This is the size of the data currently in the cache.
  • wiredTiger.cache.tracked dirty bytes in the cache – This is the size of the dirty data in the cache.
  • we can look at the wiredTiger.cache.bytes read into cache value for read-heavy applications. If this value is consistently high, increasing the cache size may improve overall read performance.
  • check whether the application is read-heavy. If it is, increase the size of the replica set and distribute the read operations to secondary members of the set.
  • write-heavy, use sharding within a sharded cluster to distribute the load.
  • Replication is the propagation of data from one node to another
  • Replication sets handle this replication.
  • Sometimes, data isn’t replicated as quickly as we’d like.
  • a particularly thorny problem if the lag between a primary and secondary node is high and the secondary becomes the primary
  • use the db.printSlaveReplicationInfo() or the rs.printSlaveReplicationInfo() command to see the status of a replica set from the perspective of the secondary member of the set.
  • shows how far behind the secondary members are from the primary. This number should be as low as possible.
  • monitor this metric closely.
  • watch for any spikes in replication delay.
  • Always investigate these issues to understand the reasons for the lag.
  • One replica set is primary. All others are secondary.
  • it’s not normal for nodes to change back and forth between primary and secondary.
  • use the profiler to gain a deeper understanding of the database’s behavior.
  • Enabling the profiler can affect system performance, due to the additional activity.
  • 張 旭 on 15 Apr 21
     
    "globalLock.currentQueue.total: This number can indicate a possible concurrency issue if it's consistently high. This can happen if a lot of requests are waiting for a lock to be released."
張 旭

Connection and Privileges Needed - 0 views

www.percona.com/...privileges.html

mysql database backup percona xtradb

shared by 張 旭 on 02 Dec 19 - No Cached
  • Percona XtraBackup needs to be able to connect to the database server and perform operations on the server and the datadir when creating a backup, when preparing in some scenarios and when restoring it.
  • When xtrabackup is used, there are two actors involved: the user invoking the program - a system user - and the user performing action in the database server - a database user.
  • these are different users in different places, even though they may have the same username.
  • ...1 more annotation...
  • Once connected to the server, in order to perform a backup you will need READ and EXECUTE permissions at a filesystem level in the server’s datadir.
  • 張 旭 on 02 Dec 19
     
    "Percona XtraBackup needs to be able to connect to the database server and perform operations on the server and the datadir when creating a backup, when preparing in some scenarios and when restoring it. "
張 旭

Deploy a Replica Set - MongoDB Manual - 0 views

docs.mongodb.com/...deploy-replica-set

database mongodb

shared by 張 旭 on 13 Oct 20 - No Cached
  • Three member replica sets provide enough redundancy to survive most network partitions and other system failures.
張 旭

Convert a Standalone to a Replica Set - MongoDB Manual - 0 views

docs.mongodb.com/...vert-standalone-to-replica-set

database mongodb

shared by 張 旭 on 13 Oct 20 - No Cached
  • Restart the instance. Use the --replSet option to specify the name of the new replica set.
  • 張 旭 on 13 Oct 20
     
    "Restart the instance. Use the --replSet option to specify the name of the new replica set. "
張 旭

The for_each Meta-Argument - Configuration Language | Terraform | HashiCorp Developer - 0 views

developer.hashicorp.com/...for_each

devops terraform

shared by 張 旭 on 23 Jan 23 - No Cached
  • A given resource or module block cannot use both count and for_each
  • The for_each meta-argument accepts a map or a set of strings, and creates an instance for each item in that map or set
  • each.key — The map key (or set member) corresponding to this instance.
  • ...10 more annotations...
  • each.value — The map value corresponding to this instance. (If a set was provided, this is the same as each.key.)
  • for_each keys cannot be the result (or rely on the result of) of impure functions, including uuid, bcrypt, or timestamp, as their evaluation is deferred during the main evaluation step.
  • The value used in for_each is used to identify the resource instance and will always be disclosed in UI output, which is why sensitive values are not allowed.
  • if you would like to call keys(local.map), where local.map is an object with sensitive values (but non-sensitive keys), you can create a value to pass to for_each with toset([for k,v in local.map : k]).
  • for_each can't refer to any resource attributes that aren't known until after a configuration is applied (such as a unique ID generated by the remote API when an object is created).
  • he for_each argument does not implicitly convert lists or tuples to sets.
  • Transform a multi-level nested structure into a flat list by using nested for expressions with the flatten function.
  • Instances are identified by a map key (or set member) from the value provided to for_each
  • Within nested provisioner or connection blocks, the special self object refers to the current resource instance, not the resource block as a whole.
  • Conversion from list to set discards the ordering of the items in the list and removes any duplicate elements.
張 旭

Container Runtimes | Kubernetes - 0 views

kubernetes.io/...container-runtimes

kubernetes container docker devops

shared by 張 旭 on 25 Jan 23 - No Cached
  • Kubernetes releases before v1.24 included a direct integration with Docker Engine, using a component named dockershim. That special direct integration is no longer part of Kubernetes
  • You need to install a container runtime into each node in the cluster so that Pods can run there.
  • Kubernetes 1.26 requires that you use a runtime that conforms with the Container Runtime Interface (CRI).
  • ...9 more annotations...
  • On Linux, control groups are used to constrain resources that are allocated to processes.
  • Both kubelet and the underlying container runtime need to interface with control groups to enforce resource management for pods and containers and set resources such as cpu/memory requests and limits.
  • When the cgroupfs driver is used, the kubelet and the container runtime directly interface with the cgroup filesystem to configure cgroups.
  • The cgroupfs driver is not recommended when systemd is the init system
  • When systemd is chosen as the init system for a Linux distribution, the init process generates and consumes a root control group (cgroup) and acts as a cgroup manager.
  • Two cgroup managers result in two views of the available and in-use resources in the system.
  • Changing the cgroup driver of a Node that has joined a cluster is a sensitive operation. If the kubelet has created Pods using the semantics of one cgroup driver, changing the container runtime to another cgroup driver can cause errors when trying to re-create the Pod sandbox for such existing Pods. Restarting the kubelet may not solve such errors.
  • The approach to mitigate this instability is to use systemd as the cgroup driver for the kubelet and the container runtime when systemd is the selected init system.
  • Kubernetes 1.26 defaults to using v1 of the CRI API. If a container runtime does not support the v1 API, the kubelet falls back to using the (deprecated) v1alpha2 API instead.
張 旭

Choose when to run jobs | GitLab - 0 views

docs.gitlab.com/...job_control.html

gitlab devops cicd

shared by 張 旭 on 28 Dec 21 - No Cached
  • Rules are evaluated in order until the first match.
  • no rules match, so the job is not added to any other pipeline.
  • define a set of rules to exclude jobs in a few cases, but run them in all other cases
  • ...32 more annotations...
  • use all rules keywords, like if, changes, and exists, in the same rule. The rule evaluates to true only when all included keywords evaluate to true.
  • use parentheses with && and || to build more complicated variable expressions.
  • Use workflow to specify which types of pipelines can run.
  • every push to an open merge request’s source branch causes duplicated pipelines.
  • avoid duplicate pipelines by changing the job rules to avoid either push (branch) pipelines or merge request pipelines.
  • do not mix only/except jobs with rules jobs in the same pipeline.
  • For behavior similar to the only/except keywords, you can check the value of the $CI_PIPELINE_SOURCE variable
  • commonly used variables for if clauses
  • rules:changes expressions to determine when to add jobs to a pipeline
  • Use !reference tags to reuse rules in different jobs.
  • Use except to define when a job does not run.
  • only or except used without refs is the same as only:refs / except/refs
  • If you change multiple files, but only one file ends in .md, the build job is still skipped.
  • If you use multiple keywords with only or except, the keywords are evaluated as a single conjoined expression.
  • only includes the job if all of the keys have at least one condition that matches.
  • except excludes the job if any of the keys have at least one condition that matches.
  • With only, individual keys are logically joined by an AND
  • With except, individual keys are logically joined by an OR
  • To specify a job as manual, add when: manual to the job in the .gitlab-ci.yml file.
  • Use protected environments to define a list of users authorized to run a manual job.
  • Use when: delayed to execute scripts after a waiting period, or if you want to avoid jobs immediately entering the pending state.
  • To split a large job into multiple smaller jobs that run in parallel, use the parallel keyword
  • run a trigger job multiple times in parallel in a single pipeline, but with different variable values for each instance of the job.
  • The @ symbol denotes the beginning of a ref’s repository path. To match a ref name that contains the @ character in a regular expression, you must use the hex character code match \x40.
  • Compare a variable to a string
  • Check if a variable is undefined
  • Check if a variable is empty
  • Check if a variable exists
  • Check if a variable is empty
  • Matches are found when using =~.
  • Matches are not found when using !~.
  • Join variable expressions together with && or ||
  • 張 旭 on 28 Dec 21
     
    "Rules are evaluated in order until the first match."
張 旭

kube-proxy | Kubernetes - 0 views

kubernetes.io/...kube-proxy

kubernetes networking

shared by 張 旭 on 09 Jun 22 - No Cached
  • The Kubernetes network proxy runs on each node. This reflects services as defined in the Kubernetes API on each node and can do simple TCP, UDP, and SCTP stream forwarding or round robin TCP, UDP, and SCTP forwarding across a set of backends.
  • Service cluster IPs and ports are currently found through Docker-links-compatible environment variables specifying ports opened by the service proxy.
  • 張 旭 on 09 Jun 22
     
    "The Kubernetes network proxy runs on each node. This reflects services as defined in the Kubernetes API on each node and can do simple TCP, UDP, and SCTP stream forwarding or round robin TCP, UDP, and SCTP forwarding across a set of backends."
張 旭

Building a RESTful API in a Rails application - 0 views

www.airpair.com/...ful-api-in-a-rails-application

rails api REST

shared by 張 旭 on 05 Dec 16 - No Cached
  • designing and implementing a REST API in an intentionally simplistic task management web application, and will cover some best practices to ensure maintainability of the code.
  • each individual request should have no context of the requests that came before it.
  • each request that modifies the database should act on one and only one row of one and only one table
  • ...10 more annotations...
  • The resource endpoints should return representations of the resource as data, usually XML or JSON.
  • POST for create, PUT for update, PATCH for upsert (update and insert).
  • an existing API should never be modified, except for critical bugfixes
  • Rather than changing existing endpoints, expose a new version
  • using unique database ids in the route chain allows users to access short routes, and simplifies resource lookup
  • while exposing internal database ids to the consumer and requiring the consumer to maintain a reference to ids on their end
  • The downfall is longer nested routes
  • require reauthentication on a per-request level
  • Devise.secure_compare helps avoid timing attacks
  • Defensive programming is a software design principle that dictates that a piece of software should be designed to continue functioning in unforeseen circumstances.
張 旭

Rails Routing from the Outside In - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/routing.html

rails router path url namespace

shared by 張 旭 on 09 Mar 14 - Cached
  • Resource routing allows you to quickly declare all of the common routes for a given resourceful controller.
  • Rails would dispatch that request to the destroy method on the photos controller with { id: '17' } in params.
  • a resourceful route provides a mapping between HTTP verbs and URLs to controller actions.
  • ...86 more annotations...
  • each action also maps to particular CRUD operations in a database
  • resource :photo and resources :photos creates both singular and plural routes that map to the same controller (PhotosController).
  • One way to avoid deep nesting (as recommended above) is to generate the collection actions scoped under the parent, so as to get a sense of the hierarchy, but to not nest the member actions.
  • to only build routes with the minimal amount of information to uniquely identify the resource
  • The shallow method of the DSL creates a scope inside of which every nesting is shallow
  • These concerns can be used in resources to avoid code duplication and share behavior across routes
  • add a member route, just add a member block into the resource block
  • You can leave out the :on option, this will create the same member route except that the resource id value will be available in params[:photo_id] instead of params[:id].
  • Singular Resources
  • use a singular resource to map /profile (rather than /profile/:id) to the show action
  • Passing a String to get will expect a controller#action format
  • workaround
  • organize groups of controllers under a namespace
  • route /articles (without the prefix /admin) to Admin::ArticlesController
  • route /admin/articles to ArticlesController (without the Admin:: module prefix)
  • Nested routes allow you to capture this relationship in your routing.
  • helpers take an instance of Magazine as the first parameter (magazine_ads_url(@magazine)).
  • Resources should never be nested more than 1 level deep.
  • via the :shallow option
  • a balance between descriptive routes and deep nesting
  • :shallow_path prefixes member paths with the specified parameter
  • Routing Concerns allows you to declare common routes that can be reused inside other resources and routes
  • Rails can also create paths and URLs from an array of parameters.
  • use url_for with a set of objects
  • In helpers like link_to, you can specify just the object in place of the full url_for call
  • insert the action name as the first element of the array
  • This will recognize /photos/1/preview with GET, and route to the preview action of PhotosController, with the resource id value passed in params[:id]. It will also create the preview_photo_url and preview_photo_path helpers.
  • pass :on to a route, eliminating the block:
  • Collection Routes
  • This will enable Rails to recognize paths such as /photos/search with GET, and route to the search action of PhotosController. It will also create the search_photos_url and search_photos_path route helpers.
  • simple routing makes it very easy to map legacy URLs to new Rails actions
  • add an alternate new action using the :on shortcut
  • When you set up a regular route, you supply a series of symbols that Rails maps to parts of an incoming HTTP request.
  • :controller maps to the name of a controller in your application
  • :action maps to the name of an action within that controller
  • optional parameters, denoted by parentheses
  • This route will also route the incoming request of /photos to PhotosController#index, since :action and :id are
  • use a constraint on :controller that matches the namespace you require
  • dynamic segments don't accept dots
  • The params will also include any parameters from the query string
  • :defaults option.
  • set params[:format] to "jpg"
  • cannot override defaults via query parameters
  • specify a name for any route using the :as option
  • create logout_path and logout_url as named helpers in your application.
  • Inside the show action of UsersController, params[:username] will contain the username for the user.
  • should use the get, post, put, patch and delete methods to constrain a route to a particular verb.
  • use the match method with the :via option to match multiple verbs at once
  • Routing both GET and POST requests to a single action has security implications
  • 'GET' in Rails won't check for CSRF token. You should never write to the database from 'GET' requests
  • use the :constraints option to enforce a format for a dynamic segment
  • constraints
  • don't need to use anchors
  • Request-Based Constraints
  • the same name as the hash key and then compare the return value with the hash value.
  • constraint values should match the corresponding Request object method return type
    • 張 旭
      張 旭 on 11 Apr 16
       
      應該就是檢查來源的 request， 如果是某個特定的 request 來訪問的，就通過。
  • blacklist
    • 張 旭
      張 旭 on 11 Apr 16
       
      這裡有點複雜 ...
  • redirect helper
  • reuse dynamic segments from the match in the path to redirect
  • this redirection is a 301 "Moved Permanently" redirect.
  • root method
  • put the root route at the top of the file
  • The root route only routes GET requests to the action.
  • root inside namespaces and scopes
  • For namespaced controllers you can use the directory notation
  • Only the directory notation is supported
  • use the :constraints option to specify a required format on the implicit id
  • specify a single constraint to apply to a number of routes by using the block
  • non-resourceful routes
  • :id parameter doesn't accept dots
  • :as option lets you override the normal naming for the named route helpers
  • use the :as option to prefix the named route helpers that Rails generates for a rout
  • prevent name collisions
  • prefix routes with a named parameter
  • This will provide you with URLs such as /bob/articles/1 and will allow you to reference the username part of the path as params[:username] in controllers, helpers and views
  • :only option
  • :except option
  • generate only the routes that you actually need can cut down on memory use and speed up the routing process.
  • alter path names
  • http://localhost:3000/rails/info/routes
  • rake routes
  • setting the CONTROLLER environment variable
  • Routes should be included in your testing strategy
  • assert_generates assert_recognizes assert_routing
張 旭

Blog Tutorial - Adding a layer - CakePHP Cookbook v2.x documentation - 1 views

book.cakephp.org/...part-two.html

cakephp MVC framework php development

shared by 張 旭 on 08 Sep 13 - No Cached
  • Cake views are just presentation-flavored fragments that fit inside an application’s layout. For most applications they’re HTML mixed with PHP, but they may end up as XML, CSV, or even binary data.
  • Layouts are presentation code that is wrapped around a view, and can be defined and switched between
  • if the HTTP method of the request was POST, try to save the data using the Post model.
  • ...6 more annotations...
  • You can also specify URLs relative to the base of the application in the form of /controller/action/param1/param2.
  • Every CakePHP request includes a CakeRequest object which is accessible using $this->request.
  • When a user uses a form to POST data to your application, that information is available in $this->request->data.
  • The $this->Form->input() method is used to create form elements of the same name.
  • postLink() will create a link that uses Javascript to do a POST request deleting our post.
  • Allowing content to be deleted using GET requests is dangerous
張 旭

Best practices for writing Dockerfiles - Docker Documentation - 0 views

docs.docker.com/...dockerfile_best-practices

docker tutorial deploy

shared by 張 旭 on 29 May 15 - No Cached
  • Run only one process per container
  • use current Official Repositories as the basis for your image
  • put long or complex RUN statements on multiple lines separated with backslashes.
  • ...16 more annotations...
  • CMD instruction should be used to run the software contained by your image, along with any arguments
  • CMD should be given an interactive shell (bash, python, perl, etc)
  • COPY them individually, rather than all at once
  • COPY is preferred
  • using ADD to fetch packages from remote URLs is strongly discouraged
  • always use COPY
  • The best use for ENTRYPOINT is to set the image's main command, allowing that image to be run as though it was that command (and then use CMD as the default flags).
  • the image name can double as a reference to the binary as shown in the command above
  • ENTRYPOINT instruction can also be used in combination with a helper script
  • The VOLUME instruction should be used to expose any database storage area, configuration storage, or files/folders created by your docker container.
  • use USER to change to a non-root user
  • avoid installing or using sudo
  • avoid switching USER back and forth frequently.
  • always use absolute paths for your WORKDIR
  • ONBUILD is only useful for images that are going to be built FROM a given image
  • The “onbuild” image will fail catastrophically if the new build's context is missing the resource being added.
張 旭

Active Record Migrations - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/migrations.html

rails migration ruby database model

shared by 張 旭 on 24 Jan 14 - Cached
  • a convenient way to alter your database schema
  • each migration as being a new 'version' of the database
  • On databases that support transactions with statements that change the schema, migrations are wrapped in a transaction
  • ...14 more annotations...
  • a UTC timestamp identifying the migration
  • references(also available as belongs_to)
  • produce join tables if JoinTable is part of the name
  • The model and scaffold generators will create migrations appropriate for adding a new model
  • The create_table method is one of the most fundamental
  • By default, create_table will create a primary key called id
  • the default is ENGINE=InnoDB
  • Migration method create_join_table creates a HABTM join table.
  • By default, create_join_table will create two columns with no options
  • change_table, used for changing existing tables
  • execute method to execute arbitrary SQL
  • The change method is the primary way of writing migrations
  • migration definitions
  • write the up and down methods instead of using the change method
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

Active Record Basics - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/active_record_basics.html

ruby rails programming development framework model database object

shared by 張 旭 on 22 Jan 14 - No Cached
  • the model - which is the layer of the system responsible for representing business data and logic.
  • Active Record facilitates the creation and use of business objects whose data requires persistent storage to a database
  • Database Table - Plural with underscores separating words
  • ...33 more annotations...
  • objects carry both persistent data and behavior which operates on that data
  • Object-Relational Mapping, commonly referred to as its abbreviation ORM, is a technique that connects the rich objects of an application to tables in a relational database management system
  • Represent associations between these models
  • Validate models before they get persisted to the database
  • The idea is that if you configure your applications in the very same way most of the times then this should be the default way.
  • Rails will pluralize your class names to find the respective database table.
  • use the ActiveRecord::Base.table_name= method to specify the table name
  • Model Class - Singular with the first letter of each word capitalized
  • Foreign keys - These fields should be named following the pattern singularized_table_name_id
  • Primary keys - By default, Active Record will use an integer column named id as the table's primary key
  • created_at
  • updated_at
  • (table_name)_count - Used to cache the number of belonging objects on associations.
  • Object Relational Mapping
  • Single Table Inheritance (STI)
  • rake db:rollback
  • ActiveRecord::Base.primary_key=
  • CRUD is an acronym for the four verbs we use to operate on data: Create, Read, Update and Delete.
  • new method will return a new object
  • create will return the object and save it to the database.
  • Using the new method, an object can be instantiated without being saved
  • user.save will commit the record to the database
  • update_all class method
  • an Active Record object can be destroyed which removes it from the database
  • Validation is a very important issue to consider when persisting to database, so the methods create, save and update take it into account when running: they return false when validation fails and they didn't actually perform any operation on database.
  • a bang counterpart
  • Active Record callbacks allow you to attach code to certain events in the life-cycle of your models
  • Rails keeps track of which files have been committed to the database and provides rollback features
  • rake db:migrate
  • class_name.yml
  • Convention over Configuration
    • 張 旭
      張 旭 on 12 Apr 16
       
      Model 是單數，Table 是複數。想象一下，處理 Object 的時候是逐一處理，但是存放的地方是放了一堆 Objects。
    • 張 旭
      張 旭 on 12 Apr 16
       
      外鍵是單數的形式，這也很好理解：因為關聯到的是一個外部的 Object
張 旭

| Docker Documentation - 0 views

docs.docker.com/...builder

docker volume

shared by 張 旭 on 06 Dec 18 - No Cached
  • The host directory is declared at container run-time: The host directory (the mountpoint) is, by its nature, host-dependent. This is to preserve image portability, since a given host directory can’t be guaranteed to be available on all hosts.
  • This Dockerfile results in an image that causes docker run to create a new mount point at /myvol and copy the greeting file into the newly created volume.
  • 張 旭 on 06 Dec 18
     
    "The host directory is declared at container run-time: The host directory (the mountpoint) is, by its nature, host-dependent. This is to preserve image portability, since a given host directory can't be guaranteed to be available on all hosts."
張 旭

Docker ARG, ENV and .env - a Complete Guide · vsupalov.com - 1 views

vsupalov.com/docker-arg-env-variable-guide

docker development system server environment

shared by 張 旭 on 10 Dec 18 - No Cached
  • understand and use Docker build-time variables, environment variables and docker-compose templating the right way.
  • ARG is only available during the build of a Docker image (RUN etc), not after the image is created and containers are started from it (ENTRYPOINT, CMD).
  • ENV values are available to containers, but also RUN-style commands during the Docker build starting with the line where they are introduced.
  • ...20 more annotations...
  • set an environment variable in an intermediate container using bash (RUN export VARI=5 && …) it will not persist in the next command.
  • An env_file, is a convenient way to pass many environment variables to a single command in one batch.
  • not be confused with a .env file
  • the dot in front of env - .env, not an “env_file”.
  • If you have a file named .env in your project, it’s only used to put values into the docker-compose.yml file which is in the same folder. Those are used with Docker Compose and Docker Stack.
  • Just type docker-compose config. This way you’ll see how the docker-compose.yml file content looks after the substitution step has been performed without running anything else.
  • ARG are also known as build-time variables. They are only available from the moment they are ‘announced’ in the Dockerfile with an ARG instruction up to the moment when the image is built.
  • Running containers can’t access values of ARG variables.
  • ENV variables are also available during the build, as soon as you introduce them with an ENV instruction. However, unlike ARG, they are also accessible by containers started from the final image.
  • ENV values can be overridden when starting a container,
  • If you don’t provide a value to expected ARG variables which don’t have a default, you’ll get an error message.
  • args block
  • You can use ARG to set the default values of ENV vars.
  • dynamic on-build env values
  • 2. Pass environment variable values from your host
  • 1. Provide values one by one
  • 3. Take values from a file (env_file)
  • for each RUN statement, a new container is launched from an intermediate image.
  • An image is saved by the end of the command, but environment variables do not persist that way.
  • The precedence is, from stronger to less-strong: stuff the containerized application sets, values from single environment entries, values from the env_file(s) and finally Dockerfile defaults.
張 旭

Using Workflows to Schedule Jobs - CircleCI - 1 views

circleci.com/workflows

circleci CI deploy system

shared by 張 旭 on 25 Nov 18 - No Cached
  • A workflow is a set of rules for defining a collection of jobs and their run order.
  • Schedule workflows for jobs that should only run periodically.
  • run multiple jobs in parallel
  • ...37 more annotations...
  • rerun just the failed job
  • Builds without workflows require a build job.
  • Refer the YAML Anchors/Aliases documentation for information about how to alias and reuse syntax to keep your .circleci/config.yml file small.
  • workflow orchestration with two parallel jobs
  • jobs run according to configured requirements, each job waiting to start until the required job finishes successfully
  • requires: key
  • fans-out to run a set of acceptance test jobs in parallel, and finally fans-in to run a common deploy job.
  • Holding a Workflow for a Manual Approval
  • Workflows can be configured to wait for manual approval of a job before continuing to the next job
  • add a job to the jobs list with the key type: approval
  • approval is a special job type that is only available to jobs under the workflow key
  • The name of the job to hold is arbitrary - it could be wait or pause, for example, as long as the job has a type: approval key in it.
  • schedule a workflow to run at a certain time for specific branches.
  • The triggers key is only added under your workflows key
  • using cron syntax to represent Coordinated Universal Time (UTC) for specified branches.
  • By default, a workflow is triggered on every git push
  • the commit workflow has no triggers key and will run on every git push
  • The nightly workflow has a triggers key and will run on the specified schedule
  • Cron step syntax (for example, */1, */20) is not supported.
  • use a context to share environment variables
  • use the same shared environment variables when initiated by a user who is part of the organization.
  • CircleCI does not run workflows for tags unless you explicitly specify tag filters.
  • CircleCI branch and tag filters support the Java variant of regex pattern matching.
  • Each workflow has an associated workspace which can be used to transfer files to downstream jobs as the workflow progresses.
  • The workspace is an additive-only store of data.
  • Jobs can persist data to the workspace
  • Downstream jobs can attach the workspace to their container filesystem.
  • Attaching the workspace downloads and unpacks each layer based on the ordering of the upstream jobs in the workflow graph.
  • Workflows that include jobs running on multiple branches may require data to be shared using workspaces
  • To persist data from a job and make it available to other jobs, configure the job to use the persist_to_workspace key.
  • Files and directories named in the paths: property of persist_to_workspace will be uploaded to the workflow’s temporary workspace relative to the directory specified with the root key.
  • Configure a job to get saved data by configuring the attach_workspace key.
  • persist_to_workspace
  • attach_workspace
  • To rerun only a workflow’s failed jobs, click the Workflows icon in the app and select a workflow to see the status of each job, then click the Rerun button and select Rerun from failed.
  • if you do not see your workflows triggering, a configuration error is preventing the workflow from starting.
  • check your Workflows page of the CircleCI app (not the Job page)
  • 張 旭 on 25 Nov 18
     
    "A workflow is a set of rules for defining a collection of jobs and their run order."
張 旭

Bash Reference Manual: Shell Parameter Expansion - 1 views

www.gnu.org/...Shell-Parameter-Expansion.html

shell script programming

shared by 張 旭 on 30 Nov 18 - No Cached
  • parameter expansion
  • command substitution
  • arithmetic expansion
  • ...16 more annotations...
  • The parameter name or symbol to be expanded may be enclosed in braces, which are optional but serve to protect the variable to be expanded from characters immediately following it which could be interpreted as part of the name.
  • When braces are used, the matching ending brace is the first ‘}’ not escaped by a backslash or within a quoted string, and not within an embedded arithmetic expansion, command substitution, or parameter expansion.
  • ${parameter}
  • braces are required
  • If the first character of parameter is an exclamation point (!), and parameter is not a nameref, it introduces a level of variable indirection.
  • ${parameter:-word} If parameter is unset or null, the expansion of word is substituted. Otherwise, the value of parameter is substituted.
  • ${parameter:=word} If parameter is unset or null, the expansion of word is assigned to parameter.
  • ${parameter:?word} If parameter is null or unset, the expansion of word (or a message to that effect if word is not present) is written to the standard error and the shell, if it is not interactive, exits.
  • ${parameter:+word} If parameter is null or unset, nothing is substituted, otherwise the expansion of word is substituted.
  • ${parameter:offset} ${parameter:offset:length}
  • Substring expansion applied to an associative array produces undefined results.
  • ${parameter/pattern/string} The pattern is expanded to produce a pattern just as in filename expansion.
  • If pattern begins with ‘/’, all matches of pattern are replaced with string.
  • Normally only the first match is replaced
  • The ‘^’ operator converts lowercase letters matching pattern to uppercase
  • the ‘,’ operator converts matching uppercase letters to lowercase.
« First ‹ Previous 41 - 60 of 98 Next › Last »
Showing 20▼ items per page