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張 旭

Running Terraform in Automation | Terraform - HashiCorp Learn - 0 views

learn.hashicorp.com/...unning-terraform-in-automation

devops terraform config

shared by 張 旭 on 11 Apr 19 - No Cached
  • In default usage, terraform init downloads and installs the plugins for any providers used in the configuration automatically, placing them in a subdirectory of the .terraform directory.
  • allows each configuration to potentially use different versions of plugins.
  • In automation environments, it can be desirable to disable this behavior and instead provide a fixed set of plugins already installed on the system where Terraform is running. This then avoids the overhead of re-downloading the plugins on each execution
  • ...12 more annotations...
  • the desire for an interactive approval step between plan and apply.
  • terraform init -input=false to initialize the working directory.
  • terraform plan -out=tfplan -input=false to create a plan and save it to the local file tfplan.
  • terraform apply -input=false tfplan to apply the plan stored in the file tfplan.
  • the environment variable TF_IN_AUTOMATION is set to any non-empty value, Terraform makes some minor adjustments to its output to de-emphasize specific commands to run.
  • it can be difficult or impossible to ensure that the plan and apply subcommands are run on the same machine, in the same directory, with all of the same files present.
  • to allow only one plan to be outstanding at a time.
  • forcing plans to be approved (or dismissed) in sequence
  • -auto-approve
  • The -auto-approve option tells Terraform not to require interactive approval of the plan before applying it.
  • obtain the archive created in the previous step and extract it at the same absolute path. This re-creates everything that was present after plan, avoiding strange issues where local files were created during the plan step.
  • a "build artifact"
  • 張 旭 on 11 Apr 19
     
    "In default usage, terraform init downloads and installs the plugins for any providers used in the configuration automatically, placing them in a subdirectory of the .terraform directory. "
張 旭

如何在 Ubuntu 18.04 下正确配置网络 - 运维之美 - 0 views

www.hi-linux.com/...49513.html

networking ubuntu server network

shared by 張 旭 on 09 Apr 20 - No Cached
  • 張 旭 on 09 Apr 20
     
    "systemd-resolve --status"
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.
張 旭

AskF5 | Manual Chapter: Working with Partitions - 0 views

techdocs.f5.com/...8.html

bigip network

shared by 張 旭 on 05 May 20 - No Cached
  • During BIG-IP® system installation, the system automatically creates a partition named Common
  • An administrative partition is a logical container that you create, containing a defined set of BIG-IP® system objects.
  • No user can delete partition Common itself.
  • ...9 more annotations...
  • With respect to permissions, all users on the system except those with a user role of No Access have read access to objects in partition Common, and by default, partition Common is their current partition.
  • The current partition is the specific partition to which the system is currently set for a logged-in user.
  • A partition access assignment gives a user some level of access to the specified partition.
  • assigning partition access to a user does not necessarily give the user full access to all objects in the partition
  • user account objects also reside in partitions
  • when you first install the BIG-IP system, every existing user account (root and admin) resides in partition Common
  • the partition in which a user account object resides does not affect the partition or partitions to which that user is granted access to manage other BIG-IP objects
  • the object it references resides in partition Common
  • a referenced object must reside either in the same partition as the object that is referencing it
張 旭

Rails Environment Variables · RailsApps - 1 views

railsapps.github.io/ils-environment-variables.html

rails environment system variable

shared by 張 旭 on 13 Mar 17 - No Cached
  • You can pass local configuration settings to an application using environment variables.
  • Operating systems (Linux, Mac OS X, Windows) provide mechanisms to set local environment variables, as does Heroku and other deployment platforms.
  • In general, you shouldn’t save email account credentials or private API keys to a shared git repository.
  • ...10 more annotations...
  • You could “hardcode” your Gmail username and password into the file but that would expose it to everyone who has access to your git repository.
  • It’s important to learn to use the Unix shell if you’re commited to improving your skills as a developer.
  • The gem reads a config/application.yml file and sets environment variables before anything else is configured in the Rails application.
  • make sure this file is listed in the .gitignore file so it isn’t checked into the git repository
  • Rails provides a config.before_configuration
  • YAML.load(File.open(env_file)).each do |key, value| ENV[key.to_s] = value end if File.exists?(env_file)
  • Heroku is a popular choice for low cost, easily configured Rails application hosting.
  • heroku config:add
  • the dotenv Ruby gem
  • Foreman is a tool for starting and configuring multiple processes in a complex application
張 旭

MySQL :: MySQL 5.7 Reference Manual :: 20.2 Introducing InnoDB Cluster - 0 views

dev.mysql.com/...nodb-cluster-introduction.html

mysql cluster database HA

shared by 張 旭 on 19 Mar 17 - No Cached
  • A group of MySQL servers can be configured to create a cluster using MySQL Shell
  • The cluster of servers has a single master, called the primary, which acts as the read-write master.
  • Multiple secondary servers are replicas of the master
  • ...6 more annotations...
  • A client application is connected to the primary via MySQL Router
  • MySQL Shell also requires Python 2.7 and above to run cluster provisioning scripts
  • AdminAPI, which enables you to create and administer an InnoDB cluster, using either JavaScript or Python scripting
  • Caches the metadata of the InnoDB cluster and performs high availability routing to the MySQL Server instances which make up the cluster
  • Group Replication mechanism to allow data to be replicated from the primary to the secondaries in the cluster
  • AdminAPI is available as of MySQL Shell 1.0.8.
張 旭

MySQL :: MySQL 5.7 Reference Manual :: 20.4 Getting Started with InnoDB Cluster - 0 views

dev.mysql.com/...b-cluster-getting-started.html

mysql cluster HA router database

shared by 張 旭 on 19 Mar 17 - No Cached
  • InnoDB cluster instances are created and managed through the MySQL Shell.
  • To create a new InnoDB cluster, the MySQL Shell must be connected to the MySQL Server instance. By default, this MySQL Server instance is the seed instance of the new InnoDB cluster and hold the initial data set.
  • Sandbox instance are only suitable for deploying and running on your local machine.
  • ...3 more annotations...
  • A minimum of three instances are required to create an InnoDB cluster
  • reverts to read-only mode
  • MySQL Shell provides two scripting languages: JavaScript and Python.
張 旭

MySQL :: MySQL 5.7 Reference Manual :: 19.1 Group Replication Background - 0 views

dev.mysql.com/...up-replication-background.html

mysql cluster HA system database replication

shared by 張 旭 on 19 Mar 17 - No Cached
  • the component can be removed and the system should continue to operate as expected
  • network partitioning
  • split brain scenarios
  • ...8 more annotations...
  • the ultimate challenge is to fuse the logic of the database and data replication with the logic of having several servers coordinated in a consistent and simple way
  • MySQL Group Replication provides distributed state machine replication with strong coordination between servers.
  • Servers coordinate themselves automatically when they are part of the same group
  • The group can operate in a single-primary mode with automatic primary election, where only one server accepts updates at a time.
  • For a transaction to commit, the majority of the group have to agree on the order of a given transaction in the global sequence of transactions
  • Deciding to commit or abort a transaction is done by each server individually, but all servers make the same decision
  • group communication protocols
  • the Paxos algorithm. It acts as the group communication systems engine.
張 旭

MySQL :: MySQL 5.7 Reference Manual :: 19.1.1.2 Group Replication - 0 views

dev.mysql.com/...group-replication-summary.html

mysql HA system database replication

shared by 張 旭 on 19 Mar 17 - No Cached
  • The replication group is a set of servers that interact with each other through message passing.
  • The communication layer provides a set of guarantees such as atomic message and total order message delivery.
  • a multi-master update everywhere replication protocol
  • ...8 more annotations...
  • a replication group is formed by multiple servers and each server in the group may execute transactions independently
  • Read-only (RO) transactions need no coordination within the group and thus commit immediately
  • any RW transaction the group needs to decide whether it commits or not, thus the commit operation is not a unilateral decision from the originating server
  • when a transaction is ready to commit at the originating server, the server atomically broadcasts the write values (rows changed) and the correspondent write set (unique identifiers of the rows that were updated). Then a global total order is established for that transaction.
  • all servers receive the same set of transactions in the same order
  • The resolution procedure states that the transaction that was ordered first commits on all servers, whereas the transaction ordered second aborts, and thus is rolled back on the originating server and dropped by the other servers in the group. This is in fact a distributed first commit wins rule
  • Group Replication is a shared-nothing replication scheme where each server has its own entire copy of the data
  • MySQL Group Replication protocol
張 旭

CertSimple | An nginx config for 2017 - 0 views

certsimple.com/...nx-http2-load-balancing-config

nginx web server performance

shared by 張 旭 on 19 Mar 17 - No Cached
  • HAProxy can't terminate a HTTP/2 connection itself.
  • a server OS which includes OpenSSL 1.02 to have ALPN.
  • a new nginx (anything newer than 1.9.5 supports HTTP/2)
  • ...6 more annotations...
  • we like HTTPS/non-www since HTTPS is needed for current browsers and non-www is short.
  • visit the Mozilla TLS Generator to get the latest cipher suites and TLS versions
  • add the necessary headers for GeoIP and proper logging.
  • HTML5 SSE simpler than websockets
  • nginx -t
  • Scan your site with SSL Labs scan
crazylion lee

What Google Learned From Its Quest to Build the Perfect Team - The New York Times - 0 views

www.nytimes.com/...to-build-the-perfect-team.html

manager management

shared by crazylion lee on 12 May 17 - No Cached
  • crazylion lee on 12 May 17
     
    "What Google Learned From Its Quest to Build the Perfect Team"
張 旭

Ruby on Rails 實戰聖經 | 自動化測試 - 0 views

ihower.tw/testing.html

rails test ruby programming

shared by 張 旭 on 14 Jun 17 - No Cached
  • 最小的測試粒度叫做Unit Test單元測試，會對個別的類別和方法測試結果如預期。再大一點的粒度稱作Integration Test整合測試，測試多個元件之間的互動正確。最大的粒度則是Acceptance Test驗收測試，從用戶觀點來測試整個軟體。
  • 單元測試，通常會由開發者自行負責測試，因為只有你自己清楚每個類別和方法的內部結構是怎麼設計的。
  • 哪來的時間做自動化測試呢？這個想法是相當短視和業餘的想法
  • ...18 more annotations...
  • 這其實是一種投資，如果是簡單的程式，也許你手動執行一次就寫對了，但是如果是複雜的程式，往往第一次不會寫對，你會浪費很多時間在檢查到底你寫的程式的正確性，而寫測試就可以大大的節省這些時間。更不用說你明天，下個禮拜或下個月需要再確認其他程式有沒有副作用影響的時候，你有一組測試程式可以大大節省手動檢查的時間。
  • 幾乎每種語言都有一套叫做xUnit測試框架的測試工具
  • 標準流程是 1. (Setup) 設定測試資料 2. (Exercise) 執行要測試的方法 3. (Verify) 檢查結果是否正確 4. (Teardown) 清理還原資料
  • RSpec是一套改良版的xUnit測試框架，非常風行於Rails社群
  • 個別的單元測試應該是獨立不會互相影響的
  • 一個it區塊，就是一個單元測試，裡面的expect方法會進行驗證。
  • RSpec裡，我們又把一個小單元測試叫做example
  • BDD(Behavior-driven development)測試框架，相較於TDD用test思維，測試程式的結果。BDD強調的是用spec思維，描述程式應該有什麼行為。
  • describe和context幫助你組織分類，都是可以任意套疊的。
  • 每個it就是一小段測試，在裡面我們會用expect(…).to來設定期望
  • let可以用來簡化上述的before用法，並且支援lazy evaluation和memoized，也就是有需要才初始，並且不同單元測試之間，只會初始化一次，可以增加測試執行效率
  • let!則會在測試一開始就先初始一次，而不是lazy evaluation。
  • 先列出來預計要寫的測試，或是暫時不要跑的測試
  • specify和example都是it方法的同義字。
  • 進階一點你可以自己寫Matcher
  • RSpec分成數種不同測試，分別是Model測試、Controller測試、View測試、Helper測試、Route和Request測試
  • Rails內建有Fixture功能可以建立假資料，方法是為每個Model使用一份YAML資料。
  • 記得確認每個測試案例之間的測試資料需要清除
張 旭

A Good Vimrc - 1 views

dougblack.io/...a-good-vimrc.html

vim programming development

shared by 張 旭 on 15 Apr 17 - No Cached
  • Don't put any lines in your vimrc that you don't understand.
  • the absolute worst way to make your environment better is to just copy it wholesale from others
  • adding features one by one to your vimrc aids in overall Vim comprehension
  • ...3 more annotations...
  • custom keybindings
  • Vim doesn't model undo as a simple stack. In Vim it's a tree.
  • Don't put anything in your .vimrc you don't understand!
張 旭

Rails Application Templates - Ruby on Rails Guides - 1 views

guides.rubyonrails.org/ils_application_templates.html

rails development template

shared by 張 旭 on 09 Jan 18 - No Cached
  • Application templates are simple Ruby files containing DSL for adding gems/initializers etc. to your freshly created Rails project or an existing Rails project.
  • copy_file will accept relative paths to your template's location
張 旭

Override Files - Configuration Language - Terraform by HashiCorp - 0 views

www.terraform.io/...override.html

terraform devops

shared by 張 旭 on 15 Jun 21 - No Cached
  • In both the required_version and required_providers settings, each override constraint entirely replaces the constraints for the same component in the original block.
  • If both the base block and the override block both set required_version then the constraints in the base block are entirely ignored.
  • Terraform normally loads all of the .tf and .tf.json files within a directory and expects each one to define a distinct set of configuration objects.
  • ...14 more annotations...
  • If two files attempt to define the same object, Terraform returns an error.
  • a human-edited configuration file in the Terraform language native syntax could be partially overridden using a programmatically-generated file in JSON syntax.
  • Terraform has special handling of any configuration file whose name ends in _override.tf or _override.tf.json
  • Terraform initially skips these override files when loading configuration, and then afterwards processes each one in turn (in lexicographical order).
  • merges the override block contents into the existing object.
  • Over-use of override files hurts readability, since a reader looking only at the original files cannot easily see that some portions of those files have been overridden without consulting all of the override files that are present.
  • When using override files, use comments in the original files to warn future readers about which override files apply changes to each block.
  • A top-level block in an override file merges with a block in a normal configuration file that has the same block header.
  • Within a top-level block, an attribute argument within an override block replaces any argument of the same name in the original block.
  • Within a top-level block, any nested blocks within an override block replace all blocks of the same type in the original block.
  • The contents of nested configuration blocks are not merged.
  • If more than one override file defines the same top-level block, the overriding effect is compounded, with later blocks taking precedence over earlier blocks
  • The settings within terraform blocks are considered individually when merging.
  • If the required_providers argument is set, its value is merged on an element-by-element basis, which allows an override block to adjust the constraint for a single provider without affecting the constraints for other providers.
  • 張 旭 on 15 Jun 21
     
    "In both the required_version and required_providers settings, each override constraint entirely replaces the constraints for the same component in the original block. "
張 旭

Speeding up Docker image build process of a Rails application | BigBinary Blog - 1 views

blog.bigbinary.com/...ss-of-a-rails-application.html

docker kubernetes rails devops system

shared by 張 旭 on 23 Oct 19 - No Cached
  • we do not want to execute bundle install and rake assets:precompile tasks while starting a container in each pod which would prevent that pod from accepting any requests until these tasks are finished.
  • run bundle install and rake assets:precompile tasks while or before containerizing the Rails application.
  • Kubernetes pulls the image, starts a Docker container using that image inside the pod and runs puma server immediately.
  • ...7 more annotations...
  • Since source code changes often, the previously cached layer for the ADD instruction is invalidated due to the mismatching checksums.
  • The ARG instruction in the Dockerfile defines RAILS_ENV variable and is implicitly used as an environment variable by the rest of the instructions defined just after that ARG instruction.
  • RUN instructions are used to install gems and precompile static assets using sprockets
  • Instead, Docker automatically re-uses the previously built layer for the RUN bundle install instruction if the Gemfile.lock file remains unchanged.
  • everyday we need to build a lot of Docker images containing source code from varying Git branches as well as with varying environments.
  • it is hard for Docker to cache layers for bundle install and rake assets:precompile tasks and re-use those layers during every docker build command run with different application source code and a different environment.
  • By default, Bundler installs gems at the location which is set by Rubygems.
  • 張 旭 on 23 Oct 19
     
    "we do not want to execute bundle install and rake assets:precompile tasks while starting a container in each pod which would prevent that pod from accepting any requests until these tasks are finished."
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