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張 旭

Syntax - Configuration Language | Terraform | HashiCorp Developer - 0 views

developer.hashicorp.com/...configuration

devops terraform

shared by 張 旭 on 22 Jan 23 - No Cached
  • the native syntax of the Terraform language, which is a rich language designed to be relatively easy for humans to read and write.
  • Terraform's configuration language is based on a more general language called HCL, and HCL's documentation usually uses the word "attribute" instead of "argument."
  • A particular block type may have any number of required labels, or it may require none
  • ...34 more annotations...
  • After the block type keyword and any labels, the block body is delimited by the { and } characters
  • Identifiers can contain letters, digits, underscores (_), and hyphens (-). The first character of an identifier must not be a digit, to avoid ambiguity with literal numbers.
  • The # single-line comment style is the default comment style and should be used in most cases.
  • he idiomatic style is to use the Unix convention
  • Indent two spaces for each nesting level.
  • align their equals signs
  • Use empty lines to separate logical groups of arguments within a block.
  • Use one blank line to separate the arguments from the blocks.
  • "meta-arguments" (as defined by the Terraform language semantics)
  • Avoid separating multiple blocks of the same type with other blocks of a different type, unless the block types are defined by semantics to form a family.
  • Resource names must start with a letter or underscore, and may contain only letters, digits, underscores, and dashes.
  • Each resource is associated with a single resource type, which determines the kind of infrastructure object it manages and what arguments and other attributes the resource supports.
  • Each resource type is implemented by a provider, which is a plugin for Terraform that offers a collection of resource types.
  • By convention, resource type names start with their provider's preferred local name.
  • Most publicly available providers are distributed on the Terraform Registry, which also hosts their documentation.
  • The Terraform language defines several meta-arguments, which can be used with any resource type to change the behavior of resources.
  • use precondition and postcondition blocks to specify assumptions and guarantees about how the resource operates.
  • Some resource types provide a special timeouts nested block argument that allows you to customize how long certain operations are allowed to take before being considered to have failed.
  • Timeouts are handled entirely by the resource type implementation in the provider
  • Most resource types do not support the timeouts block at all.
  • A resource block declares that you want a particular infrastructure object to exist with the given settings.
  • Destroy resources that exist in the state but no longer exist in the configuration.
  • Destroy and re-create resources whose arguments have changed but which cannot be updated in-place due to remote API limitations.
  • Expressions within a Terraform module can access information about resources in the same module, and you can use that information to help configure other resources. Use the <RESOURCE TYPE>.<NAME>.<ATTRIBUTE> syntax to reference a resource attribute in an expression.
  • resources often provide read-only attributes with information obtained from the remote API; this often includes things that can't be known until the resource is created, like the resource's unique random ID.
  • data sources, which are a special type of resource used only for looking up information.
  • some dependencies cannot be recognized implicitly in configuration.
  • local-only resource types exist for generating private keys, issuing self-signed TLS certificates, and even generating random ids.
  • The behavior of local-only resources is the same as all other resources, but their result data exists only within the Terraform state.
  • The count meta-argument accepts a whole number, and creates that many instances of the resource or module.
  • count.index — The distinct index number (starting with 0) corresponding to this instance.
  • the count value must be known before Terraform performs any remote resource actions. This means count can't refer to any resource attributes that aren't known until after a configuration is applied
  • Within nested provisioner or connection blocks, the special self object refers to the current resource instance, not the resource block as a whole.
  • This was fragile, because the resource instances were still identified by their index instead of the string values in the list.
  • 張 旭 on 22 Jan 23
     
    "the native syntax of the Terraform language, which is a rich language designed to be relatively easy for humans to read and write. "
張 旭

Provisioners Without a Resource | Terraform | HashiCorp Developer - 0 views

developer.hashicorp.com/...null_resource

devops terraform

shared by 張 旭 on 23 Jan 23 - No Cached
  • triggers - A map of values which should cause this set of provisioners to re-run. Values are meant to be interpolated references to variables or attributes of other resources.
  • 張 旭 on 23 Jan 23
     
    "triggers - A map of values which should cause this set of provisioners to re-run. Values are meant to be interpolated references to variables or attributes of other resources. "
張 旭

Handlebars.js: Minimal Templating on Steroids - 0 views

handlebarsjs.com

javascript mustache jquery template library

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

A Guide to Testing Rails Applications - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/testing.html

rails test ruby unit

shared by 張 旭 on 08 May 16 - Cached
  • Rails tests can also simulate browser requests and thus you can test your application's response without having to test it through your browser.
  • your tests will need a database to interact with as well.
  • By default, every Rails application has three environments: development, test, and production
  • ...25 more annotations...
  • models directory is meant to hold tests for your models
  • controllers directory is meant to hold tests for your controllers
  • integration directory is meant to hold tests that involve any number of controllers interacting
  • Fixtures are a way of organizing test data; they reside in the fixtures folder
  • The test_helper.rb file holds the default configuration for your tests
  • Fixtures allow you to populate your testing database with predefined data before your tests run
  • Fixtures are database independent written in YAML.
  • one file per model.
  • Each fixture is given a name followed by an indented list of colon-separated key/value pairs.
  • Keys which resemble YAML keywords such as 'yes' and 'no' are quoted so that the YAML Parser correctly interprets them.
  • define a reference node between two different fixtures.
  • ERB allows you to embed Ruby code within templates
  • The YAML fixture format is pre-processed with ERB when Rails loads fixtures.
  • Rails by default automatically loads all fixtures from the test/fixtures folder for your models and controllers test.
  • Fixtures are instances of Active Record.
  • access the object directly
  • test_helper.rb specifies the default configuration to run our tests. This is included with all the tests, so any methods added to this file are available to all your tests.
  • test with method names prefixed with test_.
  • An assertion is a line of code that evaluates an object (or expression) for expected results.
  • bin/rake db:test:prepare
  • Every test contains one or more assertions. Only when all the assertions are successful will the test pass.
  • rake test command
  • run a particular test method from the test case by running the test and providing the test method name.
  • The . (dot) above indicates a passing test. When a test fails you see an F; when a test throws an error you see an E in its place.
  • we first wrote a test which fails for a desired functionality, then we wrote some code which adds the functionality and finally we ensured that our test passes. This approach to software development is referred to as Test-Driven Development (TDD).
crazylion lee

Image Kernels explained visually - 0 views

setosa.io/image-kernels

image-processing

shared by crazylion lee on 20 Aug 16 - No Cached
  • crazylion lee on 20 Aug 16
     
    "An image kernel is a small matrix used to apply effects like the ones you might find in Photoshop or Gimp, such as blurring, sharpening, outlining or embossing. They're also used in machine learning for 'feature extraction', a technique for determining the most important portions of an image. In this context the process is referred to more generally as "convolution" (see: convolutional neural networks.)"
crazylion lee

CSS Reference - A free visual guide to the most popular CSS properties. - 0 views

cssreference.io

css css3 visual guide reference

shared by crazylion lee on 26 Nov 16 - No Cached
  • crazylion lee on 26 Nov 16
     
    "A free visual guide to CSS"
crazylion lee

https://states-language.net/spec.html#example - 0 views

states-language.net/spec.html

amazon statemachine state_machine json

shared by crazylion lee on 04 Dec 16 - No Cached
  • crazylion lee on 04 Dec 16
     
    "This document describes a JSON-based language used to describe state machines declaratively. The state machines thus defined may be executed by software. In this document, the software is referred to as "the interpreter"."
crazylion lee

Realtime Multi-Person 2D Pose Estimation using Part Affinity Fields - 0 views

www.gitxiv.com/...estimation-using-part-affinity

pose 2d programming computer Science

shared by crazylion lee on 30 Jan 17 - No Cached
  • crazylion lee on 30 Jan 17
     
    "We present a realtime approach for multi-person 2D pose estimation that predicts vector fields, which we refer to as Part Affinity Fields (PAFs), that directly expose the association between anatomical parts in an image. The architecture is designed to jointly learn part locations and their association, via two branches of the same sequential prediction process."
crazylion lee

Heavy Metal and Natural Language Processing - Part 1 - 0 views

www.degeneratestate.org/...ral-language-processing-part-1

heavy metal natural language processing

shared by crazylion lee on 10 Jul 16 - No Cached
  • crazylion lee on 10 Jul 16
     
    " In this post I refer to lyrics of certain bands as being "Metal". I know some people have strong feelings about how genres are defined, and would probably disagree with me about some of the bands I call metal in this post. I call these band "Metal" here for the sake of brevity only, and I apologise in advance. "
crazylion lee

Security/Server Side TLS - MozillaWiki - 0 views

wiki.mozilla.org/...Server_Side_TLS

ssl tls https

shared by crazylion lee on 24 Nov 14 - No Cached
  • crazylion lee on 24 Nov 14
     
    The goal of this document is to help operational teams with the configuration of TLS on servers. All Mozilla sites and deployment should follow the recommendations below. The Operations Security (OpSec) team maintains this document as a reference guide to navigate the TLS landscape. It contains information on TLS protocols, known issues and vulnerabilities, configuration examples and testing tools. Changes are reviewed and merged by the OpSec team, and broadcasted to the various Operational teams.
張 旭

Run Reference - Docker Documentation - 0 views

docs.docker.com/run

docker system deploy

shared by 張 旭 on 29 Oct 14 - No Cached
  • In detached mode (-d=true or just -d), all I/O should be done through network connections or shared volumes because the container is no longer listening to the command line where you executed docker run.
  • start the process in the container and attach the console to the process's standard input, output, and standard error. It can even pretend to be a TTY (this is what most command line executables expect) and pass along signals.
  • For interactive processes (like a shell) you will typically want a tty as well as persistent standard input (STDIN), so you'll use -i -t together in most interactive cases.
張 旭

Active Record Migrations - Ruby on Rails Guides - 0 views

edgeguides.rubyonrails.org/active_record_migrations.html

rails database model migration

shared by 張 旭 on 12 Apr 16 - No Cached
    • 張 旭
      張 旭 on 12 Apr 16
       
       跟 belongs_to 與 has_many 設定對應的 Migrattion
    • 張 旭
      張 旭 on 12 Apr 16
       
      has_and_belongs_to_many 的對應？
  • add_column and remove_column
  • ...114 more annotations...
  • allowing your schema and changes to be database independent.
  • each migration as being a new 'version' of the database
  • each migration modifies it to add or remove tables, columns, or entries
  • Active Record will also update your db/schema.rb file to match the up-to-date structure of your database.
  • A primary key column called id will also be added implicitly, as it's the default primary key for all Active Record models
  • roll this migration back, it will remove the table
  • timestamps macro adds two columns, created_at and updated_at
  • On databases that support transactions with statements that change the schema, migrations are wrapped in a transaction
  • reversible
  • use up and down instead of change
  • Migrations are stored as files in the db/migrate directory, one for each migration class.
  • a UTC timestamp identifying
  • Rails uses this timestamp to determine which migration should be run and in what order
  • "AddXXXToYYY" or "RemoveXXXFromYYY"
  • use a Ruby DSL
  • column type as references
  • part_number:string:index
  • a migration to remove a column
  • "CreateXXX"
  • change_column_null
  • AddUserRefToProducts
  • :references
  • produce join tables if JoinTable is part of the name
  • CreateJoinTable
  • The model and scaffold generators will create migrations appropriate for adding a new model.
  • enclosed by curly braces and follow the field type
  • create_table
  • By default, create_table will create a primary key called id
  • add an index on the new column
  • when using MySQL, the default is ENGINE=InnoDB
  • create_join_table creates an HABTM (has and belongs to many) join table
  • To customize the name of the table, provide a :table_name option:
  • create_join_table also accepts a block
  • change_table, used for changing existing tables
  • remove
  • rename
  • add_column
  • change_column
  • remove_column
  • change_column_default
  • place an SQL fragment in the :options option.
  • limit
  • precision
  • scale
  • polymorphic
  • default
  • index
  • add_foreign_key
  • Active Record only supports single column foreign keys.
  • use the old style of migration using up and down methods instead of the change method.
  • .connection.execute
  • change_table is also reversible, as long as the block does not call change, change_default or remove.
  • remove_column is reversible if you supply the column type as the third argument
  • Complex migrations may require processing that Active Record doesn't know how to reverse
  • reversible
  • Using reversible will ensure that the instructions are executed in the right order too.
  • add_column add_foreign_key add_index add_reference add_timestamps change_column_default (must supply a :from and :to option) change_column_null create_join_table create_table disable_extension drop_join_table drop_table (must supply a block) enable_extension remove_column (must supply a type) remove_foreign_key (must supply a second table) remove_index remove_reference remove_timestamps rename_column rename_index rename_table
  • :column_options option
  • have the option :null set to false by default
  • By default, the name of the join table comes from the union of the first two arguments provided to create_join_table
  • in alphabetical order
  • change_column command is irreversible.
    • 張 旭
      張 旭 on 12 Apr 16
       
      關聯物在前，被關聯物在後。 A 關聯到 B
  • If the column names can not be derived from the table names, you can use the :column and :primary_key options.
  • figure out the column name
  • foreign key for a specific column
  • foreign key by name
    • 張 旭
      張 旭 on 12 Apr 16
       
      不懂 column 跟 name 的用法差異，基本上一樣。
  • Active Record knows how to reverse the migration automatically
    • 張 旭
      張 旭 on 12 Apr 16
       
      使用內建的 method，Rails 比較容易自動 rollback
    • 張 旭
      張 旭 on 12 Apr 16
       
      除了幾個特殊的 change_ 跟 remove_
  • should use reversible or write the up and down methods instead of using the change method
  • If your migration is irreversible, you should raise ActiveRecord::IrreversibleMigration from your down method.
  • DontUseConstraintForZipcodeValidationMigration
  • rails db:migrate
  • the db:migrate task also invokes the db:schema:dump task, which will update your db/schema.rb file to match the structure of your database.
  • specify a target version
  • all migrations up to and including 20080906120000
  • run the down method on all the migrations down to, but not including, 20080906120000
  • rails db:rollback
  • db:migrate:redo task is a shortcut for doing a rollback and then migrating back up again
    • 張 旭
      張 旭 on 12 Apr 16
       
      舊版的還是 rake！
  • STEP parameter
  • db:setup task will create the database, load the schema and initialize it with the seed data
  • db:reset task will drop the database and set it up again. This is functionally equivalent to rails db:drop db:setup.
  • run a specific migration up or down, the db:migrate:up and db:migrate:down
  • the RAILS_ENV environment variable
  • db:migrate VERBOSE=false will suppress all output.
  • If you have already run the migration, then you cannot just edit the migration and run the migration again: Rails thinks it has already run the migration and so will do nothing when you run rails db:migrate.
  • must rollback the migration (for example with bin/rails db:rollback), edit your migration and then run rails db:migrate to run the corrected version.
  • editing existing migrations is not a good idea.
  • should write a new migration that performs the changes you require
  • revert method can be helpful when writing a new migration to undo previous migrations in whole or in part
  • require_relative
  • revert
  • They are not designed to be edited, they just represent the current state of the database.
  • Schema Files for
  • Schema files are also useful if you want a quick look at what attributes an Active Record object has
  • annotate_models gem automatically adds and updates comments at the top of each model summarizing the schema if you desire that functionality.
  • database-independent
  • multiple databases
  • db/schema.rb cannot express database specific items such as triggers, stored procedures or check constraints
  • you can execute custom SQL statements, the schema dumper cannot reconstitute those statements from the database
  • db:structure:dump
    • 張 旭
      張 旭 on 12 Apr 16
       
      資料庫種類不相依的 schema 付出的代價就是有些特殊的資料庫特性無法描述出來，例如 trigger；如果有在 migration 寫 SQL 的，簡單說 schema dumper 這邊就要設定成 :sql 而不是預設的 :ruby
  • set in config/application.rb by the config.active_record.schema_format setting, which may be either :sql or :ruby.
  • check them into source control.
  • db/schema.rb contains the current version number of the database
  • Validations such as validates :foreign_key, uniqueness: true are one way in which models can enforce data integrity
  • The :dependent option on associations allows models to automatically destroy child objects when the parent is destroyed.
  • Migrations can also be used to add or modify data
  • Initial
  • To add initial data after a database is created, Rails has a built-in 'seeds' feature that makes the process quick and easy.
  • db/seeds.rb
  • rails db:seed
張 旭

Password management in Django | Django documentation | Django - 0 views

docs.djangoproject.com/...passwords

python django password

shared by 張 旭 on 18 Oct 18 - No Cached
  • Each password validator must provide a help text to explain the requirements to the user, validate a given password and return an error message if it does not meet the requirements, and optionally receive passwords that have been set.
  • By default, validators are used in the forms to reset or change passwords and in the createsuperuser and changepassword management commands
  • Validators aren’t applied at the model level,
張 旭

2.0 Project Tutorial - CircleCI - 0 views

circleci.com/...project-walkthrough

circle CI deploy

shared by 張 旭 on 09 Nov 18 - No Cached
  • The .circleci/config.yml file may be comprised of several Jobs.
  • a job is comprised of several Steps
  • which are commands that execute in the container that is defined in the first image: key in the file. This first image is also referred to as the primary container.
  • ...5 more annotations...
  • Every .circleci/config.yml file must have a job named build
  • Executor of the underlying technology
  • Image is a Docker image
  • Steps starting with a required checkout Step and followed by run: keys that execute commands sequentially on the primary container.
  • Docker images are typically configured using environment variables,
張 旭

Best practices for writing Dockerfiles | Docker Documentation - 0 views

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

docker system

shared by 張 旭 on 28 Sep 18 - No Cached
  • building efficient images
  • Docker builds images automatically by reading the instructions from a Dockerfile -- a text file that contains all commands, in order, needed to build a given image.
  • A Docker image consists of read-only layers each of which represents a Dockerfile instruction.
  • ...47 more annotations...
  • The layers are stacked and each one is a delta of the changes from the previous layer
  • When you run an image and generate a container, you add a new writable layer (the “container layer”) on top of the underlying layers.
  • By “ephemeral,” we mean that the container can be stopped and destroyed, then rebuilt and replaced with an absolute minimum set up and configuration.
  • Inadvertently including files that are not necessary for building an image results in a larger build context and larger image size.
  • To exclude files not relevant to the build (without restructuring your source repository) use a .dockerignore file. This file supports exclusion patterns similar to .gitignore files.
  • minimize image layers by leveraging build cache.
  • if your build contains several layers, you can order them from the less frequently changed (to ensure the build cache is reusable) to the more frequently changed
  • avoid installing extra or unnecessary packages just because they might be “nice to have.”
  • Each container should have only one concern.
  • Decoupling applications into multiple containers makes it easier to scale horizontally and reuse containers
  • Limiting each container to one process is a good rule of thumb, but it is not a hard and fast rule.
  • Use your best judgment to keep containers as clean and modular as possible.
  • do multi-stage builds and only copy the artifacts you need into the final image. This allows you to include tools and debug information in your intermediate build stages without increasing the size of the final image.
  • avoid duplication of packages and make the list much easier to update.
  • When building an image, Docker steps through the instructions in your Dockerfile, executing each in the order specified.
  • the next instruction is compared against all child images derived from that base image to see if one of them was built using the exact same instruction. If not, the cache is invalidated.
  • simply comparing the instruction in the Dockerfile with one of the child images is sufficient.
  • For the ADD and COPY instructions, the contents of the file(s) in the image are examined and a checksum is calculated for each file.
  • If anything has changed in the file(s), such as the contents and metadata, then the cache is invalidated.
  • cache checking does not look at the files in the container to determine a cache match.
  • In that case just the command string itself is used to find a match.
    • 張 旭
      張 旭 on 28 Sep 18
       
      RUN apt-get 這樣的指令，直接比對指令內容的意思。
  • Whenever possible, use current official repositories as the basis for your images.
  • Using RUN apt-get update && apt-get install -y ensures your Dockerfile installs the latest package versions with no further coding or manual intervention.
  • cache busting
  • Docker executes these commands using the /bin/sh -c interpreter, which only evaluates the exit code of the last operation in the pipe to determine success.
  • set -o pipefail && to ensure that an unexpected error prevents the build from inadvertently succeeding.
  • The CMD instruction should be used to run the software contained by your image, along with any arguments.
  • CMD should almost always be used in the form of CMD [“executable”, “param1”, “param2”…]
  • CMD should rarely be used in the manner of CMD [“param”, “param”] in conjunction with ENTRYPOINT
  • The ENV instruction is also useful for providing required environment variables specific to services you wish to containerize,
  • Each ENV line creates a new intermediate layer, just like RUN commands
  • COPY is preferred
  • COPY only supports the basic copying of local files into the container
  • the best use for ADD is local tar file auto-extraction into the image, as in ADD rootfs.tar.xz /
  • If you have multiple Dockerfile steps that use different files from your context, COPY them individually, rather than all at once.
  • using ADD to fetch packages from remote URLs is strongly discouraged; you should use curl or wget instead
  • 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
  • The VOLUME instruction should be used to expose any database storage area, configuration storage, or files/folders created by your docker container.
  • use VOLUME for any mutable and/or user-serviceable parts of your image
  • If you absolutely need functionality similar to sudo, such as initializing the daemon as root but running it as non-root), consider using “gosu”.
  • always use absolute paths for your WORKDIR
  • An ONBUILD command executes after the current Dockerfile build completes.
  • Think of the ONBUILD command as an instruction the parent Dockerfile gives to the child Dockerfile
  • A Docker build executes ONBUILD commands before any command in a child Dockerfile.
  • Be careful when putting ADD or COPY in ONBUILD. The “onbuild” image fails catastrophically if the new build’s context is missing the resource being added.
張 旭

Practical persistent cloud storage for Docker in AWS using RexRay - pt 4 - 0 views

blog.vizuri.com/ocker-in-aws-using-rexray-pt-4

docker volume disk aws storage

shared by 張 旭 on 14 Sep 18 - No Cached
  • Docker volumes can then be created and managed via the plugin, as requests are passed by Docker, and then orchestrated by the local server.
  • volumes are usually protected from deletion via a reference count.
  • Using the plugin means that the reference count is kept at the node level, so the plugin is only aware of the containers on a single node.
  • ...3 more annotations...
  • The S3FS plugin as of version 0.9.2 cannot delete an S3 bucket unless the bucket is empty, and has never been used (just created) as a Docker volume.
  • Starting with Docker 1.13 a new plugin system was introduced in which the plugin runs inside of a container.
  • Even though the plugin is a container image, you cannot start it using either docker image pull or docker container run; you need to use the docker plugin set of sub‑commands.
  • 張 旭 on 14 Sep 18
     
    "Docker volumes can then be created and managed via the plugin, as requests are passed by Docker, and then orchestrated by the local server."
張 旭

Better Specs { rspec guidelines with ruby } - 0 views

www.betterspecs.org

rails ruby test programming rspec

shared by 張 旭 on 14 Jun 17 - No Cached
  • # when referring to an instance method's name
  • . (or ::) when referring to a class method's name
  • Be clear about what method you are describing.
  • ...9 more annotations...
  • When describing a context, start its description with "when" or "with".
  • is_expected.to respond_with
  • In isolated unit specs, you want each example to specify one (and only one) behavior.
  • Contexts are a powerful method to make your tests clear and well organized
  • not isolated
  • est valid, edge and invalid case.
  • new projects always use the expect syntax
  • On one line expectations or with implicit subject we should use is_expected.to
  • When you have to assign a variable instead of using a before block to create an instance variable, use let.
張 旭

cryptography - What's the difference between SSL, TLS, and HTTPS? - Information Securit... - 0 views

security.stackexchange.com/...ence-between-ssl-tls-and-https

security ssl system https

shared by 張 旭 on 23 Jun 17 - No Cached
  • TLS is the new name for SSL
  • HTTPS is HTTP-within-SSL/TLS
  • SSL (TLS) establishes a secured, bidirectional tunnel for arbitrary binary data between two hosts
  • ...10 more annotations...
  • HTTP is meant to run over a bidirectional tunnel for arbitrary binary data; when that tunnel is an SSL/TLS connection, then the whole is called "HTTPS".
  • "SSL" means "Secure Sockets Layer".
  • "TLS" means "Transport Layer Security".
  • The name was changed to avoid any legal issues with Netscape so that the protocol could be "open and free" (and published as a RFC).
    • 張 旭
      張 旭 on 23 Jun 17
       
      看起來其實就指同一件事，只是講 TLS 可以避開 SSL 這個有產權糾紛的名諱。
  • not just Internet-based sockets
  • "HTTPS" is supposed to mean "HyperText Transfer Protocol Secure",
  • Other protocol acronyms have been built the same way, e.g. SMTPS, IMAPS, FTPS... all of them being a bare protocol that "got secured" by running it within some SSL/TLS.
  • To make the confusing perfect: SSL (secure socket layer) often refers to the old protocol variant which starts with the handshake right away and therefore requires another port for the encrypted protocol such as 443 instead of 80.
  • TLS (transport layer security) often refers to the new variant which allows to start with an unencrypted traditional protocol and then issuing a command (usually STARTTLS) to initialize the handshake.
  • Whether you use SSL or TLS for this depends on the configuration of your browser and of the server (there usually is an option to allow SSLv2, SSLv3 or TLS 1.x).
張 旭

How To Use Bash's Job Control to Manage Foreground and Background Processes | DigitalOcean - 0 views

www.digitalocean.com/...round-and-background-processes

linux system server command

shared by 張 旭 on 06 Feb 18 - No Cached
  • Most processes that you start on a Linux machine will run in the foreground. The command will begin execution, blocking use of the shell for the duration of the process.
  • By default, processes are started in the foreground. Until the program exits or changes state, you will not be able to interact with the shell.
  • stop the process by sending it a signal
  • ...17 more annotations...
  • Linux terminals are usually configured to send the "SIGINT" signal (typically signal number 2) to current foreground process when the CTRL-C key combination is pressed.
  • Another signal that we can send is the "SIGTSTP" signal (typically signal number 20).
  • A background process is associated with the specific terminal that started it, but does not block access to the shell
  • start a background process by appending an ampersand character ("&") to the end of your commands.
  • type commands at the same time.
  • The [1] represents the command's "job spec" or job number. We can reference this with other job and process control commands, like kill, fg, and bg by preceding the job number with a percentage sign. In this case, we'd reference this job as %1.
  • Once the process is stopped, we can use the bg command to start it again in the background
  • By default, the bg command operates on the most recently stopped process.
  • Whether a process is in the background or in the foreground, it is rather tightly tied with the terminal instance that started it
  • When a terminal closes, it typically sends a SIGHUP signal to all of the processes (foreground, background, or stopped) that are tied to the terminal.
  • a terminal multiplexer
  • start it using the nohup command
  • appending output to ‘nohup.out’
  • pgrep -a
  • The disown command, in its default configuration, removes a job from the jobs queue of a terminal.
  • You can pass the -h flag to the disown process instead in order to mark the process to ignore SIGHUP signals, but to otherwise continue on as a regular job
  • The huponexit shell option controls whether bash will send its child processes the SIGHUP signal when it exits.
張 旭

Volumes - Kubernetes - 0 views

kubernetes.io/...volumes

kubernetes volume disk nfs

shared by 張 旭 on 28 May 19 - No Cached
  • On-disk files in a Container are ephemeral,
  • when a Container crashes, kubelet will restart it, but the files will be lost - the Container starts with a clean state
  • In Docker, a volume is simply a directory on disk or in another Container.
  • ...105 more annotations...
  • A Kubernetes volume, on the other hand, has an explicit lifetime - the same as the Pod that encloses it.
  • a volume outlives any Containers that run within the Pod, and data is preserved across Container restarts.
    • 張 旭
      張 旭 on 06 Jul 19
       
      Kubernetes Volume 是跟著 Pod 的生命週期在走
  • Kubernetes supports many types of volumes, and a Pod can use any number of them simultaneously.
  • To use a volume, a Pod specifies what volumes to provide for the Pod (the .spec.volumes field) and where to mount those into Containers (the .spec.containers.volumeMounts field).
  • A process in a container sees a filesystem view composed from their Docker image and volumes.
  • Volumes can not mount onto other volumes or have hard links to other volumes.
  • Each Container in the Pod must independently specify where to mount each volume
  • localnfs
  • cephfs
  • awsElasticBlockStore
  • glusterfs
  • vsphereVolume
  • An awsElasticBlockStore volume mounts an Amazon Web Services (AWS) EBS Volume into your Pod.
  • the contents of an EBS volume are preserved and the volume is merely unmounted.
  • an EBS volume can be pre-populated with data, and that data can be “handed off” between Pods.
  • create an EBS volume using aws ec2 create-volume
  • the nodes on which Pods are running must be AWS EC2 instances
  • EBS only supports a single EC2 instance mounting a volume
  • check that the size and EBS volume type are suitable for your use!
  • A cephfs volume allows an existing CephFS volume to be mounted into your Pod.
  • the contents of a cephfs volume are preserved and the volume is merely unmounted.
    • 張 旭
      張 旭 on 06 Jul 19
       
      相當於自己的 AWS EBS
  • CephFS can be mounted by multiple writers simultaneously.
  • have your own Ceph server running with the share exported
  • configMap
  • The configMap resource provides a way to inject configuration data into Pods
  • When referencing a configMap object, you can simply provide its name in the volume to reference it
  • volumeMounts: - name: config-vol mountPath: /etc/config volumes: - name: config-vol configMap: name: log-config items: - key: log_level path: log_level
  • create a ConfigMap before you can use it.
  • A Container using a ConfigMap as a subPath volume mount will not receive ConfigMap updates.
  • An emptyDir volume is first created when a Pod is assigned to a Node, and exists as long as that Pod is running on that node.
  • When a Pod is removed from a node for any reason, the data in the emptyDir is deleted forever.
  • By default, emptyDir volumes are stored on whatever medium is backing the node - that might be disk or SSD or network storage, depending on your environment.
  • you can set the emptyDir.medium field to "Memory" to tell Kubernetes to mount a tmpfs (RAM-backed filesystem)
  • volumeMounts: - mountPath: /cache name: cache-volume volumes: - name: cache-volume emptyDir: {}
  • An fc volume allows an existing fibre channel volume to be mounted in a Pod.
  • configure FC SAN Zoning to allocate and mask those LUNs (volumes) to the target WWNs beforehand so that Kubernetes hosts can access them.
  • Flocker is an open-source clustered Container data volume manager. It provides management and orchestration of data volumes backed by a variety of storage backends.
  • emptyDir
  • flocker
  • A flocker volume allows a Flocker dataset to be mounted into a Pod
  • have your own Flocker installation running
  • A gcePersistentDisk volume mounts a Google Compute Engine (GCE) Persistent Disk into your Pod.
  • Using a PD on a Pod controlled by a ReplicationController will fail unless the PD is read-only or the replica count is 0 or 1
  • A glusterfs volume allows a Glusterfs (an open source networked filesystem) volume to be mounted into your Pod.
  • have your own GlusterFS installation running
  • A hostPath volume mounts a file or directory from the host node’s filesystem into your Pod.
  • a powerful escape hatch for some applications
  • access to Docker internals; use a hostPath of /var/lib/docker
  • allowing a Pod to specify whether a given hostPath should exist prior to the Pod running, whether it should be created, and what it should exist as
  • specify a type for a hostPath volume
  • the files or directories created on the underlying hosts are only writable by root.
  • hostPath: # directory location on host path: /data # this field is optional type: Directory
  • An iscsi volume allows an existing iSCSI (SCSI over IP) volume to be mounted into your Pod.
  • have your own iSCSI server running
  • A feature of iSCSI is that it can be mounted as read-only by multiple consumers simultaneously.
  • A local volume represents a mounted local storage device such as a disk, partition or directory.
  • Local volumes can only be used as a statically created PersistentVolume.
  • Compared to hostPath volumes, local volumes can be used in a durable and portable manner without manually scheduling Pods to nodes, as the system is aware of the volume’s node constraints by looking at the node affinity on the PersistentVolume.
  • If a node becomes unhealthy, then the local volume will also become inaccessible, and a Pod using it will not be able to run.
  • PersistentVolume spec using a local volume and nodeAffinity
  • PersistentVolume nodeAffinity is required when using local volumes. It enables the Kubernetes scheduler to correctly schedule Pods using local volumes to the correct node.
  • PersistentVolume volumeMode can now be set to “Block” (instead of the default value “Filesystem”) to expose the local volume as a raw block device.
  • When using local volumes, it is recommended to create a StorageClass with volumeBindingMode set to WaitForFirstConsumer
  • An nfs volume allows an existing NFS (Network File System) share to be mounted into your Pod.
  • NFS can be mounted by multiple writers simultaneously.
  • have your own NFS server running with the share exported
  • A persistentVolumeClaim volume is used to mount a PersistentVolume into a Pod.
  • PersistentVolumes are a way for users to “claim” durable storage (such as a GCE PersistentDisk or an iSCSI volume) without knowing the details of the particular cloud environment.
  • A projected volume maps several existing volume sources into the same directory.
  • All sources are required to be in the same namespace as the Pod. For more details, see the all-in-one volume design document.
  • Each projected volume source is listed in the spec under sources
  • A Container using a projected volume source as a subPath volume mount will not receive updates for those volume sources.
  • RBD volumes can only be mounted by a single consumer in read-write mode - no simultaneous writers allowed
  • A secret volume is used to pass sensitive information, such as passwords, to Pods
  • store secrets in the Kubernetes API and mount them as files for use by Pods
  • secret volumes are backed by tmpfs (a RAM-backed filesystem) so they are never written to non-volatile storage.
  • create a secret in the Kubernetes API before you can use it
  • A Container using a Secret as a subPath volume mount will not receive Secret updates.
  • StorageOS runs as a Container within your Kubernetes environment, making local or attached storage accessible from any node within the Kubernetes cluster.
  • Data can be replicated to protect against node failure. Thin provisioning and compression can improve utilization and reduce cost.
  • StorageOS provides block storage to Containers, accessible via a file system.
  • A vsphereVolume is used to mount a vSphere VMDK Volume into your Pod.
  • supports both VMFS and VSAN datastore.
  • create VMDK using one of the following methods before using with Pod.
  • share one volume for multiple uses in a single Pod.
  • The volumeMounts.subPath property can be used to specify a sub-path inside the referenced volume instead of its root.
  • volumeMounts: - name: workdir1 mountPath: /logs subPathExpr: $(POD_NAME)
  • env: - name: POD_NAME valueFrom: fieldRef: apiVersion: v1 fieldPath: metadata.name
  • Use the subPathExpr field to construct subPath directory names from Downward API environment variables
  • enable the VolumeSubpathEnvExpansion feature gate
  • The subPath and subPathExpr properties are mutually exclusive.
  • There is no limit on how much space an emptyDir or hostPath volume can consume, and no isolation between Containers or between Pods.
  • emptyDir and hostPath volumes will be able to request a certain amount of space using a resource specification, and to select the type of media to use, for clusters that have several media types.
  • the Container Storage Interface (CSI) and Flexvolume. They enable storage vendors to create custom storage plugins without adding them to the Kubernetes repository.
  • all volume plugins (like volume types listed above) were “in-tree” meaning they were built, linked, compiled, and shipped with the core Kubernetes binaries and extend the core Kubernetes API.
  • Container Storage Interface (CSI) defines a standard interface for container orchestration systems (like Kubernetes) to expose arbitrary storage systems to their container workloads.
  • Once a CSI compatible volume driver is deployed on a Kubernetes cluster, users may use the csi volume type to attach, mount, etc. the volumes exposed by the CSI driver.
  • The csi volume type does not support direct reference from Pod and may only be referenced in a Pod via a PersistentVolumeClaim object.
  • This feature requires CSIInlineVolume feature gate to be enabled:--feature-gates=CSIInlineVolume=true
  • In-tree plugins that support CSI Migration and have a corresponding CSI driver implemented are listed in the “Types of Volumes” section above.
  • Mount propagation allows for sharing volumes mounted by a Container to other Containers in the same Pod, or even to other Pods on the same node.
  • Mount propagation of a volume is controlled by mountPropagation field in Container.volumeMounts.
  • HostToContainer - This volume mount will receive all subsequent mounts that are mounted to this volume or any of its subdirectories.
  • Bidirectional - This volume mount behaves the same the HostToContainer mount. In addition, all volume mounts created by the Container will be propagated back to the host and to all Containers of all Pods that use the same volume.
  • Edit your Docker’s systemd service file. Set MountFlags as follows:MountFlags=shared
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