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張 旭

153 ☞ Sourcing a shell script in Make - 0 views

blog.153.io/...source-a-shell-script-in-make

makefile programming shell script

shared by 張 旭 on 24 Dec 18 - No Cached
  • Make runs its commands in a subshell, so the variables exported by source aren’t available to other commands.
  • Make and Bash have awfully similar syntaces for setting variables
  • Make doesn’t parse quotes
  • ...2 more annotations...
  • needs to run before any target
  • If there’s a target for makefile, and its prerequisites are new, the target will run before anything, because the makefile might change.
張 旭

A Clear, Concise & Comfy Code Review Checklist - DEV Community - 0 views

dev.to/...code-review-checklist-14ke

programming code development

shared by 張 旭 on 29 Dec 18 - No Cached
  • 2 blocks doing similar things might be allowable, but 3 or more is a definitive red cross from me!
  • This would ultimately be integrated into your CI/CD pipelines running on each build/commit/deploy too; stopping any rogue commits getting in.
  • not to say that every code block that is duplicated needs to be refactored
  • ...13 more annotations...
  • Refactoring is a cyclical process
  • Before accessing variables within objects and collections make sure they are there! PLEASE!
  • If that variable is a constant or won't be changed then use the Const keyword in applicable languages and the CAPITALISATION convention to let users aware of your decisions about them.
  • The name of a method is more important than we give it credit for, when a method changes so should its name.
  • Make sure you are returning the right thing, trying to make it as generic as possible.
  • Void should do something, not change something!
  • Private vs Public, this is a big topic
  • keeping an eye of the access level of a method can stop issues further down the line
  • Gherkin is a Business Readable, Domain Specific Language created especially for behavior descriptions.
  • specify the 3 main points of a test, including what you expect to happen using the following keywords GIVEN,  WHEN / AND , THEN.
  • look at how the code is structured, make sure methods aren't too long, don't have too many branches, and that for and if statements could be simplified.
  • Use your initiative and discuss if a rewrite would benefit maintainability for the future.
  • it's unnecessary to leave commented code when working in and around areas with them.
張 旭

What are Docker : images? - Project Atomic - 0 views

www.projectatomic.io/...at-are-docker-none-none-images

docker system

shared by 張 旭 on 18 Sep 18 - No Cached
  • Now we understand what these <none>:<none> images stand for. They stand for intermediate images and can be seen using docker images -a
  • They don’t result into a disk space problem but it is definitely a screen real estate problem
  • dangling images
  • ...7 more annotations...
  • Another style of <none>:<none> images are the dangling images which can cause disk space problems.
  • In programming languages like Java or Golang a dangling block of memory is a block that is not referenced by any piece of code.
  • a dangling file system layer in Docker is something that is unused and is not being referenced by any images.
  • intermediate images
  • do docker images and see <none>:<none> images in the list, these are dangling images and needs to be pruned.
  • These dangling images are produced as a result of docker build or pull command.
  • docker rmi $(docker images -f "dangling=true" -q)
張 旭

https://www.conventionalcommits.org/en/v1.0.0-beta.2/ - 0 views

www.conventionalcommits.org/...v1.0.0-beta.2

git commit programming code

shared by 張 旭 on 20 Sep 18 - No Cached
  • standardized commit message
  • fix patches a bug in your codebase
  • feat introduces a new feature to the codebase
  • ...11 more annotations...
  • a breaking API change
  • A breaking change can be part of commits of any type. e.g., a fix:, feat: & chore: types would all be valid, in addition to any other type.
  • We also recommend improvement for commits that improve a current implementation without adding a new feature or fixing a bug.
  • he type feat MUST be used when a commit adds a new feature to your application or library
  • followed by a colon and a space
  • The type fix MUST be used when a commit represents a bug fix for your application.
  • An optional scope MAY be provided after a type.
  • A description MUST immediately follow the type/scope prefix.
  • A footer MAY be provided one blank line after the body (or after the description if body is missing).
  • A breaking change MUST consist of the uppercase text BREAKING CHANGE, followed by a colon and a space
  • Types other than feat and fix MAY be used in your commit messages.
  • 張 旭 on 20 Sep 18
     
    "standardized commit message"
張 旭

Bash If Statements: Beginner to Advanced - DEV Community - 0 views

dev.to/...ents-beginner-to-advanced-25e6

bash shell programming

shared by 張 旭 on 18 Jan 19 - No Cached
  • "[" is a command. It's actually syntactic sugar for the built-in command test which checks and compares its arguments. The "]" is actually an argument to the [ command that tells it to stop checking for arguments!
  • why > and < get weird inside single square brackets -- Bash actually thinks you're trying to do an input or output redirect inside a command!
  • the [[ double square brackets ]] and (( double parens )) are not exactly commands. They're actually Bash language keywords, which is what makes them behave a little more predictably.
  • ...8 more annotations...
  • The [[ double square brackets ]] work essentially the same as [ single square brackets ], albeit with some more superpowers like more powerful regex support.
  • The (( double parentheses )) are actually a construct that allow arithmetic inside Bash.
  • If the results inside are zero, it returns an exit code of 1. (Essentially, zero is "falsey.")
  • the greater and less-than symbols work just fine inside arithmetic parens.
  • exit code 0 for success.
  • exit code 1 for failure.
  • If the regex works out, the return code of the double square brackets is 0, and thus the function returns 0. If not, everything returns 1. This is a really great way to name regexes.
  • the stuff immediately after the if can be any command in the whole wide world, as long as it provides an exit code, which is pretty much always.
  • 張 旭 on 18 Jan 19
     
    ""[" is a command. It's actually syntactic sugar for the built-in command test which checks and compares its arguments. The "]" is actually an argument to the [ command that tells it to stop checking for arguments!"
張 旭

Advanced Argument Handling in Bash - DEV Community - 0 views

dev.to/...argument-handling-in-bash-377b

bash shell programming

shared by 張 旭 on 21 Mar 19 - No Cached
  • Required Values: ${1:?Error Message}
  • Default Values: ${1:-default}
  • Assign a Default: ${var:=value} Very similar to the default values above.
  • ...3 more annotations...
  • shift takes these arguments and removes the first one, shifting each of the rest down by one place in line.
  • on any of the options that accept an argument, that argument will be stored in the variable $OPTARG automagically for you.
  • getopts command
  • 張 旭 on 21 Mar 19
     
    "Required Values: ${1:?Error Message}"
張 旭

Handling Arguments in Bash Scripts - DEV Community - 0 views

dev.to/...arguments-in-bash-scripts-3o5m

bash shell programming

shared by 張 旭 on 21 Mar 19 - No Cached
  • positional arguments. They hold the arguments given after your script as it was run on the command line
  • $0: The Script Name
  • $#: Argument Count
  • ...2 more annotations...
  • $?: Most Recent Exit Code
  • When you quote $*, it will output all of the arguments received as one single string, separated by a space1 regardless of how they were quoted going in, but it will quote that string so that it doesn't get split up later.
  • 張 旭 on 21 Mar 19
     
    "positional arguments. They hold the arguments given after your script as it was run on the command line"
張 旭

Rails API Testing Best Practices - 0 views

matthewlehner.net/rails-api-testing-guidelines

rails api programming development

shared by 張 旭 on 29 Jun 17 - No Cached
  • Writing an API is almost a given with modern web applications
  • A properly designed API should return two things: an HTTP response status-code and the response body.
  • Testing the status-code is necessary
  • ...6 more annotations...
  • testing the response body should just verify that the application is sending the right content.
  • Unauthorized
  • Forbidden
  • Your test should also ensure that any desired business logic gets completed as expected.
  • Request specs provide a thin wrapper around Rails’ integration tests, and are designed to drive behavior through the full stack
  • we’ll be doing json = JSON.parse(response.body) a lot. This should be a helper method.
張 旭

Search and filter Rails models without bloating your controller - Justin Weiss - 0 views

www.justinweiss.com/...thout-bloating-your-controller

rails search development programming database model scope

shared by 張 旭 on 01 Jul 17 - No Cached
  • Rails includes scopes, which can provide you with a lot of what you need for simple searching, filtering, and sorting.
  • scope chaining
  • filtering and searching of your models with one line in the controller and one line in the model.
  • ...2 more annotations...
  • .public_send
  • ClassMethods
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

Four-Phase Test - 0 views

robots.thoughtbot.com/four-phase-test

test programming development

shared by 張 旭 on 20 Jun 17 - No Cached
張 旭

dry-rb - Home - 0 views

dry-rb.org

ruby programming development

shared by 張 旭 on 02 Oct 16 - No Cached
  • crazylion lee on 02 Oct 16
     
    "dry-rb is a collection of next-generation Ruby libraries, each intended to encapsulate a common task"
張 旭

phusion/baseimage-docker - 1 views

github.com/...baseimage-docker

docker ubuntu base system

shared by 張 旭 on 24 Jun 15 - No Cached
    • 張 旭
      張 旭 on 24 Jun 15
       
      原始的 docker 在執行命令時，預設就是將傳入的 COMMAND 當成 PID 1 的程序，執行完畢就結束這個  docker，其他的 daemons 並不會執行，而 baseimage 解決了這個問題。
    • crazylion lee
      crazylion lee on 17 Dec 15
       
      好棒棒
  • docker exec
  • Through SSH
  • ...57 more annotations...
  • docker exec -t -i YOUR-CONTAINER-ID bash -l
  • Login to the container
  • Baseimage-docker only advocates running multiple OS processes inside a single container.
  • Password and challenge-response authentication are disabled by default. Only key authentication is allowed.
  • A tool for running a command as another user
  • The Docker developers advocate the philosophy of running a single logical service per container. A logical service can consist of multiple OS processes.
  • All syslog messages are forwarded to "docker logs".
  • Baseimage-docker advocates running multiple OS processes inside a single container, and a single logical service can consist of multiple OS processes.
  • Baseimage-docker provides tools to encourage running processes as different users
  • sometimes it makes sense to run multiple services in a single container, and sometimes it doesn't.
  • Splitting your logical service into multiple OS processes also makes sense from a security standpoint.
  • using environment variables to pass parameters to containers is very much the "Docker way"
  • Baseimage-docker provides a facility to run a single one-shot command, while solving all of the aforementioned problems
  • the shell script must run the daemon without letting it daemonize/fork it.
  • All executable scripts in /etc/my_init.d, if this directory exists. The scripts are run in lexicographic order.
  • variables will also be passed to all child processes
  • Environment variables on Unix are inherited on a per-process basis
  • there is no good central place for defining environment variables for all applications and services
  • centrally defining environment variables
  • One of the ideas behind Docker is that containers should be stateless, easily restartable, and behave like a black box.
  • a one-shot command in a new container
  • immediately exit after the command exits,
  • However the downside of this approach is that the init system is not started. That is, while invoking COMMAND, important daemons such as cron and syslog are not running. Also, orphaned child processes are not properly reaped, because COMMAND is PID 1.
  • add additional daemons (e.g. your own app) to the image by creating runit entries.
  • Nginx is one such example: it removes all environment variables unless you explicitly instruct it to retain them through the env configuration option.
  • Mechanisms for easily running multiple processes, without violating the Docker philosophy
  • Ubuntu is not designed to be run inside Docker
  • According to the Unix process model, the init process -- PID 1 -- inherits all orphaned child processes and must reap them
  • Syslog-ng seems to be much more stable
  • cron daemon
  • Rotates and compresses logs
  • /sbin/setuser
  • A tool for installing apt packages that automatically cleans up after itself.
  • a single logical service inside a single container
  • A daemon is a program which runs in the background of its system, such as a web server.
  • The shell script must be called run, must be executable, and is to be placed in the directory /etc/service/<NAME>. runsv will switch to the directory and invoke ./run after your container starts.
  • If any script exits with a non-zero exit code, the booting will fail.
  • If your process is started with a shell script, make sure you exec the actual process, otherwise the shell will receive the signal and not your process.
  • any environment variables set with docker run --env or with the ENV command in the Dockerfile, will be picked up by my_init
  • not possible for a child process to change the environment variables of other processes
  • they will not see the environment variables that were originally passed by Docker.
  • We ignore HOME, SHELL, USER and a bunch of other environment variables on purpose, because not ignoring them will break multi-user containers.
  • my_init imports environment variables from the directory /etc/container_environment
  • /etc/container_environment.sh - a dump of the environment variables in Bash format.
  • modify the environment variables in my_init (and therefore the environment variables in all child processes that are spawned after that point in time), by altering the files in /etc/container_environment
  • my_init only activates changes in /etc/container_environment when running startup scripts
  • environment variables don't contain sensitive data, then you can also relax the permissions
  • Syslog messages are forwarded to the console
  • syslog-ng is started separately before the runit supervisor process, and shutdown after runit exits.
  • RUN apt-get update && apt-get upgrade -y -o Dpkg::Options::="--force-confold"
  • /sbin/my_init --skip-startup-files --quiet --
  • By default, no keys are installed, so nobody can login
  • provide a pregenerated, insecure key (PuTTY format)
  • RUN /usr/sbin/enable_insecure_key
  • docker run YOUR_IMAGE /sbin/my_init --enable-insecure-key
  • RUN cat /tmp/your_key.pub >> /root/.ssh/authorized_keys && rm -f /tmp/your_key.pub
  • The default baseimage-docker installs syslog-ng, cron and sshd services during the build process
張 旭

The Twelve-Factor App - 0 views

12factor.net/backing-services

programming application development

shared by 張 旭 on 27 Jan 19 - No Cached
  • A backing service is any service the app consumes over the network as part of its normal operation.
  • A deploy of the twelve-factor app should be able to swap out a local MySQL database with one managed by a third party (such as Amazon RDS) without any changes to the app’s code.
  • only the resource handle in the config needs to change
  • ...2 more annotations...
  • Each distinct backing service is a resource.
  • Resources can be attached to and detached from deploys at will.
張 旭

The Twelve-Factor App - 0 views

12factor.net/port-binding

development application programming

shared by 張 旭 on 20 Feb 19 - No Cached
  • The twelve-factor app is completely self-contained
  • using dependency declaration to add a webserver library to the app, such as Tornado for Python, Thin for Ruby, or Jetty for Java and other JVM-based languages.
  • the port-binding approach means that one app can become the backing service for another app
張 旭

The Twelve-Factor App - 0 views

12factor.net/disposability

development application programming

shared by 張 旭 on 20 Feb 19 - No Cached
  • they can be started or stopped at a moment’s notice.
  • Processes should strive to minimize startup time
  • Processes shut down gracefully when they receive a SIGTERM signal from the process manager.
  • ...4 more annotations...
  • returning the current job to the work queue
  • all jobs are reentrant, which typically is achieved by wrapping the results in a transaction, or making the operation idempotent
  • Processes should also be robust against sudden death, in the case of a failure in the underlying hardware.
  • a twelve-factor app is architected to handle unexpected, non-graceful terminations
張 旭

The Twelve-Factor App - 0 views

12factor.net/logs

development application programming

shared by 張 旭 on 20 Feb 19 - No Cached
  • Logs are the stream of aggregated, time-ordered events collected from the output streams of all running processes and backing services.
  • Logs have no fixed beginning or end, but flow continuously as long as the app is operating.
  • each running process writes its event stream, unbuffered, to stdout.
  • ...2 more annotations...
  • long-term archival. These archival destinations are not visible to or configurable by the app, and instead are completely managed by the execution environment.
  • Most significantly, the stream can be sent to a log indexing and analysis system such as Splunk, or a general-purpose data warehousing system such as Hadoop/Hive.
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