Category Archives: Uncategorized

Running multiple commands in docker in parallel

Went through foreman/goreman/forego and all of them either did not:
– support not printing the name
– support killing all when one finishes
– support sending signals to all children

But this does:

## Install parallel with `done` support
RUN \
  curl -sL http://ftp.gnu.org/gnu/parallel/parallel-20180422.tar.bz2 > /tmp/parallel.tar.bz2 && \
  cd /tmp && tar -xvjf /tmp/parallel.tar.bz2 && cd parallel* && \
  ./configure && make install && rm -rf /tmp/parallel*

# stream output and stop all commands if any of them finish/fail
parallel --no-notice --ungroup --halt 'now,done=1' {1} ::: 'sleep 10' 'sleep 20'

Chef install google-cloud-sdk without package manager

A tiny chef snipped to install gcloud without using a package manager (to get the latest version without waiting)

gcloud_version = node["foo"]["google-cloud-sdk_version"]
gcloud_file = "google-cloud-sdk-#{gcloud_version}-linux-x86_64.tar.gz"
gcloud_folder = "https://dl.google.com/dl/cloudsdk/channels/rapid/downloads"
gcloud_installer = "https://dl.google.com/dl/cloudsdk/channels/rapid/install_google_cloud_sdk.bash"
execute "gcloud_install" do
  # clean up ... download installer but select the version we want ... install ... link
  command "rm -rf $CLOUDSDK_INSTALL_DIR/google-cloud-sdk && curl #{gcloud_installer} | sed 's;__SDK_URL_DIR=.*;__SDK_URL_DIR=#{gcloud_folder};' | sed 's/__SDK_TGZ=.*/__SDK_TGZ=#{gcloud_file}/' | bash && ln -sf $CLOUDSDK_INSTALL_DIR/google-cloud-sdk/bin/gcloud /usr/local/bin/gcloud"
  env(
    "CLOUDSDK_CORE_DISABLE_PROMPTS" => "true",
    "CLOUDSDK_INSTALL_DIR" => "/opt", # prefix
  )
  not_if { `true && gcloud -v`.include?(gcloud_version) } # ~FC048
end

Digging into Ruby Hashes with dig_set and dig_fetch

Hash#dig is fun, but sometimes I want to be strict … so I use dig_fetch … and dig_set to set a value without running into nil / MethodMissing errors.

# before
hash.dig(:a, :b, :c) # any of these could be nil ...
hash.fetch(:a).fetch(:b).fetch(:a) # repetitive and only shows last key

# after
hash.dig_fetch(:a, :b, :a)


  Hash.class_eval do
    def dig_fetch(*keys, last, &block)
      block ||= ->(*) { raise KeyError, "key not found: #{(keys << last).inspect}" }
      before = (keys.any? ? dig(*keys) || {} : self)
      before.fetch(last, &block)
    end

    def dig_set(keys, value)
      raise ArgumentError, "No key given" if keys.empty?
      keys = keys.dup
      last = keys.pop
      failed = ->(*) { raise KeyError, "key not found: #{(keys << last).inspect}" }
      nested = keys.inject(self) { |h, k| h.fetch(k, &failed) }
      nested[last] = value
    end
  end

Bundler + Rails: realpath expand_path and symlinked vendor/bundle cause ‘already loaded’ errors

Symlinked vendor/bundle results in double load errors since:

  • rails adds the realpath of each engines lib (and various other folders) to the $LOAD_PATH
  • bundler adds the symlinked version to the $LOAD_PATH
  • require_relative uses the realpath

which looks like: `already initialized constant Arturo::Middleware::MISSING_FEATURE_ERROR`

Reproduce:

  • bundle install –path vendor/bundle
  • mv vendor/bundle tmp
  • cd vendor && ln -s ../tmp/bundle bundle
  • enable eager_load + preload_frameworks in config/environment/development.rb
  • rails runner 1

Ruby issue

Patch:

# Gemfile
require_relative 'lib/bundler_realpath'
 
# lib/bundler_realpath.rb
# https://grosser.it/2017/08/19/bundler-rails-realpath-expand_path-and-symlinked-vendorbundle-cause-already-loaded-errors
Bundler::Runtime.prepend(Module.new do
  def setup(*)
    super
  ensure
    linked_bundle = File.expand_path(Bundler.bundle_path)
    real_bundle = File.realpath(Bundler.bundle_path)
    if linked_bundle != real_bundle
      $LOAD_PATH.each_with_index do |path, i|
        $LOAD_PATH[i] = path.sub(linked_bundle, real_bundle)
      end
    end
  end
end)