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

fast npm install check to ensure it is up to date

Ensures that everyone has npm up to date without running “npm install”
Ideally this should be wrapped as “npm check” command, but we use a ruby/rake based workflow anyway.

  desc 'make sure npm is installed'
  task :ensure_npm do
    expected = JSON.parse(File.read('package-lock.json')).fetch('dependencies')
    satisfied = expected.all? do |name, data|
      expected_version = data.fetch('version')
      pack = "node_modules/#{name}/package.json"
      next unless File.exist?(pack)
      resolved = JSON.parse(File.read(pack))
      resolved.fetch('version') == expected_version || # regular
        resolved.fetch('_resolved') == expected_version # git
    end
    sh "npm install" unless satisfied
  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