Class: Katello::Util::CdnVarSubstitutor

Inherits:
Object
  • Object
show all
Defined in:
app/lib/katello/util/cdn_var_substitutor.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(cdn_resource) ⇒ CdnVarSubstitutor

cdn_resource - an object providing access to CDN. It has to provide a get method that takes a path (e.g. /content/rhel/6.2/listing) and returns the body response)



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# File 'app/lib/katello/util/cdn_var_substitutor.rb', line 9

def initialize(cdn_resource)
  @resource = cdn_resource
  @substitutions = Thread.current[:cdn_var_substitutor_cache] || {}
  @good_listings = Set.new
  @bad_listings = Set.new
end

Instance Attribute Details

#bad_listings ⇒ Object (readonly)

Returns the value of attribute bad_listings.



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# File 'app/lib/katello/util/cdn_var_substitutor.rb', line 5

def bad_listings
  @bad_listings
end

#good_listings ⇒ Object (readonly)

Returns the value of attribute good_listings.



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# File 'app/lib/katello/util/cdn_var_substitutor.rb', line 4

def good_listings
  @good_listings
end

Class Method Details

.with_cache(&_block) ⇒ Object

using substitutor from whithin the block makes sure that every request is made only once.



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# File 'app/lib/katello/util/cdn_var_substitutor.rb', line 18

def self.with_cache(&_block)
  Thread.current[:cdn_var_substitutor_cache] = {}
  yield
ensure
  Thread.current[:cdn_var_substitutor_cache] = nil
end

Instance Method Details

#precalculate(paths_with_vars) ⇒ Object

precalcuclate all paths at once - let’s you discover errors and stop before it causes more pain



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# File 'app/lib/katello/util/cdn_var_substitutor.rb', line 27

def precalculate(paths_with_vars)
  paths_with_vars.uniq.reduce({}) do |ret, path_with_vars|
    ret[path_with_vars] = substitute_vars(path_with_vars)
    ret
  end
end

#substituable?(path) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'app/lib/katello/util/cdn_var_substitutor.rb', line 89

def substituable?(path)
  path.include?("$")
end

#substitute_vars(path_with_vars) ⇒ Object

takes path e.g. “/rhel/server/5/$releasever/$basearch/os” returns hash substituting variables:

{ {"releasever" => "6Server", "basearch" => "i386"} =>  "/rhel/server/5/6Server/i386/os",
  {"releasever" => "6Server", "basearch" => "x86_64"} =>  "/rhel/server/5/6Server/x84_64/os"}

values are loaded from CDN



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# File 'app/lib/katello/util/cdn_var_substitutor.rb', line 41

def substitute_vars(path_with_vars)
  if path_with_vars =~ /^(.*\$\w+)(.*)$/
    prefix_with_vars, suffix_without_vars =  Regexp.last_match[1], Regexp.last_match[2]
  else
    prefix_with_vars, suffix_without_vars = "", path_with_vars
  end

  prefixes_without_vars = substitute_vars_in_prefix(prefix_with_vars)
  paths_without_vars = prefixes_without_vars.reduce({}) do |h, (substitutions, prefix_without_vars)|
    h[substitutions] = prefix_without_vars + suffix_without_vars
    h
  end
  return paths_without_vars
end

#substitute_vars_in_prefix(prefix_with_vars) ⇒ Object

prefix_with_vars is the part of url containing some vars. We can cache calcualted values for this parts. So for example for:

"/a/$b/$c/d"
"/a/$b/$c/e"

prefix_with_vars is “/a/$b/$c” and we store the result after resolving for the first path.



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# File 'app/lib/katello/util/cdn_var_substitutor.rb', line 62

def substitute_vars_in_prefix(prefix_with_vars)
  paths_with_vars = { {} => prefix_with_vars}
  prefixes_without_vars = @substitutions[prefix_with_vars]

  unless prefixes_without_vars
    prefixes_without_vars = {}
    until paths_with_vars.empty?
      substitutions, path = paths_with_vars.shift

      if substituable? path
        for_each_substitute_of_next_var substitutions, path do |new_substitution, new_path|
          begin
            paths_with_vars[new_substitution] = new_path
          rescue Errors::SecurityViolation
            # Some paths may not be accessible
            @resource.log :warn, "#{new_path} is not accessible, ignoring"
          end
        end
      else
        prefixes_without_vars[substitutions] = path
      end
    end
    @substitutions[prefix_with_vars] = prefixes_without_vars
  end
  return prefixes_without_vars
end

#valid_substitutions(content, substitutions) ⇒ Object 



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# File 'app/lib/katello/util/cdn_var_substitutor.rb', line 93

def valid_substitutions(content, substitutions)
  validate_all_substitutions_accepted(content, substitutions)
  content_url = content.contentUrl
  real_path = gsub_vars(content_url, substitutions)

  if substituable?(real_path)
    fail Errors::CdnSubstitutionError, _("Missing arguments %{substitutions} for %{content_url}") %
        { substitutions: substitutions_needed(real_path).join(', '),
          content_url: real_path }
  else
    is_valid = valid_path?(real_path, 'repodata/repomd.xml') || valid_path?(real_path, 'PULP_MANIFEST')
    unless is_valid
      @resource.log :error, "No valid metadata files found for #{real_path}"
      fail Errors::CdnSubstitutionError, _("%{substitutions} are not valid substitutions for %{content_url}."\
             " No valid metadata files found for %{real_path}") %
        { substitutions: substitutions, content_url: content.contentUrl, real_path: real_path}
    end
  end
end