module Sprockets::ManifestUtils

def find_directory_manifest(dirname, logger = Logger.new($stderr))

Returns String filename.

# => "/app/public/assets/.sprockets-manifest-abc123.json"
find_directory_manifest("/app/public/assets")

Examples

dirname - String dirname

Public: Find or pick a new manifest filename for target build directory. 
def find_directory_manifest(dirname, logger = Logger.new($stderr))
  entries = File.directory?(dirname) ? Dir.entries(dirname) : []
  manifest_entries = entries.select { |e| e =~ MANIFEST_RE }
  if manifest_entries.length > 1
    manifest_entries.sort!
    logger.warn("Found multiple manifests: #{manifest_entries}. Choosing the first alphabetically: #{manifest_entries.first}")
  end
  entry = manifest_entries.first || generate_manifest_path
  File.join(dirname, entry)
end

def generate_manifest_path

Return String path.

all bets are off.
guessing the location. If directory indexes are enabled on the server,
a random hex string is appended to the filename to prevent people from
like Apache. To help in other environments that may not control this,
filename is prefixed with a "." which is usually hidden by web servers
alongside public assets for convenience. To avoid being served, the
Manifests are not intended to be accessed publicly, but typically live

Public: Generate a new random manifest path. 
def generate_manifest_path
  ".sprockets-manifest-#{SecureRandom.hex(16)}.json"
end