code: def warmup(self):
          
          self.logger.debug("Warming up...")
  
          try:
              if not isinstance(self.source, Manifest) and self.source:
                  self.source = load_manifest(self.source)
              if not isinstance(self.target, Manifest) and self.target:
                  self.target = load_manifest(self.target)
              self.main_manifest = self.target or self.source
          except lib.BadCredentialsException:
              e = sys.exc_info()[1]
              self.logger.error(str(e))
              raise SprinterException("Fatal error! Bad credentials to grab manifest!")
  
          if not getattr(self, 'namespace', None):
              if self.target:
                  self.namespace = self.target.namespace
              elif not self.namespace and self.source:
                  self.namespace = self.source.namespace
              else:
                  raise SprinterException("No environment name has been specified!")
  
          self.directory_root = self.custom_directory_root
  
          if not self.directory:
              if not self.directory_root:
                  self.directory_root = os.path.join(self.root, self.namespace)
  
              self.directory = Directory(self.directory_root,
                                         shell_util_path=self.shell_util_path)
  
          if not self.injections:
              self.injections = Injections(wrapper="%s_%s" % (self.sprinter_namespace.upper(),
                                                              self.namespace),
                                           override="SPRINTER_OVERRIDES")
          if not self.global_injections:
              self.global_injections = Injections(wrapper="%s" % self.sprinter_namespace.upper() + "GLOBALS",
                                                  override="SPRINTER_OVERRIDES")
          # append the bin, in the case sandboxes are necessary to
          # execute commands further down the sprinter lifecycle
          os.environ['PATH'] = self.directory.bin_path() + ":" + os.environ['PATH']
          self.warmed_up = True
docs: initialize variables necessary to perform a sprinter action