- diff --git a/dockerfile_parse/parser.py b/dockerfile_parse/parser.py

- index 615d7a8..25b6536 100644

- --- a/dockerfile_parse/parser.py

- +++ b/dockerfile_parse/parser.py

- @@ -66,11 +66,12 @@ class Envs(dict):

- 

- 

-  class DockerfileParser(object):

- -    def __init__(self, path=None, cache_content=False, env_replace=True):

- +    def __init__(self, path=None, cache_content=False, env_replace=True, parent_env=None):

-          """

-          Initialize path to Dockerfile

-          :param path: path to (directory with) Dockerfile

-          :param cache_content: cache Dockerfile content inside DockerfileParser

- +        :param parent_env: python dict of inherited env vars from parent image

-          """

-          path = path or '.'

-          if path.endswith(DOCKERFILE_FILENAME):

- @@ -91,6 +92,14 @@ class DockerfileParser(object):

- 

-          self.env_replace = env_replace

- 

- +        if isinstance(parent_env, dict):

- +            logger.debug("Setting inherited parent image ENV vars: %s", parent_env)

- +            self.parent_env = parent_env

- +        elif parent_env != None:

- +            assert isinstance(parent_env, dict)

- +        else:

- +            self.parent_env = {}

- +

-      @property

-      def lines(self):

-          """

- @@ -106,7 +115,7 @@ class DockerfileParser(object):

-                      self.cached_content = ''.join(lines)

-                  return lines

-          except (IOError, OSError) as ex:

- -            logger.error("Couldn't retrieve lines from dockerfile: %s" % repr(ex))

- +            logger.error("Couldn't retrieve lines from dockerfile: %r", ex)

-              raise

- 

-      @lines.setter

- @@ -122,7 +131,7 @@ class DockerfileParser(object):

-              with open(self.dockerfile_path, 'w') as dockerfile:

-                  dockerfile.writelines([u2b(l) for l in lines])

-          except (IOError, OSError) as ex:

- -            logger.error("Couldn't write lines to dockerfile: %s" % repr(ex))

- +            logger.error("Couldn't write lines to dockerfile: %r", ex)

-              raise

- 

-      @property

- @@ -140,7 +149,7 @@ class DockerfileParser(object):

-                      self.cached_content = content

-                  return content

-          except (IOError, OSError) as ex:

- -            logger.error("Couldn't retrieve content of dockerfile: %s" % repr(ex))

- +            logger.error("Couldn't retrieve content of dockerfile: %r", ex)

-              raise

- 

-      @content.setter

- @@ -156,7 +165,7 @@ class DockerfileParser(object):

-              with open(self.dockerfile_path, 'w') as dockerfile:

-                  dockerfile.write(u2b(content))

-          except (IOError, OSError) as ex:

- -            logger.error("Couldn't write content to dockerfile: %s" % repr(ex))

- +            logger.error("Couldn't write content to dockerfile: %r", ex)

-              raise

- 

-      @property

- @@ -290,7 +299,7 @@ class DockerfileParser(object):

-          if name != 'LABEL' and name != 'ENV':

-              raise ValueError("Unsupported instruction '%s'", name)

-          instructions = {}

- -        envs = {}

- +        envs = self.parent_env.copy()

-          for insndesc in self.structure:

-              this_insn = insndesc['instruction']

-              if this_insn in (name, 'ENV'):

- @@ -354,7 +363,7 @@ class DockerfileParser(object):

-          elif name == 'ENV':

-              existing = self.envs

- 

- -        logger.debug("setting %s instructions: %r" % (name, instructions))

- +        logger.debug("setting %s instructions: %r", name, instructions)

- 

-          to_delete = [k for k in existing if k not in instructions]

-          for key in to_delete:

- 

- diff --git a/tests/test_parser.py b/tests/test_parser.py

- index 8f63a04..e47fefe 100644

- --- a/tests/test_parser.py

- +++ b/tests/test_parser.py

- @@ -86,6 +86,35 @@ USER  {0}""".format(NON_ASCII)

-          base_img = dfparser.baseimage

-          assert base_img.startswith('fedora')

- 

- +    def test_get_parent_env(self, tmpdir):

- +        tmpdir_path = str(tmpdir.realpath())

- +        p_env = {"bar": "baz"}

- +        df1 = DockerfileParser(tmpdir_path, env_replace=True, parent_env=p_env)

- +        df1.lines = [

- +            "FROM parent\n",

- +            "ENV foo=\"$bar\"\n",

- +            "LABEL label=\"$foo $bar\"\n"

- +        ]

- +

- +        # Even though we inherit an ENV, this .envs count should only be for the

- +        # ENVs defined in *this* Dockerfile as we're parsing the Dockerfile and

- +        # the parent_env is only to satisfy use of inhereted ENVs.

- +        assert len(df1.envs) == 1

- +        assert df1.envs.get('foo') == 'baz'

- +        assert len(df1.labels) == 1

- +        assert df1.labels.get('label') == 'baz baz'

- +

- +    def test_get_parent_env_from_scratch(self, tmpdir):

- +        tmpdir_path = str(tmpdir.realpath())

- +        p_env = {"bar": "baz"}

- +        df1 = DockerfileParser(tmpdir_path, env_replace=True, parent_env=p_env)

- +        df1.lines = [

- +            "FROM scratch\n",

- +        ]

- +

- +        assert not df1.envs

- +

- +

-      def test_get_instructions_from_df(self, dfparser, instruction):

-          dfparser.content = ""

-          lines = []

- Version:        0.0.11

- Release:        4%{?dist}

- BuildRequires:  python2-six

- %endif

- %setup -n %{srcname}-%{version}

- %endif

- SHA512 (dockerfile-parse-0.0.11.tar.gz) = 0e14c1f964f736a50e96d5a235390f93691fc43514d833a886d75fe166b2fdb3424bf1eac25ec1271c73239114f877d35d998033e554c13b1a8bd96bef31941e