Support building with Dockerfile outside of context

Signed-off-by: Joffrey F <joffrey@docker.com>

docker/api/build.py

 import json
 import logging
 import os
+import random
 
 from .. import auth
 from .. import constants
@@ -148,6 +149,15 @@ class BuildApiMixin(object):
                         lambda x: x != '' and x[0] != '#',
                         [l.strip() for l in f.read().splitlines()]
                     ))
+            if dockerfile and os.path.relpath(dockerfile, path).startswith(
+                    '..'):
+                with open(dockerfile, 'r') as df:
+                    dockerfile = (
+                        '.dockerfile.{0:x}'.format(random.getrandbits(160)),
+                        df.read()
+                    )
+            else:
+                dockerfile = (dockerfile, None)
             context = utils.tar(
                 path, exclude=exclude, dockerfile=dockerfile, gzip=gzip
             )

docker/utils/build.py

@@ -2,23 +2,33 @@ import os
 import re
 
 from ..constants import IS_WINDOWS_PLATFORM
+from .utils import create_archive
 from fnmatch import fnmatch
 from itertools import chain
-from .utils import create_archive
+
+
+_SEP = re.compile('/|\\\\') if IS_WINDOWS_PLATFORM else re.compile('/')
 
 
 def tar(path, exclude=None, dockerfile=None, fileobj=None, gzip=False):
     root = os.path.abspath(path)
     exclude = exclude or []
+    dockerfile = dockerfile or (None, None)
+    extra_files = []
+    if dockerfile[1] is not None:
+        dockerignore_contents = '\n'.join(
+            (exclude or ['.dockerignore']) + [dockerfile[0]]
+        )
+        extra_files = [
+            ('.dockerignore', dockerignore_contents),
+            dockerfile,
+        ]
     return create_archive(
-        files=sorted(exclude_paths(root, exclude, dockerfile=dockerfile)),
-        root=root, fileobj=fileobj, gzip=gzip
+        files=sorted(exclude_paths(root, exclude, dockerfile=dockerfile[0])),
+        root=root, fileobj=fileobj, gzip=gzip, extra_files=extra_files
     )
 
 
-_SEP = re.compile('/|\\\\') if IS_WINDOWS_PLATFORM else re.compile('/')
-
-
 def exclude_paths(root, patterns, dockerfile=None):
     """
     Given a root directory path and a list of .dockerignore patterns, return

docker/utils/utils.py

@@ -88,13 +88,17 @@ def build_file_list(root):
     return files
 
 
-def create_archive(root, files=None, fileobj=None, gzip=False):
+def create_archive(root, files=None, fileobj=None, gzip=False,
+                   extra_files=None):
     if not fileobj:
         fileobj = tempfile.NamedTemporaryFile()
     t = tarfile.open(mode='w:gz' if gzip else 'w', fileobj=fileobj)
     if files is None:
         files = build_file_list(root)
     for path in files:
+        if path in [e[0] for e in extra_files]:
+            # Extra files override context files with the same name
+            continue
         full_path = os.path.join(root, path)
 
         i = t.gettarinfo(full_path, arcname=path)
@@ -123,6 +127,12 @@ def create_archive(root, files=None, fileobj=None, gzip=False):
         else:
             # Directories, FIFOs, symlinks... don't need to be read.
             t.addfile(i, None)
+
+    for name, contents in extra_files:
+        info = tarfile.TarInfo(name)
+        info.size = len(contents)
+        t.addfile(info, io.BytesIO(contents.encode('utf-8')))
+
     t.close()
     fileobj.seek(0)
     return fileobj

tests/integration/api_build_test.py

@@ -407,3 +407,36 @@ class BuildTest(BaseAPIIntegrationTest):
 
         assert excinfo.value.status_code == 400
         assert 'invalid platform' in excinfo.exconly()
+
+    def test_build_out_of_context_dockerfile(self):
+        base_dir = tempfile.mkdtemp()
+        self.addCleanup(shutil.rmtree, base_dir)
+        with open(os.path.join(base_dir, 'file.txt'), 'w') as f:
+            f.write('hello world')
+        with open(os.path.join(base_dir, '.dockerignore'), 'w') as f:
+            f.write('.dockerignore\n')
+        df = tempfile.NamedTemporaryFile()
+        self.addCleanup(df.close)
+        df.write(('\n'.join([
+            'FROM busybox',
+            'COPY . /src',
+            'WORKDIR /src',
+        ])).encode('utf-8'))
+        df.flush()
+        img_name = random_name()
+        self.tmp_imgs.append(img_name)
+        stream = self.client.build(
+            path=base_dir, dockerfile=df.name, tag=img_name,
+            decode=True
+        )
+        lines = []
+        for chunk in stream:
+            lines.append(chunk)
+        assert 'Successfully tagged' in lines[-1]['stream']
+
+        ctnr = self.client.create_container(img_name, 'ls -a')
+        self.tmp_containers.append(ctnr)
+        self.client.start(ctnr)
+        lsdata = self.client.logs(ctnr).strip().split(b'\n')
+        assert len(lsdata) == 3
+        assert sorted([b'.', b'..', b'file.txt']) == sorted(lsdata)