dvc: support external repos in api functions

dvc/api.py

@@ -1,15 +1,74 @@
+from contextlib import contextmanager
+import os
+import tempfile
+
+try:
+    from contextlib import _GeneratorContextManager as GCM
+except ImportError:
+    from contextlib import GeneratorContextManager as GCM
+
+from dvc.utils import remove
+from dvc.utils.compat import urlparse
 from dvc.repo import Repo
+from dvc.external_repo import ExternalRepo
 
 
-def get_url(path, repo_dir=None, remote=None):
-    """Returns an url of `path` in default or specified remote"""
-    repo = Repo(repo_dir)
-    out, = repo.find_outs_by_path(path)
-    remote_obj = repo.cloud.get_remote(remote)
-    return str(remote_obj.checksum_to_path_info(out.checksum))
+def get_url(path, repo=None, remote=None):
+    """Returns an url of a resource specified by path in repo"""
+    with _make_repo(repo) as _repo:
+        abspath = os.path.join(_repo.root_dir, path)
+        out, = _repo.find_outs_by_path(abspath)
+        remote_obj = _repo.cloud.get_remote(remote)
+        return str(remote_obj.checksum_to_path_info(out.checksum))
 
 
-def open(path, repo_dir=None, remote=None, mode="r", encoding=None):
+def open(path, repo=None, remote=None, mode="r", encoding=None):
     """Opens a specified resource as a file descriptor"""
-    repo = Repo(repo_dir)
-    return repo.open(path, remote=remote, mode=mode, encoding=encoding)
+    args = (path,)
+    kwargs = {
+        "repo": repo,
+        "remote": remote,
+        "mode": mode,
+        "encoding": encoding,
+    }
+    return _OpenContextManager(_open, args, kwargs)
+
+
+class _OpenContextManager(GCM):
+    def __init__(self, func, args, kwds):
+        self.gen = func(*args, **kwds)
+        self.func, self.args, self.kwds = func, args, kwds
+
+    def __getattr__(self, name):
+        raise AttributeError(
+            "dvc.api.open() should be used in a with statement"
+        )
+
+
+def _open(path, repo=None, remote=None, mode="r", encoding=None):
+    with _make_repo(repo) as _repo:
+        abspath = os.path.join(_repo.root_dir, path)
+        with _repo.open(
+            abspath, remote=remote, mode=mode, encoding=encoding
+        ) as fd:
+            yield fd
+
+
+def read(path, repo=None, remote=None, mode="r", encoding=None):
+    """Read a specified resource into string"""
+    with open(path, repo, remote=remote, mode=mode, encoding=encoding) as fd:
+        return fd.read()
+
+
+@contextmanager
+def _make_repo(repo_url):
+    if not repo_url or urlparse(repo_url).scheme == "":
+        yield Repo(repo_url)
+    else:
+        tmp_dir = tempfile.mkdtemp("dvc-repo")
+        try:
+            ext_repo = ExternalRepo(tmp_dir, url=repo_url)
+            ext_repo.install()
+            yield ext_repo.repo
+        finally:
+            remove(tmp_dir)

tests/func/test_api.py

@@ -4,6 +4,7 @@
 from dvc import api
 from dvc.main import main
 from dvc.path_info import URLInfo
+from dvc.remote.config import RemoteConfig
 from .test_data_cloud import (
     _should_test_aws,
     get_aws_url,
@@ -55,33 +56,40 @@ class HDFS:
 
 
 @pytest.fixture
-def remote(request):
+def remote_url(request):
     if not request.param.should_test():
         raise pytest.skip()
-    return request.param
+    return request.param.get_url()
 
 
 def pytest_generate_tests(metafunc):
-    if "remote" in metafunc.fixturenames:
-        metafunc.parametrize("remote", remote_params, indirect=True)
+    if "remote_url" in metafunc.fixturenames:
+        metafunc.parametrize("remote_url", remote_params, indirect=True)
 
 
 def run_dvc(*argv):
     assert main(argv) == 0
 
 
-def test_get_url(repo_dir, dvc_repo, remote):
-    remote_url = remote.get_url()
-
+def test_get_url(repo_dir, dvc_repo, remote_url):
     run_dvc("remote", "add", "-d", "upstream", remote_url)
     dvc_repo.add(repo_dir.FOO)
 
     expected_url = URLInfo(remote_url) / "ac/bd18db4cc2f85cedef654fccc4a4d8"
     assert api.get_url(repo_dir.FOO) == expected_url
 
 
-def test_open(repo_dir, dvc_repo, remote):
-    run_dvc("remote", "add", "-d", "upstream", remote.get_url())
+def test_get_url_external(repo_dir, dvc_repo, erepo, remote_url):
+    _set_remote_url_and_commit(erepo.dvc, remote_url)
+
+    # Using file url to force clone to tmp repo
+    repo_url = "file://" + erepo.dvc.root_dir
+    expected_url = URLInfo(remote_url) / "ac/bd18db4cc2f85cedef654fccc4a4d8"
+    assert api.get_url(repo_dir.FOO, repo=repo_url) == expected_url
+
+
+def test_open(repo_dir, dvc_repo, remote_url):
+    run_dvc("remote", "add", "-d", "upstream", remote_url)
     dvc_repo.add(repo_dir.FOO)
     run_dvc("push")
 
@@ -90,3 +98,23 @@ def test_open(repo_dir, dvc_repo, remote):
 
     with api.open(repo_dir.FOO) as fd:
         assert fd.read() == repo_dir.FOO_CONTENTS
+
+
+def test_open_external(repo_dir, dvc_repo, erepo, remote_url):
+    _set_remote_url_and_commit(erepo.dvc, remote_url)
+    erepo.dvc.push()
+
+    # Remove cache to force download
+    shutil.rmtree(erepo.dvc.cache.local.cache_dir)
+
+    # Using file url to force clone to tmp repo
+    repo_url = "file://" + erepo.dvc.root_dir
+    with api.open(repo_dir.FOO, repo=repo_url) as fd:
+        assert fd.read() == repo_dir.FOO_CONTENTS
+
+
+def _set_remote_url_and_commit(repo, remote_url):
+    rconfig = RemoteConfig(repo.config)
+    rconfig.modify("upstream", "url", remote_url)
+    repo.scm.add([repo.config.config_file])
+    repo.scm.commit("modify remote")