Retrieve container logs before container exits / is removed

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

docker/models/containers.py

@@ -629,6 +629,9 @@ class ContainerCollection(Collection):
                 (e.g. ``SIGINT``).
             storage_opt (dict): Storage driver options per container as a
                 key-value mapping.
+            stream (bool): If true and ``detach`` is false, return a log
+                generator instead of a string. Ignored if ``detach`` is true.
+                Default: ``False``.
             sysctls (dict): Kernel parameters to set in the container.
             tmpfs (dict): Temporary filesystems to mount, as a dictionary
                 mapping a path inside the container to options for that path.
@@ -696,6 +699,7 @@ class ContainerCollection(Collection):
         """
         if isinstance(image, Image):
             image = image.id
+        stream = kwargs.pop('stream', False)
         detach = kwargs.pop("detach", False)
         if detach and remove:
             if version_gte(self.client.api._version, '1.25'):
@@ -723,23 +727,28 @@ class ContainerCollection(Collection):
         if detach:
             return container
 
-        exit_status = container.wait()
-        if exit_status != 0:
-            stdout = False
-            stderr = True
-
         logging_driver = container.attrs['HostConfig']['LogConfig']['Type']
 
+        out = None
         if logging_driver == 'json-file' or logging_driver == 'journald':
-            out = container.logs(stdout=stdout, stderr=stderr)
-        else:
-            out = None
+            out = container.logs(
+                stdout=stdout, stderr=stderr, stream=True, follow=True
+            )
+
+        exit_status = container.wait()
+        if exit_status != 0:
+            out = container.logs(stdout=False, stderr=True)
 
         if remove:
             container.remove()
         if exit_status != 0:
-            raise ContainerError(container, exit_status, command, image, out)
-        return out
+            raise ContainerError(
+                container, exit_status, command, image, out
+            )
+
+        return out if stream or out is None else b''.join(
+            [line for line in out]
+        )
 
     def create(self, image, command=None, **kwargs):
         """

tests/integration/models_containers_test.py

 import docker
 import tempfile
 from .base import BaseIntegrationTest, TEST_API_VERSION
-from ..helpers import random_name
+from ..helpers import random_name, requires_api_version
 
 
 class ContainerCollectionTest(BaseIntegrationTest):
@@ -95,7 +95,7 @@ class ContainerCollectionTest(BaseIntegrationTest):
             "alpine", "echo hello",
             log_config=dict(type='none')
         )
-        self.assertEqual(out, None)
+        assert out is None
 
     def test_run_with_json_file_driver(self):
         client = docker.from_env(version=TEST_API_VERSION)
@@ -104,7 +104,24 @@ class ContainerCollectionTest(BaseIntegrationTest):
             "alpine", "echo hello",
             log_config=dict(type='json-file')
         )
-        self.assertEqual(out, b'hello\n')
+        assert out == b'hello\n'
+
+    @requires_api_version('1.25')
+    def test_run_with_auto_remove(self):
+        client = docker.from_env(version=TEST_API_VERSION)
+        out = client.containers.run(
+            'alpine', 'echo hello', auto_remove=True
+        )
+        assert out == b'hello\n'
+
+    def test_run_with_streamed_logs(self):
+        client = docker.from_env(version=TEST_API_VERSION)
+        out = client.containers.run(
+            'alpine', 'sh -c "echo hello && echo world"', stream=True
+        )
+        logs = [line for line in out]
+        assert logs[0] == b'hello\n'
+        assert logs[1] == b'world\n'
 
     def test_get(self):
         client = docker.from_env(version=TEST_API_VERSION)

tests/unit/fake_api_client.py

@@ -43,7 +43,7 @@ def make_fake_api_client():
             fake_api.get_fake_inspect_container()[1],
         'inspect_image.return_value': fake_api.get_fake_inspect_image()[1],
         'inspect_network.return_value': fake_api.get_fake_network()[1],
-        'logs.return_value': 'hello world\n',
+        'logs.return_value': [b'hello world\n'],
         'networks.return_value': fake_api.get_fake_network_list()[1],
         'start.return_value': None,
         'wait.return_value': 0,

tests/unit/models_containers_test.py

@@ -12,7 +12,7 @@ class ContainerCollectionTest(unittest.TestCase):
         client = make_fake_client()
         out = client.containers.run("alpine", "echo hello world")
 
-        assert out == 'hello world\n'
+        assert out == b'hello world\n'
 
         client.api.create_container.assert_called_with(
             image="alpine",
@@ -24,9 +24,8 @@ class ContainerCollectionTest(unittest.TestCase):
         client.api.start.assert_called_with(FAKE_CONTAINER_ID)
         client.api.wait.assert_called_with(FAKE_CONTAINER_ID)
         client.api.logs.assert_called_with(
-            FAKE_CONTAINER_ID,
-            stderr=False,
-            stdout=True
+            FAKE_CONTAINER_ID, stderr=False, stdout=True, stream=True,
+            follow=True
         )
 
     def test_create_container_args(self):