Merge pull request #2366 from craig8/docker-fixture

Added prototype docker wrapper and fixture for docker

volttrontesting/fixtures/docker_wrapper.py

@@ -0,0 +1,75 @@
+try:
+    import docker
+
+    HAS_DOCKER = True
+except ImportError:
+    HAS_DOCKER = False
+
+import time
+import contextlib
+
+# Only allow this function if docker is available from the pip library.
+if HAS_DOCKER:
+
+    @contextlib.contextmanager
+    def create_container(image_name: str, ports: dict = None, env: dict = None, command: (list, str) = None,
+                         startup_time_seconds: int = 30) -> \
+            (docker.models.containers.Container, None):
+        """ Creates a container instance in a context that will clean up after itself.
+
+        This is a wrapper around the docker api documented at https://docker-py.readthedocs.io/en/stable/containers.html.
+        Some things that this will do automatically for the caller is make the container be ephemeral by removing it
+        once the context manager is cleaned up.
+
+        This function is being used for long running processes.  Short processes may not work correctly because
+        the execution time might be too short for the returning of data from the container.
+
+        Usage:
+
+            with create_container("mysql", {"3306/tcp": 3306}):
+                # connect to localhost:3306 with mysql using connector
+
+        :param image_name: The image name (from dockerhub) that is to be instantiated
+        :param ports:
+            a dictionary following the convention {'portincontainre/protocol': portonhost}
+
+            ::
+                # example port exposing mysql's known port.
+                {'3306/tcp': 3306}
+        :param env:
+        :param command: string or list of commands to run during the startup of the container.
+        :param startup_time_seconds: Allow this many seconds for the startup of the container before raising a
+            runtime exception (Download of image and instantiation could take a while)
+
+        :return:
+            A container object (https://docker-py.readthedocs.io/en/stable/containers.html.) or None
+        """
+
+        # Create docker client (Uses localhost as agent connection.
+        client = docker.from_env()
+        if ":" in image_name:
+            client.images.pull(image_name)
+        else:
+            # So all tags aren't pulled. According to docs https://docker-py.readthedocs.io/en/stable/images.html.
+            client.images.pull(image_name + ":latest")
+        container = client.containers.run(image_name, ports=ports, environment=env, auto_remove=True, detach=True)
+
+        if container is None:
+            raise RuntimeError(f"Unable to run image {image_name}")
+
+        error_time = time.time() + startup_time_seconds
+        invalid = False
+        while container.status != 'running':
+            if time.time() > error_time:
+                invalid = True
+                break
+            time.sleep(0.1)
+            container.reload()
+
+        if invalid:
+            yield None
+        else:
+            yield container
+
+        container.kill()
+

volttrontesting/testutils/test_fixtures.py

@@ -1,6 +1,12 @@
-
+import pytest
 from volttrontesting.fixtures.volttron_platform_fixtures import volttron_instance_web
 
+try:
+    SKIP_DOCKER = False
+    from volttrontesting.fixtures.docker_wrapper import create_container
+except ImportError:
+    SKIP_DOCKER = True
+
 
 def test_web_setup_properly(volttron_instance_web):
     instance = volttron_instance_web
@@ -9,4 +15,15 @@ def test_web_setup_properly(volttron_instance_web):
     assert instance.bind_web_address == instance.volttron_central_address
 
 
+@pytest.mark.skipif(SKIP_DOCKER, reason="No docker available in api (install pip install docker) for availability")
+def test_docker_wrapper():
+    with create_container("mysql") as container:
+        print(container.status)
+        print(container.logs())
+
+
+@pytest.mark.skipif(SKIP_DOCKER, reason="No docker available in api (install pip install docker) for availability")
+def test_docker_run_crate_latest():
+    with create_container("crate", {"4200/tcp": 4200}) as container:
+        assert container.status == 'running'