exit and show clean error message (no log) if docker connection fails

Author: nuest

repo2docker/app.py

@@ -612,9 +612,10 @@ def build(self):
                 docker_client = docker.APIClient(version="auto", **kwargs_from_env())
             except DockerException as e:
                 self.log.error(
-                    "\nDocker client initialization error. Check if docker is running on the host.\n\n"
+                    "\nDocker client initialization error: %s.\nCheck if docker is running on the host.\n",
+                    e,
                 )
-                raise
+                self.exit(1)
 
         # If the source to be executed is a directory, continue using the
         # directory. In the case of a local directory, it is used as both the

tests/unit/test_app.py

@@ -127,22 +127,23 @@ def test_root_not_allowed():
         builds.assert_called_once()
 
 
-def test_dryrun_works_without_docker(tmpdir):
+def test_dryrun_works_without_docker(tmpdir, capsys):
     with chdir(tmpdir):
         with patch.object(docker, "APIClient") as client:
             client.side_effect = docker.errors.DockerException("Error: no Docker")
             app = Repo2Docker(dry_run=True)
             app.build()
+            captured = capsys.readouterr()
+            assert "Error: no Docker" not in captured.err
 
 
-def test_error_log_without_docker(tmpdir, caplog):
+def test_error_log_without_docker(tmpdir, capsys):
     with chdir(tmpdir):
         with patch.object(docker, "APIClient") as client:
             client.side_effect = docker.errors.DockerException("Error: no Docker")
             app = Repo2Docker()
 
-            with pytest.raises(docker.errors.DockerException):
+            with pytest.raises(SystemExit):
                 app.build()
-
                 captured = capsys.readouterr()
-                assert "Check if docker is running" in captured.err
+                assert "Error: no Docker" in captured.err

tests/unit/test_argumentvalidation.py

@@ -223,7 +223,6 @@ def test_invalid_container_port_protocol_mapping_fail(temp_cwd):
     assert not validate_arguments(builddir, args_list, "Port specification")
 
 
-@pytest.mark.xfail(reason="Regression in new arg parsing")
 def test_docker_handle_fail(temp_cwd):
     """
     Test to check if r2d fails with minimal error message on not being able to connect to docker daemon
@@ -233,19 +232,22 @@ def test_docker_handle_fail(temp_cwd):
     assert not validate_arguments(
         builddir,
         args_list,
-        "Docker client initialization error. Check if docker is running on the host.",
+        "Check if docker is running on the host.",
         disable_dockerd=True,
     )
 
 
 def test_docker_handle_debug_fail(temp_cwd):
     """
-    Test to check if r2d fails with stack trace on not being able to connect to docker daemon and debug enabled
+    Test to check if r2d fails with helpful error message on not being able to connect to docker daemon and debug enabled
     """
     args_list = ["--debug"]
 
     assert not validate_arguments(
-        builddir, args_list, "docker.errors.DockerException", disable_dockerd=True
+        builddir,
+        args_list,
+        "Check if docker is running on the host.",
+        disable_dockerd=True,
     )