Backport #38884 for 2.5 - docker/docker-py guard (#38889)

* Error if docker and docker-py are simultaneously (#38884)

* Error if docker and docker-py are simultaneously installed over top of each other. Fixes #36125

* Remove duplicate installed

(cherry picked from commit 68e3ff80a7)

* Add changelog for #36470

changelogs/fragments/docker_prevent_docker_and_docker_py.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+- docker modules - Error with useful message is both docker and docker-py are found to both be installed (https://github.com/ansible/ansible/pull/38884)

lib/ansible/module_utils/docker_common.py

@@ -56,6 +56,25 @@ except ImportError as exc:
     HAS_DOCKER_ERROR = str(exc)
     HAS_DOCKER_PY = False
 
+
+# The next 2 imports ``docker.models`` and ``docker.ssladapter`` are used
+# to ensure the user does not have both ``docker`` and ``docker-py`` modules
+# installed, as they utilize the same namespace are are incompatible
+try:
+    # docker
+    import docker.models
+    HAS_DOCKER_MODELS = True
+except ImportError:
+    HAS_DOCKER_MODELS = False
+
+try:
+    # docker-py
+    import docker.ssladapter
+    HAS_DOCKER_SSLADAPTER = True
+except ImportError:
+    HAS_DOCKER_SSLADAPTER = False
+
+
 DEFAULT_DOCKER_HOST = 'unix://var/run/docker.sock'
 DEFAULT_TLS = False
 DEFAULT_TLS_VERIFY = False
@@ -144,6 +163,10 @@ class AnsibleDockerClient(Client):
             required_together=required_together_params,
             required_if=required_if)
 
+        if HAS_DOCKER_MODELS and HAS_DOCKER_SSLADAPTER:
+            self.fail("Cannot have both the docker-py and docker python modules installed together as they use the same namespace and "
+                      "cause a corrupt installation. Please uninstall both packages, and re-install only the docker-py or docker python module")
+
         if not HAS_DOCKER_PY:
             self.fail("Failed to import docker-py - %s. Try `pip install docker-py`" % HAS_DOCKER_ERROR)