docker_container: add mount endpoint collision detection (#60384)

* Add mount endpoint collision detection.

* Add changelog.

* Fix error.

changelogs/fragments/60384-docker_container-mount-endpoint-collision.yml

@@ -0,0 +1,2 @@
+minor_changes:
+- "docker_container - now tests for mount endpoint collisions (for both ``mounts`` and ``volumes``) to abort early when collisions are found"

lib/ansible/modules/cloud/docker/docker_container.py

@@ -1290,6 +1290,8 @@ class TaskParameters(DockerBaseClass):
 
         self.mounts_opt, self.expected_mounts = self._process_mounts()
 
+        self._check_mount_target_collisions()
+
         for param_name in ["device_read_bps", "device_write_bps"]:
             if client.module.params.get(param_name):
                 self._process_rate_bps(option=param_name)
@@ -1842,6 +1844,25 @@ class TaskParameters(DockerBaseClass):
             return mode
         return 'container:{0}'.format(container['Id'])
 
+    def _check_mount_target_collisions(self):
+        last = dict()
+
+        def f(t, name):
+            if t in last:
+                if name == last[t]:
+                    self.client.fail('The mount point "{0}" appears twice in the {1} option'.format(t, name))
+                else:
+                    self.client.fail('The mount point "{0}" appears both in the {1} and {2} option'.format(t, name, last[t]))
+            last[t] = name
+
+        if self.expected_mounts:
+            for t in [m['target'] for m in self.expected_mounts]:
+                f(t, 'mounts')
+        if self.volumes:
+            for v in self.volumes:
+                vs = v.split(':')
+                f(vs[0 if len(vs) == 1 else 1], 'volumes')
+
 
 class Container(DockerBaseClass):
 

test/integration/targets/docker_container/tasks/tests/mounts-volumes.yml

@@ -101,6 +101,24 @@
   register: mounts_5
   ignore_errors: yes
 
+- name: mounts (endpoint collision)
+  docker_container:
+    image: alpine:3.8
+    command: '/bin/sh -c "sleep 10m"'
+    name: "{{ cname }}"
+    state: started
+    mounts:
+    - source: /home
+      target: /x
+      type: bind
+    - source: /etc
+      target: /x
+      type: bind
+      read_only: no
+    force_kill: yes
+  register: mounts_6
+  ignore_errors: yes
+
 - name: cleanup
   docker_container:
     name: "{{ cname }}"
@@ -115,6 +133,8 @@
     - mounts_3 is not changed
     - mounts_4 is changed
     - mounts_5 is changed
+    - mounts_6 is failed
+    - "'The mount point \"/x\" appears twice in the mounts option' == mounts_6.msg"
   when: docker_py_version is version('2.6.0', '>=')
 - assert:
     that:
@@ -206,6 +226,7 @@
     - mounts_volumes_2 is not changed
     - mounts_volumes_3 is changed
     - mounts_volumes_4 is failed
+    - "'The mount point \"/tmp\" appears both in the volumes and mounts option' in mounts_volumes_4.msg"
   when: docker_py_version is version('2.6.0', '>=')
 - assert:
     that:
@@ -319,6 +340,19 @@
     force_kill: yes
   register: volumes_5
 
+- name: volumes (collision)
+  docker_container:
+    image: alpine:3.8
+    command: '/bin/sh -c "sleep 10m"'
+    name: "{{ cname }}"
+    state: started
+    volumes:
+    - "/etc:/tmp"
+    - "/home:/tmp:ro"
+    force_kill: yes
+  register: volumes_6
+  ignore_errors: yes
+
 - name: cleanup
   docker_container:
     name: "{{ cname }}"
@@ -333,6 +367,8 @@
     - volumes_3 is not changed
     - volumes_4 is changed
     - volumes_5 is changed
+    - volumes_6 is failed
+    - "'The mount point \"/tmp\" appears twice in the volumes option' in volumes_6.msg"
 
 ####################################################################
 ## volumes_from ####################################################