docker_container: fix ipc_mode and pid_mode idempotency (#47997)

* Fix ipc_mode and pid_mode idempotency when container names are used.

* Add changelog.

* Update pid_mode documentation.

changelogs/fragments/47997-docker_container-ipc-pid-mode.yml

@@ -0,0 +1,2 @@
+bugfixes:
+- "docker_container - fix ``ipc_mode`` and ``pid_mode`` idempotency if the ``host:<container-name>`` form is used (as opposed to ``host:<container-id>``)."

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

@@ -330,7 +330,8 @@ options:
     default: 'no'
   pid_mode:
     description:
-      - Set the PID namespace mode for the container. Currently only supports 'host'.
+      - Set the PID namespace mode for the container.
+      - Note that docker-py < 2.0 only supports 'host'. Newer versions allow all values supported by the docker daemon.
   privileged:
     description:
       - Give extended privileges to the container.
@@ -1003,6 +1004,8 @@ class TaskParameters(DockerBaseClass):
         self.healthcheck, self.disable_healthcheck = self._parse_healthcheck()
         self.exp_links = None
         self.volume_binds = self._get_volume_binds(self.volumes)
+        self.pid_mode = self._replace_container_names(self.pid_mode)
+        self.ipc_mode = self._replace_container_names(self.ipc_mode)
 
         self.log("volumes:")
         self.log(self.volumes, pretty_print=True)
@@ -1555,6 +1558,24 @@ class TaskParameters(DockerBaseClass):
 
         setattr(self, option, devices_list)
 
+    def _replace_container_names(self, mode):
+        """
+        Parse IPC and PID modes. If they contain a container name, replace
+        with the container's ID.
+        """
+        if mode is None or not mode.startswith('container:'):
+            return mode
+        container_name = mode[len('container:'):]
+        # Try to inspect container to see whether this is an ID or a
+        # name (and in the latter case, retrieve it's ID)
+        container = self.client.get_container(container_name)
+        if container is None:
+            # If we can't find the container, issue a warning and continue with
+            # what the user specified.
+            self.client.module.warn('Cannot find a container with name or ID "{0}"'.format(container_name))
+            return mode
+        return 'container:{0}'.format(container['Id'])
+
 
 class Container(DockerBaseClass):
 

test/integration/targets/docker_container/tasks/tests/options.yml

@@ -1781,8 +1781,8 @@
     command: '/bin/sh -c "sleep 10m"'
     name: "{{ cname }}"
     state: started
-    #ipc_mode: "container:{{ cname_h1 }}"
-    ipc_mode: shareable
+    ipc_mode: "container:{{ cname_h1 }}"
+    # ipc_mode: shareable
   register: ipc_mode_1
 
 - name: ipc_mode (idempotency)
@@ -1791,9 +1791,8 @@
     command: '/bin/sh -c "sleep 10m"'
     name: "{{ cname }}"
     state: started
-    # THIS IS CURRENTLY NOT IDEMPOTENT! SEE https://github.com/ansible/ansible/issues/45829
-    # ipc_mode: "container:{{ cname_h1 }}"
-    ipc_mode: shareable
+    ipc_mode: "container:{{ cname_h1 }}"
+    # ipc_mode: shareable
   register: ipc_mode_2
 
 - name: ipc_mode (change)
@@ -2694,7 +2693,7 @@
     command: '/bin/sh -c "sleep 10m"'
     name: "{{ cname }}"
     state: started
-    pid_mode: "container:{{ pid_mode_helper.ansible_facts.docker_container.Id }}"
+    pid_mode: "container:{{ cname_h1 }}"
   register: pid_mode_2
   ignore_errors: yes
   # docker-py < 2.0 does not support "arbitrary" pid_mode values