docker_container: fix behavior when image is not specified (#46322)

* Don't simply ignore container in present() if image is not specified.

* Use image from existing container for recreation if not specified.

* Added changelog.

* Improve comment.

changelogs/fragments/46322-docker_container-image-not-given.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+- "docker_container - the behavior is improved in case ``image`` is not specified, but needed for (re-)creating the container."

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

@@ -1912,13 +1912,17 @@ class ContainerManager(DockerBaseClass):
         container = self._get_container(self.parameters.name)
 
         # If the image parameter was passed then we need to deal with the image
-        # version comparison, otherwise we should not care
+        # version comparison. Otherwise we handle this depending on whether
-        if self.parameters.image:
+        # the container already runs or not; in the former case, in case the
+        # container needs to be restarted, we use the existing container's
+        # image ID.
         image = self._get_image()
         self.log(image, pretty_print=True)
         if not container.exists:
             # New container
             self.log('No container found')
+            if not self.parameters.image:
+                self.fail('Cannot create container when image is not specified!')
             new_container = self.container_create(self.parameters.image, self.parameters.create_parameters)
             if new_container:
                 container = new_container
@@ -1934,10 +1938,15 @@ class ContainerManager(DockerBaseClass):
                     self.diff['image_different'] = True
                 self.log("differences")
                 self.log(differences, pretty_print=True)
+                image_to_use = self.parameters.image
+                if not image_to_use and container and container.Image:
+                    image_to_use = container.Image
+                if not image_to_use:
+                    self.fail('Cannot recreate container when image is not specified or cannot be extracted from current container!')
                 if container.running:
                     self.container_stop(container.Id)
                 self.container_remove(container.Id)
-                    new_container = self.container_create(self.parameters.image, self.parameters.create_parameters)
+                new_container = self.container_create(image_to_use, self.parameters.create_parameters)
                 if new_container:
                     container = new_container