feat: allow unlimited memory_swap in docker_container (#138)

* feat: allow unlimited memory_swap in docker_container

summary: in docker_container, allow `memory_swap: values
`unlimited` and `-1` for unlimited container swap usage.

`--memory-swap=-1` is a valid docker run value allowing
unlimited swap usage. `docker_container` should allow
setting this value via `memory_swap` values `unlimited`
and `-1` as it sometimes must explicitly be set to prevent
docker from attempting to limit swap usage to double the
`--memory` value by default. In rootless docker environments,
attempting to set `memory-swap` usage limits will result in an error
if the user doesn't have the ability to do so. Allowing explicit
unlimited swap usage via docker_container will prevent these errors.

https://docs.docker.com/config/containers/resource_constraints/#--memory-swap-details

* Update tests/integration/targets/docker_container/tasks/tests/options.yml

* Apply suggestions from code review

Co-authored-by: Felix Fontein <felix@fontein.de>

plugins/modules/docker_container.py

@@ -458,7 +458,8 @@ options:
     type: str
   memory_swap:
     description:
-      - "Total memory limit (memory + swap) in format C(<number>[<unit>]).
+      - "Total memory limit (memory + swap) in format C(<number>[<unit>]), or
+        the special values C(unlimited) or C(-1) for unlimited swap usage.
         Number is a positive integer. Unit can be C(B) (byte), C(K) (kibibyte, 1024B),
         C(M) (mebibyte), C(G) (gibibyte), C(T) (tebibyte), or C(P) (pebibyte)."
       - Omitting the unit defaults to bytes.
@@ -1413,10 +1414,13 @@ class TaskParameters(DockerBaseClass):
 
         for param_name in REQUIRES_CONVERSION_TO_BYTES:
             if client.module.params.get(param_name):
-                try:
-                    setattr(self, param_name, human_to_bytes(client.module.params.get(param_name)))
-                except ValueError as exc:
-                    self.fail("Failed to convert %s to bytes: %s" % (param_name, to_native(exc)))
+                if param_name == 'memory_swap' and client.module.params.get(param_name) in ['unlimited', '-1']:
+                    setattr(self, param_name, -1)
+                else:
+                    try:
+                        setattr(self, param_name, human_to_bytes(client.module.params.get(param_name)))
+                    except ValueError as exc:
+                        self.fail("Failed to convert %s to bytes: %s" % (param_name, to_native(exc)))
 
         self.publish_all_ports = False
         self.published_ports = self._parse_publish_ports()