Add 'init' option to docker_container module to support docker's --init option (#34547)

* Add support for `--init` option to `docker_container` module

Fixes #30761

* Validate docker API's version when docker_container's init option is True

https://github.com/ansible/ansible/pull/34547#pullrequestreview-122355244
https://docs.docker.com/engine/reference/commandline/run/#options

init option requires docker API 1.25+ .

* Fix failure of sanity test

lib/ansible/module_utils/docker_common.py

@@ -187,6 +187,10 @@ class AnsibleDockerClient(Client):
         except Exception as exc:
             self.fail("Error connecting: %s" % exc)
 
+        docker_api_version = self.version()["ApiVersion"]
+        if self.module.params.get("init") and LooseVersion(docker_api_version) < LooseVersion("1.25"):
+            self.fail("docker API version is %s. Minimum version required is 1.25 to set init option." % (docker_api_version,))
+
     def log(self, msg, pretty_print=False):
         pass
         # if self.debug:

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

@@ -139,6 +139,13 @@ options:
     description:
       - Repository path and tag used to create the container. If an image is not found or pull is true, the image
         will be pulled from the registry. If no tag is included, 'latest' will be used.
+  init:
+    description:
+      - Run an init inside the container that forwards signals and reaps processes.
+        This option requires Docker API 1.25+.
+    type: bool
+    default: 'no'
+    version_added: "2.6"
   interactive:
     description:
       - Keep stdin open after a container is launched, even if not attached.
@@ -653,6 +660,7 @@ class TaskParameters(DockerBaseClass):
         self.hostname = None
         self.ignore_image = None
         self.image = None
+        self.init = None
         self.interactive = None
         self.ipc_mode = None
         self.keep_volumes = None
@@ -898,7 +906,8 @@ class TaskParameters(DockerBaseClass):
             group_add='groups',
             devices='devices',
             pid_mode='pid_mode',
-            tmpfs='tmpfs'
+            tmpfs='tmpfs',
+            init='init'
         )
 
         if HAS_DOCKER_PY_2 or HAS_DOCKER_PY_3:
@@ -1999,6 +2008,7 @@ def main():
         hostname=dict(type='str'),
         ignore_image=dict(type='bool', default=False),
         image=dict(type='str'),
+        init=dict(type='bool', default=False),
         interactive=dict(type='bool', default=False),
         ipc_mode=dict(type='str'),
         keep_volumes=dict(type='bool', default=True),