Add contrib driver for Hashicorp Nomad jobs

Based on the Kubernetes contrib, but different.

examples/nomad.py

@@ -0,0 +1,66 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright 2021 Volvo Car Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+"""
+Example Nomad Job Task.
+
+Requires:
+
+- nomad: ``pip install python-nomad``
+- A local nomad cluster up and running: https://learn.hashicorp.com/nomad
+
+You can run this code example like this:
+
+    .. code:: console
+        $ luigi --module examples.nomad PerlPi --local-scheduler
+
+Running this code will create a pi-luigi-uuid nomad job within the cluster
+"""
+
+# import os
+# import luigi
+from luigi.contrib.nomad import NomadJobTask
+
+
+class PerlPi(NomadJobTask):
+
+    name = "pi"
+    max_retrials = 3
+    spec_schema = {
+        "Type": "batch",
+        "TaskGroups": [{
+            "Name": "main",
+            "Tasks": [{
+                "Name": "pi",
+                "Driver": "docker",
+                "Config": {
+                    "image": "perl",
+                    "command": "perl",
+                    "args": ["-Mbignum=bpi", "-wle", "print bpi(2000)"]
+                },
+            }]
+        }]
+    }
+
+    # defining the two functions below allows for dependency checking,
+    # but isn't a requirement
+    # def signal_complete(self):
+    #     with self.output().open('w') as output:
+    #         output.write('')
+    #
+    # def output(self):
+    #     target = os.path.join("/tmp", "PerlPi")
+    #     return luigi.LocalTarget(target)