1 files changed, 79 insertions, 0 deletions
diff --git a/third_party/python/taskcluster_taskgraph/taskgraph/util/decision.py b/third_party/python/taskcluster_taskgraph/taskgraph/util/decision.py
new file mode 100644
index 0000000000..d0e1e1079f
--- /dev/null
+++ b/third_party/python/taskcluster_taskgraph/taskgraph/util/decision.py
@@ -0,0 +1,79 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""
+Utilities for generating a decision task from :file:`.taskcluster.yml`.
+"""
+
+
+import os
+
+import jsone
+import slugid
+import yaml
+
+from .templates import merge
+from .time import current_json_time
+from .vcs import find_hg_revision_push_info
+
+
+def make_decision_task(params, root, context, head_rev=None):
+    """Generate a basic decision task, based on the root .taskcluster.yml"""
+    with open(os.path.join(root, ".taskcluster.yml"), "rb") as f:
+        taskcluster_yml = yaml.safe_load(f)
+
+    if not head_rev:
+        head_rev = params["head_rev"]
+
+    if params["repository_type"] == "hg":
+        pushlog = find_hg_revision_push_info(params["repository_url"], head_rev)
+
+        hg_push_context = {
+            "pushlog_id": pushlog["pushid"],
+            "pushdate": pushlog["pushdate"],
+            "owner": pushlog["user"],
+        }
+    else:
+        hg_push_context = {}
+
+    slugids = {}
+
+    def as_slugid(name):
+        # https://github.com/taskcluster/json-e/issues/164
+        name = name[0]
+        if name not in slugids:
+            slugids[name] = slugid.nice()
+        return slugids[name]
+
+    # provide a similar JSON-e context to what mozilla-taskcluster provides:
+    # https://docs.taskcluster.net/reference/integrations/mozilla-taskcluster/docs/taskcluster-yml
+    # but with a different tasks_for and an extra `cron` section
+    context = merge(
+        {
+            "repository": {
+                "url": params["repository_url"],
+                "project": params["project"],
+                "level": params["level"],
+            },
+            "push": merge(
+                {
+                    "revision": params["head_rev"],
+                    # remainder are fake values, but the decision task expects them anyway
+                    "comment": " ",
+                },
+                hg_push_context,
+            ),
+            "now": current_json_time(),
+            "as_slugid": as_slugid,
+        },
+        context,
+    )
+
+    rendered = jsone.render(taskcluster_yml, context)
+    if len(rendered["tasks"]) != 1:
+        raise Exception("Expected .taskcluster.yml to only produce one cron task")
+    task = rendered["tasks"][0]
+
+    task_id = task.pop("taskId")
+    return (task_id, task)