Support both Taskcluster deployments

Part of https://bugzilla.mozilla.org/show_bug.cgi?id=1574648

.taskcluster.yml

@@ -8,7 +8,10 @@ policy:
 tasks:
   $let:
     task_common:
-      provisionerId: aws-provisioner-v1
+      provisionerId:
+        $if: "taskcluster_root_url == 'https://taskcluster.net'"
+        then: aws-provisioner-v1
+        else: proj-servo
       created: {$fromNow: ''}
       deadline: {$fromNow: '1 day'}
       extra:
@@ -53,7 +56,10 @@ tasks:
                   description: ""
                   owner: ${event.pusher.name}@users.noreply.github.com
                   source: ${event.compare}
-                workerType: servo-docker-worker
+                workerType:
+                  $if: "taskcluster_root_url == 'https://taskcluster.net'"
+                  then: servo-docker-worker
+                  else: docker
                 scopes:
                   - "assume:repo:github.com/servo/servo:branch:${branch}"
                 routes:
@@ -82,7 +88,10 @@ tasks:
               description: ""
               owner: ${event.sender.login}@users.noreply.github.com
               source: ${event.pull_request.url}
-            workerType: servo-docker-untrusted
+            workerType:
+              $if: "taskcluster_root_url == 'https://taskcluster.net'"
+              then: servo-docker-untrusted
+              else: docker-untrusted
             scopes:
               - "assume:repo:github.com/servo/servo:pull-request"
             routes:

etc/taskcluster/decision_task.py

@@ -157,7 +157,9 @@ def mocked_only():
 def linux_tidy_unit_untrusted():
     return (
         decisionlib.DockerWorkerTask("Tidy + dev build + unit tests")
-        .with_worker_type("servo-docker-untrusted")
+        .with_worker_type(
+            "servo-docker-untrusted" if CONFIG.legacy_tc_deployment else "docker-untrusted"
+        )
         .with_treeherder("Linux x64", "Tidy+Unit")
         .with_max_run_time_minutes(60)
         .with_dockerfile(dockerfile_path("build"))
@@ -731,15 +733,15 @@ def dockerfile_path(name):
 def linux_task(name):
     return (
         decisionlib.DockerWorkerTask(name)
-        .with_worker_type("servo-docker-worker")
+        .with_worker_type("servo-docker-worker" if CONFIG.legacy_tc_deployment else "docker")
         .with_treeherder_required()
     )
 
 
 def windows_task(name):
     return (
         decisionlib.WindowsGenericWorkerTask(name)
-        .with_worker_type("servo-win2016")
+        .with_worker_type("servo-win2016" if CONFIG.legacy_tc_deployment else "win2016")
         .with_treeherder_required()
     )
 
@@ -968,10 +970,15 @@ def magicleap_nightly():
 
 
 CONFIG.task_name_template = "Servo: %s"
-CONFIG.index_prefix = "project.servo.servo"
-CONFIG.docker_image_build_worker_type = "servo-docker-worker"
 CONFIG.docker_images_expire_in = build_dependencies_artifacts_expire_in
 CONFIG.repacked_msi_files_expire_in = build_dependencies_artifacts_expire_in
+if CONFIG.legacy_tc_deployment:
+    CONFIG.index_prefix = "project.servo.servo"
+    CONFIG.docker_image_build_worker_type = "servo-docker-worker"
+else:  # pragma: no cover
+    CONFIG.index_prefix = "project.servo"
+    CONFIG.default_provisioner_id = "proj-servo"
+    CONFIG.docker_image_build_worker_type = "docker"
 
 
 if __name__ == "__main__":  # pragma: no cover

etc/taskcluster/decisionlib.py

@@ -57,6 +57,15 @@ def __init__(self):
         self.git_ref = os.environ.get("GIT_REF")
         self.git_sha = os.environ.get("GIT_SHA")
 
+        root_url = os.environ.get("TASKCLUSTER_ROOT_URL")
+        self.legacy_tc_deployment = root_url == "https://taskcluster.net"
+
+        if self.legacy_tc_deployment:
+            self.default_provisioner_id = "aws-provisioner-v1"
+        else:  # pragma: no cover
+            self.default_provisioner_id = "proj-example"
+
+
     def task_id(self):
         if hasattr(self, "_task_id"):
             return self._task_id
@@ -131,7 +140,7 @@ def __init__(self, name):
         self.name = name
         self.description = ""
         self.scheduler_id = "taskcluster-github"
-        self.provisioner_id = "aws-provisioner-v1"
+        self.provisioner_id = CONFIG.default_provisioner_id
         self.worker_type = "github-worker"
         self.deadline_in = "1 day"
         self.expires_in = "1 year"

etc/taskcluster/mock.py

@@ -44,6 +44,7 @@ def findTask(self, path):
 sys.dont_write_bytecode = True
 os.environ.update(**{k: k for k in "TASK_ID TASK_OWNER TASK_SOURCE GIT_URL GIT_SHA".split()})
 os.environ["GIT_REF"] = "refs/heads/auto"
+os.environ["TASKCLUSTER_ROOT_URL"] = "https://taskcluster.net"
 import decision_task
 
 print("\n# Push:")