repokitteh: Add welcome message for new contributors

Signed-off-by: Ryan Northey <ryan@synca.io>

ci/repokitteh/modules/newcontributor.star

@@ -0,0 +1,31 @@
+
+# not sure if this is needed, or whether `pull_request` below has info already
+def get_pr_author_association(issue_number):
+  return github.call(
+    method="GET",
+    path="repos/envoyproxy/envoy/pulls/%s" % issue_number)["json"]["author_association"]
+
+def is_newcontributor(pull_request):
+  # check for any existing open PRs from user ?
+  return pull_request["author_association"] == "FIRST_TIME_CONTRIBUTOR"
+
+def should_message_newcontributor(action, pull_request):
+  return (
+    action == 'opened'
+    and is_newcontributor(pull_request))
+
+def send_newcontributor_message(sender):
+  github.issue_create_comment("""
+hi @%s, welcome and thankyou for your contribution.
+
+We will try to review your Pull Request as quickly as possible.
+
+In the meantime, please take a look at the [contribution guidelines](https://github.com/envoyproxy/envoy/blob/master/CONTRIBUTING.md) if you have not done so already.
+
+""" % sender)
+
+def _pr(action, pull_request, sender, config):
+  if should_message_newcontributor(action, pull_request):
+    send_newcontributor_message(sender)
+
+handlers.pull_request(func=_pr)

repokitteh.star

@@ -5,6 +5,7 @@ use("github.com/repokitteh/modules/review.star")
 use("github.com/repokitteh/modules/wait.star")
 use("github.com/repokitteh/modules/circleci.star", secret_token=get_secret('circle_token'))
 use("github.com/envoyproxy/envoy/ci/repokitteh/modules/azure_pipelines.star", secret_token=get_secret('azp_token'))
+use("github.com/envoyproxy/envoy/ci/repokitteh/modules/newcontributor.star")
 use(
   "github.com/envoyproxy/envoy/ci/repokitteh/modules/ownerscheck.star",
   paths=[