Update premoderator to fix Github API throttle (#4424)

* Update premoderator to fix Github API throttle

* Update premoderator script

Add exit codes and document the exit code.

* Fix indentation

scripts/premoderator.sh

@@ -1,18 +1,42 @@
-#!/bin/sh -eux -o pipefail
+#!/bin/bash
 # A naive premoderation script to allow Gitlab CI pipeline on a specific PRs' comment
 # Exits with 0, if the pipeline is good to go
+# Exits with 1, if the user is not allowed to start pipeline
+# Exits with 2, if script is unable to get issue id from CI_BUILD_REF_NAME variable
+# Exits with 3, if missing the magic comment in the pipeline to start the pipeline
 
-CURL_ARGS="-fs --connect-timeout 5 --max-time 5 --retry-max-time 20 --retry 4 --retry-delay 5"
+CURL_ARGS="-fs --retry 4 --retry-delay 5"
 MAGIC="${MAGIC:-ci check this}"
 
 # Get PR number from CI_BUILD_REF_NAME
 issue=$(echo ${CI_BUILD_REF_NAME} | perl -ne '/^pr-(\d+)-\S+$/ && print $1')
+
+if [ "$issue" = "" ]; then
+  echo "Unable to get issue id from: $CI_BUILD_REF_NAME"
+  exit 2
+fi
+
+echo "Checking for '$MAGIC' comment in PR $issue"
+
 # Get the user name from the PR comments with the wanted magic incantation casted
 user=$(curl ${CURL_ARGS} "https://api.github.com/repos/kubernetes-sigs/kubespray/issues/${issue}/comments" \
   | jq -M "map(select(.body | contains (\"$MAGIC\"))) | .[0] .user.login" | tr -d '"')
+
 # Check for the required user group membership to allow (exit 0) or decline (exit >0) the pipeline
-if [ "$user" = "null" ]; then
-	echo "User does not have permissions to start CI run"
-	exit 1
+if [ "$user" = "" ] || [ "$user" = "null" ]; then
+  echo "Missing '$MAGIC' comment from one of the OWNERS"
+  exit 3
+else
+  echo "Found comment from user: $user"
 fi
+
 curl ${CURL_ARGS} "https://api.github.com/orgs/kubernetes-sigs/members/${user}"
+
+if [ $? -ne 0 ]; then
+  echo "User does not have permissions to start CI run"
+  exit 1
+else
+  echo "$user has allowed CI to start"
+fi
+
+exit 0