GH-456: Add action to assign milestone to PR/issue (#659)

## What's Changed

Derived from the ADBC one.

Fixes #456.

---------

Co-authored-by: Sutou Kouhei <[email protected]>

Author: lidavidm

.github/workflows/dev_pr.yml

@@ -75,3 +75,10 @@ jobs:
           script: |
             const scripts = require(`${process.env.GITHUB_WORKSPACE}/.github/workflows/dev_pr.js`);
             await scripts.check_linked_issue({core, github, context, issue: ${{ steps.title-format.outputs.result }}});
+
+      - name: Assign milestone
+        if: '! github.event.pull_request.draft'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          ./.github/workflows/dev_pr_milestone.sh "${GITHUB_REPOSITORY}" ${{ github.event.number }}

.github/workflows/dev_pr_milestone.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+
+# Assign a milestone to the given PR based on the open milestones and known
+# releases.
+
+set -euo pipefail
+
+main() {
+  local -r repo="${1}"
+  local -r pr_number="${2}"
+  echo "On ${repo} pull ${pr_number}"
+
+  local -r existing_milestone=$(gh pr view "${pr_number}" \
+    --json milestone \
+    -t '{{if .milestone}}{{.milestone.title}}{{end}}')
+
+  if [[ -n "${existing_milestone}" ]]; then
+    echo "PR has milestone: ${existing_milestone}"
+    local -r milestone="${existing_milestone}"
+  else
+    local -r milestone=$(
+      gh api "/repos/${repo}/milestones" |
+        jq --raw-output '.[] | .title' |
+        grep -E '^[0-9]+\.[0-9]+\.[0-9]+$'
+      head -n1
+    )
+
+    echo "Assigning milestone: ${milestone}"
+    gh pr edit "${pr_number}" -m "${milestone}"
+  fi
+
+  local -r repo_owner=$(echo "${repo}" | cut -d'/' -f1)
+  local -r repo_name=$(echo "${repo}" | cut -d'/' -f2)
+  local -r graphql_query="{
+      repository(owner: \"${repo_owner}\", name: \"${repo_name}\") {
+        pullRequest(number: ${pr_number}) {
+          closingIssuesReferences(first: 5) {
+            edges {
+              node {
+                number
+              }
+            }
+          }
+        }
+      }
+    }"
+  local -r linked_issues=$(gh api graphql -f query="${graphql_query}" | jq -r '.data.repository.pullRequest.closingIssuesReferences.edges | .[].node.number')
+  for issue in ${linked_issues}; do
+    echo "Linked issue: ${issue}"
+    gh issue edit "${issue}" --milestone "${milestone}"
+  done
+}
+
+main "$@"