feat: add script to create GitHub milestones for tags with associated PRs

Author: SteKoe

.github/milestones.sh

@@ -0,0 +1,243 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+show_help() {
+  cat <<EOF
+Usage:
+  GITHUB_TOKEN=ghp_xxx ./create_milestone_for_tag.sh [--dry-run] owner repo tag [base]
+
+Positional arguments:
+  owner     GitHub owner/org (required)
+  repo      GitHub repository name (required)
+  tag       Tag to create milestone for (required)
+  base      Optional base tag/branch/sha to compute commits from (optional)
+
+Flags:
+  --dry-run  Print what would be done, do not call APIs that modify data.
+  --help     Show this help and exit.
+
+Examples:
+  GITHUB_TOKEN=ghp_xxx ./create_milestone_for_tag.sh octocat Hello-World v1.2.0
+  ./create_milestone_for_tag.sh --dry-run octocat Hello-World v1.2.0
+  ./create_milestone_for_tag.sh octocat Hello-World v1.2.0 previous-tag --dry-run
+EOF
+}
+
+# Parse args: flags can be anywhere
+DRYRUN=0
+POSITIONAL=()
+for arg in "$@"; do
+  case "$arg" in
+    --dry-run) DRYRUN=1; shift || true ;;
+    --help) show_help; exit 0 ;;
+    *) POSITIONAL+=("$arg"); shift || true ;;
+  esac
+done
+
+# After parsing, positional args are in POSITIONAL array
+if [[ ${#POSITIONAL[@]} -lt 3 ]]; then
+  echo "ERROR: owner, repo and tag are required."
+  show_help
+  exit 1
+fi
+
+OWNER="${POSITIONAL[0]}"
+REPO="${POSITIONAL[1]}"
+TAG="${POSITIONAL[2]}"
+BASE="${POSITIONAL[3]:-}"  # optional
+
+if [[ $DRYRUN -eq 1 ]]; then
+  echo "⚠️  Dry-run mode enabled — no changes will be made."
+fi
+
+if [[ -z "${GITHUB_TOKEN:-}" ]]; then
+  echo "ERROR: GITHUB_TOKEN environment variable must be set (PAT with repo permissions)."
+  exit 1
+fi
+
+API="https://api.github.com"
+AUTH="Authorization: token ${GITHUB_TOKEN}"
+ACCEPT="Accept: application/vnd.github.groot-preview+json"
+
+if ! command -v jq >/dev/null 2>&1; then
+  echo "ERROR: jq is required. Install jq and try again."
+  exit 1
+fi
+if ! command -v git >/dev/null 2>&1; then
+  echo "ERROR: git is required. Install git and try again."
+  exit 1
+fi
+
+# If base not provided, attempt to find previous tag ordered by creation date (descending)
+if [[ -z "$BASE" ]]; then
+  if git rev-parse --verify "$TAG" >/dev/null 2>&1; then
+    mapfile -t TAGS < <(git tag --sort=-creatordate)
+    PREV_TAG=""
+    found=0
+    for i in "${!TAGS[@]}"; do
+      if [[ "${TAGS[$i]}" == "$TAG" ]]; then
+        found=1
+        if [[ $((i+1)) -lt ${#TAGS[@]} ]]; then
+          PREV_TAG="${TAGS[$((i+1))]}"
+        fi
+        break
+      fi
+    done
+    if [[ $found -eq 0 ]]; then
+      echo "Warning: tag '$TAG' not found locally. You may need to 'git fetch --tags'."
+      BASE=""
+    else
+      if [[ -n "$PREV_TAG" ]]; then
+        echo "Detected previous tag: $PREV_TAG"
+        BASE="$PREV_TAG"
+      else
+        echo "No previous tag found (this looks like the oldest tag). Continuing with single tag commit."
+        BASE=""
+      fi
+    fi
+  else
+    echo "Warning: tag '$TAG' not found locally. Continuing; will attempt API-based fallback if needed."
+    BASE=""
+  fi
+fi
+
+# Build commit list: if BASE is empty, use the single tag's commit; otherwise range base..tag
+COMMITS=()
+if [[ -n "$BASE" ]]; then
+  # verify both reachable locally; if not present, try to fetch tags/branches from remote
+  if ! git rev-parse --verify "$BASE" >/dev/null 2>&1 || ! git rev-parse --verify "$TAG" >/dev/null 2>&1; then
+    echo "One of base or tag is not present locally. Attempting to fetch tags/heads from origin..."
+    git fetch --tags --prune --no-recurse-submodules --quiet || true
+  fi
+
+  # Re-check
+  git rev-parse --verify "$BASE" >/dev/null 2>&1 || { echo "ERROR: base '$BASE' not found locally after fetch"; exit 1; }
+  git rev-parse --verify "$TAG" >/dev/null 2>&1 || { echo "ERROR: tag '$TAG' not found locally after fetch"; exit 1; }
+
+  # list commits from base (exclusive) to tag (inclusive)
+  while IFS= read -r sha; do
+    COMMITS+=("$sha")
+  done < <(git rev-list --reverse "${BASE}..${TAG}")
+else
+  # try to get tag commit locally; if not present, fall back to GitHub compare API to get commits
+  if git rev-parse --verify "$TAG" >/dev/null 2>&1; then
+    TAG_SHA="$(git rev-list -n 1 "$TAG")"
+    COMMITS+=("$TAG_SHA")
+  else
+    echo "Tag not present locally. Falling back to GitHub compare API to get commits for tag ${TAG}..."
+    # We attempt to compare default branch...tag to get commits — best-effort
+    default_branch="$(curl -sSL -H "$AUTH" "${API}/repos/${OWNER}/${REPO}" | jq -r '.default_branch')"
+    if [[ -z "$default_branch" || "$default_branch" == "null" ]]; then
+      echo "ERROR: could not determine default branch via API."
+      exit 1
+    fi
+    # Use compare endpoint: default_branch...tag
+    cmp=$(curl -sSL -H "$AUTH" "${API}/repos/${OWNER}/${REPO}/compare/${default_branch}...${TAG}")
+    if echo "$cmp" | jq -e 'has("commits")' >/dev/null 2>&1; then
+      mapfile -t commits_from_api < <(echo "$cmp" | jq -r '.commits[]?.sha')
+      COMMITS+=("${commits_from_api[@]}")
+    else
+      echo "API compare did not return commits. Response:"
+      echo "$cmp" | jq -C .
+      exit 1
+    fi
+  fi
+fi
+
+echo "Found ${#COMMITS[@]} commit(s)."
+
+# For each commit, call GitHub API to get associated PRs
+declare -A PRS_MAP=()
+for sha in "${COMMITS[@]}"; do
+  echo "Querying PRs for commit $sha..."
+  resp="$(curl -sSL -H "$AUTH" -H "$ACCEPT" \
+    "${API}/repos/${OWNER}/${REPO}/commits/${sha}/pulls")"
+
+  if echo "$resp" | jq -e 'has("message")' >/dev/null 2>&1; then
+    msg=$(echo "$resp" | jq -r '.message // empty')
+    if [[ -n "$msg" ]]; then
+      echo "GitHub API error for commit $sha: $msg"
+      echo "Full response:"
+      echo "$resp" | jq -C .
+      exit 1
+    fi
+  fi
+
+  pr_numbers=$(echo "$resp" | jq -r '.[]?.number' || true)
+  if [[ -n "$pr_numbers" ]]; then
+    while IFS= read -r pr; do
+      if [[ -n "$pr" ]]; then
+        PRS_MAP["$pr"]=1
+        echo "  -> PR #$pr"
+      fi
+    done <<<"$pr_numbers"
+  fi
+done
+
+if [[ ${#PRS_MAP[@]} -eq 0 ]]; then
+  echo "No PRs associated with commits found. Exiting."
+  exit 0
+fi
+
+PR_LIST=()
+for k in "${!PRS_MAP[@]}"; do PR_LIST+=("$k"); done
+echo "Total unique PRs to update: ${#PR_LIST[@]}"
+
+# Check existing milestones for a matching title
+echo "Checking for existing milestone named '$TAG'..."
+MILESTONES_RESP="$(curl -sSL -H "$AUTH" "${API}/repos/${OWNER}/${REPO}/milestones?state=all&per_page=100")"
+MILESTONE_NUMBER="$(echo "$MILESTONES_RESP" | jq -r --arg TITLE "$TAG" '.[] | select(.title==$TITLE) | .number' | head -n1 || true)"
+
+if [[ -n "$MILESTONE_NUMBER" && "$MILESTONE_NUMBER" != "null" ]]; then
+  echo "Found existing milestone '$TAG' (number: $MILESTONE_NUMBER)."
+else
+  if [[ $DRYRUN -eq 1 ]]; then
+    echo "Would create milestone '$TAG' (dry-run)."
+    MILESTONE_NUMBER="DUMMY_ID"
+  else
+    echo "Creating milestone '$TAG'..."
+    create_resp="$(curl -sSL -H "$AUTH" -H "Content-Type: application/json" \
+      -d "{\"title\": \"${TAG}\", \"description\": \"Auto-created milestone for tag ${TAG}\"}" \
+      "${API}/repos/${OWNER}/${REPO}/milestones")"
+
+    if echo "$create_resp" | jq -e 'has("message")' >/dev/null 2>&1; then
+      err=$(echo "$create_resp" | jq -r '.message // empty')
+      echo "Error creating milestone: $err"
+      echo "Response: $create_resp" | jq -C .
+      exit 1
+    fi
+
+    MILESTONE_NUMBER="$(echo "$create_resp" | jq -r '.number')"
+    if [[ -z "$MILESTONE_NUMBER" || "$MILESTONE_NUMBER" == "null" ]]; then
+      echo "Failed to create milestone. Response: $create_resp"
+      exit 1
+    fi
+    echo "Created milestone '${TAG}' (number: $MILESTONE_NUMBER)."
+  fi
+fi
+
+# Patch each PR (issues endpoint) to set milestone
+for prnum in "${PR_LIST[@]}"; do
+  if [[ $DRYRUN -eq 1 ]]; then
+    echo "Would update PR #${prnum} -> milestone ${MILESTONE_NUMBER}"
+    continue
+  fi
+
+  echo "Updating PR #${prnum} -> milestone ${MILESTONE_NUMBER}..."
+  patch_resp="$(curl -sSL -X PATCH -H "$AUTH" -H "Content-Type: application/json" \
+    -d "{\"milestone\": ${MILESTONE_NUMBER}}" \
+    "${API}/repos/${OWNER}/${REPO}/issues/${prnum}")"
+
+  if echo "$patch_resp" | jq -e 'has("message")' >/dev/null 2>&1; then
+    err=$(echo "$patch_resp" | jq -r '.message // empty')
+    echo "Warning: failed to update PR #${prnum}: $err"
+    echo "Response: $patch_resp" | jq -C .
+    # continue so we attempt remaining PRs
+    continue
+  fi
+
+  echo "PR #${prnum} updated."
+done
+
+echo "Done."
+exit 0