chore: add Kokoro release config and script for OSS Exit Gate

.kokoro/release.cfg

@@ -0,0 +1,13 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+build_file: "github/google-api-ads-ruby/.kokoro/release.sh"
+
+# Default to DRY_RUN=true for safety; can be overridden via API or UI
+env_vars: {
+  key: "DRY_RUN"
+  value: "true"
+}
+
+container_properties {
+  docker_image: "us-central1-docker.pkg.dev/kokoro-container-bakery/kokoro/ubuntu/ubuntu2204/full:current"
+}

.kokoro/release.sh

@@ -0,0 +1,93 @@
+#!/bin/bash
+set -euo pipefail
+set +x
+
+# Default to dry-run for safety unless DRY_RUN=false is explicitly passed.
+DRY_RUN="${DRY_RUN:-true}"
+if [[ "${DRY_RUN}" != "true" && "${DRY_RUN}" != "false" ]]; then
+  echo "ERROR: DRY_RUN must be 'true' or 'false' (got '${DRY_RUN}')." >&2
+  exit 1
+fi
+
+REPO_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+cd "${REPO_DIR}"
+
+echo "=== Building and Releasing from: ${REPO_DIR} (DRY_RUN=${DRY_RUN}) ==="
+
+EXIT_GATE_PROJECT="oss-exit-gate-prod"
+EXIT_GATE_LOCATION="us"
+EXIT_GATE_REPOSITORY="google-api-ads-ruby--rubygems"
+
+build_and_stage_gem() {
+  local dir="$1"
+  local pkg="$2"
+  pushd "${REPO_DIR}/${dir}" >/dev/null
+  rm -f *.gem
+  gem build "${pkg}.gemspec"
+  local gem_file
+  gem_file="$(ls "${pkg}"-*.gem | head -n 1)"
+  local ver="${gem_file#${pkg}-}"
+  ver="${ver%.gem}"
+
+  if gcloud artifacts packages describe "${pkg}" \
+      --project="${EXIT_GATE_PROJECT}" \
+      --location="${EXIT_GATE_LOCATION}" \
+      --repository="${EXIT_GATE_REPOSITORY}" &>/dev/null; then
+    gcloud artifacts packages delete "${pkg}" \
+      --project="${EXIT_GATE_PROJECT}" \
+      --location="${EXIT_GATE_LOCATION}" \
+      --repository="${EXIT_GATE_REPOSITORY}" \
+      --quiet
+  fi
+
+  set +x
+  local token
+  token="$(gcloud auth print-access-token)"
+  curl -fsSL -X POST \
+    -H "Authorization: Bearer ${token}" \
+    -H "Content-Type: application/octet-stream" \
+    --data-binary @"${gem_file}" \
+    "https://us-ruby.pkg.dev/${EXIT_GATE_PROJECT}/${EXIT_GATE_REPOSITORY}/api/v1/gems" >&2
+  unset token
+  popd >/dev/null
+  echo "${ver}"
+}
+
+SAVON_VER="$(build_and_stage_gem "ads_savon" "google-ads-savon")"
+COMMON_VER="$(build_and_stage_gem "ads_common" "google-ads-common")"
+DFP_VER="$(build_and_stage_gem "ad_manager_api" "google-dfp-api")"
+
+if [[ "${DRY_RUN}" == "true" ]]; then
+  echo "=== DRY_RUN is enabled. Skipping manifest upload to Exit Gate. ==="
+  exit 0
+fi
+
+cat <<EOF > manifest.json
+{
+  "publish_all": false,
+  "publishing_groups": [
+    {
+      "packages": [
+        {
+          "name": "google-ads-savon",
+          "version": "${SAVON_VER}"
+        },
+        {
+          "name": "google-ads-common",
+          "version": "${COMMON_VER}"
+        },
+        {
+          "name": "google-dfp-api",
+          "version": "${DFP_VER}"
+        }
+      ]
+    }
+  ]
+}
+EOF
+
+EXIT_GATE_BUCKET="gs://oss-exit-gate-prod-projects-bucket/google-api-ads-ruby/rubygems/manifests"
+MANIFEST_NAME="manifest-$(date +%Y%m%d%H%M%S).json"
+
+echo "=== Uploading manifest to ${EXIT_GATE_BUCKET}/${MANIFEST_NAME} ==="
+gcloud storage cp manifest.json "${EXIT_GATE_BUCKET}/${MANIFEST_NAME}"