storage: add getStatus hook

src/storage/s3.js

@@ -10,6 +10,7 @@ exports = module.exports = {
     injectPrivateFields,
 
     getAvailableSize,
+    getStatus,
 
     upload,
     exists,
@@ -156,6 +157,23 @@ async function getAvailableSize(apiConfig) {
     return Number.POSITIVE_INFINITY;
 }
 
+async function getStatus(apiConfig) {
+    assert.strictEqual(typeof apiConfig, 'object');
+
+    const s3 = createS3Client(apiConfig, { retryStrategy: RETRY_STRATEGY });
+
+    const listParams = {
+        Bucket: apiConfig.bucket,
+        Prefix: path.join(apiConfig.prefix, 'snapshot'),
+        MaxKeys: 1
+    };
+
+    const [listError] = await safe(s3.listObjectsV2(listParams));
+    if (listError) return { status: 'inactive', message: `Error listing objects. ${formatError(listError)}` };
+
+    return { state: 'active' };
+}
+
 async function upload(apiConfig, remotePath) {
     assert.strictEqual(typeof apiConfig, 'object');
     assert.strictEqual(typeof remotePath, 'string');