From 4d2eeb52b3bdef8ba7ff1ccf273b8ddb500c3c81 Mon Sep 17 00:00:00 2001
From: shiftinv <me@shiftinv.cc>
Date: Sun, 4 Sep 2022 15:34:19 +0200
Subject: [PATCH] feat: add metadata headers to response

---
 lib/config.ts  |  3 +++
 lib/webhook.ts | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/lib/config.ts b/lib/config.ts
index ba3503b..7749b2a 100644
--- a/lib/config.ts
+++ b/lib/config.ts
@@ -17,4 +17,7 @@ export default {
     maxWebhookRetries: parseInt(get("MAX_RETRIES", "3")),
     maxWebhookRetryMs: parseInt(get("MAX_RETRY_MS", "30000")),
     mainRedirect: get("MAIN_REDIRECT", null),
+
+    // set by deno deploy
+    deployId: get("DENO_DEPLOYMENT_ID", "<unknown>"),
 };
diff --git a/lib/webhook.ts b/lib/webhook.ts
index c64e406..f6de1f0 100644
--- a/lib/webhook.ts
+++ b/lib/webhook.ts
@@ -47,5 +47,23 @@ export async function sendWebhook(
         log.warning(`retrying after ${resetms}ms (retry ${retries})`);
         await sleep(resetms);
     } while (true);
+
+    // clone response to make headers mutable
+    res = new Response(res.body, res);
+
+    // set metadata headers
+    const meta: Record<string, string> = {
+        "deploy": config.deployId,
+    };
+    if (retries) meta["retries"] = retries.toString();
+
+    setMetadata(res, meta);
+
     return res;
 }
+
+function setMetadata(res: Response, meta: Record<string, string>): void {
+    for (const [key, value] of Object.entries(meta)) {
+        res.headers.set(`x-webhook-filter-${key}`, value);
+    }
+}