feat: record AP parsing failures, save activity in db for 24h

public/language/en-GB/admin/settings/activitypub.json

@@ -65,7 +65,8 @@
 	"content.break-string-help": "This delimiter can be manually inserted by power users when composing new topics. It instructs NodeBB to use content up until that point as part of the <code>summary</code>. If this string is not used, then the character count fallback applies. (Default: <code>[...]</code>)",
 	"content.world-default-cid": "Default category ID for &quot;World&quot; page composer",
 
-	"analytics.intro": "From this page you can view the state of your instance's federation with other servers",
+	"analytics.intro": "This page provides an overview of the state of your forum's federation with other instances/servers",
+	"analytics.details": "NodeBB tracks ActivityPub activity receipts and sends, and you are able to view them by hostname, either hourly or daily. Note that the metrics are only incremented on <em>successful</em> receipts and sends.",
 	"analytics.by-hostname": "Filter by Hostname",
 	"analytics.received": "Received Activities",
 	"analytics.sent": "Sent Activites",

src/activitypub/index.js

@@ -481,6 +481,18 @@ ActivityPub.record.send = async ({ type, target }) => {
 	]);
 };
 
+ActivityPub.record.receiptError = async (body) => {
+	const { id, actor } = body;
+	const now = Date.now();
+	const { hostname } = new URL(actor);
+	await Promise.all([
+		db.sortedSetAdd('ap.errors', now, id),
+		db.set(`ap.errors:${id}`, JSON.stringify(body)),
+		analytics.increment(['ap.inErr', `ap.inErr:byHost:${hostname}`]),
+	]);
+	await db.expire(`ap.errors:${id}`, 60 * 60 * 24); // 24 hours
+};
+
 ActivityPub.buildRecipients = async function (object, options) {
 	/**
 	 * - Builds a list of targets for activitypub.send to consume

src/controllers/activitypub/index.js

@@ -272,6 +272,7 @@ Controller.postInbox = async (req, res) => {
 		await activitypub.record.receipt(req.body);
 		await helpers.formatApiResponse(202, res);
 	} catch (e) {
+		activitypub.record.receiptError(req.body);
 		helpers.formatApiResponse(500, res, e).catch(err => winston.error(err.stack));
 	}
 };

src/views/admin/federation/analytics.tpl

@@ -5,6 +5,7 @@
 		<div id="spy-container" class="col-12 col-md-8 px-0 mb-4" tabindex="0">
 			<div class="mb-4">
 				<p class="lead">[[admin/settings/activitypub:analytics.intro]]</p>
+				<p>[[admin/settings/activitypub:analytics.details]]</p>
 
 				<div class="mb-3 row">
 					<div class="col-6">