Implemented Ghost site changed webhook handler (#5)

refs [MOM-300](https://linear.app/tryghost/issue/MOM-300/update-actor-data-with-ghost-site-settings#comment-4e49803f) Implemented Ghost site changed webhook handler so that when the settings for a Ghost instance are updated, the actor data is also updated in the database (name, description, icon). For this to work, the Ghost instance needs to setup a webhook for the `Site Changed` event and point it to the `<host>/.ghost/activitypub/webhooks/site/changed` endpoint
TryGhost · Jul 25, 2024 · c8df524 · c8df524
1 parent c952c9e
commit c8df524
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Showing 7 changed files with 230 additions and 132 deletions.
diff --git a/package.json b/package.json
@@ -35,6 +35,7 @@
     "@sentry/node": "8.13.0",
     "hono": "4.4.6",
     "knex": "3.1.0",
+    "ky": "1.4.0",
     "mysql2": "3.10.1",
     "uuid": "10.0.0",
     "x-forwarded-fetch": "0.2.0"

diff --git a/src/app.ts b/src/app.ts
@@ -14,6 +14,7 @@ import {
     Group,
     Organization,
     Service,
+    Update,
 } from '@fedify/fedify';
 import { federation } from '@fedify/fedify/x/hono';
 import { Hono, Context } from 'hono';
@@ -42,9 +43,10 @@ import {
     followDispatcher,
     acceptDispatcher,
     createDispatcher,
+    updateDispatcher,
 } from './dispatchers';
 
-import { inboxHandler, postPublishedWebhook, followAction } from './handlers';
+import { followAction, inboxHandler, postPublishedWebhook, siteChangedWebhook } from './handlers';
 
 if (process.env.SENTRY_DSN) {
     Sentry.init({ dsn: process.env.SENTRY_DSN });
@@ -135,6 +137,11 @@ fedify.setObjectDispatcher(
     `/.ghost/activitypub/create/{id}`,
     createDispatcher,
 );
+fedify.setObjectDispatcher(
+    Update,
+    `/.ghost/activitypub/update/{id}`,
+    updateDispatcher,
+);
 
 /** Hono */
 
@@ -212,6 +219,7 @@ app.use(async (ctx, next) => {
 
 app.get('/.ghost/activitypub/inbox/:handle', inboxHandler);
 app.post('/.ghost/activitypub/webhooks/post/published', postPublishedWebhook);
+app.post('/.ghost/activitypub/webhooks/site/changed', siteChangedWebhook);
 app.post('/.ghost/activitypub/actions/follow/:handle', followAction);
 
 /** Federation wire up */

diff --git a/src/constants.ts b/src/constants.ts
@@ -0,0 +1,4 @@
+export const ACTOR_DEFAULT_HANDLE = 'index';
+export const ACTOR_DEFAULT_NAME = 'Local Ghost site';
+export const ACTOR_DEFAULT_ICON = 'https://ghost.org/favicon.ico';
+export const ACTOR_DEFAULT_SUMMARY = 'This is a summary';
diff --git a/src/dispatchers.ts b/src/dispatchers.ts
@@ -2,119 +2,18 @@ import {
     Article,
     Accept,
     Follow,
-    Image,
     Person,
     RequestContext,
     lookupObject,
-    generateCryptoKeyPair,
-    exportJwk,
-    importJwk,
     Create,
     Note,
     Activity,
+    Update,
 } from '@fedify/fedify';
 import { v4 as uuidv4 } from 'uuid';
 import { addToList } from './kv-helpers';
 import { ContextData } from './app';
-
-type PersonData = {
-    id: string;
-    name: string;
-    summary: string;
-    preferredUsername: string;
-    icon: string;
-    inbox: string;
-    outbox: string;
-    following: string;
-    followers: string;
-};
-
-async function getUserData(ctx: RequestContext<ContextData>, handle: string) {
-    const existing = await ctx.data.db.get<PersonData>(['handle', handle]);
-
-    if (existing) {
-        let icon = null;
-        try {
-            icon = new Image({ url: new URL(existing.icon) });
-        } catch (err) {
-            console.log('Could not create Image from Icon value', existing.icon);
-            console.log(err);
-        }
-        return {
-            id: new URL(existing.id),
-            name: existing.name,
-            summary: existing.summary,
-            preferredUsername: existing.preferredUsername,
-            icon,
-            inbox: new URL(existing.inbox),
-            outbox: new URL(existing.outbox),
-            following: new URL(existing.following),
-            followers: new URL(existing.followers),
-            publicKeys: (await ctx.getActorKeyPairs(handle)).map(
-                (key) => key.cryptographicKey,
-            ),
-        };
-    }
-
-    const data = {
-        id: ctx.getActorUri(handle),
-        name: `Local Ghost site`,
-        summary: 'This is a summary',
-        preferredUsername: handle,
-        icon: new Image({ url: new URL('https://ghost.org/favicon.ico') }),
-        inbox: ctx.getInboxUri(handle),
-        outbox: ctx.getOutboxUri(handle),
-        following: ctx.getFollowingUri(handle),
-        followers: ctx.getFollowersUri(handle),
-        publicKeys: (await ctx.getActorKeyPairs(handle)).map(
-            (key) => key.cryptographicKey,
-        ),
-    };
-
-    const dataToStore: PersonData = {
-        id: data.id.href,
-        name: data.name,
-        summary: data.summary,
-        preferredUsername: data.preferredUsername,
-        icon: 'https://ghost.org/favicon.ico',
-        inbox: data.inbox.href,
-        outbox: data.outbox.href,
-        following: data.following.href,
-        followers: data.followers.href,
-    };
-
-    await ctx.data.db.set(['handle', handle], data);
-
-    return data;
-}
-
-async function getUserKeypair(ctx: ContextData, handle: string) {
-    const existing = await ctx.db.get<{ publicKey: any; privateKey: any }>([
-        'keypair',
-        handle,
-    ]);
-
-    if (existing) {
-        return {
-            publicKey: await importJwk(existing.publicKey, 'public'),
-            privateKey: await importJwk(existing.privateKey, 'private'),
-        };
-    }
-
-    const keys = await generateCryptoKeyPair();
-
-    const data = {
-        publicKey: keys.publicKey,
-        privateKey: keys.privateKey,
-    };
-
-    await ctx.db.set(['keypair', handle], {
-        publicKey: await exportJwk(data.publicKey),
-        privateKey: await exportJwk(data.privateKey),
-    });
-
-    return data;
-}
+import { getUserData, getUserKeypair } from './user';
 
 export async function actorDispatcher(
     ctx: RequestContext<ContextData>,
@@ -384,6 +283,18 @@ export async function createDispatcher(
     return Create.fromJsonLd(exists);
 }
 
+export async function updateDispatcher(
+    ctx: RequestContext<ContextData>,
+    data: Record<'id', string>,
+) {
+    const id = ctx.getObjectUri(Update, data);
+    const exists = await ctx.data.globaldb.get([id.href]);
+    if (!exists) {
+        return null;
+    }
+    return Update.fromJsonLd(exists);
+}
+
 export async function noteDispatcher(
     ctx: RequestContext<ContextData>,
     data: Record<'id', string>,

diff --git a/src/handlers.ts b/src/handlers.ts
@@ -6,12 +6,44 @@ import {
     isActor,
     Create,
     Note,
+    Update,
+    PUBLIC_COLLECTION
 } from '@fedify/fedify';
 import { Context, Next } from 'hono';
+import ky from 'ky';
 import { v4 as uuidv4 } from 'uuid';
 import { addToList } from './kv-helpers';
 import { toURL } from './toURL';
 import { ContextData, HonoContextVariables, fedify } from './app';
+import type { PersonData } from './user';
+import {
+    ACTOR_DEFAULT_HANDLE,
+    ACTOR_DEFAULT_ICON,
+    ACTOR_DEFAULT_NAME,
+    ACTOR_DEFAULT_SUMMARY
+} from './constants';
+
+type GhostSiteSettings = {
+    site: {
+        description: string;
+        icon: string;
+        title: string;
+    }
+}
+
+async function getGhostSiteSettings(host: string): Promise<GhostSiteSettings> {
+    const settings = await ky
+        .get(`https://${host}/ghost/api/admin/site/`)
+        .json<Partial<GhostSiteSettings>>();
+
+    return {
+        site: {
+            description: settings?.site?.description || ACTOR_DEFAULT_SUMMARY,
+            title: settings?.site?.title || ACTOR_DEFAULT_NAME,
+            icon: settings?.site?.icon || ACTOR_DEFAULT_ICON
+        }
+    };
+}
 
 async function postToArticle(ctx: RequestContext<ContextData>, post: any) {
     if (!post) {
@@ -121,6 +153,61 @@ export async function postPublishedWebhook(
     });
 }
 
+export async function siteChangedWebhook(
+    ctx: Context<{ Variables: HonoContextVariables }>,
+    next: Next,
+) {
+    try {
+        // Retrieve site settings from Ghost
+        const host = ctx.req.header('host') || '';
+
+        const settings = await getGhostSiteSettings(host);
+
+        // Update the database
+        const handle = ACTOR_DEFAULT_HANDLE;
+        const db = ctx.get('db');
+
+        const current = await db.get<PersonData>(['handle', handle]);
+        const updated =  {
+            ...current,
+            icon: settings.site.icon,
+            name: settings.site.title,
+            summary: settings.site.description,
+        }
+
+        await db.set(['handle', handle], updated);
+
+        // Publish activity
+        const apCtx = fedify.createContext(ctx.req.raw as Request, {
+            db,
+            globaldb: ctx.get('globaldb'),
+        });
+
+        const actor = await apCtx.getActor(handle);
+
+        const update = new Update({
+            id: apCtx.getObjectUri(Update, { id: uuidv4() }),
+            actor: actor?.id,
+            to: PUBLIC_COLLECTION,
+            object: actor
+        });
+
+        await ctx.get('globaldb').set([update.id!.href], await update.toJsonLd());
+        await addToList(db, ['outbox'], update.id!.href);
+        await apCtx.sendActivity({ handle }, 'followers', update);
+    } catch (err) {
+        console.log(err);
+    }
+
+    // Return 200 OK
+    return new Response(JSON.stringify({}), {
+        headers: {
+            'Content-Type': 'application/activity+json',
+        },
+        status: 200,
+    });
+}
+
 export async function inboxHandler(
     ctx: Context<{ Variables: HonoContextVariables }>,
     next: Next,