Mastodon

Mastodon accounts belong to individual servers. OpenPost can register an app when someone connects to a public HTTPS server. You can also configure a fixed app for a server your team uses.

Connect a public server

1. In OpenPost, choose your workspace and open Settings → Workspace → Social accounts → Mastodon.
2. Select Continue to Mastodon, then enter the address of the server that hosts your account, such as https://mastodon.social. Do not enter your profile URL.
3. Continue to the server's authorization page and approve OpenPost.
4. By default, Mastodon shows an authorization code. Copy it and return to OpenPost. In the Mastodon connection dialog, select Code, paste it into Authorization code, and select Connect account.
5. Publish a short test post and open the resulting link from its publication details.

OpenPost registers the app on that server through POST /api/v1/apps with read write scopes and keeps the client secret encrypted. The default redirect is urn:ietf:wg:oauth:2.0:oob, which makes Mastodon display a code instead of redirecting to a callback. See Mastodon's app registration and authorization documentation.

Configure a fixed server app

Use this path if you want to preconfigure a known server or its app registration endpoint is unavailable to OpenPost.

1. On that Mastodon server, open Preferences → Development → New application. Name the app OpenPost, add read and write permissions, and register urn:ietf:wg:oauth:2.0:oob as the redirect URI. Save the app and copy its client ID and secret. Server menus can differ.

2. Add the server and credentials to MASTODON_SERVERS in your server environment. Keep the JSON on one line in .env:

   MASTODON_SERVERS=[{"name":"Team server","client_id":"your-client-id","client_secret":"your-client-secret","instance_url":"https://social.example"}]

3. Recreate OpenPost with docker compose up -d --force-recreate openpost to load the changed environment. The server should appear as a choice when connecting Mastodon.

You can instead save a Mastodon app in Instance → Configuration → Provider apps. If you change MASTODON_REDIRECT_URI, register that exact URI on the Mastodon app too. The default out-of-band flow needs no public callback.

If the connection fails

• Enter the server origin, for example https://social.example, without a username or path. OpenPost accepts public HTTPS instances.
• If app registration fails, ask the server administrator whether it accepts new OAuth apps, or configure a fixed app for that server.
• If Mastodon rejects the authorization code, start the connection again and copy the new code. Check that the app's registered redirect URI matches MASTODON_REDIRECT_URI.
• If a fixed server is missing, check the MASTODON_SERVERS JSON and the container logs after restart.