MediaGoblin: Photo sharing and more
By Kenton Varda - 01 Aug 2014
Today we’re releasing a port of yet another crowd-funded open source web app, MediaGoblin. You can think of MediaGoblin as a Free Software alternative to Flickr, SoundCloud, YouTube, and others.
The app is on the app list now – try it on the demo server.
MediaGoblin is our first app to take full advantage of Sandstorm’s new user identification features. Whenever a request comes in from a user, Sandstorm’s front-end proxy adds a few headers related to authentication and authorization:
X-Sandstorm-Username: Specifies the user’s display name, e.g. “Kenton Varda”. This name is not unique nor stable; it is meant only for displaying to other users.X-Sandstorm-User-Id: A hex string identifying the user. This ID is both unique and stable, so it can be used to identify when the same user returns multiple times.X-Sandstorm-Permissions: A list of permissions that have been shared with this user via the Sandstorm sharing interface. An app can define what permissions are available to share in its package config. However, note that we have not yet implemented the full sharing UI, so for now the creator of the app instance is granted all permissions and everyone else is granted none. It’s up to the app to actually implement this permissions, so for now you can simply use it to distinguish between the owner and non-owners.
Our MediaGoblin port uses these headers to automatically populate MediaGoblin’s internal user list. This way you get MediaGoblin’s commenting and other multi-user features without the need to separately log into it.
Note that there are a few things missing from this port, which we plan to fix in the future:
- Currently, under the hood, apps are exposed only at ephemeral hostnames; the hostname may change every time you use the app. This is great for security but means that apps cannot expose APIs, since API clients want a persistent URL to talk to. Atom feeds are a kind of API. So, for now, we have disabled Atom feeds in our port. This is unfortunate, as it changes MediaGoblin from “federated” to “isolated”. That said, enabling APIs is high on our wish list of features, so expect this to return in the future.
- Related to the above, it’s currently not possible to deep-link into an app,
since it runs in an iframe. So, sending someone an individual photo with
MediaGoblin is hard. We can fix this by automatically passing through any
additional path added to the outer app URL, and creating a
postMessage()-based API for apps to tell the Sandstorm shell what the current path should be. - Due to a limitation in our proxy implementation, we currently do not support very large file uploads. As a result, we had to disable video uploads for now. We plan to fix this soon.
- Currently, if you wish to share your MediaGoblin content, you must share the app instance by copy/pasting the URL. When another user visits that URL, your MediaGoblin server starts up to handle the request. This differs from Ghost and Hacker CMS which are able to publish web content in such a way that the server does not need to start up for every visitor, only for the editor. Unfortunately, this means that a widely-shared MediaGoblin instance may be expensive as it may have to run frequently; Sandstorm normally tries to cut costs by only running servers a small fraction of the time. We’d like to change the app to take advantage of Sandstorm’s web publishing features like Ghost and Hacker CMS do, so that the server only needs to run when a visitor posts a comment, uploads media, or otherwise makes a change. However, this may require some invasive changes to MediaGoblin, so we’ll need to discuss them with MediaGoblin’s developers.
- MediaGoblin implements a number of permissions which can be granted to users, such as permissions to comment, upload media, etc. We eventually want permissions to be set using Sandstorm’s unified sharing model, but as described above it is not yet complete. So, for the time being, you have to set users’ permissions inside the MediaGoblin user management interface.
All that said, despite some missing features, Sandstorm is by far the quickest way to get MediaGoblin up and running. We hope our port allows this great piece of Free Software to reach a wider audience than it could before.
And if you’d like to see the missing features fixed in the future, be sure to fund our Indiegogo campaign. :)