App Links: Support for FOSDEM Schedule app for Android

[johnjohndoe]

Context

• Android allows to register apps as official apps for a website/domain.
• Once the fosdem.org is prepared then apps can recognize a link to a session. When a user clicks such a link then the app can pick up this link and open the corresponding screen in the app.
• There is two release signing keys because Google Play and F-Droid use different ones.
• All that is needed from the FOSDEM website is to put a JSON file into a specific path:
  • https://fosdem.org/.well-known/assetlinks.json

assetlinks.json file

Please add the following file to the public directory /.well-known of the FOSDEM website:

[
    {
        "relation":
        [
            "delegate_permission/common.handle_all_urls"
        ],
        "target":
        {
            "namespace": "android_app",
            "package_name": "info.metadude.android.fosdem.schedule",
            "sha256_cert_fingerprints":
            [
                "89:4C:4F:D6:CB:AB:E4:C9:F9:2A:43:A8:25:E7:45:25:0A:17:7D:A0:1A:D0:30:1E:DD:22:3C:03:22:C7:C0:03",
                "FF:A0:BD:6F:43:2A:A8:B4:43:00:24:87:BC:73:27:70:7F:A4:E6:71:FC:8E:F4:51:59:C5:B6:AD:8B:9D:0F:E6"
            ]
        }
    },
    {
        "relation":
        [
            "delegate_permission/common.handle_all_urls"
        ],
        "target":
        {
            "namespace": "android_app",
            "package_name": "info.metadude.android.fosdem.schedule.debug",
            "sha256_cert_fingerprints":
            [
                "D8:E7:B5:B1:50:BB:1E:39:58:A8:AA:E9:95:09:92:68:74:DC:C5:03:79:E5:9C:FD:CC:9A:1B:43:4F:D0:F9:F6"
            ]
        }
    }
]

Related

• https://developer.android.com/training/app-links/about

[Wilm0r]

Would this benefit all FOSDEM apps or just the one with package name info.metadude.android.fosdem?

[johnjohndoe]

Only that one for now. Feel free to add your SHA256 hashes. But for App Links to function correctly, you will need to configure your app further.

[johnjohndoe]

@gerryd Will the JSON file be deployed in time for FOSDEM 2026? Please note that mobile apps cannot be deployed on short notice due to the unforeseeable time taken by the stores.

[gerryd]

@johnjohndoe I undortunately don't have time to check (impact etc) this right now; I pinged the co-maintainers internally!

[johanvdw]

How does it work: if a users goes to the fosdem website and clicks a schedule link do they get an option to open in the app or the website? Or will it send them to the app immediately?
Strictly speaking the second is maybe not ideal, especially if people go to the website to double check what the app does.

[Wilm0r]

I'm not an expert on this but common.handle_all_urls reads as if any fosdem.org URL could get intercepted.

[johnjohndoe]

@johanvdw Clicking a valid session link takes you into the app immediately. That is the main idea of app links. Users can opt-out in the app's "open by default" system settings - or obviously by not installing the app.

Here is a video recording which shows immediate navigation into the app and out to the website from a session link shown in the app.
EventFahrplan/EventFahrplan#843

[johanvdw]

How is determined what is a schedule link and what is not? Is this up to the app? What about other pages on the fosdem website, or schedule pages like fringe? What about subdomains?

[johnjohndoe]

The domain, subdomains, paths are to be configured in the app, see e.g. https://github.com/EventFahrplan/EventFahrplan/blob/master/app%2Fsrc%2Fccc39c3%2FAndroidManifest.xml#L19

Only content which is represented in the app should be covered by app links. For FOSDEM this would be restricted to session links.

[bastischubert]

As discussed during todays FIT meeting we'll just do it for this year.
i'm about to implement it after todays meeting

[bastischubert]

tagging @cbeyls if he also needs this for https://github.com/cbeyls/fosdem-companion-android
tagging @Wilm0r if he also needs this for https://github.com/Wilm0r/giggity

[Wilm0r]

Bit hard to rush out this functionality safely (and it doesn't seem that useful to me), but thanks for the heads-up @bastischubert :)

Trying to finish some other improvements before next weekend though.