add to documentation: register MBTiles for use

[danbjoseph]

We're developing an offline-compatible geostorytelling tool that will run MBtiles. It would be amazing to set up a site on the POSM to host that. I think that's just a question of configuring a local URL service in nginx, right?

if you register the MBTiles archive in /etc/tessera.conf.d/, tiles will be served up under /tiles/<name>/...
(so you don't need to include your own tile server)
(via @mojodna)

[dalekunce]

tried this. Tiles don't show up in field papers or in iD. It actually caused other working tiles to stop working.

{
  "/tiles/mlm": "mbtiles:///opt/data/aoi/mlm/tiles/mlm.mbtiles"
}

[mojodna]

How did you register it? Were there associated error messages?

https://github.com/posm/posm-imagery-updater is the component responsible for updating configs so that iD can see available imagery sources (IIRC, the URL template needs to be pasted into FP for use there).

[dalekunce]

Didn't know about the next step. I added a json file in the tessera.conf.d folder. File size is bigger than 256mb if that is somehow related to #4

{
  "/tiles/mlm_sat/mlm_sat": "mbtiles:///opt/data/aoi/mlm_sat/tiles/mlm_sat.mbtiles"
}

The tessera logs don't show any errors.