Providing MapLibre-compatible style JSON from openstreetmap-tile-server

[Previous: Self-hosting maps on my laptop]

In the previous post I showed how to run OSM tile server stack locally.

Now I’ve managed to connect a MapLibre GL JS front end to my local tile server and it’s showing maps!

(It’s running inside Element Web, the awesome Matrix messenger I am working on. NOTE: this is a very, very early prototype!)

In the previous post I ran a docker run command to launch the tile server.

This time, I had to create a file style.json:

  "version": 8,
  "sources": {
    "localsource": {
      "type": "raster",
      "tiles": [
      "tileSize": 256,
      "attribution": "Maps Copyright 2018 <a href=\"\">Geofabrik GmbH</a> and <a href=\"\">OpenStreetMap Contributors</a>"
  "layers": [
      "id": "locallayer",
      "source": "localsource",
      "type": "raster"

and then I launched the tile server with that file available in the document root:

docker run \
    -p 8080:80 \
    -v $PWD/style.json:/var/www/html/style.json \
    -v openstreetmap-data:/var/lib/postgresql/12/main \
    -v openstreetmap-rendered-tiles:/var/lib/mod_tile \
    -e THREADS=24 \
    -e ALLOW_CORS=enabled \
    -d overv/openstreetmap-tile-server:1.3.10 \

Now I can point my MapLibre GL JS at that style file with code something like this: = new maplibregl.Map({
    container: my_container,
    style: "",
    center: [0, 0],
    zoom: 13,

Very excited to be drawing maps without any requests leaving my machine!

Self-hosting maps on my laptop

[See also: Providing MapLibre-compatible style JSON from openstreetmap-tile-server]

As part of my research for working on location sharing for Element Web, the Matrix-based instant messenger, I have been learning about tile servers.

I managed to get OSM tile server stack working on my laptop:

Here are a couple useful pages I read during my research:

Today I managed to run a real tile server on my laptop, using data downloaded from OpenStreetMap in a way that I think complies with their terms of use.

To run these commands you will need Docker, and hopefully nothing much else.

Download the data

I downloaded the UK data like this:

wget ''

You can find downloads for other regions at

Import it

Then I ran an import, which converts the PBF data into tiles that can be shown in a UI:

docker volume create openstreetmap-data
docker volume create openstreetmap-rendered-tiles
docker run \
    -v $PWD/great-britain-latest.osm.pbf:/data.osm.pbf \
    -v openstreetmap-data:/var/lib/postgresql/12/main \
    -v openstreetmap-rendered-tiles:/var/lib/mod_tile \
    -e THREADS=24 \
    overv/openstreetmap-tile-server:1.3.10 \

(Change “great-britain” to match what you downloaded.)

On my quite powerful laptop this took 39 minutes to run.

Run the tile server

Finally, I launched the server:

(Make sure you’ve done the “Import it” step first.)

docker run \
    -p 8080:80 \
    -v openstreetmap-data:/var/lib/postgresql/12/main \
    -v openstreetmap-rendered-tiles:/var/lib/mod_tile \
    -e THREADS=24 \
    -e ALLOW_CORS=enabled \
    -d overv/openstreetmap-tile-server:1.3.10 \

This should launch the docker container in the background, which you can check with docker ps.

Test it

You can now grab a single file by going to, or interact with the map properly at

It was quite unresponsive at first, but once it had cached the tiles I was looking at, it was very smooth.

Streaming to Twitch and PeerTube simultaneously using nginx on Oracle cloud

Simulcasting RTMP using NGINX

I want people to be able to watch my Matrix and Rust live coding streams using free software, so I’d like to simulcast to PeerTube as well as Twitch.

This is possible using NGINX and its RTMP module. It does involve building NGINX from source, but I actually found that reasonably easy to do.

Why Oracle cloud?

I would never recommend using Oracle for anything, but they do provide up to two virtual machines in their cloud for free, and the one I am using has been consistently available with very good connectivity, in a London data centre since I set it up several months ago.

So, we are making our lives more difficult by trying to do this on Oracle Linux, which is a derivative of RHEL.

Building NGINX and its RTMP module on Oracle Linux

I ran these commands on my Oracle cloud instance (running Oracle Linux):

sudo yum install git pcre-devel openssl-devel
mkdir nginx
cd nginx
git clone
cd nginx-1.21.4
./configure --add-module=../nginx-rtmp-module/
sudo make install

After all this NGINX was installed to /usr/local/nginx/.

Creating the NGINX config file for RTMP simulcasting

Next I edited the NGINX config file by typing:

sudo nano /usr/local/nginx/conf/nginx.conf

And pasted in this config at the bottom of the file:

rtmp {
    server {
        listen 1935;
        chunk_size 4096;
        application live {
            live on;
            record off;
            push rtmp://;
            push rtmp://;

Notice that you will need to get your Twitch stream key from Twitch -> Creator Dashboard -> Settings -> Stream, then Copy next to the Primary Stream Key.

To get a PeerTube stream ID, you will need to go to your PeerTube page and click Publish, then Go Live, choose your channel and choose Go Live. Note that if you want the streams to record and be available later, you have to create a new stream key each time you start a stream, and change it in nginx.conf.

If you use a different PeerTube server (I use then you’ll need to change the server name in the config file above too.

Make sure your config file is saved with the right URLs in it.

Opening ports

To send RTMP traffic to my server, I needed to open the right port to the Oracle cloud instance. That involved creating an ingress rule, and adding a firewall rule.

Creating an ingress rule

In the web interface, I went to the menu in the top left, clicked Compute, then Instances.

I clicked on my instance’s name, then I clicked on the name of the subnet in the details (on the right).

I clicked on Default security list for…, then Add Ingress Rules.

I made an ingress rule with Source Type=CIDR, Source CIDR=, IP Protocol=TCP, Source Port Range=(blank, meaning all), Destination Port Range=1935

Adding a firewall rule

Then I ssh’d into the machine and ran these commands to create a firewall rule allowing the traffic:

sudo firewall-cmd --zone=public --permanent --add-port=1935/tcp
sudo firewall-cmd --reload

Stop and Start NGINX

After creating the config file and opening the right port, I needed to start NGINX.

Every time I change the config file, I need to restart it.

If it’s already running, I stop it with:

sudo /usr/local/nginx/sbin/nginx -s stop

and then I start it up again with

sudo /usr/local/nginx/sbin/nginx

I can check whether it’s happy by looking at the log files, for example to see any errors:

less /usr/local/nginx/logs/error.log

Starting the stream

Now I go into OBS and go to File -> Settings -> Stream and choose the type as Custom, and the Server as rtmp:// (But instead of I put the public IP address of my instance, which I found by clicking the name of the instance in the Oracle cloud management console.)

New game: Tron – frantic multiplayer retro action

My newest game is out now on Smolpxl Games – Tron:

Pixellated lines fight each other to stay alive

Play at

It’s a frantic multiplayer retro pixellated thingy playable in your browser. Try to stay alive longer than everyone else!

This version allows many players (up to 16 if you can manage it), and is quite pure in its implementation.

There are bots to play against, and you can gather your friends around a keyboard to play together.

Part of the motivation for writing this game was to test my new smolpxl-remote remote-play system, but this is not enabled yet, so watch this space…

I love playing games with other people – preferably at least 3 other people. In theory you could have 8 players around a keyboard playing this – send me a picture if you try!

One feature I worked on in the Smolpxl library for this game: saving configuration to local storage (and asking permission to do so). I ended up with a very ugly hack to do this, so a bit more work is needed before I merge it into the library.

New Job at Element (Matrix)

I started a new job today at Element!

It has been a long-standing ambition of mine to work in Free and Open Source software, and I am very excited to work for a company that is the main developer of a really important project: the Matrix communication network.

I don’t know much about what I’ll be doing yet, but finding an open source company with a decent business model that is prepared to pay me is very exciting. The fact that they have offices that are close enough for me to go for is another huge bonus.

Wish me luck, and I’ll let you know what I’m working on when it becomes more clear.