Setting Up Your Web Server

Setting Up Your Web Server

Compiling the stylesheet

We now have a fully working CartoCSS stylesheet. Before Mapnik can use it, we need to compile it into XML using the command-line carto compiler. First of all, we use OSM Bright’s own preprocessor, which we need to edit for our setup:

cp configure.py.sample configure.py
gedit configure.py

Change the config line pointing to ~/Documents/Mapbox/project to /usr/local/share/maps/style instead, and change dbname from osm to gis. Save and exit.

Run the pre-processor and then carto:

./make.py
cd ../OSMBright/
carto project.mml > OSMBright.xml

 Run make.py

./make.py

This will create a new folder called “build” with your new project, customized with the variables you set in configure.py and install a copy of this build to your MapBox project folder. If you open up TileMill you should see your new map in the project listing.

Click on the map to view it in the editing interface.

You now have a Mapnik XML stylesheet at /usr/local/share/maps/style/OSMBright/OSMBright.xml .

Setting up your webserver

Next we need to plug renderd and mod_tile into the Apache webserver, ready to receive tile requests.

Configure renderd

Change the the renderd settings by editing the /usr/local/etc/renderd.conf (you’ll need to do it as root via “sudo”) and change the following five lines, uncommenting (removing the ‘;’) when required. They are found in the [renderd], [mapnik] and [default] sections.

socketname=/var/run/renderd/renderd.sock
plugins_dir=/usr/local/lib/mapnik/input
font_dir=/usr/share/fonts/truetype/ttf-dejavu
XML=/usr/local/share/maps/style/OSMBright/OSMBright.xml
HOST=localhost

Create the files required for the mod_tile system to run (remember to change username to your user’s name):

sudo mkdir /var/run/renderd
sudo chown username /var/run/renderd
sudo mkdir /var/lib/mod_tile
sudo chown username /var/lib/mod_tile

Configure mod_tile

Next, we need to tell the Apache web server about our new mod_tile installation.

Using your favourite text editor, create the file /etc/apache2/conf-available/mod_tile.conf and add one line:

LoadModule tile_module /usr/lib/apache2/modules/mod_tile.so

Apache’s default website configuration file needs to be modified to include mod_tile settings. Modify the file /etc/apache2/sites-available/000-default.conf to include the following lines immediately after the admin e-mail address line:

LoadTileConfigFile /usr/local/etc/renderd.conf
ModTileRenderdSocketName /var/run/renderd/renderd.sock
# Timeout before giving up for a tile to be rendered
ModTileRequestTimeout 0
# Timeout before giving up for a tile to be rendered that is otherwise missing
ModTileMissingRequestTimeout 30

Tell Apache that you have added the new module, and restart it:

sudo a2enconf mod_tile
sudo service apache2 reload

Tuning your system

A tile server can put a lot of load on hardware and software. The default settings may therefore not be appropriate and a significant improvement can potentially be achieved through tuning various parameters.

Tuning postgresql

The default configuration for PostgreSQL 9.4 needs to be tuned for the amount of data you are about to add to it. Edit the file /etc/postgresql/9.4/main/postgresql.conf and make the following changes:

shared_buffers = 128MB
checkpoint_segments = 20
maintenance_work_mem = 256MB
autovacuum = off

These changes require a kernel configuration change, which needs to be applied every time that the computer is rebooted. As root via “sudo”, edit /etc/sysctl.conf and add these lines near the top after the other “kernel” definitions:

# Increase kernel shared memory segments - needed for large databases
kernel.shmmax=268435456

Reboot your computer. Run this:

sudo sysctl kernel.shmmax

and verify that it displays as 268435456.

 

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