integration of update and tile expire procedure

see https://ircama.github.io/osm-carto-tutorials/updating-data/

Implements https://github.com/Overv/openstreetmap-tile-server/issues/2

README.md

@@ -9,41 +9,74 @@ First create a Docker volume to hold the PostgreSQL database that will contain t
     docker volume create openstreetmap-data
 
 Next, download an .osm.pbf extract from geofabrik.de for the region that you're interested in. You can then start importing it into PostgreSQL by running a container and mounting the file as `/data.osm.pbf`. For example:
-
-    docker run -v /absolute/path/to/luxembourg.osm.pbf:/data.osm.pbf -v openstreetmap-data:/var/lib/postgresql/10/main overv/openstreetmap-tile-server import
-
+```
+    docker run -v /absolute/path/to/luxembourg.osm.pbf:/data.osm.pbf \
+               -v openstreetmap-data:/var/lib/postgresql/10/main \
+               overv/openstreetmap-tile-server \
+               import
+```
 If the container exits without errors, then your data has been successfully imported and you are now ready to run the tile server.
 
+### optional step to allow consecutive updates of osm extracts
+
+if your import is a extract of planet and is based on polygon then you should download this polynom data and use follwing command for the import procedure:
+```
+    docker run -v /absolute/path/to/luxembourg.osm.pbf:/data.osm.pbf \
+               -v /absolute/path/to/luxembourg.poly:/data.poly \
+               -v /openstreetmap-data:/var/lib/postgresql/10/main \
+               overv/openstreetmap-tile-server \
+               import
+```
 ## Running the server
 
 Run the server like this:
-
-    docker run -p 80:80 -v openstreetmap-data:/var/lib/postgresql/10/main -d overv/openstreetmap-tile-server run
-
+```
+    docker run -p 80:80 \
+               -v openstreetmap-data:/var/lib/postgresql/10/main \
+               -d overv/openstreetmap-tile-server \
+               run
+```
 Your tiles will now be available at `http://localhost:80/tile/{z}/{x}/{y}.png`. The demo map in `leaflet-demo.html` will then be available on `http://localhost:80`. Note that it will initially quite a bit of time to render the larger tiles for the first time.
 
 ## Preserving rendered tiles
 
 Tiles that have already been rendered will be stored in `/var/lib/mod_tile`. To make sure that this data survives container restarts, you should create another volume for it:
-
+```
     docker volume create openstreetmap-rendered-tiles
-    docker run -p 80:80 -v openstreetmap-data:/var/lib/postgresql/10/main -v openstreetmap-rendered-tiles:/var/lib/mod_tile -d overv/openstreetmap-tile-server run
+    docker run -p 80:80
+               -v openstreetmap-data:/var/lib/postgresql/10/main
+               -v openstreetmap-rendered-tiles:/var/lib/mod_tile
+               -d overv/openstreetmap-tile-server \
+               run
+```
+## Performance tuning and tweaking
 
-## Performance tuning
+### update and tile expire procedure
+
+The environment variable "UPDATES" (default value =disabled) allows you to run the container with consecutive updates.
+```
+docker run -p 80:80 \
+           -v openstreetmap-data:/var/lib/postgresql/10/main \
+           -v openstreetmap-rendered-tiles:/var/lib/mod_tile \
+           -d overv/openstreetmap-tile-server \
+           -e UPDATES=enabled \
+           run
+```
+Details for update procedure and invoked scripts can you find here [link](https://ircama.github.io/osm-carto-tutorials/updating-data/)
 
 ### THREADS
 
 The import and tile serving processes use 4 threads by default, but this number can be changed by setting the `THREADS` environment variable. For example:
-
+```
     docker run -p 80:80 -e THREADS=24 -v openstreetmap-data:/var/lib/postgresql/10/main -d overv/openstreetmap-tile-server run
-
+```
 ### AUTOVACUUM
 
 The database use the autovacuum feature by default. This behavior can be changed with `AUTOVACUUM` environment variable. For example:
 
     docker run -p 80:80 -e AUTOVACUUM=off -v openstreetmap-data:/var/lib/postgresql/10/main -d overv/openstreetmap-tile-server
 
-## Benchmarks
+### Benchmarks
 
 You can find an example of the import performance to expect with this image on the [OpenStreetMap wiki](https://wiki.openstreetmap.org/wiki/Osm2pgsql/benchmarks#debian_9_.2F_openstreetmap-tile-server).