diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..a1891f9
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.idea
+*.*~
+osm_pbf/*.pbf
+osm_pbf/*.state.txt
diff --git a/base-pbf/readme.md b/base-pbf/readme.md
deleted file mode 100644
index fca8662..0000000
--- a/base-pbf/readme.md
+++ /dev/null
@@ -1 +0,0 @@
-This folder should contain a *.pbf and *.state.txt.
\ No newline at end of file
diff --git a/docker-compose.yml b/docker-compose.yml
index 51b3ca6..e33efc4 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,14 +1,16 @@
storage:
- build: osm-storage
+ image: ubuntu:latest
hostname: storage
volumes:
- - ../docker-osmupdate/base_pbf:/home/base_pbf
+ # These are sharable to other containers
+ - ./osm_pbf:/home/osm_pbf
- ./settings:/home/settings
+ - /home/import_done
+ - /home/import_queue
+ - /home/cache
db:
- image: etrimaille/postgis
- #image: kartoza/postgis
- #build: ../docker-postgis
+ image: kartoza/postgis
hostname: db
environment:
- USERNAME=docker
@@ -16,8 +18,8 @@ db:
# - HSTORE=true
imposm:
- image: etrimaille/imposm
- #build: ../docker-imposm3
+ #image: kartoza/imposm
+ build: docker-imposm3
volumes_from:
- storage
links:
@@ -28,12 +30,14 @@ imposm:
- PORT=5432
- HOST=db
- DATEBASE=gis
+ # in seconds
- TIME=120
osmupdate:
- image: etrimaille/osmupdate
- #build: ../docker-osmupdate
+ #image: etrimaille/osmupdate
+ build: docker-osmupdate
volumes_from:
- storage
environment:
- - TIME=120
\ No newline at end of file
+ # in seconds
+ - TIME=120
diff --git a/docker-imposm3/.idea/.name b/docker-imposm3/.idea/.name
deleted file mode 100644
index 994d59b..0000000
--- a/docker-imposm3/.idea/.name
+++ /dev/null
@@ -1 +0,0 @@
-docker-imposm3
\ No newline at end of file
diff --git a/docker-imposm3/.idea/docker-imposm3.iml b/docker-imposm3/.idea/docker-imposm3.iml
deleted file mode 100644
index d0876a7..0000000
--- a/docker-imposm3/.idea/docker-imposm3.iml
+++ /dev/null
@@ -1,8 +0,0 @@
-
-
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-imposm3/.idea/encodings.xml b/docker-imposm3/.idea/encodings.xml
deleted file mode 100644
index d821048..0000000
--- a/docker-imposm3/.idea/encodings.xml
+++ /dev/null
@@ -1,4 +0,0 @@
-
-
-
-
\ No newline at end of file
diff --git a/docker-imposm3/.idea/inspectionProfiles/Project_Default.xml b/docker-imposm3/.idea/inspectionProfiles/Project_Default.xml
deleted file mode 100644
index 9def44c..0000000
--- a/docker-imposm3/.idea/inspectionProfiles/Project_Default.xml
+++ /dev/null
@@ -1,20 +0,0 @@
-
-
-
-
-
-
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-imposm3/.idea/inspectionProfiles/profiles_settings.xml b/docker-imposm3/.idea/inspectionProfiles/profiles_settings.xml
deleted file mode 100644
index 3b31283..0000000
--- a/docker-imposm3/.idea/inspectionProfiles/profiles_settings.xml
+++ /dev/null
@@ -1,7 +0,0 @@
-
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-imposm3/.idea/misc.xml b/docker-imposm3/.idea/misc.xml
deleted file mode 100644
index 7b4d854..0000000
--- a/docker-imposm3/.idea/misc.xml
+++ /dev/null
@@ -1,4 +0,0 @@
-
-
-
-
\ No newline at end of file
diff --git a/docker-imposm3/.idea/modules.xml b/docker-imposm3/.idea/modules.xml
deleted file mode 100644
index cce79ba..0000000
--- a/docker-imposm3/.idea/modules.xml
+++ /dev/null
@@ -1,8 +0,0 @@
-
-
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-imposm3/.idea/scopes/scope_settings.xml b/docker-imposm3/.idea/scopes/scope_settings.xml
deleted file mode 100644
index 922003b..0000000
--- a/docker-imposm3/.idea/scopes/scope_settings.xml
+++ /dev/null
@@ -1,5 +0,0 @@
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-imposm3/.idea/vcs.xml b/docker-imposm3/.idea/vcs.xml
deleted file mode 100644
index 94a25f7..0000000
--- a/docker-imposm3/.idea/vcs.xml
+++ /dev/null
@@ -1,6 +0,0 @@
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-imposm3/.idea/workspace.xml b/docker-imposm3/.idea/workspace.xml
deleted file mode 100644
index 03fd26b..0000000
--- a/docker-imposm3/.idea/workspace.xml
+++ /dev/null
@@ -1,857 +0,0 @@
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- true
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- true
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- 1437474153749
-
- 1437474153749
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-imposm3/README.md b/docker-imposm3/README.md
index ee837f4..f9cec8d 100644
--- a/docker-imposm3/README.md
+++ b/docker-imposm3/README.md
@@ -1,6 +1,13 @@
## Docker Imposm
-The container will look for an OSM file (*.pbf) and its state file (*.state.txt) in BASE_PBF.
+This image will take care of doing the initial load for the selected region
+(e.g. planet, or a country such as Malawi) into your database. It will then
+apply at a regulart interval (default is 2 minutes) any diff that arrives
+in the /home/import_queue folder to the postgis OSM database. The diffs
+are fetched by a separate container (see osm_update container).
+
+The container will look for an OSM file (*.pbf) and its state file
+(*.state.txt) in BASE_PBF.
With -e, you can add some settings :
- TIME = 120, seconds between 2 executions of the script
@@ -17,4 +24,4 @@ With -e, you can add some settings :
- OPTIMIZE = false, check (Imposm)[http://imposm.org/docs/imposm3/latest/tutorial.html#optimize]
- DBSCHEMA_PRODUCTION = public, check (Imposm)[http://imposm.org/docs/imposm3/latest/tutorial.html#deploy-production-tables]
- DBSCHEMA_IMPORT = import, check (Imposm)[http://imposm.org/docs/imposm3/latest/tutorial.html#deploy-production-tables]
- - DBSCHEMA_BACKUP = backup, check (Imposm)[http://imposm.org/docs/imposm3/latest/tutorial.html#deploy-production-tables]
\ No newline at end of file
+ - DBSCHEMA_BACKUP = backup, check (Imposm)[http://imposm.org/docs/imposm3/latest/tutorial.html#deploy-production-tables]
diff --git a/docker-imposm3/importer.py b/docker-imposm3/importer.py
index 559d7e4..a84c0c4 100644
--- a/docker-imposm3/importer.py
+++ b/docker-imposm3/importer.py
@@ -10,6 +10,7 @@ from sys import stderr
# In docker-compose, we should wait the DB is ready.
sleep(30)
+# All these default values can be overwritten by env vars
default = {
'TIME': 120,
'USER': 'docker',
@@ -19,7 +20,7 @@ default = {
'PORT': '5432',
'SETTINGS': 'settings',
'CACHE': 'cache',
- 'BASE_PBF': 'base_pbf',
+ 'OSM_PBF': 'osm_pbf',
'IMPORT_DONE': 'import_done',
'IMPORT_QUEUE': 'import_queue',
'SRID': '4326',
@@ -60,7 +61,7 @@ postgis_uri = 'postgis://%s:%s@%s/%s' % (
default['DATABASE'])
# Check folders.
-folders = ['IMPORT_QUEUE', 'IMPORT_DONE', 'BASE_PBF', 'SETTINGS', 'CACHE']
+folders = ['IMPORT_QUEUE', 'IMPORT_DONE', 'OSM_PBF', 'SETTINGS', 'CACHE']
for folder in folders:
if not isabs(default[folder]):
# Get the absolute path.
@@ -76,19 +77,19 @@ state_file = None
osm_file = None
mapping_file = None
post_import_file = None
-for f in listdir(default['BASE_PBF']):
+for f in listdir(default['OSM_PBF']):
if f.endswith('.state.txt'):
- state_file = join(default['BASE_PBF'], f)
+ state_file = join(default['OSM_PBF'], f)
if f.endswith('.osm.pbf'):
- osm_file = join(default['BASE_PBF'], f)
+ osm_file = join(default['OSM_PBF'], f)
if not osm_file:
- print >> stderr, 'OSM file *.pbf is missing in %s' % default['BASE_PBF']
+ print >> stderr, 'OSM file *.pbf is missing in %s' % default['OSM_PBF']
exit()
if not state_file:
- print >> stderr, 'State file *.state.txt is missing in %s' % default['BASE_PBF']
+ print >> stderr, 'State file *.state.txt is missing in %s' % default['OSM_PBF']
exit()
for f in listdir(default['SETTINGS']):
diff --git a/docker-osm-storage/Dockerfile b/docker-osm-storage/Dockerfile
deleted file mode 100644
index c4f8c76..0000000
--- a/docker-osm-storage/Dockerfile
+++ /dev/null
@@ -1,8 +0,0 @@
-FROM ubuntu:latest
-MAINTAINER Etienne Trimaille
-
-WORKDIR /home
-RUN mkdir settings import_done import_queue base_pbf cache
-VOLUME /home/settings /home/import_done /home/import_queue /home/base_pbf /home/cache
-
-CMD True
\ No newline at end of file
diff --git a/docker-osmupdate/.idea/.name b/docker-osmupdate/.idea/.name
deleted file mode 100644
index 076c77d..0000000
--- a/docker-osmupdate/.idea/.name
+++ /dev/null
@@ -1 +0,0 @@
-docker-osmupdate
\ No newline at end of file
diff --git a/docker-osmupdate/.idea/docker-osmupdate.iml b/docker-osmupdate/.idea/docker-osmupdate.iml
deleted file mode 100644
index 1be76f1..0000000
--- a/docker-osmupdate/.idea/docker-osmupdate.iml
+++ /dev/null
@@ -1,8 +0,0 @@
-
-
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-osmupdate/.idea/encodings.xml b/docker-osmupdate/.idea/encodings.xml
deleted file mode 100644
index d821048..0000000
--- a/docker-osmupdate/.idea/encodings.xml
+++ /dev/null
@@ -1,4 +0,0 @@
-
-
-
-
\ No newline at end of file
diff --git a/docker-osmupdate/.idea/inspectionProfiles/Project_Default.xml b/docker-osmupdate/.idea/inspectionProfiles/Project_Default.xml
deleted file mode 100644
index 86a287d..0000000
--- a/docker-osmupdate/.idea/inspectionProfiles/Project_Default.xml
+++ /dev/null
@@ -1,13 +0,0 @@
-
-
-
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-osmupdate/.idea/inspectionProfiles/profiles_settings.xml b/docker-osmupdate/.idea/inspectionProfiles/profiles_settings.xml
deleted file mode 100644
index 3b31283..0000000
--- a/docker-osmupdate/.idea/inspectionProfiles/profiles_settings.xml
+++ /dev/null
@@ -1,7 +0,0 @@
-
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-osmupdate/.idea/misc.xml b/docker-osmupdate/.idea/misc.xml
deleted file mode 100644
index 7b4d854..0000000
--- a/docker-osmupdate/.idea/misc.xml
+++ /dev/null
@@ -1,4 +0,0 @@
-
-
-
-
\ No newline at end of file
diff --git a/docker-osmupdate/.idea/modules.xml b/docker-osmupdate/.idea/modules.xml
deleted file mode 100644
index b9e5349..0000000
--- a/docker-osmupdate/.idea/modules.xml
+++ /dev/null
@@ -1,8 +0,0 @@
-
-
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-osmupdate/.idea/scopes/scope_settings.xml b/docker-osmupdate/.idea/scopes/scope_settings.xml
deleted file mode 100644
index 922003b..0000000
--- a/docker-osmupdate/.idea/scopes/scope_settings.xml
+++ /dev/null
@@ -1,5 +0,0 @@
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-osmupdate/.idea/vcs.xml b/docker-osmupdate/.idea/vcs.xml
deleted file mode 100644
index 94a25f7..0000000
--- a/docker-osmupdate/.idea/vcs.xml
+++ /dev/null
@@ -1,6 +0,0 @@
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-osmupdate/.idea/workspace.xml b/docker-osmupdate/.idea/workspace.xml
deleted file mode 100644
index c3bb32f..0000000
--- a/docker-osmupdate/.idea/workspace.xml
+++ /dev/null
@@ -1,682 +0,0 @@
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- true
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- true
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- 1437385466775
-
- 1437385466775
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
\ No newline at end of file
diff --git a/docker-osmupdate/readme.md b/docker-osmupdate/readme.md
index 83bb263..34b50c3 100644
--- a/docker-osmupdate/readme.md
+++ b/docker-osmupdate/readme.md
@@ -1,6 +1,27 @@
## Docker OSM Update
-You should have 3 folders : base_pbf, import_queue, import_done
+This docker image when run will fetch on a regular interval any new diff file
+for all the changes that have happened in the world over the update interval.
+
+You can also specify a custom url for fetching the diff if you wish to retrieve
+regional diffs rather than the global one.
+
+You can specify a polygonal area for the diff so that it will only apply features
+from the diff that fall within that area. For example providing a polygon of the
+borders of Malawi will result in only Malawi features being extracted from the diff.
+
+Note that the diff retrieved and options specified here are not related to the
+initial base map used - so for example if your initial base map is for Malawi and
+you specify a diff area in Botswana, updated features in Botswana will be applied
+to your base map which only includes features from Malawi. For this reason, take
+care to ensure that your diff area coincides with the region covered by your
+original base map.
+
+Once the diff has been downloaded, it is placed into /home/import_queue where
+it will be picked up by the long running imposm3 container, which will apply
+the diff to the database.
+
+You should have 3 folders : osm_pbf, import_queue, import_done
Put a state file in base-pbf like this one :
http://download.openstreetmap.fr/extracts/africa/south_africa.state.txt
@@ -16,5 +37,5 @@ With -e, you can add some settings :
- BASE_URL = http://planet.openstreetmap.org/replication/, change the URL to use a custom URL to fetch regional file updates.
- IMPORT_QUEUE = import_queue
- IMPORT_DONE = import_done
- - BASE_PBF = base_pbf
- - TIME = 120, secondes between two executions of the script
\ No newline at end of file
+ - OSM_PBF = osm_pbf
+ - TIME = 120, secondes between two executions of the script
diff --git a/osm_pbf/readme.md b/osm_pbf/readme.md
new file mode 100644
index 0000000..a6eec6f
--- /dev/null
+++ b/osm_pbf/readme.md
@@ -0,0 +1,4 @@
+This folder should contain a *.pbf and *.state.txt.
+
+The first pbf file encoutered will be imported, for this reason we recommend
+to only place one pbf in this folder so you can be sure which will be imported.
diff --git a/readme.md b/readme.md
index 75afebd..24a0260 100644
--- a/readme.md
+++ b/readme.md
@@ -1,7 +1,32 @@
-Copy an OSM file (*.pbf) and its state file(*.state.txt) into base-pbf. The state file contains the timestamp of the OSM file. You can add a [polygon file](http://wiki.openstreetmap.org/wiki/Osmosis/Polygon_Filter_File_Format) for the clipping.
+Copy an OSM file (*.pbf) and its state file(*.state.txt) into base-pbf.
+The state file contains the timestamp of the OSM file. You can add a
+[polygon file](http://wiki.openstreetmap.org/wiki/Osmosis/Polygon_Filter_File_Format)
+for the clipping.
Check that a *.json is present in 'settings' for the mapping.
``docker-compose build``
``docker-compose up``
-You should read the documentation about [docker-imposm](https://github.com/gustry/docker-imposm3) and [docker-osmupdate](https://github.com/Gustry/docker-osmupdate) for settings.
+You should read the documentation about [docker-imposm]
+(https://github.com/gustry/docker-imposm3) and
+[docker-osmupdate](https://github.com/Gustry/docker-osmupdate) for
+settings.
+
+
+# Example usage
+
+In this example we will set up an OSM database for South Africa that
+will poll for updates every hour.
+
+First fetch the latest South Africa osm binary dump file (.pbf) and state file.
+I will write the example as generically as possible so that you can substitute
+your own country or region here.
+
+```
+mkdir osm
+cd osm
+wget -c -O country.pbf http://download.openstreetmap.fr/extracts/africa/south_africa.osm.pbf
+wget -c http://download.openstreetmap.fr/extracts/africa/south_africa.state.txt
+```
+
+
diff --git a/settings/readme.md b/settings/readme.md
index 239b046..92ac40a 100644
--- a/settings/readme.md
+++ b/settings/readme.md
@@ -1 +1,7 @@
-This folder should contain a json file for the mapping. You can also put a SQL file, it will be executed after the PBF import.
\ No newline at end of file
+This folder should contain a json file for the mapping. You can also put a
+SQL file, it will be executed after the PBF import.
+
+Optionally you can include a .poly file (see http://wiki.openstreetmap.org/wiki/Osmosis/Polygon_Filter_File_Format)
+in this directory, which will be used as the clip extents for diffs. The
+base name of the .poly file is not important - the first .poly file encountered
+in this folder will be used.