postgis

PostGIS

The PostGIS provider manages querying for tile requests against a Postgres database (version 12+) with the PostGIS(version 3.0+) extension installed. The connection between tegola and Postgis is configured in a tegola.toml file. An example minimum connection config:

[[mvt_providers]]
name = "test_postgis"       # provider name is referenced from map layers (required)
type = "postgis"            # the type of data provider must be "postgis" for this data provider (required)
host = "localhost"          # PostGIS database host (required)
port = 5432                 # PostGIS database port (required)
database = "tegola"         # PostGIS database name (required)
user = "tegola"             # PostGIS database user (required)
password = ""               # PostGIS database password (required)

Connection Properties

• name (string): [Required] provider name is referenced from map layers. please note that when referencing an mvt_provider form a map layer the provider name must be prexied with mvt_. See example config below.
• type (string): [Required] the type of data provider. must be "postgis" to use this data provider
• host (string): [Required] PostGIS database host
• port (int): [Required] PostGIS database port (required)
• database (string): [Required] PostGIS database name
• user (string): [Required] PostGIS database user
• password (string): [Required] PostGIS database password
• srid (int): [Optional] The default SRID for the provider. Defaults to WebMercator (3857) but also supports WGS84 (4326)
• max_connections (int): [Optional] The max connections to maintain in the connection pool. Defaults to 100. 0 means no max.

Provider Layers

In addition to the connection configuration above, Provider Layers need to be configured. A Provider Layer tells tegola how to query PostGIS for a certain layer. An example minimum config:

[[mvt_providers.layers]]
name = "landuse"
# this table uses "geom" for the geometry_fieldname and "gid" for the id_fieldname so they don't need to be configured
sql = "SELECT ST_AsMVTGeom(geom,!BBOX!) AS geom, gid FROM gis.landuse WHERE geom && !BBOX!"

Provider Layers Properties

• name (string): [Required] the name of the layer. This is used to reference this layer from map layers.
• geometry_fieldname (string): [Optional] the name of the filed which contains the geometry for the feature. defaults to geom.
• id_fieldname (string): [Optional] the name of the feature id field. defaults to gid.
• srid (int): [Optional] the SRID of the layer. Supports 3857 (WebMercator) or 4326 (WGS84).
• geometry_type (string): [Optional] the layer geometry type. If not set, the table will be inspected at startup to try and infer the gemetry type. Valid values are: Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, GeometryCollection.
• sql (string): [Required] custom SQL to use use. Supports the following tokens:
  • !BBOX! - [Required] will be replaced with the bounding box of the tile before the query is sent to the database. !bbox! and!BOX! are supported as well for compatibilitiy with queries from Mapnik and MapServer styles.
  • !X! - [Optional] will replaced with the "X" value of the requested tile.
  • !Y! - [Optional] will replaced with the "Y" value of the requested tile.
  • !Z! - [Optional] will replaced with the "Z" value of the requested tile.
  • !ZOOM! - [Optional] will be replaced with the "Z" (zoom) value of the requested tile.
  • !SCALE_DENOMINATOR! - [Optional] scale denominator, assuming 90.7 DPI (i.e. 0.28mm pixel size)
  • !PIXEL_WIDTH! - [Optional] the pixel width in meters, assuming 256x256 tiles
  • !PIXEL_HEIGHT! - [Optional] the pixel height in meters, assuming 256x256 tiles
  • !ID_FIELD! - [Optional] the id field name
  • !GEOM_FIELD! - [Optional] the geom field name
  • !GEOM_TYPE! - [Optional] the geom type if defined otherwise ""

Example mvt_provider and map config

When referencing the provider in the map section, one must prepend mvt_ to the name.

Example:

[[mvt_providers]]
name = "test_postgis"       
type = "postgis"            
host = "localhost"          
port = 5432                 
database = "tegola"         
user = "tegola"             
password = ""

  [[mvt_providers.layers]]
  name = "landuse"
  sql = "SELECT ST_AsMVTGeom(geom,!BBOX!) AS geom, gid FROM gis.landuse WHERE geom && !BBOX!"

[[maps]]
name = "cities"
center = [-90.2,38.6,3.0]  # where to center of the map (lon, lat, zoom)

    [[maps.layers]]
    name = "landuse"
    # note the mvt_ prefix on the name of the provider.
    provider_layer = "mvt_test_postgis.landuse" 
    min_zoom = 0
    max_zoom = 14

Note test_postgis is refered to as mvt_test_postgis

Environment Variable support

Helpful debugging environment variables:

• TEGOLA_SQL_DEBUG: specify the type of SQL debug information to output. Supports the following values:
  • LAYER_SQL: print layer SQL as they’re parsed from the config file.
  • EXECUTE_SQL: print SQL that is executed for each tile request and the number of items it returns or an error.
  • LAYER_SQL:EXECUTE_SQL: print LAYER_SQL and EXECUTE_SQL.

Example:

$ TEGOLA_SQL_DEBUG=LAYER_SQL tegola serve --config=/path/to/conf.toml

Testing

Testing is designed to work against a live PostGIS database. To see how to set up a database check this ci script. To run the PostGIS tests, the following environment variables need to be set:

$ export RUN_POSTGIS_TESTS=yes
$ export PGHOST="localhost"
$ export PGPORT=5432
$ export PGDATABASE="tegola"
$ export PGUSER="postgres"
$ export PGUSER_NO_ACCESS="tegola_no_access" # used for testing errors when user does not have read permissions on a table
$ export PGPASSWORD=""
$ export PGSSLMODE="disable"

If you're testing SSL, the following additional env vars can be set:

$ export PGSSLMODE="" // disable, allow, prefer, require, verify-ca, verify-full
$ export PGSSLKEY=""
$ export PGSSLCERT=""
$ export PGSSLROOTCERT=""