tegola

README

Tegola

Tegola is a vector tile server delivering Mapbox Vector Tiles leveraging PostGIS as the data provider.

Features

• Native geometry processing (simplification, clipping, make valid, intersection, contains, scaling, translation)
• Mapbox Vector Tile v2 specification compliant.
• Embedded viewer with auto generated style for quick data visualization and inspection.
• Support for PostGIS as a data provider. Extensible to support additional data providers.
• Local filesystem caching. Extensible design to support additional cache backends.
• Cache seeding to fill the cache prior to web requests.
• Parallelized tile serving and geometry processing.
• Support for Web Mercator (3857) and WGS84 (4326) projections.

Usage

tegola is a vector tile server
Version: v0.6.0 

Usage:
  tegola [command]

Available Commands:
  cache       Manipulate the tile cache
  help        Help about any command
  serve       Use tegola as a tile server
  version     Print the version number of tegola

Flags:
      --config string   path to config file (default "config.toml")
  -h, --help            help for tegola

Use "tegola [command] --help" for more information about a command.

Running tegola as a vector tile server

1. Download the appropriate binary of tegola for your platform via the release page.
2. After the download you will need to make the binary executable. The binary, will be name tegola_$OS_$ARCH, to follow along with the instructions make sure to rename it to tegola.
3. Setup your config file and run. Tegola expects a config.toml to be in the same directory as the binary. You can set a different location for the config.toml using a command flag:

./tegola serve --config=/path/to/config.toml

Server Endpoints

/

The server root will display a built in viewer with an auto generated style. For example:

/maps/:map_name/:z/:x/:y

Return vector tiles for a map. The URI supports the following variables:

• :map_name is the name of the map as defined in the config.toml file.
• :z is the zoom level of the map.
• :x is the row of the tile at the zoom level.
• :y is the column of the tile at the zoom level.

/maps/:map_name/:layer_name/:z/:x/:y

Return vector tiles for a map layer. The URI supports the same variables as the map URI with the additional variable:

• :layer_name is the name of the map layer as defined in the config.toml file.

/capabilities

Return a JSON encoded list of the server's configured maps and layers with various attributes.

/capabilities/:map_name

Return TileJSON details about the map.

/capabilities/:map_name/style.json

Return an auto generated Mapbox GL Style for the configured map.

Configuration

The tegola config file uses the TOML format. The following example shows how to configure a PostGIS data provider with two layers. The first layer includes a tablename, geometry_field and an id_field. The second layer uses a custom sql statement instead of the tablename property.

Under the maps section, map layers are associated with data provider layers and their min_zoom and max_zoom values are defined. Optionally, default_tags can be setup which will be encoded into the layer. If the same tags are returned from a data provider, the data provider's values will take precedence.

[webserver]
port = ":9090"              # port to bind the web server to. defaults ":8080"

[cache]                     # configure a tile cache
type = "file"               # a file cache will cache to the local file system
basepath = "/tmp/tegola"    # where to write the file cache

# register data providers
[[providers]]
name = "test_postgis"       # provider name is referenced from map layers (required)
type = "postgis"            # the type of data provider. currently only supports postgis (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)
srid = 3857                 # The default srid for this provider. Defaults to WebMercator (3857) (optional)
max_connections = 50        # The max connections to maintain in the connection pool. Default is 100. (optional)

	[[providers.layers]]
	name = "landuse"                    # will be encoded as the layer name in the tile
	tablename = "gis.zoning_base_3857"  # sql or table_name are required
	geometry_fieldname = "geom"         # geom field. default is geom
	id_fieldname = "gid"                # geom id field. default is gid
	srid = 4326                         # the srid of table's geo data. Defaults to WebMercator (3857)

	[[providers.layers]]
	name = "roads"                      # will be encoded as the layer name in the tile
	tablename = "gis.zoning_base_3857"  # sql or table_name are required
	geometry_fieldname = "geom"         # geom field. default is geom
	id_fieldname = "gid"                # geom id field. default is gid
	fields = [ "class", "name" ]        # Additional fields to include in the select statement.

	[[providers.layers]]
	name = "rivers"                     # will be encoded as the layer name in the tile
	geometry_fieldname = "geom"         # geom field. default is geom
	id_fieldname = "gid"                # geom id field. default is gid
	# Custom sql to be used for this layer. Note: that the geometery field is wraped
	# in a ST_AsBinary() and the use of the !BBOX! token
	sql = "SELECT gid, ST_AsBinary(geom) AS geom FROM gis.rivers WHERE geom && !BBOX!"

# maps are made up of layers
[[maps]]
name = "zoning"                              # used in the URL to reference this map (/maps/:map_name)

	[[maps.layers]]
	name = "landuse"                         # name is optional. If it's not defined the name of the ProviderLayer will be used.
	                                         # It can also be used to group multiple ProviderLayers under the same namespace.
	provider_layer = "test_postgis.landuse"  # must match a data provider layer
	min_zoom = 12                            # minimum zoom level to include this layer
	max_zoom = 16                            # maximum zoom level to include this layer

		[maps.layers.default_tags]           # table of default tags to encode in the tile. SQL statements will override
		class = "park"

	[[maps.layers]]
	name = "rivers"                          # name is optional. If it's not defined the name of the ProviderLayer will be used.
	                                         # It can also be used to group multiple ProviderLayers under the same namespace.
	provider_layer = "test_postgis.rivers"   # must match a data provider layer
	dont_simplify = true                     # optionally, turn off simplification for this layer. Default is false.
	min_zoom = 10                            # minimum zoom level to include this layer
	max_zoom = 18                            # maximum zoom level to include this layer

Supported PostGIS SQL tokens

The following tokens are supported in custom SQL queries for the PostGIS data provider:

• !BBOX! - [required] Will convert the z/x/y values into a bounding box to query the feature table with.
• !ZOOM! - [optional] Pass in the zoom value for the request. Useful for filtering feature results by zoom.

Environment Variables

The following environment variables can be used for debugging:

SQL_DEBUG specify the type of SQL debug information to output. Currently support two values:

• LAYER_SQL: print layer SQL as they are 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.

Usage

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

The following environment variables can be use to control various runtime options:

TEGOLA_OPTIONS specify a set of options comma (or space) seperated options.

• DontSimplifyGeo to turn off simplification for all layers.
• SimplifyMaxZoom={{int}} to set the max zoom that simplification will apply to. (14 is default)

Client side debugging

When debugging client side, it's often helpful to to see an outline of a tile along with it's Z/X/Y values. To encode a debug layer into every tile add the query string variable debug=true to the URL template being used to request tiles. For example:

http://localhost:8080/maps/mymap/{z}/{x}/{y}.vector.pbf?debug=true

The requested tile will be encode a layer with the name value set to debug and include two features:

• debug_outline: a line feature that traces the border of the tile
• debug_text: a point feature in the middle of the tile with the following tags:
  • zxy: a string with the Z, X and Y values formatted as: Z:0, X:0, Y:0

Building from source

Tegola is written in Go and requires Go 1.8+ to compile from source. To build tegola from source, make sure you have Go installed and have cloned the repository to your $GOPATH. Navigate to the repository then run the following commands:

cd cmd/tegola/
go build

You will now have a binary named tegola in the current directory which is ready for running.

Build Flags The following build flags can be used to turn off certain features of tegola:

• noS3Cache - turn off the AWS S3 cache back end.
• noRedisCache - turn off the Redis cache back end.
• noPostgisProvider - turn off the PostGIS data provider.
• noGpkgProvider - turn off the GeoPackage data provider. Note, GeoPackage uses CGO and will be turned off if the environment variable CGO_ENABLED=0 is set prior to building.
• noViewer - turn off the built in viewer.

Example of using the build flags to turn of the Redis cache back end, the GeoPackage provider and the built in viewer.

go build -tags 'noRedisCache noGpkgProvider noViewer'

Turning off CGO Tegola uses CGO for certain functionality (i.e. GeoPackge support). To build tegola without CGO use the following command:

CGO_ENABLED=0 go build

License

See license file in repo.

Documentation

Overview

Package tegola describes the basic geometeries that can be used to convert to and from.

Index

• Constants
• Variables
• func GeometeryDecorator(g Geometry, ptsPerLine int, comment string, ptDecorator func(pt Point) string) string
• func GeometryAsJSON(g Geometry, w io.Writer) error
• func GeometryAsMap(g Geometry) map[string]interface{}
• func GeometryAsString(g Geometry) string
• func IsCollectionEqual(c1, c2 Collection) bool
• func IsGeometryEqual(g1, g2 Geometry) bool
• func IsLineStringEqual(l1, l2 LineString) bool
• func IsMultiLineEqual(ml1, ml2 MultiLine) bool
• func IsMultiPointEqual(mp1, mp2 MultiPoint) bool
• func IsMultiPolygonEqual(mp1, mp2 MultiPolygon) bool
• func IsPoint3Equal(p1, p2 Point3) bool
• func IsPointEqual(p1, p2 Point) bool
• func IsPolygonEqual(p1, p2 Polygon) bool
• func LineAsPointPairs(l LineString) (pp []float64)
• type BoundingBox
• type Collection
• type Geometry
• type LineString
• type MultiLine
• type MultiPoint
• type MultiPolygon
• type Point
• type Point3
• type Polygon
• type Tile
  • func NewTile(z, x, y int) (t *Tile)
  • func NewTileLatLong(z int, lat, lon float64) (t *Tile)
  • func (t *Tile) BoundingBox() BoundingBox
  • func (t *Tile) BufferedBoundingBox() (BoundingBox, error)
  • func (t *Tile) Deg2Num() (x, y int)
  • func (t *Tile) FromPixel(srid int, pt [2]float64) (npt [2]float64, err error)
  • func (t *Tile) Init()
  • func (t *Tile) Num2Deg() (lat, lng float64)
  • func (t *Tile) PixelBounds() (bounds [2][2]float64, err error)
  • func (t *Tile) PixelBufferedBounds() (bounds [2][2]float64, err error)
  • func (t *Tile) ToPixel(srid int, pt [2]float64) (npt [2]float64, err error)
  • func (t *Tile) ZEpislon() float64
  • func (t *Tile) ZLevel() int
  • func (t *Tile) ZRes() float64

Constants

const (
	WebMercator = 3857
	WGS84       = 4326
)

const (
	DefaultEpislon    = 10.0
	DefaultExtent     = 4096
	DefaultTileBuffer = 64.0
	MaxZ              = 22
)

Variables

var (
	WebMercatorBounds = [4]float64{-20026376.39, -20048966.10, 20026376.39, 20048966.10}
	WGS84Bounds       = [4]float64{-180.0, -85.0511, 180.0, 85.0511}
)

var UnknownConversionError = fmt.Errorf("do not know how to convert value to requested value")

Functions

func GeometeryDecorator

func GeometeryDecorator(g Geometry, ptsPerLine int, comment string, ptDecorator func(pt Point) string) string

func GeometryAsJSON

func GeometryAsJSON(g Geometry, w io.Writer) error

func GeometryAsMap

func GeometryAsMap(g Geometry) map[string]interface{}

func GeometryAsString

func GeometryAsString(g Geometry) string

func IsCollectionEqual

func IsCollectionEqual(c1, c2 Collection) bool

CollectionIsEqual will check to see if the provided collections are equal. This function does not check to see if the collections contain any recursive structures, and if there are any recursive structures it will hang. If the collections contains any unknown geometries it will be assumed to not match.

func IsGeometryEqual

func IsGeometryEqual(g1, g2 Geometry) bool

GeometryIsEqual will check to see if the two given geometeries are equal. This function does not check to see if there are any recursive structures if there are any recursive structures it will hang. If the type of the geometry is unknown, it is assumed that it does not match any other geometries.

func IsLineStringEqual

func IsLineStringEqual(l1, l2 LineString) bool

IsLineStringEqual will check to see if the two linesstrings provided are equal.

func IsMultiLineEqual

func IsMultiLineEqual(ml1, ml2 MultiLine) bool

IsMultiLineEqual will check to see if the two Multilines that are provided are equal.

func IsMultiPointEqual

func IsMultiPointEqual(mp1, mp2 MultiPoint) bool

IsMultiPointEqual will check to see if the two provided multipoints are equal

func IsMultiPolygonEqual

func IsMultiPolygonEqual(mp1, mp2 MultiPolygon) bool

MultiPolygonIsEqual will check to see if the two provided multi-polygons are equal.

func IsPoint3Equal

func IsPoint3Equal(p1, p2 Point3) bool

IsPoint3Equal will check to see if the two 3d tegola points are equal.

func IsPointEqual

func IsPointEqual(p1, p2 Point) bool

IsPointEqual will check to see if the two tegola points are equal.

func IsPolygonEqual

func IsPolygonEqual(p1, p2 Polygon) bool

PolygonIsEqual will check to see if the two provided polygons are equal.

func LineAsPointPairs

func LineAsPointPairs(l LineString) (pp []float64)

Types

type BoundingBox

type BoundingBox struct {
	Minx, Miny, Maxx, Maxy float64
	// Epsilon is the tolerance for the simplification function.
	Epsilon float64
	// X,Y,Z are just for debug and display purposes.
	X, Y, Z int
	HasXYZ  bool
}

BoundingBox defines the extent of a tile

type Collection

type Collection interface {
	Geometry
	Geometries() []Geometry
}

Collection is a collections of different geometries.

type Geometry

type Geometry interface{}

Geometry describes a geometry.

type LineString

type LineString interface {
	Geometry
	Subpoints() []Point
}

LineString is a Geometry of a line.

type MultiLine

type MultiLine interface {
	Geometry
	Lines() []LineString
}

MultiLine is a Geometry with multiple individual lines.

type MultiPoint

type MultiPoint interface {
	Geometry
	Points() []Point
}

MultiPoint is a Geometry with multiple individual points.

type MultiPolygon

type MultiPolygon interface {
	Geometry
	Polygons() []Polygon
}

MultiPolygon describes a Geometry multiple intersecting polygons. There should only one exterior polygon, and the rest of the polygons should be interior polygons. The interior polygons will exclude the area from the exterior polygon.

type Point

type Point interface {
	Geometry
	X() float64
	Y() float64
}

Point is how a point should look like.

type Point3

type Point3 interface {
	Point
	Z() float64
}

Point3 is a point with three dimensions; at current is just converted and treated as a point.

type Polygon

type Polygon interface {
	Geometry
	Sublines() []LineString
}

Polygon is a multi-line Geometry where all the lines connect to form an enclose space.

type Tile

type Tile struct {
	Z         int
	X         int
	Y         int
	Lat       float64
	Long      float64
	Tolerance float64
	Extent    float64
	Buffer    float64
	// contains filtered or unexported fields
}

Tile slippy map tilenames

http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames

func NewTile

func NewTile(z, x, y int) (t *Tile)

NewTile will return a non-nil tile object.

func NewTileLatLong

func NewTileLatLong(z int, lat, lon float64) (t *Tile)

NewTileLatLong will return a non-nil tile object.

func (*Tile) BoundingBox

func (t *Tile) BoundingBox() BoundingBox

BoundingBox returns the bound box coordinates for upper left (ulx, uly) and lower right (lrx, lry) in web mercator projection ported from: https://raw.githubusercontent.com/mapbox/postgis-vt-util/master/postgis-vt-util.sql

func (*Tile) BufferedBoundingBox

func (t *Tile) BufferedBoundingBox() (BoundingBox, error)

func (*Tile) Deg2Num

func (t *Tile) Deg2Num() (x, y int)

func (*Tile) FromPixel

func (t *Tile) FromPixel(srid int, pt [2]float64) (npt [2]float64, err error)

func (*Tile) Init

func (t *Tile) Init()

func (*Tile) Num2Deg

func (t *Tile) Num2Deg() (lat, lng float64)

func (*Tile) PixelBounds

func (t *Tile) PixelBounds() (bounds [2][2]float64, err error)

func (*Tile) PixelBufferedBounds

func (t *Tile) PixelBufferedBounds() (bounds [2][2]float64, err error)

func (*Tile) ToPixel

func (t *Tile) ToPixel(srid int, pt [2]float64) (npt [2]float64, err error)

func (*Tile) ZEpislon

func (t *Tile) ZEpislon() float64

This is from Leafty

func (*Tile) ZLevel

func (t *Tile) ZLevel() int

Returns web mercator zoom level

func (*Tile) ZRes

func (t *Tile) ZRes() float64

ZRes takes a web mercator zoom level and returns the pixel resolution for that

scale, assuming 256x256 pixel tiles. Non-integer zoom levels are accepted.
ported from: https://raw.githubusercontent.com/mapbox/postgis-vt-util/master/postgis-vt-util.sql

TODO(gdey): I'm pretty sure we should be using the extent instead of 256 here. But I don't know what the magic number 40075016.6855785 is used for. 40075016.6855785 is close to 2*webmercator.MaxXExtent or 2*webmercator.MaxYExtent 40075016.6855785 is the equator in meters for WGS84 at z=0 256 is the tile width and height.