go-whosonfirst-spatial-http-sqlite

Go package implementing the whosonfirst/go-whosonfirst-spatial-www server application with support for whosonfirst/go-whosonfirst-spatial-sqlite databases.

Documentation

Documentation is incomplete at this time.

Example

package main

import (
	"context"
	_ "github.com/whosonfirst/go-whosonfirst-spatial-sqlite"
	"github.com/whosonfirst/go-whosonfirst-spatial-www/application/server"
	"log"
)

func main() {

	ctx := context.Background()
	logger := log.Default()

	err := server.Run(ctx, logger)

	if err != nil {
		logger.Fatal(err)
	}
}

Importantly this is a very thin wrapper around the application code defined in the whosonfirst/go-whosonfirst-spatial-www package to enable support for the whosonfirst/go-whosonfirst-spatial-sqlite package.

This document does not discuss how the SQLite databases used to perform spatial operations are created. Please consult the documentation in the whosonfirst/go-whosonfirst-spatial-sqlite package for details on creating these databases.

Tools

$> make cli
go build -mod vendor -o bin/server cmd/server/main.go

server

$>> ./bin/server -h
  -authenticator-uri string
    	A valid sfomuseum/go-http-auth URI. (default "null://")
  -cors-allow-credentials
    	Allow HTTP credentials to be included in CORS requests.
  -cors-origin value
    	One or more hosts to allow CORS requests from; may be a comma-separated list.
  -custom-placetypes string
    	A JSON-encoded string containing custom placetypes defined using the syntax described in the whosonfirst/go-whosonfirst-placetypes repository.
  -enable-cors
    	Enable CORS headers for data-related and API handlers.
  -enable-custom-placetypes
    	Enable wof:placetype values that are not explicitly defined in the whosonfirst/go-whosonfirst-placetypes repository.
  -enable-geojson
    	Enable GeoJSON output for point-in-polygon API calls.
  -enable-gzip
    	Enable gzip-encoding for data-related and API handlers.
  -enable-www
    	Enable the interactive /debug endpoint to query points and display results.
  -is-wof
    	Input data is WOF-flavoured GeoJSON. (Pass a value of '0' or 'false' if you need to index non-WOF documents. (default true)
  -iterator-uri string
    	A valid whosonfirst/go-whosonfirst-iterate/v2 URI. Supported schemes are: directory://, featurecollection://, file://, filelist://, geojsonl://, null://, repo://. (default "repo://")
  -leaflet-enable-draw
    	Enable the Leaflet.Draw plugin.
  -leaflet-enable-fullscreen
    	Enable the Leaflet.Fullscreen plugin.
  -leaflet-enable-hash
    	Enable the Leaflet.Hash plugin. (default true)
  -leaflet-initial-latitude float
    	The initial latitude for map views to use. (default 37.616906)
  -leaflet-initial-longitude float
    	The initial longitude for map views to use. (default -122.386665)
  -leaflet-initial-zoom int
    	The initial zoom level for map views to use. (default 14)
  -leaflet-max-bounds string
    	An optional comma-separated bounding box ({MINX},{MINY},{MAXX},{MAXY}) to set the boundary for map views.
  -leaflet-tile-url string
    	A valid Leaflet 'tileLayer' layer URL. Only necessary if -map-provider is "leaflet".
  -log-timings
    	Emit timing metrics to the application's logger
  -map-provider string
    	The name of the map provider to use. Valid options are: leaflet, protomaps, tangram
  -nextzen-apikey string
    	A valid Nextzen API key. Only necessary if -map-provider is "tangram".
  -nextzen-style-url string
    	A valid URL for loading a Tangram.js style bundle. Only necessary if -map-provider is "tangram". (default "/tangram/refill-style.zip")
  -nextzen-tile-url string
    	A valid Nextzen tile URL template for loading map tiles. Only necessary if -map-provider is "tangram". (default "https://tile.nextzen.org/tilezen/vector/v1/512/all/{z}/{x}/{y}.mvt")
  -path-api string
    	The root URL for all API handlers (default "/api")
  -path-data string
    	The URL for data (GeoJSON) handler (default "/data")
  -path-ping string
    	The URL for the ping (health check) handler (default "/health/ping")
  -path-pip string
    	The URL for the point in polygon web handler (default "/point-in-polygon")
  -path-prefix string
    	Prepend this prefix to all assets (but not HTTP handlers). This is mostly for API Gateway integrations.
  -properties-reader-uri string
    	A valid whosonfirst/go-reader.Reader URI. Available options are: [fs:// null:// repo:// sqlite:// stdin://]
  -protomaps-bucket-uri string
    	The gocloud.dev/blob.Bucket URI where Protomaps tiles are stored. Only necessary if -map-provider is "protomaps" and -protomaps-serve-tiles is true.
  -protomaps-caches-size int
    	The size of the internal Protomaps cache if serving tiles locally. Only necessary if -map-provider is "protomaps" and -protomaps-serve-tiles is true. (default 64)
  -protomaps-database string
    	The name of the Protomaps database to serve tiles from. Only necessary if -map-provider is "protomaps" and -protomaps-serve-tiles is true.
  -protomaps-serve-tiles
    	A boolean flag signaling whether to serve Protomaps tiles locally. Only necessary if -map-provider is "protomaps".
  -protomaps-tile-url string
    	A valid Protomaps .pmtiles URL for loading map tiles. Only necessary if -map-provider is "protomaps". (default "/tiles/")
  -server-uri string
    	A valid aaronland/go-http-server URI. (default "http://localhost:8080")
  -spatial-database-uri string
    	A valid whosonfirst/go-whosonfirst-spatial/data.SpatialDatabase URI. options are: [sqlite://]
  -tilezen-enable-tilepack
    	Enable to use of Tilezen MBTiles tilepack for tile-serving. Only necessary if -map-provider is "tangram".
  -tilezen-tilepack-path string
    	The path to the Tilezen MBTiles tilepack to use for serving tiles. Only necessary if -map-provider is "tangram" and -tilezen-enable-tilezen is true.
  -verbose
    	Be chatty.

For example:

$> bin/server \
	-enable-www \
	-map-provider tangram \
	-spatial-database-uri 'sqlite:///?dsn=modernc:///usr/local/data/sfomuseum-data-architecture.db' \
	-nextzen-apikey {NEXTZEN_APIKEY}

A couple things to note:

The SQLite databases specified in the sqlite:///?dsn string are expected to minimally contain the rtree and spr and properties tables confirming to the schemas defined in the go-whosonfirst-sqlite-features. They are typically produced by the go-whosonfirst-sqlite-features-index package. See the documentation in the go-whosonfirst-spatial-sqlite package for details.

When you visit http://localhost:8080 in your web browser you should see something like this:

If you don't need, or want, to expose a user-facing interface simply remove the -enable-www and -nextzen-apikey flags. For example:

$> bin/server \
	-spatial-database-uri 'sqlite:///?dsn=modernc:///usr/local/data/sfomuseum-data-architecture.db'

And then to query the point-in-polygon API you would do something like this:

$> curl -X POST -s 'http://localhost:8080/api/point-in-polygon' -d '{"latitude":37.61701894316063, "longitude":-122.3866653442383}'

{
  "places": [
    {
      "wof:id": 1360665043,
      "wof:parent_id": -1,
      "wof:name": "Central Parking Garage",
      "wof:placetype": "wing",
      "wof:country": "US",
      "wof:repo": "sfomuseum-data-architecture",
      "wof:path": "136/066/504/3/1360665043.geojson",
      "wof:superseded_by": [],
      "wof:supersedes": [
        1360665035
      ],
      "mz:uri": "https://data.whosonfirst.org/136/066/504/3/1360665043.geojson",
      "mz:latitude": 37.616332,
      "mz:longitude": -122.386047,
      "mz:min_latitude": 37.61498599208708,
      "mz:min_longitude": -122.38779093748578,
      "mz:max_latitude": 37.61767331604971,
      "mz:max_longitude": -122.38429192207244,
      "mz:is_current": 0,
      "mz:is_ceased": 1,
      "mz:is_deprecated": 0,
      "mz:is_superseded": 0,
      "mz:is_superseding": 1,
      "wof:lastmodified": 1547232156
    }
    ... and so on
}

By default, results are returned as a list of "standard places response" (SPR) elements. You can also return results as a GeoJSON FeatureCollection by passing the -enable-geojson flag to the server and including a format=geojson query parameter with requests. For example:

$> bin/server \
	-enable-geojson \
	-spatial-database-uri 'sqlite:///?dsn=modernc:///usr/local/data/sfomuseum-data-architecture.db'

And then:

$> curl -s -XPOST -H 'Accept: application/geo+json' 'http://localhost:8080/api/point-in-polygon' -d '{"latitude":37.61701894316063,"longitude":-122.3866653442383 }'

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "MultiPolygon",
        "coordinates": [ ...omitted for the sake of brevity ]
      },
      "properties": {
        "mz:is_ceased": 1,
        "mz:is_current": 0,
        "mz:is_deprecated": 0,
        "mz:is_superseded": 0,
        "mz:is_superseding": 1,
        "mz:latitude": 37.616332,
        "mz:longitude": -122.386047,
        "mz:max_latitude": 37.61767331604971,
        "mz:max_longitude": -122.38429192207244,
        "mz:min_latitude": 37.61498599208708,
        "mz:min_longitude": -122.38779093748578,
        "mz:uri": "https://data.whosonfirst.org/136/066/504/3/1360665043.geojson",
        "wof:country": "US",
        "wof:id": 1360665043,
        "wof:lastmodified": 1547232156,
        "wof:name": "Central Parking Garage",
        "wof:parent_id": -1,
        "wof:path": "136/066/504/3/1360665043.geojson",
        "wof:placetype": "wing",
        "wof:repo": "sfomuseum-data-architecture",
        "wof:superseded_by": [],
        "wof:supersedes": [
          1360665035
        ]
      }
    }
    ... and so on
  ]
}

Docker

The easiest thing is to run the docker Makefile target passing in the path to the database you want to bundle and the name of the container you want to produce.

For example:

$> make docker DATABASE=/usr/local/data/sfomuseum-architecture.db CONTAINER=spatial-sfomuseum-architecture
cp /usr/local/data/sfomuseum-architecture.db whosonfirst.db
docker build -f Dockerfile -t spatial-sfomuseum-architecture .

...docker stuff happens...

writing image sha256:4227f2761a2a4c1045554bb00d7bb32236bab086ac561c5faa88a143962e338f
naming to docker.io/library/spatial-sfomuseum-architecture

AWS

Lambda

It is possible to deploy the server tool as a "containerized Lambda function". The first thing you'll need to do is create the container (see above in the Docker section). After that you'll need to upload your container to your AWS ECS repository, the details of which are out of scope for this document.

Note: It is also possible to run the server tool as a plain-vanilla Lambda function with an EFS volume attached to it but that's even more complicated than the Docker/ECS scenario so that is also "out of scope" for the document. But it is possible (I've done it).

Next create a new Lambda function. For the sake of this example we'll call it SpatialArchitecture (to match the spatial-sfomuseum-architecture created above), choosing the "Container image" option. Associate the function with the container you've created and uploaded to your ECS account.

In the "Image configuration" section you'll need to assign the following variables:

Name	Value	Notes
CMD override	/main

In the "configuration" section you'll need to assign the following variables in the "Environment variables" sub-menu:

Name	Value	Notes
WHOSONFIRST_ENABLE_WWW	`true`
WHOSONFIRST_ENABLE_CORS	true
WHOSONFIRST_CORS_ORIGIN	*	Or configure to taste.
WHOSONFIRST_MAP_PROVIDER	string	`leaflet` It is not possible (yet) to use Tangram.js for rendering map tiles when the `server` tool is deployed as a Lambda function.
WHOSONFIRST_LEAFLET_TILE_URL	string	A valid slippy-tile URL that Leaflet can use for displaying map tiles.
WHOSONFIRST_PATH_PREFIX	string	This should match the name of API Gateway deployment "stage" (discussed below) you associate with your Lambda function.
WHOSONFIRST_SERVER_URI	`lambda://`
WHOSONFIRST_SPATIAL_DATABASE_URI	`sqlite://?dsn=modernc:///usr/local/data/whosonfirst.db`

You can also specify any of the other flags that the server tool accepts. The rules for assigning a command line flag as a environment variable are:

Replace all - characters with _ characters.
Prepend the string whosonfirst_ to the variable name.
Upper-case the new string. For example the -leaflet-initial-zoom becomes WHOSONFIRST_LEAFLET_INITIAL_ZOOM.

In the "Generation configuration" sub-menu change the default timeout to something between 10-30 seconds (or more) depending on your specific use case.

That should be all you need to do. You can test the set up by running the function and passing an empty message ({}). Nothing will happen but the function will exit without any errors.

API Gateway

Create a new "REST" API. For the sake of this example we'll call it Architecture (to match the container and Lambda function described above).

Create a new "Resource" and configure it "as proxy resource".
Delete the ANY method that will be automatically associated with the newly created resource (it will be labeled {proxy+}.
Create a new GET on the resource and set the "Integration type" to be Lambda Function and associate the Lambda function you've just created above with the resource.
Create a new POST on the resource and set the "Integration type" to be Lambda Function and associate the Lambda function you've just created above with the resource.
Create a new GET method on the root / resource. Configure the "Integration type" to be a "Lambda function" and check the "Use Lambda Proxy integration" button. Associate the Lambda function you've just created above with the resource.
One the method is created click the "Method response" tab and add a new "Response Body" for HTTP 200 status response. The "Content type" should be text/html and the "Model" should be Empty.
Create a new "Deployment stage". For the sake of this example we'll call it architecture to match the WHOSONFIRST_PATH_PREFIX environment variable in the Lambda function, described above.
Deploy the API.

Once deployed the server tool will be available at a URL like {PREFIX}.execute-api.us-east-1.amazonaws.com/architecture. For example:

https://{PREFIX}.execute-api.us-east-1.amazonaws.com/architecture/
https://{PREFIX}.execute-api.us-east-1.amazonaws.com/architecture/point-in-polygon/

# README