gounux/pg_featureserv

Lightweight RESTful Geospatial Feature Server for PostGIS in Go

pg_featureserv

A lightweight RESTful geospatial feature server for PostGIS, written in Go. It supports the OGC API - Features REST API standard.

See also our companion project pg_tileserv.

Features

• Implements the OGC API - Features standard.
  • Standard query parameters: limit, bbox, bbox-crs, property filtering, sortby, crs
  • Query parameters filter and filter-crs allow CQL filtering, with spatial support
  • Extended query parameters: offset, properties, transform, precision, groupby
• Data responses are formatted in JSON and GeoJSON
• Provides a simple HTML user interface, with web maps to view spatial data
• Uses the power of PostgreSQL to reduce the amount of code and to make data definition easy and familiar.
  • Feature collections are defined by database objects (tables and views)
  • Filters are executed in the database, and use indexes where defined
• Uses PostGIS to provide geospatial functionality:
  • Spatial filtering
  • Transforming geometry data into the output coordinate system
  • Marshalling feature data into GeoJSON
• Full-featured HTTP support
  • CORS support with configurable Allowed Origins
  • GZIP response encoding
  • HTTP and HTTPS support

For a full list of software capabilities see FEATURES.

Documentation

• User Guide
• FEATURES - full list of software capabilities
• API - summary of the web service API

Relevant Standards

• OGC API - Features - Part 1: Core
• OGC API - Features - Part 2: Coordinate Reference Systems by Reference
• DRAFT OGC API - Features - Part 3: Filtering
• DRAFT Common Query Language (CQL2)
• GeoJSON

Download

Builds of the latest code:

• Linux
• Windows
• MacOS
• Docker

Build from Source

pg_featureserv is developed under Go 1.13. It may also work with earlier versions.

• Ensure the Go compiler is installed
• Download or clone this repository into $GOPATH/src/github.com/CrunchyData/pg_featureserv
• To build the executable, run the following commands:

cd $GOPATH/src/github.com/CrunchyData/pg_featureserv/
go build

• This creates a pg_featureserv executable in the application directory
• (Optional) Run the unit tests using go test ./...

Build a Docker image

• Build the pg_featureserv executable with the command:

CGO_ENABLED=0 go build

to avoid the runtime error /lib64/libc.so.6: version 'GLIBC_2.XX' not found (required by ./pg_featureserv).

• In the $GOPATH/src/github.com/CrunchyData/pg_featureserv/ directory, build the Docker image with:

docker build -f container/Dockerfile --build-arg VERSION=<VERSION> -t crunchydata/pg_featureserv:<VERSION> ./

Replace version <VERSION> with the pg_featureserv version you are building against.

Configure the service

The configuration file is automatically read from the following locations, if it exists:

• In the system configuration directory, at /etc/pg_featureserv.toml
• Relative to the directory from which the program is run, ./config/pg_featureserv.toml
• In a root volume at /config/pg_featureserv.toml

To specify a configuration file directly use the --config commandline parameter. In this case configuration files in other locations are ignored.

Configuration Using Environment Variables

To set the database connection the environment variable DATABASE_URL can be used with a Postgres connection string:

export DATABASE_URL="host=localhost user=postgres"

Other parameters in the configuration file can be over-ridden in the environment. Prepend the upper-cased parameter name with PGFS_section_ to set the value. For example, to change the HTTP port and service title:

export PGFS_SERVER_HTTPPORT=8889
export PGFS_METADATA_TITLE="My PGFS"

SSL

For SSL support, a server private key and an authority certificate are needed. For testing purposes you can generate a self-signed key/cert pair using openssl:

openssl req  -nodes -new -x509  -keyout server.key -out server.crt

These are set in the configuration file:

TlsServerCertificateFile = "/path/server.crt"
TlsServerPrivateKeyFile = "/path/server.key"

Run the service

• Change to the application directory:
  • cd $GOPATH/src/github.com/CrunchyData/pg_featureserv
• Start the server:
  • ./pg_featureserv
• Open the service home page in a browser:
  • http:/localhost:9000/home.html

Command-line options

• -? - show command usage
• --config file.toml - specify configuration file to use
• --debug - set logging level to TRACE (can also be set in config file)
• --devel - run in development mode (e.g. HTML templates reloaded every query)
• --test - run in test mode, with an internal catalog of tables and data
• --version - display the version number

Troubleshooting

To get detailed information about service operation run with the --debug commandline parameter.

./pg_featureserv --debug

Debugging can also be enabled via the configuration file (Server.Debug=true), or in the environment:

export PGFS_SERVER_DEBUG=true

Requests Overview

Features are identified by a collection name and feature id pair.

The default response is in JSON/GeoJSON format. Append .html to the request path to see the UI page for the resource. In a web browser, to request a JSON response append .json to the path (which overrides the browser Accept header).

The example requests assume that the service is running locally and configured to listen on port 9000.

• Landing page (HTML or JSON): http://localhost:9000/
• Landing page (HTML): http://localhost:9000/index,html
• Landing page (JSON): http://localhost:9000/index.json
• OpenAPI definition: http://localhost:9000/api
• OpenAPI test UI: http://localhost:9000/api.html
• Conformance: http://localhost:9000/conformance
• Collections: http://localhost:9000/collections
• Collections UI: http://localhost:9000/collections.html
• Feature collection metadata: http://localhost:9000/collections/{name}
• Feature collection UI: http://localhost:9000/collections/{name}.html
• Features from a single feature collection: http://localhost:9000/collections/{name}/items
• Features from a single feature collection (Map UI): http://localhost:9000/collections/{name}/items.html
• Single feature from a feature collection: http://localhost:9000/collections/{name}/items/{featureid}
• Functions (JSON): http://localhost:9000/functions
• Functions UI: http://localhost:9000/functions.html
• Function metadata: http://localhost:9000/functions/{name}
• Function UI: http://localhost:9000/functions/{name}.html
• Features from a function (JSON): http://localhost:9000/functions/{name}/items
• Features from a function (Map UI): http://localhost:9000/functions/{name}/items.html

See API Summary for a summary of the web service API.