Windshaft map tiler

A Node.js based webmercator map tile server for PostGIS with Carto map styling API.

• Pluggable routing to provide customizable tile API URL endpoints
• Before and after filters to allow custom access control and caching strategies
• Can render arbitrary SQL queries
• Generates image and UTFGrid interactivity tiles
• Accepts, stores, serves, and applies map styles written in the Carto markup language (same markup as Mapbox Tilemill)
• Accepts custom map styles on a per tile basis in the tile request
• Allows setting of CORS headers to allow access to tile data from Javascript

![Puma Concolor by @eightysteele] ( http://github.com/Vizzuality/Windshaft/raw/master/examples/puma_concolor.png )

Being a dynamic map renderer, windshaft commits some map server 'sins' in its raw form. The idea is that you the developer will want to graft your own auth/metrics/caching/scaling on top of decent core components. Same old story: high cohesion, low coupling makes us happy.

Windshaft is a library used by cartodb.com, an Open Source Geospatial Database on the Cloud.

Dependencies

• Node 0.6+ & npm 1.1.2+ (for shrinkwrap support)
• Mapnik 2.0.1, 2.0.2 or 2.1.0 (http://github.com/mapnik/mapnik-reference)
• PostgreSQL >8.3.x, PostGIS >1.5.x
• Redis >2.2.x

Install

npm install

Usage

var Windshaft = require('windshaft');

// Configure pluggable URLs
// =========================
// The config object must define grainstore config (generally just
// postgres connection details), redis config, a base url and a function
// that adds 'dbname' and 'table' variables onto the Express.js req.params
// object.  In this example, the base URL is such that dbname and table will
// automatically be added to the req.params object by express.js. req2params
// can be extended to allow full control over the specifying of dbname and
// table, and also allows for the req.params object to be extended with
// other variables, such as:
//
// * sql - custom sql query to narrow results shown in map)
// * geom_type - specify the geom type (point|polygon) to get more
//               appropriate default styles
// * cache_buster - forces the creation of a new render object, nullifying
//                  existing metatile caches
// * interactivity - specify the column to use in the UTFGrid
//                   interactivity layer (defaults to null)
// * style - specify map style in the Carto map language on a per tile basis
//
// the base url is also used for persisiting and retrieving map styles via:
//
// GET  base_url + '/style' (returns a map style)
// POST base_url + '/style' (allows specifying of a style in Carto markup
//                           in the 'style' form variable).
//
// beforeTileRender and afterTileRender could be defined if you want yo
// implement your own tile cache policy. See an example below

var config = {
        base_url: '/database/:dbname/table/:table',
        req2params: function(req, callback){
          callback(null,req)
        },
        grainstore: {
          datasource: {
            user:'postgres', host: '127.0.0.1',
        		port: 5432
          }
        }, //see grainstore npm for other options
        renderCache: {
          ttl: 60000, // seconds
        },
        mapnik: {
          metatile: 4,
          bufferSize:64
        },
        redis: {host: '127.0.0.1', port: 6379},
        // this two filters are optional
        beforeTileRender: function(req, res, callback) {
            callback(null);
        },
        afterTileRender: function(req, res, tile, headers, callback) {
            callback(null, tile, headers);
        }
    };

// Initialize tile server on port 4000
var ws = new Windshaft.Server(config);
ws.listen(4000);
console.log("map tiles are now being served out of: http://localhost:4000"
            + config.base_url + '/:z/:x/:y.*');

// Specify .png, .png8 or .grid.json tiles.

See examples directory for running server and maptile viewer

Installing Mapnik

Source https://github.com/mapnik/mapnik/downloads

OSX

http://trac.mapnik.org/wiki/MacInstallation/Homebrew

Linux

There should be .deb packages out there with stable 2.0.0 packages right now. Search fro libmapnik2-dev

Tests

Windshaft has a unit and acceptance test suite. To execute them, run make check.

Troubleshooting

Postgres errors persist after configuration change

If you're seeing Postgres errors that you can't dispel through changes in your Windshaft config (e.g. ERROR: column "the_geom_webmercator" does not exist), try redis-cli flushall. Windshaft caches MML files in Redis than can contain SQL and may not expire them when you change your Windshaft config, but manually flushing redis should do the trick.

-- Thanks to the Mapnik and Mapbox team for making such flexible tools