@wikimedia/geojson-mapnikify/lib/template.xml

transform geojson with simplestyle-spec into mapnik xml

<Map srs="+init=epsg:3857">
    <Style name="geoms">
        <Rule>
            <Filter>[mapnik::geometry_type]=polygon or [fill]</Filter>
            <PolygonSymbolizer fill="[fill]" fill-opacity="[fill-opacity]" />
        </Rule>
        <Rule>
            <Filter>[mapnik::geometry_type]=linestring or [stroke]</Filter>
            <LineSymbolizer stroke="[stroke]" stroke-width="[stroke-width]" stroke-opacity="[stroke-opacity]" />
        </Rule>
    </Style>
    <Style name="points" filter-mode="first">
        <Rule>
            <Filter>[mapnik::geometry_type]=point and [marker-path]</Filter>
            <PointSymbolizer
              file="[marker-path]"
              allow-overlap="true"
              ignore-placement="true"
            />
        </Rule>
    </Style>
    <Layer name="layer" srs="+init=epsg:4326">
        <StyleName>geoms</StyleName>
        <StyleName>points</StyleName>
        <Datasource>
            <Parameter name="type">geojson</Parameter>
            <Parameter name="inline"><![CDATA[{{geojson}}]]></Parameter>
        </Datasource>
    </Layer>
</Map>