select st_asgeojson(the_geom) from street_centerline limit 1;

{"type":"MultiLineString","coordinates":[[[-65.591776562805038,41.682190576167052],[-65.591998971284028,41.682082119060382],[-65.592001213509064,41.682081025737766],[-65.593689871787177,41.681257533373952],[-65.595415661879244,41.680415888937219],[-65.595440519465640,41.680403765889309],[-65.595603134242481,41.680324459445771]]]}

ogr2ogr -f GeoJSON out.json
  "PG:host=localhost dbname=gis user=ubuntu password=toomanysecrets"
  -sql "select way,name,amenity from planet_osm_point a where a.amenity is not null"

GRANT SELECT ON geometry_columns to ubuntu;
GRANT SELECT ON geography_columns to ubuntu;
GRANT SELECT ON spatial_ref_sys to ubuntu;

SELECT jsonb_build_object(
    'type',     'FeatureCollection',
    'features', jsonb_agg(feature)
)
FROM (
  SELECT jsonb_build_object(
    'type',       'Feature',
    'id',         gid,
    'geometry',   ST_AsGeoJSON(geom)::jsonb,
    'properties', to_jsonb(row) - 'gid' - 'geom'
  ) AS feature
  FROM (SELECT * FROM input_table) row) features;