Adds extensible possibilities to the API class to support dynamic resources loading and hot-reload logic mechanisms

docs/source/crs.rst

@@ -30,7 +30,7 @@ Metadata
 The conformance class `http://www.opengis.net/spec/ogcapi-features-2/1.0/conf/crs` is present as a `conformsTo` field
 in the root landing page response.
 
-The configured CRSs, or their defaults, `crs` and `storageCRS` and optionally `storageCrsCoordinateEpoch` will be present in the "Describe Collection" response.
+The configured CRSs, or their defaults, `crs` and `storageCrs` and optionally `storageCrsCoordinateEpoch` will be present in the "Describe Collection" response.
 
 Parameters
 ----------
@@ -95,7 +95,7 @@ Suppose an addresses collection with the following CRS support in its collection
     "http://www.opengis.net/def/crs/EPSG/0/28992",
     "http://www.opengis.net/def/crs/OGC/1.3/CRS84"
    ],
-   "storageCRS": "http://www.opengis.net/def/crs/OGC/1.3/CRS84"
+   "storageCrs": "http://www.opengis.net/def/crs/OGC/1.3/CRS84"
 
 
 This allows a `bbox-crs` query using Dutch "RD" coordinates with CRS `http://www.opengis.net/def/crs/EPSG/0/28992` to retrieve

docs/source/data-publishing/ogcapi-features.rst

@@ -538,9 +538,6 @@ PostgreSQL
 
 Must have PostGIS installed.
 
-.. note::
-   Geometry must be using EPSG:4326
-
 .. code-block:: yaml
 
    providers:

docs/source/data-publishing/ogcapi-tiles.rst

@@ -22,6 +22,7 @@ pygeoapi core tile providers are listed below, along with supported features.
    `MVT-elastic`_,✅,✅,✅,❌,❌,✅
    `MVT-proxy`_,❓,❓,❓,❓,❌,✅
    `WMTSFacade`_,✅,❌,✅,✅,✅,❌
+   `MVT-postgresql`_,✅,✅,✅,✅,❌,✅
 
 Below are specific connection examples based on supported providers.
 
@@ -130,6 +131,47 @@ Following code block shows how to configure pygeoapi to read Mapbox vector tiles
              name: pbf
              mimetype: application/vnd.mapbox-vector-tile
 
+MVT-postgresql
+^^^^^^^^^^^^^^
+
+.. note::
+   Requires Python packages sqlalchemy, geoalchemy2 and psycopg2-binary
+
+.. note::
+   Must have PostGIS installed with protobuf-c support 
+
+.. note::
+   Geometry must be using EPSG:4326
+
+This provider gives support to serving tiles generated using `PostgreSQL <https://www.postgresql.org/>`_ with `PostGIS <https://postgis.net/>`_.
+The tiles are rendered on-the-fly using `ST_AsMVT <https://postgis.net/docs/ST_AsMVT.html>`_ and related methods.
+
+This code block shows how to configure pygeoapi to render Mapbox vector tiles from a PostGIS table.
+
+.. code-block:: yaml
+
+   providers:
+       - type: tile
+           name: MVT-postgresql
+           data:
+               host: 127.0.0.1
+               port: 3010 # Default 5432 if not provided
+               dbname: test
+               user: postgres
+               password: postgres
+               search_path: [osm, public]
+           id_field: osm_id
+           table: hotosm_bdi_waterways
+           geom_field: foo_geom
+           options:
+               zoom:
+                   min: 0
+                   max: 15
+           format:
+               name: pbf
+               mimetype: application/vnd.mapbox-vector-tile
+
+PostgreSQL-related connection options can also be added to `options`. Please refer to the :ref:`PostgreSQL OGC Features Provider<PostgreSQL>` documentation for more information.
 
 WMTSFacade
 ^^^^^^^^^^

pygeoapi/api/__init__.py

@@ -42,7 +42,7 @@
 
 from collections import ChainMap, OrderedDict
 from copy import deepcopy
-from datetime import datetime
+from datetime import (datetime, timezone)
 from functools import partial
 from gzip import compress
 from http import HTTPStatus
@@ -165,6 +165,32 @@ def apply_gzip(headers: dict, content: Union[str, bytes]) -> Union[str, bytes]:
     return content
 
 
+def pre_load_colls(func):
+    """
+    Decorator function that makes sure the loaded collections are updated.
+    This is used when the resources are loaded dynamically, not strictly
+    from the yaml file.
+
+    :param func: decorated function
+
+    :returns: `func`
+    """
+
+    def inner(*args, **kwargs):
+        cls = args[0]
+
+        # Validation on the method name for the provided class instance on this
+        # decoration function
+        if hasattr(cls, 'reload_resources_if_necessary'):
+            # Validate the resources are up to date
+            cls.reload_resources_if_necessary()
+
+        # Continue
+        return func(*args, **kwargs)
+
+    return inner
+
+
 class APIRequest:
     """
     Transforms an incoming server-specific Request into an object
@@ -565,9 +591,74 @@ def __init__(self, config, openapi):
         self.tpl_config = deepcopy(self.config)
         self.tpl_config['server']['url'] = self.base_url
 
+        # Now that the basic configuration is read, call the load_resources function.  # noqa
+        # This call enables the api engine to load resources dynamically.
+        # This pattern allows for loading resources coming from another
+        # source (e.g. a database) rather than from the yaml file.
+        # This, along with the @pre_load_colls decorative function, enables
+        # resources management on multiple distributed pygeoapi instances.
+        self.load_resources()
+
         self.manager = get_manager(self.config)
         LOGGER.info('Process manager plugin loaded')
 
+    def on_load_resources(self, resources: dict) -> dict:
+        """
+        Overridable function to load the available resources dynamically.
+        By default, this function simply returns the provided resources
+        as-is. This is the native behavior of the API; expecting
+        resources to be configured in the yaml config file.
+
+        :param resources: the resources as currently configured
+        (self.config['resources'])
+        :returns: the resources dictionary that's available in the API.
+        """
+
+        # By default, return the same resources object, unchanged.
+        return resources
+
+    def on_load_resources_check(self, last_loaded_resources: datetime) -> bool:  # noqa
+        """
+        Overridable function to check if the resources should be reloaded.
+        Return True in your API implementation when resources should be
+        reloaded. This implementation depends on your environment and
+        messaging broker.
+        Natively, the resources used by the pygeoapi instance are strictly
+        the ones from the yaml configuration file. It doesn't support
+        resources changing on-the-fly. Therefore, False is returned here
+        and they are never reloaded.
+        """
+
+        # By default, return False to not reload the resources.
+        return False
+
+    def load_resources(self) -> None:
+        """
+        Calls on_load_resources and reassigns the resources configuration.
+        """
+
+        # Call on_load_resources sending the current resources configuration.
+        self.config['resources'] = self.on_load_resources(self.config['resources'])  # noqa
+
+        # Copy over for the template config also
+        # TODO: Check relevancy of this line
+        self.tpl_config['resources'] = deepcopy(self.config['resources'])
+
+        # Keep track of UTC date of last time resources were loaded
+        self.last_loaded_resources = datetime.now(timezone.utc)
+
+    def reload_resources_if_necessary(self) -> None:
+        """
+        Checks if the resources should be reloaded by calling overridable
+        function 'on_load_resources_check' and then, when necessary, calls
+        'load_resources'.
+        """
+
+        # If the resources should be reloaded
+        if self.on_load_resources_check(self.last_loaded_resources):
+            # Reload the resources
+            self.load_resources()
+
     def get_exception(self, status, headers, format_, code,
                       description) -> Tuple[dict, int, str]:
         """
@@ -657,7 +748,7 @@ def _create_crs_transform_spec(
 
         if not query_crs_uri:
             if storage_crs_uri in DEFAULT_CRS_LIST:
-                # Could be that storageCRS is
+                # Could be that storageCrs is
                 # http://www.opengis.net/def/crs/OGC/1.3/CRS84h
                 query_crs_uri = storage_crs_uri
             else:
@@ -714,7 +805,7 @@ def _set_content_crs_header(
             # If empty use default CRS
             storage_crs_uri = config.get('storage_crs', DEFAULT_STORAGE_CRS)
             if storage_crs_uri in DEFAULT_CRS_LIST:
-                # Could be that storageCRS is one of the defaults like
+                # Could be that storageCrs is one of the defaults like
                 # http://www.opengis.net/def/crs/OGC/1.3/CRS84h
                 content_crs_uri = storage_crs_uri
             else:
@@ -922,6 +1013,7 @@ def conformance(api, request: APIRequest) -> Tuple[dict, int, str]:
 
 
 @jsonldify
+@pre_load_colls
 def describe_collections(api: API, request: APIRequest,
                          dataset=None) -> Tuple[dict, int, str]:
     """
@@ -1136,7 +1228,7 @@ def describe_collections(api: API, request: APIRequest,
         # OAPIF Part 2 - list supported CRSs and StorageCRS
         if collection_data_type in ['edr', 'feature']:
             collection['crs'] = get_supported_crs_list(collection_data, DEFAULT_CRS_LIST)  # noqa
-            collection['storageCRS'] = collection_data.get('storage_crs', DEFAULT_STORAGE_CRS)  # noqa
+            collection['storageCrs'] = collection_data.get('storage_crs', DEFAULT_STORAGE_CRS)  # noqa
             if 'storage_crs_coordinate_epoch' in collection_data:
                 collection['storageCrsCoordinateEpoch'] = collection_data.get('storage_crs_coordinate_epoch')  # noqa
 
@@ -1425,6 +1517,8 @@ def get_collection_schema(api: API, request: Union[APIRequest, Any],
 
     for k, v in p.fields.items():
         schema['properties'][k] = v
+        if v['type'] == 'float':
+            schema['properties'][k]['type'] = 'number'
         if v.get('format') is None:
             schema['properties'][k].pop('format', None)
 

pygeoapi/api/coverages.py

@@ -51,7 +51,7 @@
 
 from . import (
     APIRequest, API, F_JSON, SYSTEM_LOCALE, validate_bbox, validate_datetime,
-    validate_subset
+    validate_subset, pre_load_colls
 )
 
 LOGGER = logging.getLogger(__name__)
@@ -68,6 +68,7 @@
 ]
 
 
+@pre_load_colls
 def get_collection_coverage(
         api: API, request: APIRequest, dataset) -> Tuple[dict, int, str]:
     """

pygeoapi/api/itemtypes.py

@@ -63,7 +63,7 @@
 
 from . import (
     APIRequest, API, SYSTEM_LOCALE, F_JSON, FORMAT_TYPES, F_HTML, F_JSONLD,
-    validate_bbox, validate_datetime
+    validate_bbox, validate_datetime, pre_load_colls
 )
 
 LOGGER = logging.getLogger(__name__)
@@ -100,6 +100,7 @@
 ]
 
 
+@pre_load_colls
 def get_collection_queryables(api: API, request: Union[APIRequest, Any],
                               dataset=None) -> Tuple[dict, int, str]:
     """
@@ -199,6 +200,8 @@ def get_collection_queryables(api: API, request: Union[APIRequest, Any],
                 'title': k,
                 'type': v['type']
             }
+            if v['type'] == 'float':
+                queryables['properties'][k]['type'] = 'number'
             if v.get('format') is not None:
                 queryables['properties'][k]['format'] = v['format']
             if 'values' in v:
@@ -231,6 +234,7 @@ def get_collection_queryables(api: API, request: Union[APIRequest, Any],
     return headers, HTTPStatus.OK, to_json(queryables, api.pretty_print)
 
 
+@pre_load_colls
 def get_collection_items(
         api: API, request: Union[APIRequest, Any],
         dataset) -> Tuple[dict, int, str]:
@@ -397,8 +401,8 @@ def get_collection_items(
         # bbox but no bbox-crs param: assume bbox is in default CRS
         bbox_crs = DEFAULT_CRS
 
-    # Transform bbox to storageCRS
-    # when bbox-crs different from storageCRS.
+    # Transform bbox to storageCrs
+    # when bbox-crs different from storageCrs.
     if len(bbox) > 0:
         try:
             # Get a pyproj CRS instance for the Collection's Storage CRS
@@ -580,7 +584,21 @@ def get_collection_items(
         'href': f'{uri}?f={F_HTML}{serialized_query_params}'
     }])
 
-    if offset > 0:
+    next_link = False
+    prev_link = False
+
+    if 'next' in [link['rel'] for link in content['links']]:
+        LOGGER.debug('Using next link from provider')
+    else:
+        if content.get('numberMatched', -1) > (limit + offset):
+            next_link = True
+        elif len(content['features']) == limit:
+            next_link = True
+
+        if offset > 0:
+            prev_link = True
+
+    if prev_link:
         prev = max(0, offset - limit)
         content['links'].append(
             {
@@ -590,13 +608,6 @@ def get_collection_items(
                 'href': f'{uri}?offset={prev}{serialized_query_params}'
             })
 
-    next_link = False
-
-    if content.get('numberMatched', -1) > (limit + offset):
-        next_link = True
-    elif len(content['features']) == limit:
-        next_link = True
-
     if next_link:
         next_ = offset + limit
         next_href = f'{uri}?offset={next_}{serialized_query_params}'
@@ -688,6 +699,7 @@ def get_collection_items(
     return headers, HTTPStatus.OK, to_json(content, api.pretty_print)
 
 
+@pre_load_colls
 def manage_collection_item(
         api: API, request: APIRequest,
         action, dataset, identifier=None) -> Tuple[dict, int, str]:
@@ -799,6 +811,7 @@ def manage_collection_item(
         return headers, HTTPStatus.OK, ''
 
 
+@pre_load_colls
 def get_collection_item(api: API, request: APIRequest,
                         dataset, identifier) -> Tuple[dict, int, str]:
     """
@@ -999,7 +1012,7 @@ def create_crs_transform_spec(
 
     if not query_crs_uri:
         if storage_crs_uri in DEFAULT_CRS_LIST:
-            # Could be that storageCRS is
+            # Could be that storageCrs is
             # http://www.opengis.net/def/crs/OGC/1.3/CRS84h
             query_crs_uri = storage_crs_uri
         else:
@@ -1056,7 +1069,7 @@ def set_content_crs_header(
         # If empty use default CRS
         storage_crs_uri = config.get('storage_crs', DEFAULT_STORAGE_CRS)
         if storage_crs_uri in DEFAULT_CRS_LIST:
-            # Could be that storageCRS is one of the defaults like
+            # Could be that storageCrs is one of the defaults like
             # http://www.opengis.net/def/crs/OGC/1.3/CRS84h
             content_crs_uri = storage_crs_uri
         else:

pygeoapi/api/maps.py

@@ -51,7 +51,7 @@
     filter_dict_by_key_value
 )
 
-from . import APIRequest, API, validate_datetime
+from . import APIRequest, API, validate_datetime, pre_load_colls
 
 LOGGER = logging.getLogger(__name__)
 
@@ -60,6 +60,7 @@
 ]
 
 
+@pre_load_colls
 def get_collection_map(api: API, request: APIRequest,
                        dataset, style=None) -> Tuple[dict, int, str]:
     """