Fall back to STAC_URL environment variable when opening a Client

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Added
+
+- `Client.open` falls back to the `STAC_URL` environment variable if no url is provided as an argument [#48](https://github.com/stac-utils/pystac-client/pull/48)
+
 ## [v0.1.1] - 2021-04-16
 
 ### Added

pystac_client/client.py

@@ -1,4 +1,5 @@
 from copy import deepcopy
+import os
 from typing import Callable, Optional
 from urllib.request import Request
 
@@ -75,28 +76,37 @@ def __repr__(self):
         return '<Catalog id={}>'.format(self.id)
 
     @classmethod
-    def open(cls, url, headers=None):
+    def open(cls, url=None, headers=None):
         """Alias for PySTAC's STAC Object `from_file` method
 
         Parameters
         ----------
-        url : str
-            The URL of a STAC Catalog
+        url : str, optional
+            The URL of a STAC Catalog. If not specified, this will use the `STAC_URL` environment variable.
 
         Returns
         -------
         catalog : Client
         """
         import pystac_client.stac_io
 
+        if url is None:
+            url = os.environ.get("STAC_URL")
+
+        if url is None:
+            raise TypeError(
+                "'url' must be specified or the 'STAC_URL' environment variable must be set.")
+
         def read_text_method(url):
             request = Request(url, headers=headers or {})
             return pystac_client.stac_io.read_text_method(request)
 
         old_read_text_method = STAC_IO.read_text_method
         STAC_IO.read_text_method = read_text_method
-        catalog = cls.from_file(url)
-        STAC_IO.read_text_method = old_read_text_method
+        try:
+            catalog = cls.from_file(url)
+        finally:
+            STAC_IO.read_text_method = old_read_text_method
         catalog.headers = headers
         return catalog
 

tests/cassettes/test_client/TestAPI.test_environment_variable.yaml

@@ -0,0 +1,95 @@
+interactions:
+- request:
+    body: null
+    headers:
+      Connection:
+      - close
+      Host:
+      - eod-catalog-svc-prod.astraea.earth
+      User-Agent:
+      - Python-urllib/3.9
+    method: GET
+    uri: https://eod-catalog-svc-prod.astraea.earth
+  response:
+    body:
+      string: '{"conformsTo":["http://www.opengis.net/spec/ogcapi-features-1/1.0/conf/core","http://www.opengis.net/spec/ogcapi-features-1/1.0/conf/oas30","http://www.opengis.net/spec/ogcapi-features-1/1.0/conf/geojson","http://www.opengis.net/spec/ogcapi_common-2/1.0/req/collections","http://stacspec.org/spec/api/1.0.0-beta.1/core","http://stacspec.org/spec/api/1.0.0-beta.1/req/stac-search","http://stacspec.org/spec/api/1.0.0-beta.1/req/stac-response","http://stacspec.org/spec/api/1.0.0-beta.1/req/fields","http://stacspec.org/spec/api/1.0.0-beta.1/req/context","http://stacspec.org/spec/api/1.0.0-beta.1/req/sort"],"description":"Astraea
+        Earth OnDemand geospatial imagery query and analysis tool","id":"astraea","links":[{"href":"https://eod-catalog-svc-prod.astraea.earth","rel":"self","title":"Self","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth","rel":"root","title":"Root","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/api","rel":"service-desc","title":"OpenAPI
+        specification","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/api.html","rel":"service-doc","title":"API
+        documentation","type":"text/html"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections","rel":"data","title":"Collections","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections","rel":"collections","title":"Collections","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/landsat8_l1tp","rel":"child","title":"Landsat
+        8 C1 T1","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/mcd43a4","rel":"child","title":"MCD43A4
+        NBAR","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/mod11a1","rel":"child","title":"MOD11A1
+        LST","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/myd11a1","rel":"child","title":"MYD11A1
+        LST","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/mod13a1","rel":"child","title":"MOD13A1
+        VI","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/myd13a1","rel":"child","title":"MYD13A1
+        VI","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/sentinel1_l1c_grd","rel":"child","title":"Sentinel-1
+        L1C GRD","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/sentinel2_l2a","rel":"child","title":"Sentinel-2
+        L2A","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/sentinel2_l1c","rel":"child","title":"Sentinel-2
+        L1C","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/naip","rel":"child","title":"NAIP","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/maxar_open_data","rel":"child","title":"Maxar
+        Open Data","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/collections/spacenet7","rel":"child","title":"SpaceNet
+        7","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/aggregate","rel":"aggregation","title":"Aggregation","type":"application/json"},{"capabilities":{"parameters":[{"name":"composite","values":[{"description":"Default
+        View.","name":"default","title":"Default View"},{"description":"True Color
+        Composite.","name":"true_color","title":"True Color Composite"},{"description":"Normalized
+        Difference Vegetation Index.","name":"ndvi","title":"NDVI"},{"description":"Normalized
+        Difference Water Index using Green and NIR per McFeeters(1997).","name":"ndwi","title":"NDWI
+        (Green & NIR)"},{"description":"Normalized Difference Water Index using NIR
+        and SWIR per Gao(1997).","name":"ndwi2","title":"NDWI (NIR & SWIR)"},{"description":"Color
+        Infrared (Vegetation) consisting of Near-infrared, Red, and Green bands.","name":"color_infrared_veg1","title":"Color
+        Infrared Vegetation (NRG)"},{"description":"Color Infrared (Vegetation) consisting
+        of Near-infrared, Green, and Blue bands.","name":"color_infrared_veg2","title":"Color
+        Infrared Vegetation 2 (NGB)"},{"description":"False Color Infrared (Urban).","name":"false_color_urban","title":"False
+        Color (Urban)"},{"description":"Agriculture.","name":"agriculture","title":"Agriculture"},{"description":"Moisture
+        Index.","name":"moisture_index","title":"Moisture Index"},{"description":"Geology.","name":"geology","title":"Geology"},{"description":"Bathymetric.","name":"bathymetric","title":"Bathymetric"},{"description":"Atmospheric
+        Penetration.","name":"atmospheric_penetration","title":"Atmospheric Penetration"},{"description":"SWIR
+        1.","name":"swir1","title":"SWIR 1"},{"description":"SWIR 2.","name":"swir2","title":"SWIR
+        2"},{"description":"SAR VV Polarization.","name":"sar_vv","title":"SAR VV
+        Polarization"},{"description":"SAR VH Polarization.","name":"sar_vh","title":"SAR
+        VH Polarization"},{"description":"SAR HH Polarization.","name":"sar_hh","title":"SAR
+        HH Polarization"},{"description":"SAR HV Polarization.","name":"sar_hv","title":"SAR
+        HV Polarization"},{"description":"SAR False Color (Urban).","name":"sar_false_color_urban","title":"SAR
+        False Color (Urban)"}]}]},"href":"https://eod-catalog-svc-prod.astraea.earth/aggregate","rel":"aggregate","title":"Aggregate","type":"application/json"},{"capabilities":{"parameters":[{"name":"composite","values":[{"description":"Default
+        View.","name":"default","title":"Default View"},{"description":"True Color
+        Composite.","name":"true_color","title":"True Color Composite"},{"description":"Normalized
+        Difference Vegetation Index.","name":"ndvi","title":"NDVI"},{"description":"Normalized
+        Difference Water Index using Green and NIR per McFeeters(1997).","name":"ndwi","title":"NDWI
+        (Green & NIR)"},{"description":"Normalized Difference Water Index using NIR
+        and SWIR per Gao(1997).","name":"ndwi2","title":"NDWI (NIR & SWIR)"},{"description":"Color
+        Infrared (Vegetation) consisting of Near-infrared, Red, and Green bands.","name":"color_infrared_veg1","title":"Color
+        Infrared Vegetation (NRG)"},{"description":"Color Infrared (Vegetation) consisting
+        of Near-infrared, Green, and Blue bands.","name":"color_infrared_veg2","title":"Color
+        Infrared Vegetation 2 (NGB)"},{"description":"False Color Infrared (Urban).","name":"false_color_urban","title":"False
+        Color (Urban)"},{"description":"Agriculture.","name":"agriculture","title":"Agriculture"},{"description":"Moisture
+        Index.","name":"moisture_index","title":"Moisture Index"},{"description":"Geology.","name":"geology","title":"Geology"},{"description":"Bathymetric.","name":"bathymetric","title":"Bathymetric"},{"description":"Atmospheric
+        Penetration.","name":"atmospheric_penetration","title":"Atmospheric Penetration"},{"description":"SWIR
+        1.","name":"swir1","title":"SWIR 1"},{"description":"SWIR 2.","name":"swir2","title":"SWIR
+        2"},{"description":"SAR VV Polarization.","name":"sar_vv","title":"SAR VV
+        Polarization"},{"description":"SAR VH Polarization.","name":"sar_vh","title":"SAR
+        VH Polarization"},{"description":"SAR HH Polarization.","name":"sar_hh","title":"SAR
+        HH Polarization"},{"description":"SAR HV Polarization.","name":"sar_hv","title":"SAR
+        HV Polarization"},{"description":"SAR False Color (Urban).","name":"sar_false_color_urban","title":"SAR
+        False Color (Urban)"}]}]},"href":"https://eod-catalog-svc-prod.astraea.earth/search","rel":"search","title":"Search","type":"application/json"},{"href":"https://eod-catalog-svc-prod.astraea.earth/grid_id_definitions?20200218","rel":"grid_id_definitions","title":"Grid
+        ID Definitions","type":"application/json"}],"stac_extensions":["eo","proj","context"],"stac_version":"1.0.0-beta.2","title":"Astraea
+        Earth OnDemand"}'
+    headers:
+      Access-Control-Allow-Credentials:
+      - 'true'
+      Access-Control-Allow-Headers:
+      - X-Astraea-Catalog-Client
+      - Authorization, Content-Type, X-Requested-With
+      Access-Control-Allow-Origin:
+      - '*'
+      Cache-Control:
+      - no-cache, no-store, must-revalidate
+      Connection:
+      - close
+      Content-Length:
+      - '7768'
+      Content-Type:
+      - application/json
+      Date:
+      - Mon, 03 May 2021 15:27:20 GMT
+      Server:
+      - akka-http/10.2.3
+    status:
+      code: 200
+      message: OK
+version: 1

tests/test_client.py

@@ -1,4 +1,5 @@
 from datetime import datetime
+import os
 
 from dateutil.tz import tzutc
 import pystac
@@ -96,6 +97,30 @@ def test_from_file(self):
 
         assert api.title == 'Astraea Earth OnDemand'
 
+    @pytest.mark.vcr
+    def test_environment_variable(self):
+        old_stac_url = os.environ.get("STAC_URL")
+        os.environ["STAC_URL"] = ASTRAEA_URL
+        try:
+            client = Client.open()
+            assert client.title == "Astraea Earth OnDemand"
+        finally:
+            if old_stac_url:
+                os.environ["STAC_URL"] = old_stac_url
+            else:
+                del os.environ["STAC_URL"]
+
+    def test_no_url(self):
+        old_stac_url = os.environ.get("STAC_URL")
+        if old_stac_url:
+            del os.environ["STAC_URL"]
+        try:
+            with pytest.raises(TypeError):
+                Client.open()
+        finally:
+            if old_stac_url:
+                os.environ["STAC_URL"] = old_stac_url
+
 
 class TestAPISearch:
     @pytest.fixture(scope='function')