move provider string to constants and add a CHANGELOG entry

CHANGELOG.md

@@ -1,3 +1,8 @@
+## Unreleased
+
+* Adds support for Earthdata login and retrieval of collection-level metadata
+  from CMR. (Issue-15)
+
 ## v1.1.0
 
 * Extend `ini` file to include values for attributes missing from a minimal,

src/nsidc/metgen/constants.py

@@ -15,6 +15,11 @@
 # Logging
 ROOT_LOGGER = "metgenc"
 
+# Currently we support one CMR production cloud provider (NSIDC_CPRD) and one
+# UAT cloud provider (NSIDC_CPRD).
+CMR_PROD_PROVIDER = "NSIDC_CPRD"
+CMR_UAT_PROVIDER = "NSIDC_CUAT"
+
 # JSON schema locations and versions
 CNM_JSON_SCHEMA = ("nsidc.metgen.json-schema", "cumulus_sns_schema.json")
 CNM_JSON_SCHEMA_VERSION = "1.6.1"

src/nsidc/metgen/metgen.py

@@ -413,7 +413,11 @@ def edl_environment(environment):
 
 
 def edl_provider(environment):
-    return "NSIDC_CPRD" if environment.lower() == "prod" else "NSIDC_CUAT"
+    return (
+        constants.CMR_PROD_PROVIDER
+        if environment.lower() == "prod"
+        else constants.CMR_UAT_PROVIDER
+    )
 
 
 @cache