Allow schema file to be a general URI

This allows it to be read from anywhere supported by ResourcePath.

python/lsst/ap/association/packageAlerts.py

@@ -37,6 +37,7 @@
 from lsst.pex.exceptions import InvalidParameterError
 import lsst.pipe.base as pipeBase
 from lsst.utils.timer import timeMethod
+from lsst.resources import ResourcePath
 
 
 """Methods for packaging Apdb and Pipelines data into Avro alerts.
@@ -48,8 +49,8 @@ class PackageAlertsConfig(pexConfig.Config):
     """
     schemaFile = pexConfig.Field(
         dtype=str,
-        doc="Schema definition file for the avro alerts.",
-        default=alertPack.get_path_to_latest_schema()
+        doc="Schema definition file URI for the avro alerts.",
+        default=alertPack.get_uri_to_latest_schema()
     )
     minCutoutSize = pexConfig.RangeField(
         dtype=int,
@@ -75,7 +76,9 @@ class PackageAlertsTask(pipeBase.Task):
 
     def __init__(self, **kwargs):
         super().__init__(**kwargs)
-        self.alertSchema = alertPack.Schema.from_file(self.config.schemaFile)
+        uri = ResourcePath(self.config.schemaFile)
+        with uri.as_local() as schemaFile:
+            self.alertSchema = alertPack.Schema.from_file(schemaFile.ospath)
         os.makedirs(self.config.alertWriteLocation, exist_ok=True)
 
     @timeMethod