fix: handle postgres connect via cloud run

Ref: https://cloud.google.com/sql/docs/postgres/connect-functions

.vscode/settings.json

@@ -1,8 +1,10 @@
 {
   "cSpell.words": [
     "AGRC",
+    "cloudsql",
     "Codecov",
     "Dataframe",
+    "drivername",
     "Dtype",
     "featurelayer",
     "featureset",
@@ -13,14 +15,18 @@
     "instafail",
     "isort",
     "knownhosts",
+    "lowres",
+    "naturalearth",
     "Overwriter",
     "palletjack",
     "PARENTOBJECTID",
+    "PGSQL",
     "psycopg",
     "pylint",
     "pytest",
     "reclassifier",
     "sftploader",
+    "sqlalchemy",
     "unclassed",
     "yapf"
   ],

setup.py

@@ -38,6 +38,7 @@
         'pygsheets==2.0.*',
         'geopandas==0.12.*',
         'SQLAlchemy==1.4.*',
+        'pg8000==1.29.*',
         'psycopg2-binary==2.9.*',
         'numpy==1.23.*',  #: Pinned to fix "module 'numpy' has no attribute 'str'" error
     ],

src/palletjack/loaders.py

@@ -3,6 +3,7 @@
 
 import logging
 import mimetypes
+import os
 import re
 from io import BytesIO
 from pathlib import Path
@@ -12,8 +13,8 @@
 import pandas as pd
 import pysftp
 import requests
+import sqlalchemy
 from googleapiclient.http import MediaIoBaseDownload
-from sqlalchemy import create_engine
 
 from . import utils
 
@@ -439,8 +440,29 @@ class PostgresLoader:
     def __init__(self, host, database, username, password, port=5432):
         self._class_logger = logging.getLogger(__name__).getChild(self.__class__.__name__)
 
-        connection_string = f'postgresql://{username}:{password}@{host}:{port}/{database}'
-        self.engine = create_engine(connection_string)
+        if os.environ.get('FUNCTION_TARGET') is not None:  #: this is an env var specific to cloud functions
+            self._class_logger.info('running in GCF, using unix socket')
+            self.engine = sqlalchemy.create_engine(
+                sqlalchemy.engine.url.URL.create(
+                    drivername='postgresql+pg8000',
+                    username=username,
+                    password=password,
+                    database=database,
+                    query={'unix_sock': f'/cloudsql/{host}/.s.PGSQL.{port}'},  #: requires the pg8000 package
+                )
+            )
+        else:
+            self._class_logger.info('running locally, using traditional host connection')
+            self.engine = sqlalchemy.create_engine(
+                sqlalchemy.engine.url.URL.create(
+                    drivername='postgresql',
+                    username=username,
+                    password=password,
+                    database=database,
+                    host=host,
+                    port=port,
+                )
+            )
 
     def read_table_into_dataframe(self, table_name, index_column, crs, spatial_column):
         """Read a table into a dataframe