Add environment variables for connection (#1472)

* Add environment variables for connection

Use same args as in config file

#1342

* add test

* add suggestions

https://github.com/rq/rq/pull/1472#discussion_r640205865
https://github.com/rq/rq/pull/1472#discussion_r640206565

* remove unused import

rq/cli/helpers.py

@@ -5,6 +5,7 @@ from __future__ import (absolute_import, division, print_function,
 import sys
 import importlib
 import time
+import os
 from functools import partial
 
 import click
@@ -48,12 +49,21 @@ def get_redis_from_config(settings, connection_class=Redis):
         sn = Sentinel(instances, socket_timeout=socket_timeout, password=password, db=db)
         return sn.master_for(master_name)
 
+    ssl = settings.get('REDIS_SSL', False)
+    if isinstance(ssl, str):
+        if ssl.lower() in ['y', 'yes', 't', 'true']:
+            ssl = True
+        elif ssl.lower() in ['n', 'no', 'f', 'false', '']:
+            ssl = False
+        else:
+            raise ValueError('REDIS_SSL is a boolean and must be "True" or "False".')
+
     kwargs = {
         'host': settings.get('REDIS_HOST', 'localhost'),
         'port': settings.get('REDIS_PORT', 6379),
         'db': settings.get('REDIS_DB', 0),
         'password': settings.get('REDIS_PASSWORD', None),
-        'ssl': settings.get('REDIS_SSL', False),
+        'ssl': ssl,
         'ssl_ca_certs': settings.get('REDIS_SSL_CA_CERTS', None),
     }
 
@@ -235,8 +245,11 @@ class CliConfig:
         if self._connection is None:
             if self.url:
                 self._connection = self.connection_class.from_url(self.url)
-            else:
+            elif self.config:
                 settings = read_config_file(self.config) if self.config else {}
                 self._connection = get_redis_from_config(settings,
                                                          self.connection_class)
+            else:
+                self._connection = get_redis_from_config(os.environ,
+                                                         self.connection_class)
         return self._connection

tests/test_cli.py

@@ -4,6 +4,8 @@ from __future__ import (absolute_import, division, print_function,
 
 from datetime import datetime, timezone
 
+import os
+
 from click.testing import CliRunner
 from redis import Redis
 
@@ -106,6 +108,16 @@ class TestRQCli(RQTestCase):
             '123'
         )
 
+    def test_config_env_vars(self):
+        os.environ['REDIS_HOST'] = "testhost.example.com"
+
+        cli_config = CliConfig()
+
+        self.assertEqual(
+            cli_config.connection.connection_pool.connection_kwargs['host'],
+            'testhost.example.com',
+        )
+
     def test_empty_nothing(self):
         """rq empty -u <url>"""
         runner = CliRunner()