[reload config] use /bin/bash as shell for config reload

This change was introduced in
sonic-net#1687 to fix connection reset
caused by 'config reload'. The fix was to redirect output to /dev/null.
Shell will interpret 'config reload -y &> /dev/null' as request to run
the command in the background instead of redirecting stdout/stderr to
/dev/null. It looks like not the redirection fixed the issue but the
fact that it was running in background. However, it introduced another
issue because config reload takes ~1.5m so that 90/120 sec wait time is
not enough time waiting for system to become ready.

Change-Id: I9d44c0a55e4fa016bbe177524891c9b14302c761
Signed-off-by: Stepan Blyschak <[email protected]>

Author: Stepan Blyschak

tests/common/config_reload.py

@@ -24,10 +24,10 @@ def config_reload(duthost, config_source='config_db', wait=120):
     logger.info('reloading {}'.format(config_source))
 
     if config_source == 'minigraph':
-        duthost.shell('config load_minigraph -y &>/dev/null')
+        duthost.shell('config load_minigraph -y &>/dev/null', executable="/bin/bash")
         duthost.shell('config save -y')
 
     if config_source == 'config_db':
-        duthost.shell('config reload -y &>/dev/null')
+        duthost.shell('config reload -y &>/dev/null', executable="/bin/bash")
 
     time.sleep(wait)

tests/platform_tests/test_reload_config.py

@@ -27,7 +27,7 @@ def test_reload_configuration(duthost, conn_graph_facts):
     asic_type = duthost.facts["asic_type"]
 
     logging.info("Reload configuration")
-    duthost.shell("sudo config reload -y &>/dev/null")
+    duthost.shell("sudo config reload -y &>/dev/null", executable="/bin/bash")
 
     logging.info("Wait until all critical services are fully started")
     check_critical_services(duthost)

tests/vlan/test_vlan.py

@@ -184,7 +184,7 @@ def tearDown(vlan_ports_list, duthost, ptfhost, vlan_intfs_list, portchannel_int
     except RunAnsibleModuleFail as e:
         logger.error(e)
 
-    duthost.shell("config reload -y &>/dev/null")
+    duthost.shell("config reload -y &>/dev/null", executable="/bin/bash")
 
     # make sure Portchannels go up for post-test link sanity
     time.sleep(90)