Addressed Dongsheng's review comments.

client/driver/driver_config.py

@@ -34,6 +34,9 @@ DB_USER = 'dbuser'
 # Password for DB_USER
 DB_PASSWORD = 'dbpassword'
 
+# Database admin username (for tasks like restarting the database)
+ADMIN_USER = DB_USER
+
 # Database host address
 DB_HOST = 'localhost'
 

client/driver/fabfile.py

@@ -109,7 +109,7 @@ def restart_database():
             local('docker restart {}'.format(dconf.CONTAINER_NAME))
         else:
             sudo('pg_ctl -D {} -w -t 600 restart -m fast'.format(
-                dconf.PG_DATADIR), user=dconf.DB_USER)
+                dconf.PG_DATADIR), user=dconf.ADMIN_USER, capture=False)
     elif dconf.DB_TYPE == 'oracle':
         run_sql_script('restartOracle.sh')
     else:
@@ -202,7 +202,7 @@ def change_conf(next_conf=None):
     with open(tmp_conf_out, 'w') as f:
         f.write(''.join(lines))
 
-    run('cp {0} {0}.ottertune.bak'.format(dconf.DB_CONF))
+    sudo('cp {0} {0}.ottertune.bak'.format(dconf.DB_CONF))
     put(tmp_conf_out, dconf.DB_CONF, use_sudo=False)
     local('rm -f {} {}'.format(tmp_conf_in, tmp_conf_out))
 
@@ -275,7 +275,7 @@ def save_next_config(next_config, t=None):
 def free_cache():
     if dconf.HOST_CONN != 'docker':
         with show('everything'), settings(warn_only=True):  # pylint: disable=not-context-manager
-            res = sudo("sync && echo 3 | tee /proc/sys/vm/drop_caches")
+            res = sudo("sh -c \"echo 3 > /proc/sys/vm/drop_caches\"")
             if res.failed:
                 LOG.error('%s (return code %s)', res.stderr.strip(), res.return_code)
 

client/driver/utils.py

@@ -54,12 +54,14 @@ def parse_bool(value):
 
 
 @task
-def run(cmd, **kwargs):
+def run(cmd, capture=True, **kwargs):
+    capture = parse_bool(capture)
+
     try:
         if dconf.HOST_CONN == 'remote':
             res = _run(cmd, **kwargs)
         elif dconf.HOST_CONN == 'local':
-            res = local(cmd, capture=True, **kwargs)
+            res = local(cmd, capture=capture, **kwargs)
         else:  # docker
             opts = ''
             cmdd = cmd
@@ -67,7 +69,7 @@ def run(cmd, **kwargs):
                 cmdd = cmd[:-1].strip()
                 opts = '-d '
             res = local('docker exec {} -ti {} /bin/bash -c "{}"'.format(
-                opts, dconf.CONTAINER_NAME, cmdd), capture=True, **kwargs)
+                opts, dconf.CONTAINER_NAME, cmdd), capture=capture, **kwargs)
     except TypeError as e:
         err = str(e).strip()
         if 'unexpected keyword argument' in err:
@@ -80,7 +82,9 @@ def run(cmd, **kwargs):
 
 
 @task
-def sudo(cmd, user=None, **kwargs):
+def sudo(cmd, user=None, capture=True, **kwargs):
+    capture = parse_bool(capture)
+
     if dconf.HOST_CONN == 'remote':
         res = _sudo(cmd, user=user, **kwargs)
 
@@ -88,7 +92,7 @@ def sudo(cmd, user=None, **kwargs):
         pre_cmd = 'sudo '
         if user:
             pre_cmd += '-u {} '.format(user)
-        res = local(pre_cmd + cmd, capture=True, **kwargs)
+        res = local(pre_cmd + cmd, capture=capture, **kwargs)
 
     else:  # docker
         user = user or 'root'
@@ -96,7 +100,7 @@ def sudo(cmd, user=None, **kwargs):
         if user == 'root':
             opts += ' -w /'
         res = local('docker exec {} {} /bin/bash -c "{}"'.format(
-            opts, dconf.CONTAINER_NAME, cmd), capture=True)
+            opts, dconf.CONTAINER_NAME, cmd), capture=capture)
 
     return res