On sflow enable, start the docker since it is disabled by default (so…

…nic-net#773)

config/main.py

@@ -2176,6 +2176,17 @@ def enable(ctx):
 
  config_db.mod_entry('SFLOW', 'global', sflow_tbl['global'])
 
+ try:
+ proc = subprocess.Popen("systemctl is-active sflow", shell=True, stdout=subprocess.PIPE)
+ (out, err) = proc.communicate()
+ except SystemExit as e:
+ ctx.fail("Unable to check sflow status {}".format(e))
+
+ if out != "active":
+ log_info("sflow service is not enabled. Starting sflow docker...")
+ run_command("sudo systemctl enable sflow")
+ run_command("sudo systemctl start sflow")
+
 #
 # 'sflow' command ('config sflow disable')
 #