local function receive_bat_hosts()
-- read raw chunks from alfred, convert them to a nested table and call write_bat_hosts
- local fd = io.popen("alfred -r " .. type_id)
- --[[ this command returns something like
- { "54:e6:fc:b9:cb:37", "00:11:22:33:44:55 ham_wlan0\x0a00:22:33:22:33:22 ham_eth0\x0a" },
- { "90:f6:52:bb:ec:57", "00:22:33:22:33:23 spam\x0a" },
- ]]--
-
- if fd then
- local output = fd:read("*a")
- if output then
- assert(loadstring("rows = {" .. output .. "}"))()
- write_bat_hosts(rows)
+-- "alfred -r" can fail in slave nodes (returns empty stdout), so:
+-- check output is not null before writing /tmp/bat-hosts, and retry 3 times before giving up.
+ for n = 1, 3 do
+ local fd = io.popen("alfred -r " .. type_id)
+ --[[ this command returns something like
+ { "54:e6:fc:b9:cb:37", "00:11:22:33:44:55 ham_wlan0\x0a00:22:33:22:33:22 ham_eth0\x0a" },
+ { "90:f6:52:bb:ec:57", "00:22:33:22:33:23 spam\x0a" },
+ ]]--
+
+ if fd then
+ local output = fd:read("*a")
+ fd:close()
+ if output and output ~= "" then
+ assert(loadstring("rows = {" .. output .. "}"))()
+ write_bat_hosts(rows)
+ break
+ end
end
- fd:close()
end
end