HTTP service can't be started on boot

[Dmytro Milinevskyi]

I didn't have time to dig into the details but monit is not able to start http service on boot. Probably somehow related to #192. NOTE: the address is specified by ip, not by name(localhost).

Error messages:

Starting Monit 5.20.0 daemon with http interface at [127.0.0.1]:2812
HTTP server -- Cannot translate IPv4 socket [127.0.0.1]:2812 -- Name or service not known
HTTP server -- Invalid socket family 3

This is unrelated to the status of lo. If lo is down monit can't bind for another reason:

Starting Monit 5.20.0 daemon with http interface at [127.0.0.1]:2812
HTTP server -- Cannot bind: Cannot assign requested address
HTTP server -- Invalid socket family 3

The status of network is ok before monit is started. It's true the eth0 doesn't have ip address but it shouldn't be an issue.

>ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
    inet6 xxxx::xxxx:xxxx:xxxx:xxxx/64 scope link 
       valid_lft forever preferred_lft forever

>ping -c 1 localhost
PING localhost (127.0.0.1): 56 data bytes
64 bytes from 127.0.0.1: seq=0 ttl=64 time=0.152 ms
--- localhost ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 0.152/0.152/0.152 ms

The /etc/resolv.conf is empty.

All in all the service is configured by the ip address, why monit is trying to resolve it?

The configuration section:

set httpd port 2812 and
    use address 127.0.0.1
    allow localhost
    allow admin:monit

Any suggestion on how to gracefully restart monit http service?

[Dmytro Milinevskyi]

The solution I've found is to use unix socket:

set httpd unixsocket /var/run/monit.sock and
    allow localhost

[Tildeslash]

Duplicate of #537.

[Dmytro Milinevskyi]

It's not duplicate as:

• lo interface available
• using monit v5.20
• no need to resolve host if given IP

monit -V
This is Monit version 5.20.0
Built with ssl, without ipv6, with compression, without pam and with large files
Copyright (C) 2001-2016 Tildeslash Ltd. All Rights Reserved.

[Tildeslash]

Does this work? nc -4 -l 127.0.0.1 2812. Also note that the bug fix mentioned in the duplicate issue is not part of 5.20.0.

[Tildeslash]

No reply from user, assuming IP 4/6 configuration issue on user's local machine.

[Dmytro Milinevskyi]

Netcat can bind successfully. I added following commands just before launching monit in the init script:

   (rm /tmp/test; \
    nc -l -p 2812 127.0.0.1 > /tmp/test& \
    netstat -ntpl;
    echo test | nc 127.0.0.1 2812; \
    cat /tmp/test) | logger -t monit

Netcat is from busybox but it doesn't change the meaning.

Following output was captured:

 user.notice monit: Active Internet connections (only servers)
 user.notice monit: Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
 user.notice monit: tcp        0      0 127.0.0.1:7777          0.0.0.0:*               LISTEN      413/nginx
 user.notice monit: tcp        0      0 127.0.0.1:7778          0.0.0.0:*               LISTEN      413/nginx
 user.notice monit: tcp        0      0 127.0.0.1:9001          0.0.0.0:*               LISTEN      444/uwsgi
 user.notice monit: tcp        0      0 127.0.0.1:1649          0.0.0.0:*               LISTEN      392/lsh
 user.notice monit: tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      334/dropbear
 user.notice monit: tcp        0      0 127.0.0.1:2812          0.0.0.0:*               LISTEN      454/nc
 user.notice monit: tcp        0      0 127.0.0.1:1212          0.0.0.0:*               LISTEN      431/python3
 user.notice monit: tcp        0      0 :::22                   :::*                    LISTEN      334/dropbear
 user.notice monit: test
 user.info monit[459]: Starting Monit 5.20.0 daemon with http interface at [127.0.0.1]:2812
 user.info monit[461]: 'Lima' Monit 5.20.0 started
 user.err monit[461]: HTTP server -- Cannot translate IPv4 socket [127.0.0.1]:2812 -- Name or service not known
 user.err monit[461]: HTTP server -- Invalid socket family 3

[Robert Krakora]

Thanks Dmytro Milinevskyi, unixsocket solved this issue for me for monit 5.19!!!

[Tildeslash]

As mentioned, the fix is not part of Monit 5.20.0 ... it is related to AI_ADDRCONFIG resolver option, which was fixed in Monit 5.21.0.