Nagios Error - HTTP CRITICAL - Unable to open TCP socket

Nagios Error - HTTP CRITICAL - Unable to open TCP socket

Error:
Connection refused
HTTP CRITICAL - Unable to open TCP socket

Solution: 

1. Define the port with -p option rather than giving it in URL:

vi checkcommands.cfg

define command {
command_name                   check_http_solr
command_line                   $USER1$/check_http -H '$ARG1$' -u '$ARG2$' -p '$ARG3$'
}

2. Edit services file.

vi services.cfg
define service {
host_name                      example
service_description            URL Check
is_volatile                    0
check_period                   24x7
max_check_attempts             5
normal_check_interval          10
retry_check_interval           1
contact_groups                 hotline
notification_interval          120
notification_period            24x7
notification_options           c,r
check_command                  check_http_solr!example!http://example.local/solr/index/admin/ping?wt=json!8983
notifications_enabled          1
}