Applications
------------
You can use Application support to graph performance statistics from many applications.

Different applications support a variety of ways collect data: by direct connection to the application, snmpd extend, or the agent.

1. [BIND9/named](#bind9-aka-named) - Agent
2. [MySQL](#mysql) - Agent
3. [NGINX](#nginx) - Agent
4. [PowerDNS](#powerdns) - Agent
5. [PowerDNS Recursor](#powerdns-recursor) - Agent
6. [TinyDNS/djbdns](#tinydns-aka-djbdns) - Agent

* [Agent Setup](#agent-setup)

### BIND9 aka named

##### Agent
[Install the agent](#agent-setup) on this device if it isn't already and copy the `bind` script to `/usr/lib/check_mk_agent/local/`

Create stats file with appropriate permissions:
```shell
~$ touch /etc/bind/named.stats
~$ chown bind:bind /etc/bind/named.stats
```
Change `user:group` to the user and group that's running bind/named.

Bind/named configuration:
```text
options {
	...
	statistics-file "/etc/bind/named.stats";
	zone-statistics yes;
	...
};
```
Restart your bind9/named after changing the configuration.

Verify that everything works by executing `rndc stats && cat /etc/bind/named.stats`.
In case you get a `Permission Denied` error, make sure you chown'ed correctly.

Note: if you change the path you will need to change the path in `scripts/agent-local/bind`.


### MySQL

##### Agent
[Install the agent](#agent-setup) on this device if it isn't already and copy the `mysql` script to `/usr/lib/check_mk_agent/local/`

Unlike most other scripts, the MySQL script requires a configuration file `/usr/lib/check_mk_agent/local/mysql.cnf` with following content:

```php
<?php
$mysql_user = 'root';
$mysql_pass = 'toor';
$mysql_host = 'localhost';
$mysql_port = 3306;
```

### NGINX

NGINX is a free, open-source, high-performance HTTP server: https://www.nginx.org/

##### Agent
[Install the agent](#agent-setup) on this device if it isn't already and copy the `nginx` script to `/usr/lib/check_mk_agent/local/`

It's required to have the following directive in your nginx configuration responsible for the localhost server:

```text
location /nginx-status {
    stub_status on;
    access_log   off;
    allow 127.0.0.1;
    deny all;
}
```

### PowerDNS
An authoritative DNS server: https://www.powerdns.com/auth.html

##### Agent
[Install the agent](#agent-setup) on this device if it isn't already and copy the `powerdns` script to `/usr/lib/check_mk_agent/local/`


### PowerDNS Recursor
A recursive DNS server: https://www.powerdns.com/recursor.html

##### Direct
The LibreNMS polling host must be able to connect to port 8082 on the monitored device.
The web-server must be enabled, see the Recursor docs: https://doc.powerdns.com/md/recursor/settings/#webserver
There is currently no way to specify a custom port or password.

##### Agent
[Install the agent](#agent-setup) on this device if it isn't already and copy the `powerdns-recursor` script to `/usr/lib/check_mk_agent/local/`

This script uses `rec_control get-all` to collect stats.


### TinyDNS aka  djbdns

##### Agent
[Install the agent](#agent-setup) on this device if it isn't already and copy the `tinydns` script to `/usr/lib/check_mk_agent/local/`

_Note_: We assume that you use DJB's [Daemontools](http://cr.yp.to/daemontools.html) to start/stop tinydns.
And that your tinydns instance is located in `/service/dns`, adjust this path if necessary.

1. Replace your _log_'s `run` file, typically located in `/service/dns/log/run` with:
```shell
#!/bin/sh
exec setuidgid dnslog tinystats ./main/tinystats/ multilog t n3 s250000 ./main/
```
2. Create tinystats directory and chown:
```shell
mkdir /service/dns/log/main/tinystats
chown dnslog:nofiles /service/dns/log/main/tinystats
```
3. Restart TinyDNS and Daemontools: `/etc/init.d/svscan restart`
   _Note_: Some say `svc -t /service/dns` is enough, on my install (Gentoo) it doesn't rehook the logging and I'm forced to restart it entirely.


Agent Setup
-----------

To gather data from remote systems you can use LibreNMS in combination with check_mk (found [here](https://github.com/librenms/librenms-agent)).

Make sure that systemd or xinetd is installed on the host you want to run the agent on.

The agent uses TCP-Port 6556, please allow access from the **LibreNMS host** and **poller nodes** if you're using the [Distributed Polling](http://docs.librenms.org/Extensions/Distributed-Poller/) setup.

On each of the hosts you would like to use the agent on then you need to do the following:

1. Clone the `librenms-agent` repository:

```shell
cd /opt/
git clone https://github.com/librenms/librenms-agent.git
cd librenms-agent
```

2. Copy the relevant check_mk_agent to `/usr/bin`:

| linux | freebsd |
| --- | --- |
| `cp check_mk_agent /usr/bin/check_mk_agent` | `cp check_mk_agent_freebsd /usr/bin/check_mk_agent` |

```shell
chmod +x /usr/bin/check_mk_agent
```

3. Copy the service file(s) into place.

| xinetd | systemd |
| --- | --- |
| `cp check_mk_xinetd /etc/xinetd.d/check_mk` | `cp check_mk@.service check_mk.socket /etc/systemd/system` |

4. Create the relevant directories.

```shell
mkdir -p /usr/lib/check_mk_agent/plugins /usr/lib/check_mk_agent/local
```

5. Copy each of the scripts from `agent-local/` into `/usr/lib/check_mk_agent/local` that you require to be graphed.  You can find detail setup instructions for specific applications above.
6. Make each one executable that you want to use with `chmod +x /usr/lib/check_mk_agent/local/$script`
7. Enable the check_mk service

| xinetd | systemd |
| --- | --- |
| `/etc/init.d/xinetd restart` | `systemctl enable --now check_mk.socket` |


8. Login to the LibreNMS web interface and edit the device you want to monitor. Under the modules section, ensure that unix-agent is enabled.
9. Then under Applications, enable the apps that you plan to monitor.
10. Wait for around 10 minutes and you should start seeing data in your graphs under Apps for the device.