LibreNMS Error “.sock: rrd_fetch_r failed:”

The following error showed up after adding a new device to LibreNMS.

.sock:rrd_fetch_r failed: 

It was not displaying any graph data, but the device was up and connected.

Looks like the error is SELinux related. You can fix the error by resetting the security context with the following command.

sudo restorecon -RFv /opt/librenms

LibreNMS Devices Disappeared from Web Interface

What do you do when all your devices disappear from the web interface?

Everything still appears to be working. Alerts work.

Running a MySQL command to check if the devices are in the database returns all the devices

mysql -u librenms -p librenms -e 'use librenms ; select hostname,sysName,status from devices where status=1'

If we try going to /addhost we are greeted with an Error You have insuffecient permissions to view this page.

Running ./validate.php returns everything good

Potentially it could be an issue with SElinux or with Apache/NGinx

Running

audit2why < /var/log/audit/audit.log

Doesn’t return anything

No errors pop up in the Logs

Could be something happened with the LibreNMS user.

Test a different LibreNMS user and all the devices show up.

We’ve now isolated the issue to being something with out user.

Server Logs not Showing up in LibreNMS

The problem: Linux servers have been configured to send their local syslogs to LibreNMS, but are not showing up under the LibreNMS -> DEVICE -> Logs-> Syslog

After a bit of troubleshooting, found that the issue is the hostname being sent with the logs is different than what LibreNMS has for the device. It appears that some Linux distributions will or can use an abbreviated system hostname. There is a section in the LibreNMS docs about this

https://docs.librenms.org/Extensions/Syslog/#matching-syslogs-to-hosts-with-different-names

We can either do what the docs say, or we can set the host name in the rsyslog.conf file on each of the servers.

Log into the server and open up

sudo vi /etc/rsyslog.conf

At the very top, add the following line to set the hostname

$LocalHostName host.server_name_fqdn.com

Save the file and restart rsyslog

sudo systemctl restart rsyslog

Refresh the page to verify the logs are showing up in LibreNMS.

If you are still having issues, you may want to check the following

  1. SELinux on LibreNMS SELinux Audit Commands and Links, Setup LibreNMS as Syslog Server
  2. Firewall on LibreNMS FrDual Zones in Firewalld (Public/Private or External/Internal), Install LibreNMS on CentOS
  3. Read the documentation entirely through

Setup LibreNMS as Syslog Server

Using the LibreNMS documentation for setting up syslog-ng so LibreNMS can ingest logs from Cisco, Mikrotik, Ubiquiti etc. equipment.

https://docs.librenms.org/Extensions/Syslog/

Enable Syslog in LibreNMS settings

First thing we need to do is enable syslog for LibreNMS. Edit the /opt/librenms/config.php and add or enable

$config['enable_syslog'] = 1;

Install and Configure syslog-ng

Install syslog-ng with dnf or yum.

sudo dnf install -y syslog-ng

Create a config file for LibreNMS

vi /etc/syslog-ng/conf.d/librenms.conf

Put the following in the config file

source s_net {
        tcp(port(514) flags(syslog-protocol));
        udp(port(514) flags(syslog-protocol));
};

destination d_librenms {
        program("/opt/librenms/syslog.php" template ("$HOST||$FACILITY||$PRIORITY||$LEVEL||$TAG||$R_YEAR-$R_MONTH-$R_DAY $R_HOUR:$R_MIN:$R_SEC||$MSG||$PROGRAM\n") template-escape(yes));
};

log {
        source(s_net);
        source(s_sys);
        destination(d_librenms);
};

Restart and enable syslog-ng

sudo systemctl restart syslog-ng
sudo systemctl enable syslog-ng

SELinux

If we are running SELinux, we’ll need to make and apply a module to let the logs show up in the web interface.

vi librenms-rsyslog.te

Put the following in the file

module mycustom-librenms-rsyslog 1.0;

require {
        type syslogd_t;
        type httpd_sys_rw_content_t;
        type ping_exec_t;
        class process execmem;
        class dir { getattr search write };
        class file { append getattr execute open read };
}

#============= syslogd_t ==============
allow syslogd_t httpd_sys_rw_content_t:dir { getattr search write };
allow syslogd_t httpd_sys_rw_content_t:file { open read append getattr };
allow syslogd_t self:process execmem;
allow syslogd_t ping_exec_t:file execute;

Now run the following commands to make and apply our SELinux module.

checkmodule -M -m -o librenms-rsyslog.mod librenms-rsyslog.te
semodule_package -o librenms-rsyslog.pp -m librenms-rsyslog.mod
sudo semodule -i librenms-rsyslog.pp

Setting up HTTPS SSL/TLS Certificate for Grafana

Prerequisites

  1. Grafana Installed (Install guide)
  2. SSL/TLS Certificate

In this example, the server is already using Let’s Encrypt to create the certificate for a LibreNMS server. So all we are doing is copying the certificate to a Grafana directory, putting the correct permissions on it, and updating the Grafana config file to use the certificate.

Steps

  1. Copy Certificate to Grafana Directory
  2. Configure Grafana Config File
  3. Automate Certificate Copy to Grafana Directory

Copy Certificate files

In the following commands, change librenms.incredigeek.com to the directory that Let’s Encrypt is using for your fully qualified domain name (FQDN). Usually it is just your FQDN, but could also have -0001 or something appended to the end.

cp -f /etc/letsencrypt/live/librenms.incredigeek.com/privkey.pem 
/etc/grafana/ 
cp -f /etc/letsencrypt/live/librenms.incredigeek.com/fullchain.pem /etc/grafana/ 
chown root:grafana /etc/grafana/*.pem
chmod 640 /etc/grafana/*.pem Enable grafana on system bootup

In the above, we are copying the privkey.pem and fullchain.pem to /etc/grafana. We are then setting the correct owner/permissions on the files so that the Grafana service can read the certificate.

Configure Grafana Config File

This is super easy. Open up the Grafana config file in /etc/grafana.ini

vi /etc/grafana.ini

Find the following variables and configure them like so

protocol = https
cert_file = /etc/grafana/fullchain.pem
cert_key = /etc/grafana/privkey.pem

Restart Grafana

systemctl restart grafana-server.service

You should now have a working SSL certificate for the site.

Automate Certificate Copy

Let’s Encrypt certificates need to be updated frequently. This means that we should automate the above steps to avoid any down time. After all, a monitoring tool with down time defeats the purpose of monitoring.

We’ll need to create a root crontab

sudo crontab -e

Add the following changing out the FQDN to your FQDN.

0 0 1 * * cp -f /etc/letsencrypt/live/librenms.incredigeek.com/privkey.pem /etc/grafana/ && cp -f /etc/letsencrypt/live/librenms.incredigeek.com/fullchain.pem /etc/grafana/ && chown root:grafana /etc/grafana/*.pem && chmod 640 /etc/grafana/*.pem 

This is set to run once a month. Change if desired. Also change out librenms.incredigeek.com with your FQDN.

Note about domain name and IP addresses. Let’s Encrypt will not create a certificate for an IP address. You should be using a domain name instead (i.e. networkmonitoring.yourdomain.com) If the certificate is installed, and you access it via the IP address, you will receive a HTTPS error in your browser.

LibreNMS Error – Renaming of 192.168.1.20 failed. Does your web server have permission to modify the rrd files?

Renaming of 192.168.1.20 failed . Does your web server have permission to modify the rrd files?

First thing to check is verify that the IP address is not already being monitored.

If you are getting the above error while trying to rename a device in LibreNMS, you may need to rerun some of the SELinux commands from the installation.

SSH into the server and run

restorecon -RFvv /opt/librenms

Now try renaming the device. Note that you can’t rename the device if the name/ip to a name that is being used by a different device.

If you continue to have issues, check the permissions from the installation guide (Official guide here)

You can also check for SELinux errors with

audit2why < /var/log/audit/audit.log

More SELinux info here

Setting up RRDReST on CentOS 8 or AlmaLinux 9

There are some differences on setting up RRDReST on CentOS 8, Almalinux 9 vs CentOS 7

If you are setting this up to use with LibreNMS and Grafana, check out the rest of the this article. https://www.incredigeek.com/home/setting-up-grafana-on-librenms/

Installing RRDReST

All the docker commands have been swapped out for podman.

  1. Install Docker
  2. Create a compose file
  3. Run compose file to create container

Install docker

Podman is default on CentOS 8 and later and is, for the most part, a drop in replacement for Docker.

sudo yum install -y podman podman-compose
sudo systemctl enable podman

Create a Podman / Docker network to use. We’ll use this to assign a static IP address to the container. We’ll call the network rrdnet, and we’ll use the 10.89.2.0/24 range.

sudo podman network create --subnet=10.89.2.0/24 rrdnet

Create podman-compose file

Create a docker compose file

vi podman-compose.yml

Add the following

version: "3.5"
services:
  rrdrest:
    image: michaelwadman/rrdrest:latest
    container_name: rrdrest
    restart: always
    volumes:
      - "/opt/librenms/rrd:/opt/librenms/rrd:Z"
    environment:
      - TZ=America/Denver
    networks:
      rrdnet:
        ipv4_address: 10.89.2.2
        ipam:
          driver: default
          config:
            - subnet: 10.89.2.0/24
networks:
  rrdnet:
    external: true

Change the TZ to your time zone. If you have issues with the graphs, most likely something is off with the time zone between this container and Grafana/LibreNMS server

Note that the :Z is needed for SELinux to allow RRDReST to access the sub folders. AKA. the rrd files.

The container should have a 10.89.2.2 IP address. You can take all the networking sections out, and the container will receive DHCP. The problem is that the IP can change, breaking our graphs in Grafana.

Run RRDReST Container

Save the file. Then start and setup the container with

sudo podman-compose up -d

You will need your docker container IP address to setup the connection in Grafana. If you used the above docker-compose config, then it should be 10.89.2.2.

sudo docker exec -it rrdrest ip addr | grep eth0

Configure RRDRest to start on system boot with systemd

The “restart: always” option does not appear to work on systems with podman. We can create a systemd service instead.

Use the following command to automatically create a systemd file.

sudo podman generate systemd rrdrest

Copy the contents to a new file in /etc/systemd/system/

/etc/systemd/system/rrdrest.service

If you end up deleting the rrdrest container, you’ll need to update the systemd file again. You may need also need to run “systemctl daemon-reload”

Enable the new service with

systemctl enable rrdrest

Congratulations. RRDReST is now setup and running.

You can verify it’s running by checking with Podman / Docker.

sudo podman ps

You can also ping it

ping 10.89.2.2

Add Custom OID to device in LibreNMS

In the post, we’ll be adding a custom OID for a Ubiquiti Solar Charge Controller.

  • Find the device OID
  • Add the Custom OID in LibreNMS
  • Check the graph

Find the custom OID

Check out the following post if you are trying to add a Ubiquiti Solar Charge controller graph to LibreNMS. Otherwise you may need to do some googling around looking for the OID.

Add Custom OID in LibreNMS

Go to your device -> Settings(Little Gear) -> Custom OID -> +Add New OID

Adding Custom OID in LibreNMS for Ubiquiti UI Charge Controller

Couple notes about the information.
– There needs to be a 0 after the end of the OID.
– Data Type needs to be Gauge, Not Counter. A gauge can go up and down. A counter just counts up.

Hit “Test OID” and you should get a little notification saying it got a value for the OID. In this case 25572.

Test Custom OID in LibreNMS for Ubiquiti UI Charge Controller

Now Hit “Save OID”

Check the Graph

Now LibreNMS should start graphing our Custom OID. You may need to give it a minute to start showing data.

The graphs show up under Graphs -> Custom OID

Where are Custom OID Graphs?
LibreNMS Custom OID Graph

Setting up Grafana on LibreNMS

Thanks to the guys who put together the information at the following links.

https://wadman.co.nz/2021/01/02/Viewing-LibreNMS-data-in-Grafana/
https://www.reddit.com/r/LibreNMS/comments/ojc8cc/how_to_almost_natively_integrate_librenms_and/

I ran into some issues trying to get this to work. So here are some of my notes. I already had a LibreNMS installation set up.

  1. Install RRDReST
    1. Install Docker
    2. Configure Docker compose file
  2. Configure LibreNMS API User and Key
  3. Set up and Configure Grafana
    1. Install Grafana
    2. Install JSON Data Source Plugin
    3. Add LibreNMS API Data Source
    4. Add RRDReST Data Source
    5. Import Dashboard into Grafana
  4. View graphs

Installing RRDReST

NOTE FOR CENTOS 8, ALMALINUX 8 and 9
The steps for installing RRDReST are slightly different. Check out the following post.
https://www.incredigeek.com/home/setting-up-rrdrest-on-centos-8-or-almalinux-9/

I had issues installing RRDReST. I am guessing it had to do with it accessing files. I was able to install it in a docker container.

  1. Install Docker
  2. Create a compose file
  3. Install container

Install docker

sudo yum install -y docker docker-compose
sudo systemctl enable docker

Create docker compose file with the following options

vi docker-compose.yml

Change the TZ to your time zone. If you have issues with the graphs, most likely something is off with the time zone between this container and Grafana/LibreNMS server

version: "3.5"

services:

  rrdrest:
    image: michaelwadman/rrdrest:latest
    container_name: rrdrest
    restart: always
    volumes:
      - "/opt/librenms:/opt/librenms"
    environment:
      - TZ=America/Denver

Save the file and start and setup the container with

sudo docker-compose up -d

You will need your docker container IP address to setup the connection in Grafana

sudo docker exec -it rrdrest ip addr | grep eth0

Congratulations. You should now have a RRDReST docker container that will auto start on system boot and has the correct time zone.

Configure LibreNMS API User and Key

  1. Create a Grafana user in LibreNMS. (Settings Gear -> Manage Users -> Add Users)
    You could technically skip this step and use an existing user.
  2. Create API token for the newly created user (Setting Gear -> API -> API Settings)
Create a Grafana user in LibreNMS
Setup API Key for Grafana in LibreNMS

Set up and Configure Grafana

Basic steps are as follows

  1. Install Grafana
  2. Install JSON Data Source Plugin
  3. Configure Data Sources
    1. LibreNMS API
    2. RRDRest API
  4. Import Dashboard into Grafana

Install Grafana

There is not anything special with installing Grafana on the same server as LibreNMS. You can follow the official guide to install it

https://grafana.com/docs/grafana/latest/installation/

After Grafana is installed, install the JSON API data source. You can do this using the grafana-cli

grafana-cli plugins install marcusolsson-json-datasource

A note on SSL/TLS certificates. If you have an SSL certificate for LibreNMS, you can use it for grafana. If you run into issues, try copying the cert (fullchain.pem, privkey.pem) to /etc/grafana/

You’ll most likely need to change owner

sudo chown root:grafana /etc/grafana/*.pem

And maybe the file permissions.

sudo chmod 640 /etc/grafana/*.pem

Install JSON Data Source Plugin

This is fairly straight forward.

grafana-cli plugins install marcusolsson-json-datasource

Add LibreNMS API Data Source

In Grafana, go to Configuration -> Data Sources -> Add data source

  • Set Name for Data Source
  • URL should be https://your_librenms_url/api/v0
  • Add Custom HTTP Header
    • Header field should be “X-Auth-Token”
    • Value field should contain the API token we created in LibreNMS
  • Save and Test
    If you receive any errors, refer to the Troubleshooting part at the end.
Adding LibreNMS API Data Source in Grafana

Add RRDReST Data Source

In Grafana, go to Configuration -> Data Sources -> Add data source

  • Set Name for Data Source
  • URL needs to be your docker container IP address (Steps above)
  • Save and Test (Should return “Unprocessable Entity”)
Adding RRDReST API Data Source in Grafana

Import Dashboard into Grafana

Now we need a dashboard to present our data.

  • Go to Create -> Import
  • Upload JSON file (Download from here or PasteBin )
  • Under RRDReST API , select our RRDReST Data Source
  • Under LibreNMS API , select our LibreNMS Data Source
  • Click Import

You should now be able to view your dashboard and use the drop down menus to select devices

Grafana viewing bandwidth on device being monitored by LibreNMS

Troubleshooting

There were a couple of issues I ran into while trying to get everything working together.

RRDReST shows 404 Not Found

Issue: When trying to run RRDReST with uvicorn, I was never able to access the rrd files, even the test rrd files that are included when installing RRDReST. I am guessing it is either a permisions issue, or something unable to access the files.
Work around: Install RRDReST via Docker container.

Error Running uvicorn RRDReST

Error Adding LibreNMS API

Issue: Get a “JSON API: Bad Request” when trying to set up the LibreNMS API Data Source in Grafana.

Work around: Install a valid SSL Certificate and set up a DNS record so you can access LibreNMS at librenms.yourdomain.com.

More info: I would assume that “Skip TLS Verify” would work with or without a valid certificate, but it would not work for me. There are potentially some other options with modifying how Nginx or Apache is set up that would get this working. If you setup Grafana to use a SSL certificate, you may need to copy the certificate files (fullchain.pem, privkey.pem) to /etc/grafana/ and run “chown root:grafana *.pem” to let grafana have access to the files.

Grafana LibreNMS API JSON API: Bad Request