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Use host labels to organize systems, metrics, and alarms

When you use Netdata to monitor and troubleshoot an entire infrastructure, whether that's dozens or hundreds of systems, you need sophisticated ways of keeping everything organized. You need alarms that adapt to the system's purpose, or whether the parent or child in a streaming setup. You need properly-labeled metrics archiving so you can sort, correlate, and mash-up your data to your heart's content. You need to keep tabs on ephemeral Docker containers in a Kubernetes cluster.

You need host labels: a powerful new way of organizing your Netdata-monitored systems. We introduced host labels in v1.20 of Netdata, and they come pre-configured out of the box.

Let's take a peek into how to create host labels and apply them across a few of Netdata's features to give you more organization power over your infrastructure.

Create unique host labels

Host labels are defined in netdata.conf. To create host labels, open that file using edit-config.

cd /etc/netdata   # Replace this path with your Netdata config directory, if different
sudo ./edit-config netdata.conf

Create a new [host labels] section defining a new host label and its value for the system in question. Make sure not to violate any of the host label naming rules.

[host labels]
    type = webserver
    location = us-seattle
    installed = 20200218

Once you've written a few host labels, you need to enable them. Instead of restarting the entire Netdata service, you can reload labels using the helpful netdatacli tool:

netdatacli reload-labels

Your host labels will now be enabled. You can double-check these by using curl http://HOST-IP:19999/api/v1/info to read the status of your agent. For example, from a VPS system running Debian 10:

{
  ...
  "host_labels": {
    "_is_k8s_node": "false",
    "_is_parent": "false",
    "_virt_detection": "systemd-detect-virt",
    "_container_detection": "none",
    "_container": "unknown",
    "_virtualization": "kvm",
    "_architecture": "x86_64",
    "_kernel_version": "4.19.0-6-amd64",
    "_os_version": "10 (buster)",
    "_os_name": "Debian GNU/Linux",
    "type": "webserver",
    "location": "seattle",
    "installed": "20200218"
  },
  ...
}

You may have noticed a handful of labels that begin with an underscore (_). These are automatic labels.

Automatic labels

When Netdata starts, it captures relevant information about the system and converts them into automatically-generated host labels. You can use these to logically organize your systems via health entities, exporting metrics, parent-child status, and more.

They capture the following:

  • Kernel version
  • Operating system name and version
  • CPU architecture, system cores, CPU frequency, RAM, and disk space
  • Whether Netdata is running inside of a container, and if so, the OS and hardware details about the container's host
  • Whether Netdata is running inside K8s node
  • What virtualization layer the system runs on top of, if any
  • Whether the system is a streaming parent or child

If you want to organize your systems without manually creating host tags, try the automatic labels in some of the features below.

Host labels in streaming

You may have noticed the _is_parent and _is_child automatic labels from above. Host labels are also now streamed from a child to its parent node, which concentrates an entire infrastructure's OS, hardware, container, and virtualization information in one place: the parent.

Now, if you'd like to remind yourself of how much RAM a certain child node has, you can access http://localhost:19999/host/CHILD_HOSTNAME/api/v1/info and reference the automatically-generated host labels from the child system. It's a vastly simplified way of accessing critical information about your infrastructure.

⚠️ Because automatic labels for child nodes are accessible via API calls, and contain sensitive information like kernel and operating system versions, you should secure streaming connections with SSL. See the streaming documentation for details. You may also want to use access lists or expose the API only to LAN/localhost connections.

You can also use _is_parent, _is_child, and any other host labels in both health entities and metrics exporting. Speaking of which...

Host labels in health entities

You can use host labels to logically organize your systems by their type, purpose, or location, and then apply specific alarms to them.

For example, let's use configuration example from earlier:

[host labels]
    type = webserver
    location = us-seattle
    installed = 20200218

You could now create a new health entity (checking if disk space will run out soon) that applies only to any host labeled webserver:

    template: disk_fill_rate
          on: disk.space
      lookup: max -1s at -30m unaligned of avail
        calc: ($this - $avail) / (30 * 60)
       every: 15s
 host labels: type = webserver

Or, by using one of the automatic labels, for only webserver systems running a specific OS:

 host labels: _os_name = Debian*

In a streaming configuration where a parent node is triggering alarms for its child nodes, you could create health entities that apply only to child nodes:

 host labels: _is_child = true

Or when ephemeral Docker nodes are involved:

 host labels: _container = docker

Of course, there are many more possibilities for intuitively organizing your systems with host labels. See the health documentation for more details, and then get creative!

Host labels in metrics exporting

If you have enabled any metrics exporting via our experimental exporters, any new host labels you created manually are sent to the destination database alongside metrics. You can change this behavior by editing exporting.conf, and you can even send automatically-generated labels on with exported metrics.

[exporting:global]
enabled = yes
send configured labels = yes
send automatic labels = no

You can also change this behavior per exporting connection:

[opentsdb:my_instance3]
enabled = yes
destination = localhost:4242
data source = sum
update every = 10
send charts matching = system.cpu
send configured labels = no
send automatic labels = yes

By applying labels to exported metrics, you can more easily parse historical metrics with the labels applied. To learn more about exporting, read the documentation.

What's next?

Host labels are a brand-new feature to Netdata, and yet they've already propagated deeply into some of its core functionality. We're just getting started with labels, and will keep the community apprised of additional functionality as it's made available. You can also track issue #6503, which is where the Netdata team first kicked off this work.

It should be noted that while the Netdata dashboard does not expose either user-configured or automatic host labels, API queries do showcase this information. As always, we recommend you secure Netdata

If you have issues or questions around using host labels, don't hesitate to file an issue on GitHub. We're excited to make host labels even more valuable to our users, which we can only do with your input.

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