Tutorials to support v1.20 release (#7943)

* Add draft of CockroachDB tutorial

* Fixed and new images

* Support figures for images

* Change border color

* Change job

* Initialize eBPF tutorial

* Very very rough draft of host labels tutorial

* Add a few mentions of tutorial

* Fix for Thiago

* Simplify health entities

* Fixes for Thiago

* Fixes and add tutorials to collectors README

* Fixes to cockroachBD

* Remove ebpf tutorial

* remove link

* Updates for Patti and Thiago

* Add streaming security note

* Straightaway

4 files changed, 353 insertions, 2 deletions

diff --git a/docs/configuration-guide.md b/docs/configuration-guide.md
index 0c6d934e49..a30149cb2a 100644
--- a/docs/configuration-guide.md
+++ b/docs/configuration-guide.md
@@ -187,7 +187,12 @@ So, Netdata supports [simple patterns](../libnetdata/simple_pattern/).
 
 ## Netdata labels
 
-Since version 1.20, Netdata accepts user defined labels for host. The labels are defined in the section `[host labels]`.
+Beginning with  1.20, Netdata accepts user-defined **host labels**. These labels are defined in the section `[host
+labels]`.
+
+Read more about how these labels work and why they're an effective way to organize complex infrasturctures in our
+tutorial: [Use host labels to organize systems, metrics, and alarms](tutorials/using-host-labels.md).
+
 To define a label inside this section, some rules needs to be followed, or Netdata will reject the label. The following
 restrictions are applied for label names:
  
diff --git a/docs/generator/custom/css/netdata.css b/docs/generator/custom/css/netdata.css
index 7b1c2e2ef9..9aa751b0b4 100644
--- a/docs/generator/custom/css/netdata.css
+++ b/docs/generator/custom/css/netdata.css
@@ -429,6 +429,21 @@ html [data-md-color-primary="blue-grey"] .md-nav--primary .md-nav__title--site {
     font-size: 0.75rem;
 }
 
+/* Support figures and figcaptions with some styling. */
+.md-typeset figure img {
+    border-radius: 3px 3px 0 0;
+}
+
+.md-typeset figure figcaption {
+    font-size: 0.75rem;
+    font-style: italic;
+    margin-top: -8px;
+    padding: 0.5rem;
+    border-width: 0 1px 1px 1px;
+    border-color: #AEB3B7;
+    border-style: solid;
+}
+
 /*
    Installer grid
 */
@@ -443,7 +458,7 @@ html [data-md-color-primary="blue-grey"] .md-nav--primary .md-nav__title--site {
 .grid-item {
     grid-column: span 2;
     border-radius: 2px;
-    border: 1px solid black;
+    border: 1px solid #AEB3B7;
     padding: 1rem;
 }
 
diff --git a/docs/tutorials/monitor-cockroachdb.md b/docs/tutorials/monitor-cockroachdb.md
new file mode 100644
index 0000000000..7850a693f4
--- /dev/null
+++ b/docs/tutorials/monitor-cockroachdb.md
@@ -0,0 +1,128 @@
+# Monitor CockroachDB metrics with Netdata
+
+[CockroachDB](https://github.com/cockroachdb/cockroach) is an open-source project that brings SQL databases into
+scalable, disaster-resilient cloud deployments. Thanks to a [new CockroachDB
+collector](https://docs.netdata.cloud/collectors/go.d.plugin/modules/cockroachdb/) released in
+[v1.20](https://blog.netdata.cloud/posts/release-1.20/), you can now monitor any number of CockroachDB databases with
+maximum granularity using Netdata. Collect more than 50 unique metrics and put them on interactive visualizations
+designed for better visual anomaly detection.
+
+Netdata itself uses CockroachDB as part of its Netdata Cloud infrastructure, so we're happy to introduce this new
+collector and help others get started with it straightaway.
+
+Let's dive in and walk through the process of monitoring CockroachDB metrics with Netdata.
+
+## What's in this guide
+
+-   [Configure the CockroachDB collector](#configure-the-cockroachdb-collector)
+    -   [Manual setup for a local CockroachDB database](#manual-setup-for-a-local-cockroachdb-database)
+-   [Tweak CockroachDB alarms](#tweak-cockroachdb-alarms)
+
+## Configure the CockroachDB collector
+
+Because _all_ of Netdata's collectors can auto-detect the services they monitor, you _shouldn't_ need to worry about
+configuring CockroachDB. Netdata only needs to regularly query the database's `_status/vars` page to gather metrics and
+display them on the dashboard.
+
+If your CockroachDB instance is accessible through `http://localhost:8080/` or `http://127.0.0.1:8080`, your setup is
+complete. Restart Netdata with `service netdata restart`, or use the [appropriate
+method](../getting-started.md#start-stop-and-restart-netdata) for your system, and refresh your browser. You should see
+CockroachDB metrics in your Netdata dashboard!
+
+<figure>
+  <img src="https://user-images.githubusercontent.com/1153921/73564467-d7e36b00-441c-11ea-9ec9-b5d5ea7277d4.png" alt="CPU utilization charts from a CockroachDB database monitored by Netdata">
+  <figcaption>CPU utilization charts from a CockroachDB database monitored by Netdata</figcaption>
+</figure>
+
+> Note: Netdata collects metrics from CockroachDB every 10 seconds, instead of our usual 1 second, because CockroachDB
+> only updates `_status/vars` every 10 seconds. You can't change this setting in CockroachDB.
+
+If you don't see CockroachDB charts, you may need to configure the collector manually.
+
+### Manual setup for a local CockroachDB database
+
+To configure Netdata's CockroachDB collector, navigate to your Netdata configuration directory (typically at
+`/etc/netdata/`) and use `edit-config` to initialize and edit your CockroachDB configuration file.
+
+```bash
+cd /etc/netdata/ # Replace with your Netdata configuration directory, if not /etc/netdata/
+./edit-config go.d/cockroachdb.conf
+```
+
+Scroll down to the `[JOBS]` section at the bottom of the file. You will see the two default jobs there, which you can
+edit, or create a new job with any of the parameters listed above in the file. Both the `name` and `url` values are
+required, and everything else is optional.
+
+For a production cluster, you'll use either an IP address or the system's hostname. Be sure that your remote system
+allows TCP communication on port 8080, or whichever port you have configured CockroachDB's [Admin
+UI](https://www.cockroachlabs.com/docs/stable/monitoring-and-alerting.html#prometheus-endpoint) to listen on.
+
+```yaml
+# [ JOBS ]
+jobs:
+  - name: remote
+    url: http://203.0.113.0:8080/_status/vars
+
+  - name: remote_hostname
+    url: http://cockroachdb.example.com:8080/_status/vars
+```
+
+For a secure cluster, use `https` in the `url` field instead.
+
+```yaml
+# [ JOBS ]
+jobs:
+  - name: remote
+    url: https://203.0.113.0:8080/_status/vars
+    tls_skip_verify: yes # If your certificate is self-signed
+    
+  - name: remote_hostname
+    url: https://cockroachdb.example.com:8080/_status/vars
+    tls_skip_verify: yes # If your certificate is self-signed
+```
+
+You can add as many jobs as you'd like based on how many CockroachDB databases you have—Netdata will create separate
+charts for each job. Once you've edited `cockroachdb.conf` according to the needs of your infrastructure, restart
+Netdata to see your new charts.
+
+<figure>
+  <img src="https://user-images.githubusercontent.com/1153921/73564469-d7e36b00-441c-11ea-8333-02ba0e1c294c.png" alt="Charts showing a node failure during a simulated test">
+  <figcaption>Charts showing a node failure during a simulated test</figcaption>
+</figure>
+
+## Tweak CockroachDB alarms
+
+This release also includes eight pre-configured alarms for live nodes, such as whether the node is live, storage
+capacity, issues with replication, and the number of SQL connections/statements. See [health.d/cockroachdb.conf on
+GitHub](https://raw.githubusercontent.com/netdata/netdata/master/health/health.d/cockroachdb.conf) for details.
+
+You can also edit these files directly with `edit-config`:
+
+```bash
+cd /etc/netdata/ # Replace with your Netdata configuration directory, if not /etc/netdata/
+./edit-config health.d/cockroachdb.conf # You may need to use `sudo` for write privileges
+```
+
+For more information about editing the defaults or writing new alarm entities, see our health monitoring [quickstart
+guide](../../health/QUICKSTART.md).
+
+## What's next?
+
+Now that you're collecting metrics from your CockroachDB databases, let us know how it's working for you! There's always
+room for improvement or refinement based on real-world use cases. Feel free to [file an
+issue](https://github.com/netdata/netdata/issues/new?labels=bug%2C+needs+triage&template=bug_report.md) with your
+thoughts.
+
+Also, be sure to check out these useful resources:
+
+-   [Netdata's CockroachDB documentation](https://docs.netdata.cloud/collectors/go.d.plugin/modules/cockroachdb/)
+-   [Netdata's CockroachDB
+    configuration](https://github.com/netdata/go.d.plugin/blob/master/config/go.d/cockroachdb.conf)
+-   [Netdata's CockroachDB
+    alarms](https://github.com/netdata/netdata/blob/29d9b5e51603792ee27ef5a21f1de0ba8e130158/health/health.d/cockroachdb.conf)
+-   [CockroachDB homepage](https://www.cockroachlabs.com/product/)
+-   [CockroachDB documentation](https://www.cockroachlabs.com/docs/stable/)
+-   [`_status/vars` endpoint
+    docs](https://www.cockroachlabs.com/docs/stable/monitoring-and-alerting.html#prometheus-endpoint)
+-   [Monitor CockroachDB with
+    Prometheus](https://www.cockroachlabs.com/docs/stable/monitor-cockroachdb-with-prometheus.html)
diff --git a/docs/tutorials/using-host-labels.md b/docs/tutorials/using-host-labels.md
new file mode 100644
index 0000000000..4e8152e9f4
--- /dev/null
+++ b/docs/tutorials/using-host-labels.md
@@ -0,0 +1,203 @@
+# 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 `master` or `slave` 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](https://blog.netdata.cloud/posts/release-1.20/), 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`.
+
+```bash
+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](../configuration-guide.md#netdata-labels).
+
+```conf
+[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:
+
+```bash
+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:
+
+```json
+{
+  ...
+  "host_labels": {
+    "_is_master": "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,
+streaming/master 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
+-   What virtualization layer the system runs on top of, if any
+-   Whether the system is a streaming master or slave
+
+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_master` and `_is_slave` automatic labels from above. Host labels are also now streamed
+from a slave to its master agent, which concentrates an entire infrastructure's OS, hardware, container, and
+virtualization information in one place: the master.
+
+Now, if you'd like to remind yourself of how much RAM a certain slave system has, you can simply access
+`http://localhost:19999/host/SLAVE_NAME/api/v1/info` and reference the automatically-generated host labels from the
+slave system. It's a vastly simplified way of accessing critical information about your infrastructure.
+
+> ⚠️ Because automatic labels for slave 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](../..//streaming/README.md#securing-streaming-communications) for details. You may also want to use
+> [access lists](../../web/server/README.md#access-lists) or [expose the API only to LAN/localhost
+> connections](../netdata-security.md#expose-netdata-only-in-a-private-lan).
+
+You can also use `_is_master`, `_is_slave`, 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:
+
+```conf
+[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`:
+
+```yaml
+    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:
+
+```yaml
+ host labels: _os_name = Debian*
+```
+
+In a streaming configuration where a master agent is triggering alarms for its slaves, you could create health entities
+that apply only to slaves:
+
+```yaml
+ host labels: _is_slave = true
+```
+
+Or when ephemeral Docker nodes are involved:
+
+```yaml
+ host labels: _container = docker
+```
+
+Of course, there are many more possibilities for intuitively organizing your systems with host labels. See the [health
+documentation](../../health/REFERENCE.md#alarm-line-host-labels) for more details, and then get creative!
+
+## Host labels in metrics exporting
+
+If you have enabled any metrics exporting via our experimental [exporters](../../exporting/README.md), 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.
+
+```conf
+[exporting:global]
+enabled = yes
+send configured labels = yes
+send automatic labels = no
+```
+
+You can also change this behavior per exporting connection:
+
+```conf
+[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](../../exporting/README.md).
+
+## 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](https://github.com/netdata/netdata/issues/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 
+
+-   [Expose Netdata only in a private LAN](../netdata-security.md#expose-netdata-only-in-a-private-lan)
+-   [Enable TLS/SSL for web/API requests](../../web/server/README.md#enabling-tls-support)
+-   Put Netdata behind a proxy
+    -   [Use an authenticating web server in proxy
+        mode](../netdata-security.md#use-an-authenticating-web-server-in-proxy-mode)
+    -   [Nginx proxy](../Running-behind-nginx.md)
+    -   [Apache proxy](../Running-behind-apache.md)
+    -   [Lighttpd](../Running-behind-lighttpd.md)
+    -   [Caddy](../Running-behind-caddy.md)
+
+If you have issues or questions around using host labels, don't hesitate to [file an
+issue](https://github.com/netdata/netdata/issues/new?labels=bug%2C+needs+triage&template=bug_report.md) on GitHub. We're
+excited to make host labels even more valuable to our users, which we can only do with your input.