Issue #485: Document the Splunk Integration

* Wrote the 1st draft

metricshub-doc/src/site/markdown/integration/splunk.md

@@ -0,0 +1,64 @@
+keywords: splunk, integration, signal fx, splunk observability cloud
+description: How to push the metrics collected by MetricsHub to Splunk Observability Cloud
+
+# Splunk integration
+
+<!-- MACRO{toc|fromDepth=1|toDepth=2|id=toc} -->
+
+**MetricsHub** integrates seamlessly into Splunk Observability Cloud throught the [Splunk SignalFx exporter](https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/exporter/signalfxexporter). 
+
+![MetricsHub pushes the collected metrics to Splunk](../images/metricshub-splunk-diagram.png)
+
+This integration allows you to:
+
+* visualize IT infrastructure and sustainability metrics in your Splunk Observability Cloud platform 
+* be informed when hardware failures are detected.
+
+![Splunk alert for a failed disk detected by MetricsHub](../images/splunk-dashboard-hardware-main-failed-disk-alert.png)
+
+## Prerequisites
+
+Before you can start viewing the metrics collected by **MetricsHub** in Splunk Observability Cloud, you must have:
+
+1. [Installed **MetricsHub**](../installation/index.md) on one or more systems that has network access to the resources to be monitored
+2. [Configured the monitoring of your resources](../configuration/configure-monitoring.md)
+3. [configured the sustainability metrics](../guides/configure-sustainability-metrics.md)
+4. Generated an access token as explained in the [Splunk User Documentation](https://docs.splunk.com/observability/en/admin/authentication/authentication-tokens/manage-usage.html). 
+
+## Configuration
+
+### Pushing metrics to Splunk Observability Cloud
+
+1. In the `exporters` section of the `otel/otel-config.yaml` configuration file, 
+provide the access token to connect to the SignalFx exporter,
+and other additional settings:
+
+    ```yaml
+      signalfx:
+        access_token: <access_token> # Access token to send data to SignalFx.
+        realm: eu0 # SignalFx realm where the data will be received.
+        timeout: 10s # Timeout for the send operations.
+        sync_host_metadata: true # Whether the exporter should scrape host metadata.
+    ```
+2. Declare the exporter in the pipeline section of `otel/otel-config.yaml`:
+
+    ```yaml
+      service:
+        extensions: [health_check, basicauth]
+        pipelines:
+          metrics:
+            receivers: [otlp, prometheus/internal]
+            processors: [memory_limiter, batch, metricstransform]
+            exporters: [signalfx] # List SignalFx here
+    ```
+3. Finally, restart **MetricsHub** to ensure that the configuration changes are taken into account.
+
+### Using the Hardware dashboards
+
+**MetricsHub** includes a collection of dashboards to expose infrastructure observability and sustainability KPIs:
+
+Dashboard                                                                                                                  | Description                                                                                     |
+-----------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------|
+| **Hardware - Main**![Hardware Main - Overview of all monitored sites](../images/splunk-dashboard-hardware-main.png)                            | Overview of all monitored systems, focusing on key hardware and sustainability metrics.         |
+|**Hardware - Site**![Hardware Site - Metrics associated to one site and its monitored hosts](../images/splunk-dashboard-hardware-site.png)     | Metrics specific to a particular site (a data center or a server room) and its monitored hosts. |
+|**Hardware - Host** ![Hardware Host - Metrics associated to one host and its internal components](../images/splunk-dashboard-hardware-host.png) | Metrics associated with one *host* and its internal devices. |

metricshub-doc/src/site/markdown/prometheus/prometheus.md

@@ -39,12 +39,12 @@ Before you can start viewing the metrics collected by **MetricsHub** in Promethe
 3. Declare the exporter in the pipeline section of **otel/otel-config.yaml**:
 
     ```yaml
-    service:
-      extensions: [health_check]
-      pipelines:
-        metrics:
-          receivers: [otlp, prometheus/internal]
-          processors: [memory_limiter, batch, resourcedetection, metricstransform]
-          exporters: [prometheusremotewrite/your-prom-server] # Declare your prometheus prometheusremotewrite exporter
+      service:
+        extensions: [health_check, basicauth]
+        pipelines:
+          metrics:
+            receivers: [otlp, prometheus/internal]
+            processors: [memory_limiter, batch, metricstransform]
+            exporters: [prometheusremotewrite/com-mh, prometheus] # List here the platform of your choice
     ```
 4. Finally, restart Prometheus then MetricsHub to ensure that the configuration changes take effect.

metricshub-doc/src/site/site.xml

@@ -102,6 +102,7 @@
 			<item name="Prometheus" href="prometheus/prometheus.html" />
 				<item name="Prometheus AlertManager" href="prometheus/alertmanager.html" />
 				<item name="Grafana Dashboards" href="prometheus/grafana.html" />
+			<item name="Splunk" href="integration/splunk.html" />
 		</menu>
 
 		<menu name="Guides">