Docs: Refactor data sources content (#57573)

* Docs: Revise data source index * Docs: Consolidate data source administration docs * Docs: Revise panels docs related to data sources * Docs: Revise Alertmanager data source * Docs: Reorganize AWS CloudWatch data source docs * Docs: Reorganize Azure Monitor data source docs * Docs: Move azuremonitor to azure-monitor * Docs: Revise Elasticsearch docs * Docs: Move Elasticsearch index into bundle * Docs: Revise GCM docs * Docs: Revise Graphite docs * Docs: Move Graphite index into bundle * Docs: Revise InfluxDB docs * Docs: Revise Jaeger docs * Docs: Move Jaeger index into bundle * Docs: Revise Loki docs * Docs: Move Loki index into bundle * Docs: Revise MS SQL docs * Docs: Move MS SQL index into bundle * Docs: Revise Prometheus docs * Docs: Move Prometheus index into bundle * Docs: Revise Tempo docs * Docs: Move Tempo index into bundle * Docs: Revise TestData DB docs * Docs: Move TestData DB index into bundle * Docs: Revise Zipkin docs * Docs: Move Zipkin index into bundle * Docs: Move other data sources' index pages into bundles * Docs: Revise frontmatter * Fixing hugo markdown errors * Docs: Add query editor and template var sections to overview doc * Docs: Remove CTAs across data source docs * Docs: Remove CTA * Docs: Remove CTA * Docs: Fix links, images, typos, and usage consistency. * Docs: Fix typos * Docs: Fix CI issues * Update docs/sources/datasources/_index.md Co-authored-by: Torkel Ödegaard <torkel@grafana.com> * Update docs/sources/datasources/_index.md Co-authored-by: Torkel Ödegaard <torkel@grafana.com> * Docs: Fix query editor links * Update docs/sources/panels-visualizations/_index.md Co-authored-by: Torkel Ödegaard <torkel@grafana.com> * Update docs/sources/panels-visualizations/_index.md Co-authored-by: Torkel Ödegaard <torkel@grafana.com> * Docs: Rebundle child pages per writers' toolkit * Docs: Fix prettier for CI * Docs: Fix relrefs from outside data sources docs * Docs: Fix broken relrefs within datasources * Docs: Fix relrefs to data sources docs * Fixed some more refs Co-authored-by: Torkel Ödegaard <torkel@grafana.com>
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+---
+aliases:
+  - /docs/grafana/latest/datasources/elasticsearch/template-variables/
+  - /docs/grafana/latest/data-sources/elasticsearch/template-variables/
+description: Using template variables with Elasticsearch in Grafana
+keywords:
+  - grafana
+  - elasticsearch
+  - templates
+  - variables
+  - queries
+menuTitle: Template variables
+title: Elasticsearch template variables
+weight: 400
+---
+
+# Elasticsearch template variables
+
+Instead of hard-coding details such as server, application, and sensor names in metric queries, you can use variables.
+Grafana lists these variables in dropdown select boxes at the top of the dashboard to help you change the data displayed in your dashboard.
+Grafana refers to such variables as template variables.
+
+For an introduction to templating and template variables, refer to the [Templating]({{< relref "../../../dashboards/variables" >}}) and [Add and manage variables]({{< relref "../../../dashboards/variables/add-template-variables" >}}) documentation.
+
+## Choose a variable syntax
+
+The Elasticsearch data source supports two variable syntaxes for use in the **Query** field:
+
+- `$varname`, such as `hostname:$hostname`, which is easy to read and write but doesn't let you use a variable in the middle of a word.
+- `[[varname]]`, such as `hostname:[[hostname]]`
+
+When the _Multi-value_ or _Include all value_ options are enabled, Grafana converts the labels from plain text to a Lucene-compatible condition.
+For details, see the [Multi-value variables]({{< relref "../../../dashboards/variables/add-template-variables#multi-value-variables" >}}) documentation.
+
+## Use variables in queries
+
+You can use other variables inside the query.
+This example is used to define a variable named `$host`:
+
+```
+{"find": "terms", "field": "hostname", "query": "source:$source"}
+```
+
+This uses another variable named `$source` inside the query definition.
+Whenever you change the value of the `$source` variable via the dropdown, Grafana triggers an update of the `$host` variable to contain only hostnames filtered by, in this case, the `source` document property.
+
+These queries by default return results in term order (which can then be sorted alphabetically or numerically as for any variable).
+To produce a list of terms sorted by doc count (a top-N values list), add an `orderBy` property of "doc_count".
+This automatically selects a descending sort.
+
+> **Note:** To use an ascending sort (`asc`) with doc_count (a bottom-N list), set `order: "asc"`. However, Elasticsearch [discourages this](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-terms-aggregation.html#search-aggregations-bucket-terms-aggregation-order) because sorting by ascending doc count can return inaccurate results.
+
+To keep terms in the doc count order, set the variable's Sort dropdown to **Disabled**.
+You can alternatively use other sorting criteria, such as **Alphabetical**, to re-sort them.
+
+```
+{"find": "terms", "field": "hostname", "orderBy": "doc_count"}
+```
+
+## Template variable examples
+
+{{< figure src="/static/img/docs/elasticsearch/elastic-templating-query-7-4.png" max-width="500px" class="docs-image--no-shadow" caption="Query with template variables" >}}
+
+In the above example, a Lucene query filters documents based on the `hostname` property using a variable named `$hostname`.
+The example also uses a variable in the _Terms_ group by field input box, which you can use to quickly change how data is grouped.
+
+To view an example dashboard on Grafana Play, see the [Elasticsearch Templated Dashboard](https://play.grafana.org/d/CknOEXDMk/elasticsearch-templated?orgId=1d).