K8s: modules (#2071)

* rough draft

* add upgrade considerations

* changes from SME meeting

Author: kaitlynmichael

content/operate/kubernetes/re-databases/modules.md

@@ -0,0 +1,102 @@
+---
+Title: Configure modules
+alwaysopen: false
+categories:
+- docs
+- operate
+- kubernetes
+description: Deploy Redis Enterprise databases with modules using the Redis Enterprise operator for Kubernetes.
+linkTitle: Configure modules
+weight: 15
+---
+
+Redis Enterprise modules extend Redis functionality with additional data types, commands, and capabilities. The Redis Enterprise operator supports deploying databases with modules through the `RedisEnterpriseDatabase` (REDB) and `RedisEnterpriseActiveActiveDatabase` (REAADB) custom resources.
+
+## Prerequisites
+
+Before you begin, verify that you have:
+
+- [Redis Enterprise operator deployed]({{< relref "/operate/kubernetes/deployment/quick-start" >}}) in your Kubernetes cluster
+- [Redis Enterprise Cluster (REC)]({{< relref "/operate/kubernetes/re-clusters" >}}) running and in a healthy state
+- Modules uploaded to the Redis Enterprise cluster (see [Check available modules](#check-available-modules))
+
+## Available modules
+
+Redis Enterprise includes several built-in modules:
+
+| Module | Name | Description |
+|--------|------|-------------|
+| **[RediSearch]({{< relref "/develop/interact/search-and-query" >}})** | `search` | Full-text search and secondary indexing |
+| **[RedisJSON]({{< relref "/develop/data-types/json" >}})** | `ReJSON` | JSON data type support |
+| **[RedisTimeSeries]({{< relref "/develop/data-types/timeseries" >}})** | `timeseries` | Time series data structures |
+| **[RedisBloom]({{< relref "/develop/data-types/probabilistic" >}})** | `bf` | Probabilistic data structures (Bloom filters, etc.) |
+
+### Check available modules
+
+Before configuring databases with modules, check which modules are available in your cluster:
+
+```bash
+kubectl get rec <cluster-name> -o jsonpath='{.status.modules}' | jq
+```
+
+This command shows the modules installed in the cluster along with their available versions.
+
+{{< note >}}
+Use the `NAME` field instead of the `DISPLAY_NAME` field when configuring databases with modules.
+{{< /note >}}
+
+## Install additional modules
+
+If you need to install additional modules or specific versions, upload them using the Redis Enterprise API. See [Upload module v2]({{< relref "/operate/rs/references/rest-api/requests/modules/#post-module-v2" >}}) for more information.
+
+## Module configuration
+
+Each module in the [`modulesList`]({{< relref "/operate/kubernetes/reference/api/redis_enterprise_database_api#specmoduleslist" >}}) supports the following fields:
+
+- **name** (required): The module name (for example, "search", "ReJSON")
+- **version** (optional): Specific module version. For Active-Active databases, if specified for one participating cluster, it must be specified for all participating clusters. If omitted, modules will auto-update.
+- **config** (optional): Module-specific configuration parameters
+
+For detailed module configuration options and parameters, see [Redis modules]({{< relref "/develop/reference/modules" >}}).
+
+## Upgrade considerations
+
+When upgrading Redis Enterprise clusters or the operator with modules, follow these guidelines:
+
+#### Pre-upgrade planning
+
+- **Check module compatibility**: Verify that your current module versions are compatible with the target Redis Enterprise version. Check each module's [`min_redis_version`](https://redis.io/docs/latest/operate/rs/references/rest-api/objects/module/) requirement.
+- **Review module dependencies**: Some modules may have specific version requirements or dependencies
+- **Document current configurations**: Record all module versions and configurations before upgrading
+- **Test in non-production**: Always test module upgrades in a development or staging environment first
+
+#### Module version management during upgrades
+
+- **Upload required modules**: Ensure all necessary module versions are uploaded to the cluster before upgrading
+- **Version consistency**: For Active-Active databases, ensure module versions are consistent across all participating clusters. If you specify a version for one cluster, specify the same version for all clusters. Omit versions to allow auto-updates.
+- **Compatibility requirements**: Consult the Redis Enterprise documentation for module compatibility matrices and verify each module's [`min_redis_version`](https://redis.io/docs/latest/operate/rs/references/rest-api/objects/module/) requirement
+
+#### Upgrade sequence
+
+1. **Upload new module versions** (if required) to the cluster before upgrading Redis Enterprise
+2. **Upgrade the Redis Enterprise cluster** following standard upgrade procedures
+3. **Verify module functionality** after the cluster upgrade completes
+4. **Update database configurations** if new module versions require configuration changes
+
+#### Post-upgrade verification
+
+- **Check module status**: Verify all modules are loaded correctly: `kubectl get rec <cluster-name> -o jsonpath='{.status.modules}'`
+- **Test module functionality**: Validate that module-specific commands and features work as expected
+- **Monitor performance**: Watch for any performance changes after the upgrade
+- **Update documentation**: Record the new module versions and any configuration changes
+
+For detailed upgrade procedures, see [Upgrade Redis Enterprise clusters]({{< relref "/operate/kubernetes/upgrade/upgrade-redis-cluster" >}}).
+
+## Related information
+
+- [Database controller]({{< relref "/operate/kubernetes/re-databases/db-controller" >}}) - Learn how to create and manage Redis Enterprise databases
+- [Active-Active databases]({{< relref "/operate/kubernetes/active-active" >}}) - Set up globally distributed Active-Active databases
+- [Database connectivity]({{< relref "/operate/kubernetes/networking/database-connectivity" >}}) - Connect applications to your Redis Enterprise databases
+- [REDB API reference]({{< relref "/operate/kubernetes/reference/api/redis_enterprise_database_api" >}}) - Complete API specification for REDB resources
+- [REAADB API reference]({{< relref "/operate/kubernetes/reference/api/redis_enterprise_active_active_database_api" >}}) - API reference for Active-Active databases
+- [Redis modules documentation](https://redis.io/docs/latest/develop/reference/modules/) - Official Redis modules documentation