# Group Filtering

By default, the K2K Offset Mapping App synchronizes all consumer groups for which offset mappings exist for at least one replicated topic. \
As such, no additional filtering is required for standard deployments.

<details>

<summary>Example</summary>

Given the consumer groups:

* &#x20;`fraud-detection-app`
* &#x20;`metrics-collection-app`&#x20;

If both have committed offsets for the topic `card-transactions`, and that topic is being replicated by K2K, the Offset Mapping App will translate and sync their committed offsets.

</details>

{% hint style="warning" %}
In order for the consumer offset mapping functionality to work, both of the following requirements must be met:

* K2K must be configured to publish offset mappings.
* The `k2k-offset-mapping` application must be configured and deployed.

Without both components active, consumer group offsets on the target cluster will not be translated.
{% endhint %}

This behavior can be customized in two ways:

* **Regex Pattern:** A regular expression can be provided to select only the consumer groups whose names match the pattern. This is useful for targeting a specific subset of groups based on a naming convention.
* **Explicit List:** A static list of consumer group names can be provided to restrict synchronization to only those specific groups.

## Regex Filtering

When used, only the groups matched by the provided regular expression will be synced.

```yaml
groups:
  consumerGroups: "transactions-.*"
```

## Explicit List

When used, only the groups present in the list will be monitored and synced.

```yaml
groups:
  consumerGroups: 
    - transaction-monitoring-group
    - fraud-detection-group
```


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