# redpanda_common

> For the complete documentation index, see [llms.txt](https://docs.redpanda.com/llms.txt). Component-specific: [cloud-data-platform-full.txt](https://docs.redpanda.com/cloud-data-platform-full.txt)

---
title: redpanda_common
latest-operator-version: v26.1.4
latest-console-tag: v3.7.3
latest-connect-version: 4.93.0
latest-redpanda-tag: v26.1.9
docname: connect/components/inputs/redpanda_common
page-component-name: cloud-data-platform
page-version: master
page-component-version: master
page-component-title: Cloud
page-relative-src-path: connect/components/inputs/redpanda_common.adoc
page-edit-url: https://github.com/redpanda-data/cloud-docs/edit/main/modules/develop/pages/connect/components/inputs/redpanda_common.adoc
page-git-created-date: "2025-06-25"
page-git-modified-date: "2026-05-26"
---

<!-- Source: https://docs.redpanda.com/cloud-data-platform/develop/connect/components/inputs/redpanda_common.md -->

**Type:** Input ▼

[Input](https://docs.redpanda.com/cloud-data-platform/develop/connect/components/inputs/redpanda_common/)[Output](https://docs.redpanda.com/cloud-data-platform/develop/connect/components/outputs/redpanda_common/)

**Available in:** Cloud, [Self-Managed](https://docs.redpanda.com/connect/components/inputs/redpanda_common/%20%22View%20the%20Self-Managed%20version%20of%20this%20component%22)

> ⚠️ **WARNING: Deprecated in 4.68.0**
>
> Deprecated in 4.68.0
>
> This component is deprecated and will be removed in the next major version release. Please consider moving onto the unified [`redpanda` input](https://docs.redpanda.com/cloud-data-platform/develop/connect/components/inputs/redpanda/) and [`redpanda` output](https://docs.redpanda.com/cloud-data-platform/develop/connect/components/outputs/redpanda/) components.

Consumes data from a Redpanda (Kafka) broker, using credentials from a common `redpanda` configuration block.

To avoid duplicating Redpanda cluster credentials in your `redpanda_common` input, output, or any other components in your data pipeline, you can use a single [`redpanda` configuration block](https://docs.redpanda.com/cloud-data-platform/develop/connect/components/redpanda/about/). For more details, see the [Pipeline example](#pipeline-example).

> 📝 **NOTE**
>
> If you need to move topic data between Redpanda clusters or other Apache Kafka clusters, consider using the [`redpanda` input](https://docs.redpanda.com/cloud-data-platform/develop/connect/components/inputs/redpanda/) and [output](https://docs.redpanda.com/cloud-data-platform/develop/connect/components/outputs/redpanda/) instead.

#### Common

```yml
inputs:
  label: ""
  redpanda_common:
    topics: [] # No default (optional)
    regexp_topics_include: [] # No default (optional)
    regexp_topics_exclude: [] # No default (optional)
    transaction_isolation_level: read_uncommitted
    consumer_group: "" # No default (optional)
    auto_replay_nacks: true
```

#### Advanced

```yml
inputs:
  label: ""
  redpanda_common:
    topics: [] # No default (optional)
    regexp_topics_include: [] # No default (optional)
    regexp_topics_exclude: [] # No default (optional)
    rack_id: ""
    instance_id: ""
    rebalance_timeout: 45s
    session_timeout: 1m
    heartbeat_interval: 3s
    start_offset: earliest
    fetch_max_bytes: 50MiB
    fetch_max_wait: 5s
    fetch_min_bytes: 1B
    fetch_max_partition_bytes: 1MiB
    transaction_isolation_level: read_uncommitted
    consumer_group: "" # No default (optional)
    commit_period: 5s
    partition_buffer_bytes: 1MB
    topic_lag_refresh_period: 5s
    max_yield_batch_bytes: 32KB
    auto_replay_nacks: true
    timely_nacks_maximum_wait: "" # No default (optional)
```

## [](#pipeline-example)Pipeline example

This data pipeline reads data from `topic_A` and `topic_B` on a Redpanda cluster, and then writes the data to `topic_C` on the same cluster. The cluster details are configured within the `redpanda` configuration block, so you only need to configure them once. This is a useful feature when you have multiple inputs and outputs in the same data pipeline that need to connect to the same cluster.

```none
input:
  redpanda_common:
    topics: [ topic_A, topic_B ]

output:
  redpanda_common:
    topic: topic_C
    key: ${! @id }

redpanda:
  seed_brokers: [ "127.0.0.1:9092" ]
  tls:
    enabled: true
  sasl:
    - mechanism: SCRAM-SHA-512
      password: bar
      username: foo
```

## [](#consumer-groups)Consumer groups

When you specify a consumer group in your configuration, this input consumes one or more topics and automatically balances the topic partitions across any other connected clients with the same consumer group. Otherwise, topics are consumed in their entirety or with explicit partitions.

### [](#delivery-guarantees)Delivery guarantees

If you choose to use consumer groups, the offsets of records received by Redpanda Connect are committed automatically. In the event of restarts, this input uses the committed offsets to resume data consumption where it left off.

Redpanda Connect guarantees at-least-once delivery. Records are only confirmed as delivered when all downstream outputs that a record is routed to have also confirmed delivery.

## [](#ordering)Ordering

To preserve the order of topic partitions:

-   Records consumed from each partition are processed and delivered in the order that they are received

-   Only one batch of records of a given partition is processed at a time


This approach means that although records from different partitions may be processed in parallel, records from the same partition are processed in sequential order.

### [](#delivery-errors)Delivery errors

The order in which records are delivered may be disrupted by delivery errors and any error-handling mechanisms that start up. Redpanda Connect uses at-least-once delivery unless instructed otherwise, and this includes reattempting delivery of data when the ordering of that data is no longer guaranteed.

For example, a batch of records is sent to an output broker and only a subset of records are delivered. In this scenario, Redpanda Connect (by default) attempts to deliver the records that failed, even though these delivery failures may have been sent before records that were delivered successfully.

#### [](#use-a-fallback-output)Use a fallback output

To prevent delivery errors from disrupting the order of records, you must specify a [`fallback`](https://docs.redpanda.com/cloud-data-platform/develop/connect/components/outputs/fallback/) output in your pipeline configuration. When adding a `fallback` output, it is good practice to set the `auto_retry_nacks` field to `false`. This also improves the throughput of your pipeline.

For example, the following configuration includes a `fallback` output. If Redpanda Connect fails to write delivery errors to the `foo` topic, it then attempts to write them into a dead letter queue topic (`foo_dlq`), which is retried indefinitely as a way to apply back pressure.

```yaml
output:
  fallback:
    - redpanda_common:
        topic: foo
    - retry:
        output:
          redpanda_common:
            topic: foo_dlq
```

## [](#batching)Batching

Records are processed and delivered from each partition in the same batches as they are received from brokers. Batch sizes are dynamically sized in order to optimize throughput, but you can tune them further using the following configuration fields:

-   `fetch_max_partition_bytes`

-   `fetch_max_bytes`


You can break batches down further using the [`split`](https://docs.redpanda.com/cloud-data-platform/develop/connect/components/processors/split/) processor.

## [](#metrics)Metrics

This input emits a `redpanda_lag` metric with `topic` and `partition` labels for each consumed topic. The metric records the number of produced messages that remain to be read from each topic/partition pair by the specified consumer group.

## [](#metadata)Metadata

This input adds the following metadata fields to each message:

-   `kafka_key`

-   `kafka_topic`

-   `kafka_partition`

-   `kafka_offset`

-   `kafka_lag`

-   `kafka_timestamp_ms`

-   `kafka_timestamp_unix`

-   `kafka_tombstone_message`

-   All record headers


## [](#fields)Fields

### [](#auto_replay_nacks)`auto_replay_nacks`

Whether to automatically replay messages that are rejected (nacked) at the output level. If the cause of rejections is persistent, leaving this option enabled can result in back pressure.

Set `auto_replay_nacks` to `false` to delete rejected messages. Disabling auto replays can greatly improve memory efficiency of high throughput streams, as the original shape of the data is discarded immediately upon consumption and mutation.

**Type**: `bool`

**Default**: `true`

### [](#commit_period)`commit_period`

The period of time between each commit of the current partition offsets. Offsets are always committed during shutdown.

**Type**: `string`

**Default**: `5s`

### [](#consumer_group)`consumer_group`

An optional consumer group. When this value is specified:

-   The partitions of any topics, specified in the `topics` field, are automatically distributed across consumers sharing a consumer group

-   Partition offsets are automatically committed and resumed under this name


Consumer groups are not supported when you specify explicit partitions to consume from in the `topics` field.

**Type**: `string`

### [](#fetch_max_bytes)`fetch_max_bytes`

The maximum number of bytes that a broker tries to send during a fetch.

If individual records are larger than the `fetch_max_bytes` value, brokers will still send them.

**Type**: `string`

**Default**: `50MiB`

### [](#fetch_max_partition_bytes)`fetch_max_partition_bytes`

The maximum number of bytes that are consumed from a single partition in a fetch request. This field is equivalent to the Java setting `fetch.max.partition.bytes`.

If a single batch is larger than the `fetch_max_partition_bytes` value, the batch is still sent so that the client can make progress.

**Type**: `string`

**Default**: `1MiB`

### [](#fetch_max_wait)`fetch_max_wait`

The maximum period of time a broker can wait for a fetch response to reach the required minimum number of bytes (`fetch_min_bytes`).

**Type**: `string`

**Default**: `5s`

### [](#fetch_min_bytes)`fetch_min_bytes`

The minimum number of bytes that a broker tries to send during a fetch. This field is equivalent to the Java setting `fetch.min.bytes`.

**Type**: `string`

**Default**: `1B`

### [](#heartbeat_interval)`heartbeat_interval`

When you specify a `consumer_group`, `heartbeat_interval` sets how frequently a consumer group member should send heartbeats to Apache Kafka. Apache Kafka uses heartbeats to make sure that a group member’s session is active.

You must set `heartbeat_interval` to less than one-third of `session_timeout`.

This field is equivalent to the Java `heartbeat.interval.ms` setting and accepts Go duration format strings such as `10s` or `2m`.

**Type**: `string`

**Default**: `3s`

### [](#instance_id)`instance_id`

When you specify a [`consumer_group`](#consumer_group), assign a unique value to `instance_id` to define the group’s static membership, which can prevent unnecessary rebalances during reconnections.

When you assign an instance ID, the client does not automatically leave the consumer group when it disconnects. To remove the client, you must use an external admin command on behalf of the instance ID.

**Type**: `string`

**Default**: `""`

### [](#max_yield_batch_bytes)`max_yield_batch_bytes`

The maximum size (in bytes) for each batch yielded by this input. This value must be less than or equal to the `partition_buffer_bytes`. If using Redpanda output, this value should not be greater than the `max_message_bytes` option value (1MB by default), and for high-throughput scenarios they should be equal.

**Type**: `string`

**Default**: `32KB`

### [](#partition_buffer_bytes)`partition_buffer_bytes`

A buffer size (in bytes) for each consumed partition, which allows the internal queuing of records before they are flushed. Increasing this value may improve throughput but results in higher memory utilization.

Each buffer can grow slightly beyond this value.

**Type**: `string`

**Default**: `1MB`

### [](#rack_id)`rack_id`

A rack specifies where the client is physically located, and changes fetch requests to consume from the closest replica as opposed to the leader replica.

**Type**: `string`

**Default**: `""`

### [](#rebalance_timeout)`rebalance_timeout`

When you specify a [`consumer_group`](#consumer_group), `rebalance_timeout` sets a time limit for all consumer group members to complete their work and commit offsets after a rebalance has begun. The timeout excludes the time taken to detect a failed or late heartbeat, which indicates a rebalance is required. This field accepts Go duration format strings such as `100ms`, `1s`, or `5s`.

**Type**: `string`

**Default**: `45s`

### [](#regexp_topics_exclude)`regexp_topics_exclude[]`

A list of regular expression patterns for excluding topics when regex mode is enabled (using `regexp_topics_include` or the deprecated `regexp_topics` boolean). Topics matching any of these patterns will be excluded from consumption, even if they match include patterns.

Each pattern is a full regular expression evaluated against the complete topic name. Patterns are not anchored by default, so use `^` and `$` for exact matching. Exclude patterns are applied after include patterns, providing fine-grained control over topic selection.

Example: `regexp_topics_exclude: ["^_", ".**-temp$", ".**-test.*"]` excludes topics starting with underscore, ending with `-temp`, or containing `-test`.

**Type**: `array`

### [](#regexp_topics_include)`regexp_topics_include[]`

A list of regular expression patterns for matching topics to consume from. When specified, the client will periodically refresh the list of matching topics based on the `metadata_max_age` interval.

Each pattern is a full regular expression evaluated against the complete topic name. Patterns are not anchored by default, so `logs_.` **matches `my-logs_events` and `logs_errors`. Use `^logs_.`**`$` to match only topics starting with `logs_`.

This field enables regex mode (replacing the deprecated `regexp_topics` boolean) and cannot be used together with explicit `topics` lists. Use `regexp_topics_exclude` to filter out specific patterns from the matched topics.

Example: `regexp_topics_include: ["events_.**", "logs_.**"]` consumes from all topics starting with `events_` or `logs_`.

**Type**: `array`

```yaml
# Examples:
regexp_topics_include:
  - logs_.*
  - metrics_.*

# ---

regexp_topics_include:
  - "events_[0-9]+"
```

### [](#session_timeout)`session_timeout`

When you specify a `consumer_group`, `session_timeout` sets the maximum interval between heartbeats sent by a consumer group member to the broker. If a broker doesn’t receive a heartbeat from a group member before the timeout expires, it removes the member from the consumer group and initiates a rebalance. This field accepts Go duration format strings such as `100ms`, `1s`, or `5s`.

**Type**: `string`

**Default**: `1m`

### [](#start_offset)`start_offset`

Specify the offset from which this input starts or restarts consuming messages. Restarts occur when the `OffsetOutOfRange` error is seen during a fetch.

**Type**: `string`

**Default**: `earliest`

| Option | Summary |
| --- | --- |
| committed | Prevents consuming a partition in a group if the partition has no prior commits. Corresponds to Kafka’s auto.offset.reset=none option |
| earliest | Start from the earliest offset. Corresponds to Kafka’s auto.offset.reset=earliest option. |
| latest | Start from the latest offset. Corresponds to Kafka’s auto.offset.reset=latest option. |

### [](#timely_nacks_maximum_wait)`timely_nacks_maximum_wait`

EXPERIMENTAL: Specify a maximum period of time in which each message can be consumed and awaiting either acknowledgement or rejection before rejection is instead forced. This can be useful for avoiding situations where certain downstream components can result in blocked confirmation of delivery that exceeds SLAs. Accepts Go duration format strings such as `100ms`, `1s`, or `5s`.

**Type**: `string`

### [](#topic_lag_refresh_period)`topic_lag_refresh_period`

The interval between refresh cycles. During each cycle, this input queries the Redpanda Connect server to calculate the topic lag minus the number of produced messages that remain to be read from each topic/partition pair by the specified consumer group. This field accepts Go duration format strings such as `100ms`, `1s`, or `5s`.

**Type**: `string`

**Default**: `5s`

### [](#topics)`topics[]`

A list of topics to consume from. Use commas to separate multiple topics in a single element.

When a `consumer_group` is specified, partitions are automatically distributed across consumers of a topic. Otherwise, all partitions are consumed.

Alternatively, you can specify explicit partitions to consume by using a colon after the topic name. For example, `foo:0` would consume the partition `0` of the topic foo. This syntax supports ranges. For example, `foo:0-10` would consume partitions `0` through to `10` inclusive.

It is also possible to specify an explicit offset to consume from by adding another colon after the partition. For example, `foo:0:10` would consume the partition `0` of the topic `foo` starting from the offset `10`. If the offset is not present (or remains unspecified) then the field `start_offset` determines which offset to start from.

**Type**: `array`

```yaml
# Examples:
topics:
  - foo
  - bar

# ---

topics:
  - things.*

# ---

topics:
  - "foo,bar"

# ---

topics:
  - "foo:0"
  - "bar:1"
  - "bar:3"

# ---

topics:
  - "foo:0,bar:1,bar:3"

# ---

topics:
  - "foo:0-5"
```

### [](#transaction_isolation_level)`transaction_isolation_level`

The isolation level for handling transactional messages. This setting determines how transactions are processed and affects data consistency guarantees.

**Type**: `string`

**Default**: `read_uncommitted`

| Option | Summary |
| --- | --- |
| read_committed | If set, only committed transactional records are processed. |
| read_uncommitted | If set, then uncommitted records are processed. |