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kafka_franz

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 and redpanda output components.

A Kafka input using the Franz Kafka client library.

  • Common

  • Advanced

input:
  label: ""
  kafka_franz:
    seed_brokers: [] # No default (required)
    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
input:
  label: ""
  kafka_franz:
    seed_brokers: [] # No default (required)
    client_id: redpanda-connect
    tls:
      enabled: false
      skip_cert_verify: false
      enable_renegotiation: false
      root_cas: ""
      root_cas_file: ""
      client_certs: []
    sasl: [] # No default (optional)
    metadata_max_age: 1m
    request_timeout_overhead: 10s
    conn_idle_timeout: 20s
    tcp:
      connect_timeout: 0s
      keep_alive:
        idle: 15s
        interval: 15s
        count: 9
      tcp_user_timeout: 0s
    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)
    checkpoint_limit: 1024
    commit_period: 5s
    multi_header: false
    batching:
      count: 0
      byte_size: 0
      period: ""
      check: ""
      processors: [] # No default (optional)
    topic_lag_refresh_period: 5s
    auto_replay_nacks: true
    timely_nacks_maximum_wait: "" # No default (optional)

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.

This input often out-performs the traditional kafka input and provides more useful logs and error messages.

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

auto_replay_nacks

Whether to automatically replay rejected messages (negative acknowledgements, or nacks) at the output level. If the cause of rejections persists, 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

batching

Configure a batching policy that applies to individual topic partitions, so that the input batches messages together before flushing them for processing. Batching can improve performance and is useful for windowed processing. Batching this way preserves the ordering of topic partitions.

Type: object

# Examples:
batching:
  byte_size: 5000
  count: 0
  period: 1s

# ---

batching:
  count: 10
  period: 1s

# ---

batching:
  check: this.contains("END BATCH")
  count: 0
  period: 1m

batching.byte_size

The maximum total size (in bytes) that a batch can reach before it is flushed. When the combined size of all messages in the batch reaches or exceeds this limit, the batch is immediately sent to the next stage (such as a processor or output).

Set to 0 to disable size-based batching. When disabled, messages are flushed based on other conditions (such as count or period).

Type: int

Default: 0

batching.check

A Bloblang query that returns a boolean value indicating whether a message should end a batch.

Type: string

Default: ""

# Examples:
check: this.type == "end_of_transaction"

batching.count

The number of messages at which the batch is flushed. Set to 0 to disable count-based batching.

Type: int

Default: 0

batching.period

The length of time after which an incomplete batch is flushed regardless of its size. This field accepts Go duration format strings such as 100ms, 1s, or 5s. Supported time units are ns, us, ms, s, m, and h.

Type: string

Default: ""

# Examples:
period: 1s

# ---

period: 1m

# ---

period: 500ms

batching.processors[]

A list of processors to apply to a batch as it is flushed. This allows you to aggregate and archive the batch however you see fit. All resulting messages are flushed as a single batch, so splitting the batch into smaller batches with these processors has no effect.

Type: array<processor>

# Examples:
processors:
  - archive:
      format: concatenate


# ---

processors:
  - archive:
      format: lines


# ---

processors:
  - archive:
      format: json_array

checkpoint_limit

The maximum number of messages that are processed in parallel inside the same partition before back pressure is applied.

When a message with a specific offset is delivered to the output, the offset is only committed when all messages of previous offsets have also been delivered. This behavior ensures at-least-once delivery guarantees. However, in the event of crashes or server faults, it also increases the likelihood of duplicates. To decrease this risk, reduce the checkpoint_limit value.

Type: int

Default: 1024

client_id

An identifier for the client connection. This identifier appears in broker logs and metrics, which helps you identify the Redpanda Connect instance that is connecting.

Type: string

Default: redpanda-connect

commit_period

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

Type: string

Default: 5s

conn_idle_timeout

The approximate amount of time that connections can remain idle before they are closed. In the worst case, a connection can stay idle for up to twice this value. This field accepts Go duration format strings such as 100ms, 1s, or 5s.

Type: string

Default: 20s

consumer_group

An optional consumer group. When you specify this value:

  • The partitions of any topics specified in the topics field are automatically distributed across consumers that share the 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

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 still send them.

This field is equivalent to the Java setting fetch.max.bytes.

Type: string

Default: 50MiB

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

The maximum period of time a broker can wait for a fetch response to reach the required minimum number of bytes (fetch_min_bytes). This field is equivalent to the Java setting fetch.max.wait.ms.

Type: string

Default: 5s

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

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.

This value must be lower than session_timeout, and should be no higher 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

When you specify a consumer_group, set instance_id to define the group’s static membership, which can prevent unnecessary rebalances during reconnections. The value must be unique per consumer within the group.

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

Type: string

Default: ""

metadata_max_age

The maximum period of time after which metadata is refreshed. This field accepts Go duration format strings such as 100ms, 1s, or 5s.

Lower values provide more responsive topic and partition discovery but may increase broker load. Higher values reduce broker queries but can delay detection of topology changes.

This interval also controls how frequently regex topic patterns are re-evaluated to discover new matching topics.

Type: string

Default: 1m

multi_header

Decode headers into lists to allow the handling of multiple values with the same key.

Type: bool

Default: false

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

When you specify a consumer_group, rebalance_timeout sets how long consumer group members can take to complete their work and commit offsets after a rebalance has begun. The time that a member takes to detect the rebalance (from a heartbeat) counts against this timeout. This field accepts Go duration format strings such as 100ms, 1s, or 5s.

Type: string

Default: 45s

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<string>

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<string>

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

# ---

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

request_timeout_overhead

Additional time to apply as overhead when calculating request deadlines. For most requests, the deadline is this overhead alone. For requests that define their own timeout field, the overhead is added on top of that timeout, which helps prevent premature timeouts.

This field is roughly equivalent to Apache Kafka’s request.timeout.ms parameter, but grants extra time to requests that have timeout fields.

Type: string

Default: 10s

sasl[]

Specify one or more methods or mechanisms of SASL authentication. They are tried in order. If the broker supports the first SASL mechanism, all connections use it. If the first mechanism fails, the client picks the first supported mechanism. If the broker does not support any client mechanisms, all connections fail.

Type: array<object>

# Examples:
sasl:
  - mechanism: SCRAM-SHA-512
    password: bar
    username: foo

sasl[].aws

Contains AWS-specific fields for when sasl.mechanism is set to AWS_MSK_IAM.

Type: object

sasl[].aws.credentials

Manually configure the AWS credentials to use (optional). For more information, see the Amazon Web Services guide.

Type: object

sasl[].aws.credentials.from_ec2_role

Use the credentials of a host EC2 machine configured to assume an IAM role associated with the instance.

Type: bool

sasl[].aws.credentials.id

The ID of the AWS credentials to use.

Type: string

sasl[].aws.credentials.profile

The profile from ~/.aws/credentials to use.

Type: string

sasl[].aws.credentials.role

The ARN of the role to assume.

Type: string

sasl[].aws.credentials.role_external_id

An external ID to use when assuming a role.

Type: string

sasl[].aws.credentials.secret

The secret for the AWS credentials in use.

This field contains sensitive information that usually shouldn’t be added to a configuration directly. For more information, see Manage Secrets before adding it to your configuration.

Type: string

sasl[].aws.credentials.token

The token for the AWS credentials in use. Required only when using short-term credentials.

Type: string

sasl[].aws.endpoint

A custom endpoint URL for AWS API requests. Use this to connect to AWS-compatible services or local testing environments instead of the standard AWS endpoints.

Type: string

sasl[].aws.region

The AWS region in which your resources are hosted.

Type: string

sasl[].aws.tcp

Configure TCP socket-level settings to optimize network performance and reliability. These low-level controls are useful for:

  • Unresponsive hosts: Set connect_timeout to limit how long a connection attempt can take (the default 0s sets no limit)

  • Long-lived connections: Configure keep_alive settings to detect and recover from stale connections

  • Unstable networks: Tune keep-alive probes to balance between quick failure detection and avoiding false positives

  • Linux systems with specific requirements: Use tcp_user_timeout (Linux 2.6.37+) to control data acknowledgment timeouts

Most users should keep the default values. Only modify these settings if you’re experiencing connection stability issues or have specific network requirements.

Type: object

sasl[].aws.tcp.connect_timeout

Maximum amount of time a dial will wait for a connect to complete. Zero disables.

Type: string

Default: 0s

sasl[].aws.tcp.keep_alive

TCP keep-alive probe configuration.

Type: object

sasl[].aws.tcp.keep_alive.count

Maximum unanswered keep-alive probes before dropping the connection. Zero defaults to 9.

Type: int

Default: 9

sasl[].aws.tcp.keep_alive.idle

Duration the connection must be idle before sending the first keep-alive probe. Zero defaults to 15s. Negative values disable keep-alive probes.

Type: string

Default: 15s

sasl[].aws.tcp.keep_alive.interval

Duration between keep-alive probes. Zero defaults to 15s.

Type: string

Default: 15s

sasl[].aws.tcp.tcp_user_timeout

Maximum time to wait for acknowledgment of transmitted data before killing the connection. Linux-only (kernel 2.6.37+), ignored on other platforms. When enabled, keep_alive.idle must be greater than this value per RFC 5482. Zero disables.

Type: string

Default: 0s

sasl[].extensions

Key/value pairs to add to OAUTHBEARER authentication requests.

Type: object<string>

sasl[].mechanism

The SASL mechanism to use for authentication.

Type: string

Option Summary

AWS_MSK_IAM

AWS IAM based authentication as specified by the 'aws-msk-iam-auth' java library.

OAUTHBEARER

OAuth Bearer based authentication.

PLAIN

Plain text authentication.

REDPANDA_CLOUD_SERVICE_ACCOUNT

Redpanda Cloud Service Account authentication when running in Redpanda Cloud.

SCRAM-SHA-256

SCRAM based authentication as specified in RFC5802.

SCRAM-SHA-512

SCRAM based authentication as specified in RFC5802.

none

Disable sasl authentication

sasl[].password

The password to use for PLAIN or SCRAM-* authentication.

This field contains sensitive information that usually shouldn’t be added to a configuration directly. For more information, see Manage Secrets before adding it to your configuration.

Type: string

Default: ""

sasl[].token

The token to use for a single session’s OAUTHBEARER authentication.

Type: string

Default: ""

sasl[].username

The username to use for PLAIN or SCRAM-* authentication.

Type: string

Default: ""

seed_brokers[]

A list of broker addresses used to establish connections. If an item of the list contains commas, it is expanded into multiple addresses.

Type: array<string>

# Examples:
seed_brokers:
  - "localhost:9092"

# ---

seed_brokers:
  - "foo:9092"
  - "bar:9092"

# ---

seed_brokers:
  - "foo:9092,bar:9092"

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

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.

tcp

Configure TCP socket-level settings to optimize network performance and reliability. These low-level controls are useful for:

  • Unresponsive hosts: Set connect_timeout to limit how long a connection attempt can take (the default 0s sets no limit)

  • Long-lived connections: Configure keep_alive settings to detect and recover from stale connections

  • Unstable networks: Tune keep-alive probes to balance between quick failure detection and avoiding false positives

  • Linux systems with specific requirements: Use tcp_user_timeout (Linux 2.6.37+) to control data acknowledgment timeouts

Most users should keep the default values. Only modify these settings if you’re experiencing connection stability issues or have specific network requirements.

Type: object

tcp.connect_timeout

Maximum amount of time a dial will wait for a connect to complete. Zero disables.

Type: string

Default: 0s

tcp.keep_alive

TCP keep-alive probe configuration.

Type: object

tcp.keep_alive.count

Maximum unanswered keep-alive probes before dropping the connection. Zero defaults to 9.

Type: int

Default: 9

tcp.keep_alive.idle

Duration the connection must be idle before sending the first keep-alive probe. Zero defaults to 15s. Negative values disable keep-alive probes.

Type: string

Default: 15s

tcp.keep_alive.interval

Duration between keep-alive probes. Zero defaults to 15s.

Type: string

Default: 15s

tcp.tcp_user_timeout

Maximum time to wait for acknowledgment of transmitted data before killing the connection. Linux-only (kernel 2.6.37+), ignored on other platforms. When enabled, keep_alive.idle must be greater than this value per RFC 5482. Zero disables.

Type: string

Default: 0s

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

tls

Configure Transport Layer Security (TLS) settings to secure network connections. This includes options for standard TLS as well as mutual TLS (mTLS) authentication where both client and server authenticate each other using certificates. Key configuration options include enabled to enable TLS, client_certs for mTLS authentication, root_cas/root_cas_file for custom certificate authorities, and skip_cert_verify for development environments.

Type: object

tls.client_certs[]

A list of client certificates for mutual TLS (mTLS) authentication. Configure this field to enable mTLS, authenticating the client to the server with these certificates.

You must set tls.enabled: true for the client certificates to take effect.

Certificate pairing rules: For each certificate item, provide either:

  • Inline PEM data using both cert and key or

  • File paths using both cert_file and key_file.

Mixing inline and file-based values within the same item is not supported.

Type: array<object>

Default: []

# Examples:
client_certs:
  - cert: foo
    key: bar


# ---

client_certs:
  - cert_file: ./example.pem
    key_file: ./example.key

tls.client_certs[].cert

The plaintext certificate to use for TLS authentication. Must be paired with the corresponding private key in the key field when using inline PEM data for mTLS client certificates.

Type: string

Default: ""

tls.client_certs[].cert_file

The path to a file containing the certificate to use for TLS authentication. Must be paired with the corresponding private key file in the key_file field when using file-based configuration for mTLS client certificates.

Type: string

Default: ""

tls.client_certs[].key

Private key for mTLS client certificate as inline PEM data. Must correspond to the client certificate specified in the cert field. Use this field together with cert when providing certificate data inline rather than through files.

This field contains sensitive information that usually shouldn’t be added to a configuration directly. For more information, see Manage Secrets before adding it to your configuration.

Type: string

Default: ""

tls.client_certs[].key_file

Path to private key file for mTLS client certificate in PEM format. Must correspond to the client certificate specified in the cert_file field. Use this field together with cert_file when loading certificate data from files.

Type: string

Default: ""

tls.client_certs[].password

The password to use for the private key (specified in the key or key_file fields), if it is password-protected. The PKCS#1 and PKCS#8 formats are supported. Supports environment variable interpolation for secure password management.

The pbeWithMD5AndDES-CBC algorithm is obsolete and not supported for the PKCS#8 format. This algorithm does not authenticate the ciphertext, making it vulnerable to padding oracle attacks that can let an attacker recover the plaintext.

This field contains sensitive information that usually shouldn’t be added to a configuration directly. For more information, see Manage Secrets before adding it to your configuration.

Type: string

Default: ""

# Examples:
password: foo

# ---

password: ${KEY_PASSWORD}

tls.enable_renegotiation

Whether to allow the remote server to repeatedly request renegotiation. Enable this option if you’re seeing the error message local error: tls: no renegotiation.

Type: bool

Default: false

tls.enabled

Whether to enable TLS for secure connections. Set to true to enable TLS encryption. Required to be true for other TLS options (like client_certs, root_cas, etc.) to take effect.

Type: bool

Default: false

tls.root_cas

Specify a root certificate authority to use (optional). This is a string that represents a certificate chain from the parent-trusted root certificate, through possible intermediate signing certificates, to the host certificate. Use either this field for inline certificate data or root_cas_file for file-based certificate loading.

This field contains sensitive information that usually shouldn’t be added to a configuration directly. For more information, see Manage Secrets before adding it to your configuration.

Type: string

Default: ""

# Examples:
root_cas: |-
  -----BEGIN CERTIFICATE-----
  ...
  -----END CERTIFICATE-----

tls.root_cas_file

Specify the path to a root certificate authority file (optional). This is a file, often with a .pem extension, which contains a certificate chain from the parent-trusted root certificate, through possible intermediate signing certificates, to the host certificate. Use either this field for file-based certificate loading or root_cas for inline certificate data.

Type: string

Default: ""

# Examples:
root_cas_file: ./root_cas.pem

tls.skip_cert_verify

Whether to skip server-side certificate verification. Set to true only for testing environments as this reduces security by disabling certificate validation. When using self-signed certificates or in development, this may be necessary, but should never be used in production. Consider using root_cas or root_cas_file to specify trusted certificates instead of disabling verification entirely.

Type: bool

Default: false

topic_lag_refresh_period

The interval between consumer lag refreshes. During each cycle, this input asks the brokers for the consumer group’s committed offsets and the partition end offsets, and records the difference (the number of unread messages) for each topic partition in the consumer lag metric and the kafka_lag metadata field. Lag is only refreshed when consumer_group is set. This field accepts Go duration format strings such as 100ms, 1s, or 5s.

Type: string

Default: 5s

topics[]

A list of topics to consume from. You can list multiple comma-separated topics in a single element.

If you specify a consumer_group, partitions are automatically distributed across consumers of a topic. Otherwise, all partitions are consumed.

Alternatively, add a colon after the topic name to set the explicit partitions to consume. For example, foo:0 consumes the partition 0 of the topic foo. This syntax also supports ranges. For example, foo:0-10 consumes all partitions from 0 through to 10 inclusive.

Finally, add another colon after the partition to set an explicit offset to consume from. For example, foo:0:10 consumes 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<string>

# 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

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.