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layout title nav_order parent
default Peer forwarder 12 Managing Data Prepper

Peer forwarder

Peer forwarder is an HTTP service that performs peer forwarding of an event between Data Prepper nodes for aggregation. This HTTP service uses a hash-ring approach to aggregate events and determine which Data Prepper node it should handle on a given trace before rerouting it to that node. Currently, peer forwarder is supported by the aggregate, service_map_stateful, and otel_trace_raw processors.

Peer forwarder groups events based on the identification keys provided by the supported processors. For service_map_stateful and otel_trace_raw, the identification key is traceId by default and cannot be configured. The aggregate processor is configured using the identification_keys configuration option. From here, you can specify which keys to use for peer forwarder. See Aggregate Processor page for more information about identification keys.

Peer discovery allows Data Prepper to find other nodes that it will communicate with. Currently, peer discovery is provided by a static list, a DNS record lookup, or AWS Cloud Map.

Discovery modes

The following sections provide information about discovery modes.

Static

Static discovery mode allows a Data Prepper node to discover nodes using a list of IP addresses or domain names. See the following YAML file for an example of static discovery mode:

peer_forwarder:4
  discovery_mode: static
  static_endpoints: ["data-prepper1", "data-prepper2"]

DNS lookup

DNS discovery is preferred over static discovery when scaling out a Data Prepper cluster. DNS discovery configures a DNS provider to return a list of Data Prepper hosts when given a single domain name. This list consists of a DNS A record, and a list of IP addresses of a given domain. See the following YAML file for an example of DNS lookup:

peer_forwarder:
  discovery_mode: dns
  domain_name: "data-prepper-cluster.my-domain.net"

AWS Cloud Map

AWS Cloud Map provides API-based service discovery as well as DNS-based service discovery.

Peer forwarder can use the API-based service discovery in AWS Cloud Map. To support this, you must have an existing namespace configured for API instance discovery. You can create a new one by following the instructions provided by the AWS Cloud Map documentation.

Your Data Prepper configuration needs to include the following:

  • aws_cloud_map_namespace_name – Set to your AWS Cloud Map namespace name.
  • aws_cloud_map_service_name – Set to the service name within your specified namespace.
  • aws_region – Set to the AWS Region in which your namespace exists.
  • discovery_mode – Set to aws_cloud_map.

Your Data Prepper configuration can optionally include the following:

  • aws_cloud_map_query_parameters – Key-value pairs are used to filter the results based on the custom attributes attached to an instance. Results include only those instances that match all of the specified key-value pairs.

Example configuration

See the following YAML file example of AWS Cloud Map configuration:

peer_forwarder:
  discovery_mode: aws_cloud_map
  aws_cloud_map_namespace_name: "my-namespace"
  aws_cloud_map_service_name: "data-prepper-cluster"
  aws_cloud_map_query_parameters:
    instance_type: "r5.xlarge"
  aws_region: "us-east-1"

IAM policy with necessary permissions

Data Prepper must also be running with the necessary permissions. The following AWS Identity and Access Management (IAM) policy shows the necessary permissions:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "CloudMapPeerForwarder",
            "Effect": "Allow",
            "Action": "servicediscovery:DiscoverInstances",
            "Resource": "*"
        }
    ]
}

Configuration

The following table provides optional configuration values.

Value Type Description
port Integer A value between 0 and 65535 that represents the port that the peer forwarder server is running on. Default value is 4994.
request_timeout Integer Represents the request timeout duration in milliseconds for the peer forwarder HTTP server. Default value is 10000.
server_thread_count Integer Represents the number of threads used by the peer forwarder server. Default value is 200.
client_thread_count Integer Represents the number of threads used by the peer forwarder client. Default value is 200.
maxConnectionCount Integer Represents the maximum number of open connections for the peer forwarder server. Default value is 500.
discovery_mode String Represents the peer discovery mode to be used. Allowable values are local_node, static, dns, and aws_cloud_map. Defaults to local_node, which processes events locally.
static_endpoints List Contains the endpoints of all Data Prepper instances. Required if discovery_mode is set to static.
domain_name String Represents the single domain name to query DNS against. Typically used by creating multiple DNS A records for the same domain. Required if discovery_mode is set to dns.
aws_cloud_map_namespace_name String Represents the AWS Cloud Map namespace when using AWS Cloud Map service discovery. Required if discovery_mode is set to aws_cloud_map.
aws_cloud_map_service_name String Represents the AWS Cloud Map service when using AWS Cloud Map service discovery. Required if discovery_mode is set to aws_cloud_map.
aws_cloud_map_query_parameters Map Key-value pairs used to filter the results based on the custom attributes attached to an instance. Only instances that match all the specified key-value pairs are returned.
buffer_size Integer Represents the maximum number of unchecked records the buffer accepts (the number of unchecked records equals the number of records written into the buffer plus the number of records that are still processing and not yet checked by the Checkpointing API). Default is 512.
batch_size Integer Represents the maximum number of records that the buffer returns on read. Default is 48.
aws_region String Represents the AWS Region that uses ACM, Amazon S3, or AWS Cloud Map and is required when any of the following conditions are met:
- The use_acm_certificate_for_ssl setting is set to true.
- Either ssl_certificate_file or ssl_key_file specifies an Amazon Simple Storage Service (Amazon S3) URI (for example, s3://mybucket/path/to/public.cert).
- The discovery_mode is set to aws_cloud_map.
drain_timeout Duration Represents the amount of time that peer forwarder will wait to complete data processing before shutdown.

SSL configuration

The following table provides optional SSL configuration values that allow you to set up a trust manager for the peer forwarder client in order to connect to other Data Prepper instances.

Value Type Description
ssl Boolean Enables TLS/SSL. Default value is true.
ssl_certificate_file String Represents the SSL certificate chain file path or Amazon S3 path. The following is an example of an Amazon S3 path: s3://<bucketName>/<path>. Defaults to the default certificate file,config/default_certificate.pem. See Default Certificates for more information about how the certificate is generated.
ssl_key_file String Represents the SSL key file path or Amazon S3 path. Amazon S3 path example: s3://<bucketName>/<path>. Defaults to config/default_private_key.pem which is the default private key file. See Default Certificates for more information about how the private key file is generated.
ssl_insecure_disable_verification Boolean Disables the verification of the server's TLS certificate chain. Default value is false.
ssl_fingerprint_verification_only Boolean Disables the verification of the server's TLS certificate chain and instead verifies only the certificate fingerprint. Default value is false.
use_acm_certificate_for_ssl Boolean Enables TLS/SSL using the certificate and private key from AWS Certificate Manager (ACM). Default value is false.
acm_certificate_arn String Represents the ACM certificate Amazon Resource Name (ARN). The ACM certificate takes precedence over Amazon S3 or the local file system certificate. Required if use_acm_certificate_for_ssl is set to true.
acm_private_key_password String Represents the ACM private key password that will be used to decrypt the private key. If it's not provided, a random password will be generated.
acm_certificate_timeout_millis Integer Represents the timeout in milliseconds required for ACM to get certificates. Default value is 120000.
aws_region String Represents the AWS Region that uses ACM, Amazon S3, or AWS Cloud Map. Required if use_acm_certificate_for_ssl is set to true or ssl_certificate_file. Also required when the ssl_key_file is set to use the Amazon S3 path or if discovery_mode is set to aws_cloud_map.

Example configuration

The following YAML file provides an example configuration:

peer_forwarder:
  ssl: true
  ssl_certificate_file: "<cert-file-path>"
  ssl_key_file: "<private-key-file-path>"

Authentication

Authentication is optional and is a Map that enables mutual TLS (mTLS). It can either be mutual_tls or unauthenticated. The default value is unauthenticated. The following YAML file provides an example of authentication:

peer_forwarder:
  authentication:
    mutual_tls:

Metrics

Core peer forwarder introduces the following custom metrics. All the metrics are prefixed by core.peerForwarder.

Timer

Peer forwarder's timer capability provides the following information:

  • requestForwardingLatency: Measures latency of requests forwarded by the peer forwarder client.
  • requestProcessingLatency: Measures latency of requests processed by the peer forwarder server.

Counter

The following table provides counter metric options.

Value Description
requests Measures the total number of forwarded requests.
requestsFailed Measures the total number of failed requests. Applies to requests with an HTTP response code other than 200.
requestsSuccessful Measures the total number of successful requests. Applies to requests with HTTP response code 200.
requestsTooLarge Measures the total number of requests that are too large to be written to the peer forwarder buffer. Applies to requests with HTTP response code 413.
requestTimeouts Measures the total number of requests that time out while writing content to the peer forwarder buffer. Applies to requests with HTTP response code 408.
requestsUnprocessable Measures the total number of requests that fail due to an unprocessable entity. Applies to requests with HTTP response code 422.
badRequests Measures the total number of requests with a bad request format. Applies to requests with HTTP response code 400.
recordsSuccessfullyForwarded Measures the total number of successfully forwarded records.
recordsFailedForwarding Measures the total number of records that fail to be forwarded.
recordsToBeForwarded Measures the total number of records to be forwarded.
recordsToBeProcessedLocally Measures the total number of records to be processed locally.
recordsActuallyProcessedLocally Measures the total number of records actually processed locally. This value is the sum of recordsToBeProcessedLocally and recordsFailedForwarding.
recordsReceivedFromPeers Measures the total number of records received from remote peers.

Gauge

peerEndpoints Measures the number of dynamically discovered peer Data Prepper endpoints. For static mode, the size is fixed.