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Amazon Managed Streaming for Apache Kafka (Amazon MSK) Module

This Terraform module configures and launches an Amazon MSK cluster.

Amazon Managed Streaming for Apache Kafka (Amazon MSK) is a fully managed service that enables you to build and run applications that use Apache Kafka to process streaming data. Amazon MSK provides the control-plane operations, such as those for creating, updating, and deleting clusters. Managing all the data-plane operations, such running producers and consumers, is up to you.

It runs open-source versions of Apache Kafka, meaning existing applications, tooling, and plugins from partners and the Apache Kafka community are supported without requiring changes to application code. You can read more about supported Apache Kafka versions in the official documentation.

Note that this module does not support Amazon MSK Serverless, which is still in preview.

Cluster Configuration​

Amazon MSK provides a default configuration for brokers, topics, and Apache ZooKeeper nodes. You can also create custom configurations with var.server_properties and use them to create new MSK clusters or to update existing clusters.

Capacity Planning​

When planning the capacity for your cluster, there are multiple factors that need to be taken into consideration, including:

  • Performance and throughput
  • Fault tolerance
  • Storage capacity

To ensure high availability for production workloads, it is recommended to have a topic replication factor > 1. This means that your topics are partitioned and replicated across multiple brokers in the cluster, leading to better fault tolerance and parallelism for your consumers. As a rule of thumb, the optimal number of partitions for a topic should be equal to, or a multiple of, the number of brokers in your cluster. Note that the number of partitions can only be increased, not decreased.

See https://docs.aws.amazon.com/msk/latest/developerguide/bestpractices.html for further details on planning the capacity and configuration of your cluster.

Storage Auto Scaling​

Amount of required EBS storage depends on multiple factors, for example number of topics, amount and size of your data, data retention and replication factor. As such it is not possible to give an exact recommendation, instead the storage requirements should be calculated based on your use case. It is important to monitor disk usage and increase disk size when needed.

The module will set the initial EBS volume size with input variable initial_ebs_volume_size and automatically scale the broker volumes up until broker_storage_autoscaling_max_capacity is reached. You can optionally disable scale in with input variable disable_broker_storage_scale_in. You can use broker_storage_autoscaling_target_percentage to control the scaling threshold.

Monitoring​

Monitoring With CloudWatch​

Amazon MSK integrates with Amazon CloudWatch so that you can collect, view, and analyze metrics for your MSK serverless cluster. You can set the monitoring level for an MSK cluster to one of the following: DEFAULT, PER_BROKER, PER_TOPIC_PER_BROKER, or PER_TOPIC_PER_PARTITION. You can read more about metrics and monitoring here: https://docs.aws.amazon.com/msk/latest/developerguide/metrics-details.html

Open Monitoring with Prometheus​

You can also monitor your MSK cluster with Prometheus, an open-source monitoring system for time-series metric data. You can also use tools that are compatible with Prometheus-formatted metrics or tools that integrate with Amazon MSK Open Monitoring, like Datadog, Lenses, New Relic, and Sumo logic. You can read more about Open Monitoring with Prometheus here: https://docs.aws.amazon.com/msk/latest/developerguide/open-monitoring.html

All metrics emitted by Apache Kafka to JMX are accessible using open monitoring with Prometheus. For information about Apache Kafka metrics, see Monitoring in the Apache Kafka documentation.

Encryption​

Amazon MSK allows you to enable encryption at rest and in transit. The certificates that Amazon MSK uses for encryption must be renewed every 13 months. Amazon MSK automatically renews these certificates for all clusters.

Encryption at Rest​

Amazon MSK integrates with AWS Key Management Service (KMS) to offer transparent server-side encryption. Amazon MSK always encrypts your data at rest. When you create an MSK cluster, you can specify the AWS KMS customer master key (CMK) with var.encryption_at_rest_kms_key_arn that you want Amazon MSK to use to encrypt your data at rest. If no key is specified, an AWS managed KMS (aws/msk managed service) key will be used for encrypting the data at rest.

Encryption in Transit​

Amazon MSK uses TLS 1.2. By default, it encrypts data in transit between the brokers of your MSK cluster. You can override this default using var.encryption_in_transit_in_cluster input variable at the time you create the cluster. You can also control client-to-broker encryption using var.encryption_in_transit_client_broker input variable.

Logging​

Broker logs enable you to troubleshoot your Apache Kafka applications and to analyze their communications with your MSK cluster. You can deliver Apache Kafka broker logs to one or more of the following destination types:

  • Amazon CloudWatch Logs
  • Amazon S3
  • Amazon Kinesis Data Firehose.

You can read more about MSK logging here: https://docs.aws.amazon.com/msk/latest/developerguide/msk-logging.html

Authentication and Authorization​

You can use IAM to authenticate clients and to allow or deny Apache Kafka actions. Alternatively, you can use TLS or SASL/SCRAM to authenticate clients, and Apache Kafka ACLs to allow or deny actions. You can read more about available authentication and authorization options here: https://docs.aws.amazon.com/msk/latest/developerguide/kafka_apis_iam.html

Connecting to Kafka brokers​

Once you've used this module to deploy the Kafka brokers, you'll want to connect to them from Kafka clients (e.g., Kafka consumers and producers in your apps) to read and write data. To do this, you typically need to configure the bootstrap.servers property for your Kafka client with the IP addresses of a few of your Kafka brokers (you don't need all the IPs, as the rest will be discovered automatically via ZooKeeper):

--bootstrap.servers=10.0.0.4:9092,10.0.0.5:9092,10.0.0.6:9092

Depending on which client authentication method you configured, there are a number of output variables (bootstrap_brokers_*) that provide you with a list of bootstrap servers. You can also get the list of bootstrap servers using the AWS Cli:

$ aws kafka get-bootstrap-brokers --cluster-arn ClusterArn

{
    "BootstrapBrokerStringSaslIam": "b-1.myTestCluster.123z8u.c2.kafka.us-west-1.amazonaws.com:9098,b-2.myTestCluster.123z8u.c2.kafka.us-west-1.amazonaws.com:9098"
}

MSK Connect​

MSK Connect is a feature of Amazon MSK that makes it easy for developers to stream data to and from their Apache Kafka clusters. With MSK Connect, you can deploy fully managed connectors built for Kafka Connect that move data into or pull data from popular data stores like Amazon S3 and Amazon OpenSearch Service. You can deploy connectors developed by 3rd parties like Debezium for streaming change logs from databases into an Apache Kafka cluster, or deploy an existing connector with no code changes. Connectors automatically scale to adjust for changes in load and you pay only for the resources that you use.

Kafka Cluster Migration​

You can mirror or migrate your cluster using MirrorMaker, which is part of Apache Kafka. Kafka MirrorMaker is a utility that helps to replicate the data between two Apache Kafka clusters within or across regions.

For further information about migrating Kafka clusters, see: https://docs.aws.amazon.com/msk/latest/developerguide/migration.html

ZooKeeper​

Kafka depends on ZooKeeper to work. Amazon MSK manages the Apache ZooKeeper nodes for you. Each Amazon MSK cluster includes the appropriate number of Apache ZooKeeper nodes for your Apache Kafka cluster at no additional cost.

Controlling Access to Apache ZooKeeper​

For security reasons you may want to limit access to the Apache ZooKeeper nodes that are part of your Amazon MSK cluster. To limit access to the nodes, you can assign a separate security group to them. You can then decide who gets access to that security group.

As ZooKeeper security group configuration requires manual actions, this module does not include support for that. To change the security group for ZooKeeper, follow these instructions: https://docs.aws.amazon.com/msk/latest/developerguide/zookeeper-security.html

Reference​

Required​

cluster_namestringrequired

The name of the Kafka cluster (e.g. kafka-stage). This variable is used to namespace all resources created by this module.

cluster_sizenumberrequired

The number of brokers to have in the cluster.

instance_typestringrequired

Specify the instance type to use for the kafka brokers (e.g. kafka.m5.large). See https://docs.aws.amazon.com/msk/latest/developerguide/msk-create-cluster.html#broker-instance-types for available instance types.

kafka_versionstringrequired

Kafka version to install. See https://docs.aws.amazon.com/msk/latest/developerguide/supported-kafka-versions.html for a list of supported versions.

subnet_idslist(string)required

The subnet IDs into which the broker instances should be deployed. You should typically pass in one subnet ID per node in the cluster_size variable. The number of broker nodes must be a multiple of subnets. We strongly recommend that you run Kafka in private subnets.

vpc_idstringrequired

The ID of the VPC in which to deploy the cluster.

Optional​

additional_security_group_idslist(string)optional

A list of Security Group IDs that should be added to the MSK cluster broker instances.

[]
allowed_inbound_cidr_blockslist(string)optional

A list of CIDR-formatted IP address ranges that will be allowed to connect to the Kafka brokers.

[]

A list of security group IDs that will be allowed to connect to the Kafka brokers.

[]

Max capacity of broker node EBS storage (in GiB)

100

Broker storage utilization percentage at which scaling is triggered.

70
client_sasl_scram_secret_arnslist(string)optional

List of ARNs for SCRAM secrets stored in the Secrets Manager service.

[]

Optional list of ACM Certificate Authority Amazon Resource Names (ARNs).

[]
cloudwatch_log_groupstringoptional

Name of the Cloudwatch Log Group to deliver logs to.

null
custom_tagsmap(string)optional

Custom tags to apply to the Kafka broker nodes and all related resources.

{}
Example
     {
       key1 = "value1"
       key2 = "value2"
     }

custom_tags_security_groupmap(string)optional

A map of custom tags to apply to the Security Group for this MSK Cluster. The key is the tag name and the value is the tag value.

{}
Example
     {
       key1 = "value1"
       key2 = "value2"
     }

Flag indicating whether broker storage should never be scaled in.

false

Whether SASL IAM client authentication is enabled.

false

Whether SASL SCRAM client authentication is enabled.

false
enable_client_tlsbooloptional

Whether TLS client authentication is enabled.

false

Indicates whether you want to enable or disable streaming broker logs to Cloudwatch Logs.

false

Indicates whether you want to enable or disable streaming broker logs to Kinesis Data Firehose.

false
enable_s3_logsbooloptional

Indicates whether you want to enable or disable streaming broker logs to S3.

false

You may specify a KMS key short ID or ARN (it will always output an ARN) to use for encrypting your data at rest. If no key is specified, an AWS managed KMS ('aws/msk' managed service) key will be used for encrypting the data at rest.

null

Encryption setting for data in transit between clients and brokers. Valid values: TLS, TLS_PLAINTEXT, and PLAINTEXT. Default value is TLS.

"TLS"

Whether data communication among broker nodes is encrypted. Default value: true.

true
enhanced_monitoringstringoptional

Specify the desired enhanced MSK CloudWatch monitoring level. See https://docs.aws.amazon.com/msk/latest/developerguide/metrics-details.html for valid values.

"DEFAULT"

Name of the Kinesis Data Firehose delivery stream to deliver logs to.

null

The initial size of the EBS volume (in GiB) for the data drive on each broker node.

50

Indicates whether you want to enable or disable the Prometheus JMX Exporter.

true

Indicates whether you want to enable or disable the Prometheus Node Exporter.

true

Override automatically created Service-linked role for storage autoscaling. If not provided, Application Auto Scaling creates the appropriate service-linked role for you.

null
s3_logs_bucketstringoptional

Name of the S3 bucket to deliver logs to.

null
s3_logs_prefixstringoptional

Prefix to append to the folder name.

null
server_propertiesmap(string)optional

Contents of the server.properties file. Supported properties are documented in the MSK Developer Guide (https://docs.aws.amazon.com/msk/latest/developerguide/msk-configuration-properties.html).

{}
Example
     {
       "auto.create.topics.enable" = "true"
       "default.replication.factor" = "2"
     }