Custom SMT for Confluent Cloud Limitations and Support

This page describes the limitations and support for Custom SMTs. Be sure to review all the information in this page before proceeding with the Quick start.

Limitations

• Custom SMTs can only be used with fully-managed Connectors.

• Custom SMTs scope to a specific environment and CSP, including AWS, Microsoft Azure, and Google Cloud.

• Custom SMT on Azure requires Confluent CLI version 4.49.0 or later.

• Custom SMT on Google Cloud requires Confluent CLI version 4.56.0 or later.

• Only available for clusters within Private Networking setups (Peering, Transit Gateway, Private Network Interface, Privatelink) on AWS, Microsoft Azure, and Google Cloud.

• Default limit for Custom SMTs per fully-managed connector is 10.

• Default limit for uploaded Custom SMT artifact files is 10 per Confluent environment.

• Default limit for Custom artifact file size is 100 MB.

• Message size limit of ~2MB (4MB on the wire size).

• Custom SMT JARs must be compiled using Java 21, Java 17 or earlier. JARs compiled with Java 25 are not supported.

• Custom SMT performance does not automatically scale with the number of connector tasks. You must manually tune connector capacity for different workloads.

• Custom SMTs support Log4j2 and slf4j for logging. For Log4j2, use log4j-api and log4j-core with provided scope. For slf4j, use slf4j-api with provided scope.

Important

Confluent may scan files uploaded through Custom SMT to detect security risks.

Shared Responsibility

Confluent supports the underlying Custom SMT infrastructure in Confluent Cloud only. It is your responsibility to troubleshoot Custom SMT issues for connectors you build or that were provided to you from others. The following provides additional details about shared support responsibilities.

Shared responsibilities matrix

• Customer Managed: The customer is responsible for self-managing these services. Confluent does not provide any support for customer-managed services and features with Custom SMTs.

• Confluent Managed: Confluent is responsible for managing these services and providing support.

Supported regions

You can use Custom SMTs with fully-managed connectors in the following AWS, Azure, and Google Cloud regions supported by Confluent Cloud.

AWS regions

Americas

Americas Custom SMT

AWS Region	Location	Custom SMT
us-east-1	Virginia, USA	✓
us-east-2	Ohio, USA	✓
us-west-2	Oregon, USA	✓
ca-central-1	Canada Central	✓
ca-west-1	Calgary, Canada
sa-east-1	São Paulo, Brazil

Asia Pacific

Asia Pacific Custom SMT

AWS Region	Location	Custom SMT
ap-east-1	Hong Kong	✓
ap-northeast-1	Tokyo, Japan
ap-northeast-2	Seoul, South Korea
ap-northeast-3	Osaka, Japan
ap-south-1	Mumbai, India	✓
ap-south-2	Hyderabad, India
ap-southeast-1	Singapore	✓
ap-southeast-2	Sydney, Australia	✓
ap-southeast-3	Jakarta, Indonesia
ap-southeast-4	Melbourne, Australia
ap-southeast-5	Malaysia
ap-southeast-7	Thailand

Europe

Europe Custom SMT

AWS Region	Location	Custom SMT
eu-central-1	Frankfurt, Germany	✓
eu-central-2	Zurich, Switzerland
eu-north-1	Stockholm, Sweden
eu-south-1	Milan, Italy
eu-south-2	Spain
eu-west-1	Ireland	✓
eu-west-2	London, UK	✓
eu-west-3	Paris, France

Middle East, Africa and Other

AWS Middle East, Africa and Other Custom SMT

AWS Region	Location	Custom SMT
me-south-1	Bahrain
me-central-1	UAE
af-south-1	Cape Town, South Africa	✓
il-central-1	Tel Aviv, Israel

Azure regions

Americas

Azure Americas Custom SMT

Azure Region	Location	Custom SMT
canadacentral	Toronto, Canada
mexicocentral	Mexico Central
brazilsouth	Sao Paulo state, Brazil	✓
centralus	Iowa, USA	✓
eastus	Virginia, USA	✓
eastus2	Virginia, USA	✓
southcentralus	Texas, USA
westus2	Washington, USA	✓
westus3	Phoenix, USA

Asia Pacific

Azure Asia Pacific Custom SMT

Azure Region	Location	Custom SMT
australiaeast	New South Wales, Australia	✓
centralindia	Pune, India	✓
eastasia	Hong Kong
japaneast	Tokyo, Japan
koreacentral	Seoul, South Korea
southeastasia	Singapore	✓
newzealandnorth	New Zealand North

Europe

Azure Europe Custom SMT

Azure Region	Location	Custom SMT
francecentral	Paris, France
germanywestcentral	Frankfurt, Germany	✓
northeurope	Ireland	✓
norwayeast	Oslo, Norway
swedencentral	Gävle, Sweden
switzerlandnorth	Zurich, Switzerland
uksouth	London, UK	✓
westeurope	Netherlands	✓
italynorth	Milan, Italy
spaincentral	Spain
austriaeast	Vienna, Austria

Google Cloud regions

Americas

Google Cloud Americas Custom SMT

GCP Region	Location	Custom SMT
northamerica-northeast1	Montreal, Canada
northamerica-northeast2	Toronto, Canada
southamerica-east1	São Paulo, Brazil
southamerica-west1	Santiago, Chile
us-central1	Iowa, USA	✓
us-east1	Carolina, USA	✓
us-east4	Virginia, USA	✓
us-west1	Oregon, USA
us-west2	Los Angeles, USA
us-west3	Salt Lake City, USA
us-west4	Las Vegas, USA	✓
us-south1	Dallas, USA

Asia Pacific

Google Cloud Asia Pacific Custom SMT

GCP Region	Location	Custom SMT
asia-east1	Taiwan
asia-east2	Hong Kong
asia-northeast1	Tokyo, Japan
asia-northeast2	Osaka, Japan
asia-northeast3	Seoul, South Korea
asia-south1	Mumbai, India	✓
asia-south2	Delhi, India
asia-southeast1	Singapore	✓
asia-southeast2	Jakarta, Indonesia
australia-southeast1	Sydney, Australia
australia-southeast2	Melbourne, Australia

Europe

Google Cloud Europe Custom SMT

GCP Region	Location	Custom SMT
europe-central2	Warsaw, Poland
europe-north1	Finland
europe-southwest1	Madrid, Spain
europe-west1	Belgium	✓
europe-west2	London, UK	✓
europe-west3	Frankfurt, Germany	✓
europe-west4	Netherlands	✓
europe-west6	Zurich, Switzerland
europe-west8	Milan, Italy
europe-west9	Paris, France
europe-west12	Turin, Italy

Middle East, Africa and Other

Google Cloud Middle East, Africa and Other Custom SMT

GCP Region	Location	Custom SMT
me-west1	Tel Aviv, Israel
me-central1	Doha, Qatar
me-central2	Dammam, Saudi Arabia

Observability / Logs

You can view the Confluent Cloud Custom SMT events alongside fully-managed connector events in the Confluent Cloud Console. For more details on how to view these events, see View Connector Events for Confluent Cloud.