Configure and Deploy Confluent Private Cloud Gateway using Docker

Configure and deploy Confluent Private Cloud Gateway (Confluent Gateway) using Docker. You can use this deployment path to run Confluent Gateway on-premises, in private cloud VPCs, and across hybrid environments.

For general requirements and considerations, see Requirements and considerations. For Docker-specific requirements, see Docker software requirements.

The high-level steps to deploy Confluent Gateway using Docker are:

Configure Confluent Gateway by defining streaming domains, routes, and administration settings in a Docker Compose file.
Deploy Confluent Gateway by pulling the Confluent Gateway Docker image and starting the service with Docker Compose.

After deployment, configure security and reconfigure clients to use the Confluent Gateway endpoint. For more information, see Next steps.

Configure Confluent Gateway using Docker Compose

Provide the configuration settings in a Docker Compose YAML file. This guide uses docker-compose.yaml as an example.

The top-level layout for the Confluent Gateway configuration file is as follows:

gateway:
  image:                  --- [1]
  name:                   --- [2]
  streamingDomains: []    --- [3]
  secretStores: []        --- [4]
  routes: []              --- [5]
  admin: {}               --- [6]

[1] The Confluent Gateway Docker image in the pattern: confluentinc/cpc-gateway:<version_tag>. <version_tag> is the Confluent Gateway version.
[2] The Confluent Gateway instance identifier.
[3] A list of streaming domains that represent Apache Kafka® clusters. For more information, see Streaming domains configuration.
[4] A list of secret stores. Required for authentication swapping. See Secret store configuration for details.
[5] A list of client routing rules. For more information, see Routes configuration.
[6] Admin and metrics configuration. For more information, see Administration and metrics configuration.

Streaming domains configuration

Streaming domains are logical representations of your Kafka clusters in Confluent Gateway.

gateway:
  streamingDomains:
    - name:               --- [1]
      type:               --- [2]
      kafkaCluster:       --- [3]
        name:             --- [4]
        bootstrapServers: --- [5]
          - id:           --- [6]
            endpoint:     --- [7]
            ssl:          --- [8]
        nodeIdRanges:     --- [9]
          - name:         --- [10]
            start:        --- [11]
            end:          --- [12]

[1] A unique name for the streaming domain.
[2] The type of the streaming domain. Set to kafka by default.
[3] A Kafka cluster, including Confluent Server, Confluent Private Cloud Kafka, or Apache Kafka®, that the Confluent Gateway can route traffic to.
[4] The name of the Kafka cluster.
[5] A list of Kafka bootstrap servers in the format host:port. At minimum, one bootstrap server is required per Kafka cluster. For each listener, you can define one bootstrap server.
[6] A unique identifier for the bootstrap server. Use the protocol name (such as SASL_PLAINTEXT, SSL, or PLAINTEXT_SASL_PLAIN) for clear distinction between the TLS channel type and SASL mechanism.
[7] The bootstrap endpoint of the Kafka broker in the format: host:port.
[8] Only required for SSL/SASL_SSL configuration. Supported certificate types are JKS, PKCS12, and PEM.
See the SSL configuration section for details.
[9] The node ID ranges. Only required for port-based broker identification. These should be the broker IDs defined in the Kafka deployment.
[10] The name of the node ID range.
[11] The start of the node ID range, inclusive.
[12] The end of the node ID range, inclusive.

An example configuration for a Confluent Gateway streaming domain:

streamingDomains:
  - name: sales # unique across gateway
    type: kafka # default: kafka
    kafkaCluster:
      name: sales-cluster # default: <streamingDomain.name>
      bootstrapServers:
        - id: PLAINTEXT-1
          endpoint: kafka0.example.com:9092
        - id: SASL_SSL-1
          endpoint: kafka0.example.com:9093
          ssl:  # required when using SASL_SSL/SSL
            ignoreTrust: false
            truststore:
              type: PKCS12  # default: JKS
              location: /opt/ssl/client-truststore.p12
              password:
                file: /opt/secrets/client-truststore.password
            keystore: # gateway's identity when needed
              type: PKCS12 # default: JKS
              location: /opt/ssl/gw-keystore.p12
              password:
                file: /opt/secrets/gw-keystore.password
              keyPassword:
                value: inline-password
      nodeIdRanges:
        - name: default
          start: 0              # inclusive
          end: 3                # inclusive

password can be a file path or an inline value. For details, see Password configuration.
ignoreTrust skips certificate validation. Not recommended for production. When true, Confluent Gateway ignores all other SSL settings.

Routes configuration

Routes are Confluent Gateway endpoints where client applications connect to stream data.

Confluent Gateway uses routes to define how client applications connect to Kafka clusters. Clients connect to Confluent Gateway as if it were a Kafka cluster, while Confluent Gateway handles routing and governance.

gateway:
  routes:
    - name:                         --- [1]
      endpoint:                     --- [2]
      brokerIdentificationStrategy: --- [3]
        type:                       --- [4]
        pattern:                    --- [5]
      streamingDomain:              --- [6]
        name:                       --- [7]
        bootstrapServerId:          --- [8]
      security:                     --- [9]
      fence:                        --- [10]

[1] The unique name for the route.
[2] The host:port combination that Confluent Gateway listens on. This is the external address clients use to bootstrap to the Kafka cluster.
[3] Specifies the strategy for mapping client requests to a specific Kafka broker.
[4] The type of broker identification strategy. Set to port (default) or host.
- port strategy: Each Kafka broker is identified using a unique port number. This is the default strategy.
  Clients connect to different ports to reach specific brokers (for example, port 9092 to connect with broker-0, port 9093 to connect with broker-1).
  The nodeIdRanges from the streaming domain configured in Streaming domains configuration is used. The nodeIdRanges must be present in the streaming domain associated with the route.
- host strategy: Each Kafka broker is represented using a unique hostname.
  Clients use different host names to reach specific brokers (for example, broker-0.kafka.company.com, broker-1.kafka.company.com), and Confluent Gateway routes based on the Server Name Indication (SNI) header.
  The pattern setting ([5]) is used.
[5] The pattern for the broker identification strategy. Required if the type ([4]) is host. For example, broker-$(nodeId).eu-gw.sales.example.com:9092.
[6] The reference to a streaming domain.
[7] The name of the streaming domain. Must be a valid name from the gateway.streamingDomains[].name.
[8] The bootstrap server ID. Must match kafkaCluster.bootstrapServers[].id.
[9] The security configuration. For more information, see Configure Security for Confluent Private Cloud Gateway.
[10] Optional. The fencing filter configuration. See Fencing filter for details.

An example configuration for Confluent Gateway routes:

gateway:
 routes:
   - name: eu-sales
     endpoint: eu-gw.sales.example.com:9092
     brokerIdentificationStrategy:
       type: host
       pattern: broker-$(nodeId).eu-gw.sales.example.com:9092
     streamingDomain:
       name: sales
       bootstrapServerId: SASL_SSL-1

Route filters configuration

Filters allow you to control and manage traffic flow for specific routes in Confluent Gateway. You can apply filters at the route level to enforce policies, block or allow requests, and customize error handling for different scenarios.

Fencing filter

The fencing filter in Confluent Gateway is a route-level filter that allows you to control the traffic flow on a specific route. It supports two fencing scopes:

ALL: Blocks all requests on the specified route. Useful for scenarios such as maintenance windows or when you want to temporarily disable access to a route.
NONE: Allows all requests on the specified route.

gateway:
  routes:
    - name:
      fence:
        scope:          --- [1]
        errorCode:      --- [2]
        errorMessage:   --- [3]

[1] The fencing scope of the filter. The default value is NONE. Set to ALL to block all requests on the route.
[2] Optional. The error code to return for blocked requests. The default value is BROKER_NOT_AVAILABLE.
For a list of valid error codes, see Kafka protocol error codes.
[3] Optional. The error message to return for blocked requests. The default value is This route is currently unavailable - all requests are blocked.

The following is an example configuration for a Confluent Gateway route with the fencing filter enabled:

gateway:
  routes:
    - name: eu-sales
      endpoint: eu-gw.sales.example.com:9092
      fence:
        scope: ALL
        errorCode: BROKER_NOT_AVAILABLE
        errorMessage: "Maintenance in progress - route temporarily unavailable"
      brokerIdentificationStrategy:
        type: host
        pattern: broker-$(nodeId).eu-gw.sales.example.com:9092
      streamingDomain:
        name: sales
        bootstrapServerId: SASL_SSL-1

Administration and metrics configuration

The admin section configures the Confluent Gateway administrative service, including the bind address, TCP port, metrics endpoint, JVM metrics collection, and custom metric tags.

gateway:
  admin:
    bindAddress:             --- [1]
    port:                    --- [2]
    endpoints:
      metrics:               --- [3]
    jvmMetrics:              --- [4]
      - JvmGcMetrics
      - JvmMemoryMetrics
      - JvmThreadMetrics
      - ProcessorMetrics
      - UptimeMetrics
    commonTags:              --- [5]
      host:
      region:

[1] The local address to bind admin service and to listen on for incoming connections. The default value is 0.0.0.0.
This address determines which network interfaces the Confluent Gateway uses to expose its administrative endpoints, such as metrics and liveness checks.
[2] The TCP port for exposing admin endpoints. The default value is 9190.
The Confluent Gateway serves metrics at http://{bindAddress}:{port}/metrics. It exposes a liveness check at http://{bindAddress}:{port}/livez.
[3] The metrics endpoints to be enabled and exposed. The default value is true.
[4] Standard JVM metrics captured using Micrometer classes. By default, JvmGcMetrics, JvmMemoryMetrics, JvmThreadMetrics, ProcessorMetrics, and UptimeMetrics are enabled.
[5] Optional. The common tags to be applied to all the metrics.

An example configuration for Confluent Gateway administration and metrics:

admin:
  bindAddress: 0.0.0.0
  port: 9190
  endpoints:
    metrics: true
  jvmMetrics:
    - JvmGcMetrics
    - JvmMemoryMetrics
    - JvmThreadMetrics
    - ProcessorMetrics
    - UptimeMetrics
  commonTags:
    host: pod-0
    region: us-west-2

Enterprise license configuration (optional)

Enterprise mode enables unlimited routes and requires a valid Confluent Private Cloud Enterprise license key. Trial mode (default, no key required) is limited to a maximum of four routes. For a full comparison of modes, see Deploy Confluent Private Cloud Gateway.

If you’re using Enterprise mode, follow these steps to apply your license key:

Contact Confluent to get one or more valid license keys for production use.
Configure the GATEWAY_LICENSES environment variable using the license key you obtained in the previous step.
- Option A: Set the environment variable before starting the Confluent Gateway.
```
export GATEWAY_LICENSES="your-license-key"
```
  To add multiple license keys, use the following syntax using the dollar sign ($) to escape the newline character (\n).
```
export GATEWAY_LICENSES=$'your-first-license-key\nyour-second-license-key'
```
- Option B: Edit docker-compose.yaml. You can add multiple license keys, one per line.
```
gateway:
  environment:
    GATEWAY_LICENSES: |
      your-first-license-key
      your-second-license-key
```
To verify the license status, check the Confluent Gateway logs for license information after starting the Confluent Gateway.
```
docker logs gateway | grep -i license
```

For example license configurations, see Confluent Gateway examples in GitHub.

After completing your configuration, save the file as docker-compose.yaml.

Deploy Confluent Gateway using Docker

To deploy Confluent Gateway:

Pull the Confluent Gateway Docker image to ensure you have the correct version and avoid using a stale locally cached image. For available version tags, see Confluent Gateway on GitHub.
```
docker pull confluentinc/cpc-gateway:<version_tag>
```
For example, to pull version 1.2.0:
```
docker pull confluentinc/cpc-gateway:1.2.0
```
Start Confluent Gateway using the docker-compose.yaml configuration file you set up in Configure Confluent Gateway using Docker Compose.
```
docker compose -f docker-compose.yaml up -d
```
Verify that Confluent Gateway is running.
```
docker ps
```
Confluent Gateway starts in the background after the docker compose command completes. Confirm the Confluent Gateway container appears in the output.

Next steps

After you deploy Confluent Gateway:

Configure security for the Confluent Gateway. Security configuration covers authentication, SSL/TLS, secret stores, and passwords for client-to-Confluent Gateway and Confluent Gateway-to-Kafka cluster connections.
Reconfigure clients to communicate with the Confluent Gateway endpoint by pointing their bootstrap.servers to the route endpoint defined in the Confluent Gateway configuration. For migration scenarios between Kafka clusters, see Migrate between Kafka Clusters using Confluent Private Cloud Gateway.

Troubleshoot Confluent Gateway

Use this section to collect diagnostics and resolve common issues when running Confluent Gateway with Docker. Start with the log-capture and debug-logging steps that follow, then consult the Known and common issues section for symptom-based resolutions.

Capture Confluent Gateway logs manually

Begin troubleshooting by inspecting the Confluent Gateway container logs. Most initialization failures, including network timeouts and credential errors, are captured here.

Use Docker commands to inspect the Confluent Gateway container logs.

# View all Gateway logs
docker logs gateway

# Filter for errors
docker logs gateway | grep -i error

# Filter for license-related messages
docker logs gateway | grep -i license

Enable debug logging to view stack traces

Set the global Confluent Gateway log level to DEBUG to capture detailed logs, including stack traces. This helps diagnose complex issues when running Confluent Gateway.

Update your docker-compose.yaml file to include the GATEWAY_ROOT_LOG_LEVEL environment variable:

gateway:
  environment:
    GATEWAY_ROOT_LOG_LEVEL: "DEBUG"

The GATEWAY_ROOT_LOG_LEVEL environment variable controls the global logging level for Confluent Gateway, and the DEBUG log level captures detailed system events, including stack traces.

Known and common issues

Confluent Gateway container exits or restarts repeatedly

Symptoms

The Confluent Gateway container terminates after startup.
Running the docker ps command shows the container is repeatedly restarting.
Running the docker compose up command shows that the service failed to start.
Logs contain configuration parsing errors, license validation failures, or stack traces.

Likely causes

Invalid or incomplete Confluent Gateway configuration file.
Misconfigured environment variables in the docker-compose.yaml file.

Resolution

Inspect the logs for configuration and license errors: Identify messages indicating failed YAML parsing, unknown fields, or unrecognized license keys.
```
docker logs gateway
docker logs gateway | grep -i license
```
Verify configuration file mapping: Confirm that the volumes section in your docker-compose.yaml file correctly maps the local configuration file to the expected path in the container.
Validate the configuration file structure:
- Ensure that the streamingDomains section defines at least one streaming domain and a corresponding bootstrap server.
- Ensure that the routes section defines at least one valid route definition.
Validate Enterprise mode configuration: If you are using the Enterprise license, confirm that the GATEWAY_LICENSES environment variable contains valid and unexpired license keys.

Clients can’t connect to the Confluent Gateway endpoint

Symptoms

Clients connections to the Confluent Gateway endpoint either time out or stall indefinitely during metadata requests.
Clients can directly connect to the Kafka cluster, but connections fail when routed through the Confluent Gateway.

Likely causes

The Confluent Gateway container can’t reach the Kafka bootstrap servers due to DNS, firewall, or network issues.
Clients are incorrectly configured to connect to broker addresses directly instead of the Confluent Gateway route endpoint.
The routes.endpoint value doesn’t match the host and port published by the Docker container.
The bootstrapServerId is mismatched across different sections of the configuration.

Resolution

Confirm Docker port mappings: If the Confluent Gateway route endpoint is defined as gateway.example.com:19092, ensure that your docker-compose.yaml file publishes to that port. For example:
```
gateway:
  ports:
    - "19092:19092"
```
Test Gateway to Kafka connectivity:
- From within the container network or host where Confluent Gateway runs, test connectivity to the Kafka bootstrap endpoints defined under streamingDomains.kafkaCluster.bootstrapServers[].endpoint.
- Inspect DNS resolution, firewall rules, and network routing.
Review logs for authentication issues: Inspect logs for repeated connection attempts or terminated during authentication messages. If these errors occur, verify your authentication and SSL/TLS configuration settings.
Verify broker endpoint resolution:
When using the host-based brokerIdentification strategy, clients must resolve individual broker addresses to the Confluent Gateway’s network load balancer (NLB). If your broker address pattern is defined as b$(nodeId).gateway.example.com, ensure that your DNS provider is configured to route these subdomains correctly.
Required DNS configuration:
To support dynamic broker identification, you must configure a wildcard DNS record pointing to your Confluent Gateway NLB:
Record Type
Host / Pattern
Target
A
gateway.example.com
<gateway-nlb-host>
A (Wildcard)
*.gateway.example.com
<gateway-nlb-host>
Common misconfigurations to avoid:
Avoid the following settings, which prevent clients from connecting to the brokers:
- Invalid endpoint binding: route.endpoint = 0.0.0.0
  Result: The Confluent Gateway advertises broker endpoints as localhost or 0.0.0.0 to the client. The client attempts to connect to its own local machine instead of the Confluent Gateway.
- Unresolvable host patterns: route.brokerIdentification.pattern = b$(nodeId).<unresolvable-host>
  Result: While the Confluent Gateway might start successfully, clients encounter UnknownHostException because the generated broker addresses don’t exist in your DNS registry.
- Missing wildcard records: If you only map the root domain (gateway.example.com) without the wildcard (*), individual broker lookups like b0.gateway.example.com fail.

Protocol or SSL/TLS mismatch

Symptoms

Client logs or Confluent Gateway logs show errors such as frame size exceptions or TLS handshake failures.
Clients use SASL_SSL or SSL but the route is configured as plaintext, or vice versa.

Likely causes

The client’s security.protocol doesn’t match the configured security for the route.
TLS-encrypted traffic is directed to a plaintext route endpoint, or plaintext traffic is directed to an SSL-only route.

Resolution

Confirm route configuration and restart the Confluent Gateway service to verify that client connectivity is restored.
- Inspect the gateway.routes[].security.ssl settings in the Confluent Gateway configuration file.
- If security.ssl is omitted, the route expects plaintext traffic.
- If security.ssl is defined, configure the client to use an SSL protocol, such as SASL_SSL or SSL.
Align client configuration:
- For unencrypted connections, set the client protocol to PLAINTEXT.
- When using SASL authentication without TLS, set the client protocol to SASL_PLAINTEXT.
- For TLS routing, set the client protocol to SSL or SASL_SSL and configure the truststore and keystore as required.

Authentication swap not behaving as expected

Symptoms

Clients using authentication swap fail to authenticate with the backend cluster.
Logs report errors related to secret store lookups, Java Authentication and Authorization Service (JAAS) configuration failures, or callback handler initialization.
Backend brokers report invalid credentials despite the client providing valid local certificates.

Likely causes

Route security isn’t configured with auth: swap.
The secretStore name referenced in the Confluent Gateway configuration is incorrect or missing in the routes section.
Secret store provider type is incorrect, or the credentials required to access the store are misconfigured.

Resolution

Verify route swap configuration: Ensure the defined routes perform authentication swapping.

gateway:
  routes:
    - name: <route_name>
      security:
        auth: swap
        swapConfig: <swap-config>

Avoid hardcoded broker credentials for cluster authentication: Don’t embed static broker credentials in the Confluent Gateway configuration. For swap scenarios, credentials must be dynamically resolved from a supported provider such as HashiCorp Vault, a local file, or other supported secret stores for dynamic resolution.
Validate your secret store configuration:
- Provider types are case-sensitive. Verify that you are using the exact casing required. For example, use Azure, not AZURE.
- Confirm the Confluent Gateway has the necessary permissions to read secrets from the provider.
- Ensure the Confluent Gateway can reach the secret store’s API endpoint over the network.

OAuth token endpoint not allowed

Symptoms

The Confluent Gateway fails to fetch OAuth tokens, and logs report a security restriction similar to: ... is not allowed. Update system property 'org.apache.kafka.sasl.oauthbearer.allowed.urls'to allow https://...

Likely causes

For security purposes, the Confluent Gateway requires an allowlist of outbound OAuth token requests. The configured OAuth token URL used by the identity provider isn’t included in the default allowlist.

Resolution

Add the OAuth token endpoint to the GATEWAY_OPTS environment variable in the docker-compose.yaml file:
```
gateway:
  environment:
    GATEWAY_OPTS: "-Dorg.apache.kafka.sasl.oauthbearer.allowed.urls=<tokenEndpointUri>"
```
Replace <tokenEndpointUri> with your identity provider’s OAuth token endpoint URL. For example, if you are using Microsoft Entra ID (formerly Azure AD): https://login.microsoftonline.com/<tenantId>/oauth2/v2.0/token
Restart the Confluent Gateway service to apply the configuration changes. Check the logs to ensure the not allowed error no longer appears during the authentication handshake.

License and route limit issues

Symptoms

The Confluent Gateway fails to initialize additional routes.
Logs report warnings on license or route-limit exhaustion.

Likely causes

Trial mode limits Confluent Gateway to a maximum of four routes. To configure more routes, an Enterprise license is required.

Resolution

Understand license modes: For a comparison of Trial and Enterprise modes, see Enterprise license configuration (optional).
Apply an Enterprise license: To enable more than four routes, add your license key to the GATEWAY_LICENSES environment variable in your docker-compose.yaml file. For configuration details and examples, see Enterprise license configuration (optional).
Inspect the license status: After restarting the service, verify that the Confluent Gateway has successfully recognized the license. Run docker logs gateway | grep -i license to confirm the license status.

Record Type	Host / Pattern	Target
A	`gateway.example.com`	`<gateway-nlb-host>`
A (Wildcard)	`*.gateway.example.com`	`<gateway-nlb-host>`