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Adding Security to a Running Cluster¶
You can secure a running cluster via one or more of the supported protocols discussed previously. This is done in phases:
- Incrementally bounce the cluster nodes to open additional secured port(s).
- Restart clients using the secured rather than
PLAINTEXTport (assuming you are securing the client-broker connection).
- Incrementally bounce the cluster again to enable broker-to-broker security (if this is required)
- A final incremental bounce to close the
The security implementation lets you configure different protocols for both broker-client and broker-broker communication. These must be enabled in separate bounces. A
PLAINTEXT port must be left open throughout so brokers and/or clients can continue to communicate.
When performing an incremental bounce stop the brokers cleanly via a
SIGTERM. It’s also good practice to wait for restarted replicas to return to the ISR list before moving onto the next node.
As an example, say we wish to encrypt both broker-client and broker-broker communication with SSL. In the first incremental bounce, a SSL port is opened on each node:
We then restart the clients, changing their config to point at the newly opened, secured port:
bootstrap.servers=[broker1:9092,...] security.protocol=SSL ...etc
In the second incremental server bounce we instruct Kafka to use SSL as the broker-broker protocol (which will use the same SSL port):
In the final bounce we secure the cluster by closing the
Alternatively we might choose to open multiple ports so that different protocols can be used for broker-broker and broker-client communication. Say we wished to use SSL encryption throughout (i.e. for broker-broker and broker-client communication) but we’d like to add SASL authentication to the broker-client connection also. We would achieve this by opening two additional ports during the first bounce:
Again we would then restart the clients, changing their config to point at the newly opened, SASL & SSL secured port:
bootstrap.servers=[broker1:9093,...] security.protocol=SASL_SSL ...etc
The second server bounce would switch the cluster to use encrypted broker-broker communication via the SSL port we previously opened on port 9092:
The final bounce secures the cluster by closing the
ZooKeeper can be secured independently of the Kafka cluster. The steps for doing this are covered in the ZooKeeper section.