Add support and documentation for Kafka with security

doc/technical_configuration.md

@@ -94,6 +94,39 @@ KAFNUS_TESTS_MONGO_PORT: "27017"
 
 > ✅ These environment variables are available to all sink connectors via `${env:...}` references thanks to the `config.providers=env` setting in the Kafnus Connect distributed configuration.
 
+### 🔐 Security Configuration
+
+Kafnus Connect supports Kafka authentication via SASL. You can configure security by setting the following environment variables in your Docker Compose file:
+
+```yaml
+# Security for Connect worker
+CONNECT_SECURITY_PROTOCOL: SASL_PLAINTEXT
+CONNECT_SASL_MECHANISM: PLAIN
+CONNECT_SASL_JAAS_CONFIG: >
+  org.apache.kafka.common.security.plain.PlainLoginModule required
+  username="connect-user"
+  password="connect-pass";
+
+# Security for producers and consumers
+CONNECT_PRODUCER_SECURITY_PROTOCOL: SASL_PLAINTEXT
+CONNECT_PRODUCER_SASL_MECHANISM: PLAIN
+CONNECT_PRODUCER_SASL_JAAS_CONFIG: >
+  org.apache.kafka.common.security.plain.PlainLoginModule required
+  username="connect-user"
+  password="connect-pass";
+
+CONNECT_CONSUMER_SECURITY_PROTOCOL: SASL_PLAINTEXT
+CONNECT_CONSUMER_SASL_MECHANISM: PLAIN
+CONNECT_CONSUMER_SASL_JAAS_CONFIG: >
+  org.apache.kafka.common.security.plain.PlainLoginModule required
+  username="connect-user"
+  password="connect-pass";
+```
+
+These variables are automatically applied by the `docker-entrypoint.sh` script when starting Kafka Connect in distributed mode. If `CONNECT_SECURITY_PROTOCOL` is defined, the script appends the corresponding security and SASL configuration to `connect-distributed.properties` for the worker, producer, and consumer.
+
+This ensures that all Kafka connections (incoming and outgoing) respect the authentication settings without modifying connector definitions directly.
+
 ---
 
 ## 🧩 Kafnus Connect Plugins
@@ -709,3 +742,11 @@ docker exec -it kafka /opt/kafka/bin/kafka-console-consumer.sh
 ```
 
 Check tables in PostGIS or MongoDB after running the corresponding test input.
+
+---
+
+## 📚 Operational & Advanced Topics
+
+For complete operational guidance, multi-tenant management, and security best practices, please refer to the **Kafnus main repository**:
+
+- [Advanced Topics](https://github.com/telefonicaid/kafnus/blob/main/doc/03_advanced_topics.md) – security and operational guide.

docker-entrypoint.sh

@@ -17,11 +17,14 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with kafnus. If not, see http://www.gnu.org/licenses/.
 
+#!/bin/bash
 set -e
 
 CONFIG_FILE="/home/appuser/config/connect-distributed.properties"
 
-cat > "${CONFIG_FILE}" <<EOF
+> "${CONFIG_FILE}"
+
+cat >> "${CONFIG_FILE}" <<EOF
 bootstrap.servers=${CONNECT_BOOTSTRAP_SERVERS:-kafka:9092}
 group.id=${CONNECT_GROUP_ID:-connect-cluster}
 
@@ -46,6 +49,24 @@ config.providers=env
 config.providers.env.class=org.apache.kafka.common.config.provider.EnvVarConfigProvider
 EOF
 
+# Security (optional)
+if [ -n "${CONNECT_SECURITY_PROTOCOL}" ]; then
+    cat >> "${CONFIG_FILE}" <<EOF
+
+security.protocol=${CONNECT_SECURITY_PROTOCOL}
+sasl.mechanism=${CONNECT_SASL_MECHANISM}
+sasl.jaas.config=${CONNECT_SASL_JAAS_CONFIG}
+
+producer.security.protocol=${CONNECT_PRODUCER_SECURITY_PROTOCOL:-${CONNECT_SECURITY_PROTOCOL}}
+producer.sasl.mechanism=${CONNECT_PRODUCER_SASL_MECHANISM:-${CONNECT_SASL_MECHANISM}}
+producer.sasl.jaas.config=${CONNECT_PRODUCER_SASL_JAAS_CONFIG:-${CONNECT_SASL_JAAS_CONFIG}}
+
+consumer.security.protocol=${CONNECT_CONSUMER_SECURITY_PROTOCOL:-${CONNECT_SECURITY_PROTOCOL}}
+consumer.sasl.mechanism=${CONNECT_CONSUMER_SASL_MECHANISM:-${CONNECT_SASL_MECHANISM}}
+consumer.sasl.jaas.config=${CONNECT_CONSUMER_SASL_JAAS_CONFIG:-${CONNECT_SASL_JAAS_CONFIG}}
+EOF
+fi
+
 echo ">> Starting Kafka Connect with config:"
 cat "${CONFIG_FILE}"