docs: ssl example added

.gitignore

@@ -229,3 +229,6 @@ tags
 pyvenv.cfg
 pip-selfcheck.json
 poetry.toml
+
+# local SSL cluster certificates
+kafka-certs/

examples/ssl-example/README.md

@@ -0,0 +1,88 @@
+# Kstreams SSL example
+
+This example shows how setup an SSL connection with `kstreams`. For this purpose we have to setup a local kafka SSL cluster.
+
+`ENV` varialbles are exported using the script `/scripts/ssl/export-env-variables` and loaded in python using [pydantic-settings](https://docs.pydantic.dev/latest/concepts/pydantic_settings/).
+
+Check [resources.py](https://github.com/kpn/kstreams/blob/master/examples/ssl-example/ssl_example/resources.py) to see how the backend with `SSL` is created
+
+## Requirements
+
+`python 3.8+`, `poetry`, `docker-compose`, `openssl`
+
+### Usage
+
+First create the server and client sertificates:
+
+```bash
+./scripts/ssl/ssl-setup
+```
+
+After executing the privious script, you will see a new folder called `kafka-certs`. The folder contains the `server` (inside the server folder),
+`admin` (inside the admin folder) and `client` certicicates. Do not worry about the content of them, it is just an example and they can be deleted,
+shared and recreated (it is just a local example)
+
+Now you can run the local SSL cluster:
+
+```bash
+./scripts/cluster/start
+```
+
+Second, you need to install the project dependencies dependencies. In a different terminal execute:
+
+```bash
+poetry install
+```
+
+Export the env variables:
+
+```bash
+. ./scripts/ssl/export-env-variables
+```
+
+Then we can run the project
+
+```bash
+poetry run app
+```
+
+You should see something similar to the following logs:
+
+```bash
+kstreams/examples/ssl-example via 🐳 colima is 📦 v0.1.0 via 🐍 v3.12.4 
+❯ poetry run app
+
+INFO:ssl_example.app:Starting application...
+INFO:aiokafka.consumer.subscription_state:Updating subscribed topics to: frozenset({'local--kstreams'})
+INFO:aiokafka.consumer.consumer:Subscribed to topic(s): {'local--kstreams'}
+INFO:kstreams.prometheus.monitor:Starting Prometheus Monitoring started...
+INFO:ssl_example.app:Producing event 0
+INFO:ssl_example.app:Producing event 1
+INFO:ssl_example.app:Producing event 2
+INFO:ssl_example.app:Producing event 3
+INFO:ssl_example.app:Producing event 4
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ERROR:aiokafka.consumer.group_coordinator:Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+INFO:aiokafka.consumer.group_coordinator:Discovered coordinator 1 for group example-group
+INFO:aiokafka.consumer.group_coordinator:Revoking previously assigned partitions set() for group example-group
+INFO:aiokafka.consumer.group_coordinator:(Re-)joining group example-group
+INFO:aiokafka.consumer.group_coordinator:Joined group 'example-group' (generation 1) with member_id aiokafka-0.11.0-5fb10c73-64b2-42a8-ae8a-23f59d4a3b6b
+INFO:aiokafka.consumer.group_coordinator:Elected group leader -- performing partition assignments using roundrobin
+INFO:aiokafka.consumer.group_coordinator:Successfully synced group example-group with generation 1
+INFO:aiokafka.consumer.group_coordinator:Setting newly assigned partitions {TopicPartition(topic='local--kstreams', partition=0)} for group example-group
+```
+
+## Note
+
+If you plan on using this example, pay attention to the `pyproject.toml` dependencies, where
+`kstreams` is pointing to the parent folder. You will have to set the latest version.

examples/ssl-example/docker-compose.yaml

@@ -0,0 +1,45 @@
+version: '3'
+services:
+
+  zookeeper:
+    image: "confluentinc/cp-zookeeper:7.3.0"
+    hostname: zookeeper
+    container_name: zookeeper
+    ports:
+      - 32181:32181
+    environment:
+      - ZOOKEEPER_CLIENT_PORT=32181
+  kafka:
+    volumes:
+      - ./kafka-certs/server/:/etc/kafka/secrets
+      - ./kafka-certs/admin/client.properties:/etc/kafka/config/client.properties
+    image: "confluentinc/cp-kafka:7.3.0"
+    hostname: kafka
+    container_name: kafka
+    environment:
+      KAFKA_BROKER_ID: "1"
+      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: "1"
+      KAFKA_AUTO_CREATE_TOPICS_ENABLE: "true"
+      KAFKA_ZOOKEEPER_CONNECT: "zookeeper:32181"
+      KAFKA_GROUP_INITIAL_REBALANCE_DELAY_MS: 0
+      CONFLUENT_METRICS_ENABLE: 'true'
+      CONFLUENT_SUPPORT_CUSTOMER_ID: anonymous
+      # Kafka security
+      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: SSL:SSL,SSL2:SSL
+      KAFKA_SECURITY_INTER_BROKER_PROTOCOL: SSL
+      KAFKA_ADVERTISED_LISTENERS: SSL://localhost:9092,SSL2://kafka:9093
+      KAFKA_SSL_KEYSTORE_FILENAME: keystore.jks
+      KAFKA_SSL_TRUSTSTORE_FILENAME: truststore.jks
+      KAFKA_SSL_KEY_CREDENTIALS: ssl-key-credentials
+      KAFKA_SSL_KEYSTORE_CREDENTIALS: key-store-credentials
+      KAFKA_SSL_TRUSTSTORE_CREDENTIALS: trust-store-credentials
+      KAFKA_SSL_CLIENT_AUTH: required
+      KAFKA_AUTHORIZER_CLASS_NAME: kafka.security.authorizer.AclAuthorizer
+      KAFKA_SSL_PRINCIPAL_MAPPING_RULES: RULE:^.*[Cc][Nn]=([a-zA-Z0-9._-]*).*$$/CN=$$1/,DEFAULT
+      KAFKA_SUPER_USERS: User:CN=localhost;User:CN=admin.client.company.org;
+    ports:
+      - "9092:9092"
+      - "29092:29092"
+    depends_on:
+      - zookeeper
+