Aiven

This is how to connect to Aiven Kafka from Zilla. The examples use the below Environment variables.

Environment variable	Description
TRUSTORE_PATH	The path to the truststore that stores CA cert that you want to trust.
TRUSTORE_TYPE	Keystore types such as pkcs12, jceks, and etc
TRUSTORE_PASSWORD	Truststore password.
KEYSTORE_PATH	The path to the keystore that stores access key.
KEYSTORE_TYPE	Keystore types such as pkcs12, jceks, and etc
KEYSTORE_PASSWORD	Keystore password.
CA_CERT_ALIAS	Unique string that identifies the certificate entry in the truststore.
SIGNED_CLIENT_CERT_ALIAS	A unique string that identifies the key cert entry chain in the keystore
BOOTSTRAP_SERVER_HOSTNAME	Target Kafka hostname
BOOTSTRAP_SERVER_PORT	Target Kafka port number

Aiven Parameters

The Aiven Kafka requires clients to connect via TLS mutual authentication and provides the following files Client Key, Client Certificate, and CA Certificate to achieve that. You can download them by going to Aiven Console -> Kafka Cluster -> Overview Tab as shown below.

Connection Info

you should have the following files:

• service.key - Access Key
• service.cert - Access Certificate
• ca.pem - CA Certificate

The next step is to generate the truststore and keystore.

• truststore.p12 - contains the trusted server certificates or certificate authorities
• keystore.p12 - contains the signed client certificates

You can use the scripts shown below to generate truststore.p12 and keystore.p12 files using certificates and keys downloaded from Aiven Kafka Console. Please replace all caps lock words.

truststore.p12

keytool -import -file ca.pem \
-alias YOUR_KAFKA_SIGNED_CLIENT_CERT_ALIAS \
-keystore truststore.p12

keystore.p12

openssl pkcs12 -export -in service.cert -inkey service.key \
-out keystore.p12 -name YOUR_KAFKA_CA_CERT_ALIAS \
-CAfile ca.pem

Configure Zilla

And the final step is to configure a vault with truststore and keystore, then reference the vault in the south_tls_client binding.

zilla.yaml

vaults:
  client_vault:
    type: filesystem
    options:
      trust:
        store: ${{env.TRUSTORE_PATH}}
        type: ${{env.TRUSTORE_TYPE}}
        password: ${{env.TRUSTORE_PASSWORD}}
      keys:
        store: ${{env.KEYSTORE_PATH}}
        type: ${{env.KEYSTORE_TYPE}}
        password: ${{env.KEYSTORE_PASSWORD}}
bindings:
...
  south_kafka_client:
    type: kafka
    kind: client
    options:
      servers:
        - ${{env.KAFKA_BOOTSTRAP_SERVER}}
    exit: south_tls_client
  south_tls_client:
    type: tls
    kind: client
    vault: client_vault
    options:
      trust:
        - ${{env.CA_CERT_ALIAS}}
      keys:
        - ${{env.SIGNED_CLIENT_CERT_ALIAS}}
    exit: south_tcp_client
  south_tcp_client:
    type: tcp
    kind: client

NOTE

SNI adds the domain name to the TLS handshake process so that the Zilla process reaches the right domain name and receives the correct SSL certificate.

To test the above config you can use it to add or replace the necessary bindings in the http.kafka.sasl.scram example.