Apache Kafka

Introduction

In this guide, you will explore how to connect to your own Kafka from Zilla.

A brief explanation of replaceable values from the config examples below:

Value	Description
`TRUSTORE_PATH`	The path to the `truststore` that stores CA cert that you want to trust.
`TRUSTORE_PASSWORD`	Truststore password.
`KEYSTORE_PATH`	The path to the `keystore` that stores access key.
`KEYSTORE_PASSWORD`	Keystore password.
`STORE_TYPE`	KeyStore type such as `pkcs12`, `jceks`, and etc
`CA_CERT_ALIES`	Unique string that identifies the certificate entry in the truststore.
`SIGNED_CLIENT_CERT_ALIES`	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.
`SASL_USERNAME`	SASL authorization username.
`SASL_PASSWORD`	SASL authorization password.

Connect to `PLAINTEXT` Kafka

To connect to any Kafka on PLAINTEXT protocol is as simple as defining your TCP binding as shown below.

zilla.yaml

bindings:
  kafka_client:
    type: kafka
    kind: client
    exit: tcp_client
  tcp_client:
    type: tcp
    kind: client
    options:
      host: BOOTSTRAP_SERVER_HOSTNAME
      port: BOOTSTRAP_SERVER_PORT
    routes:
      - when:
          - cidr: 0.0.0.0/0

As usual, you need to define the host and port and flush the data to the network. For the full working config please take a look at this exampleopen in new window.

Connect to Kafka over `TLS/SSL`

By default, Kafka communicates in PLAINTEXT, which means that all data is sent without encryption. However, Kafka running in production needs to expose only a secure connection that encrypts communication, and you should therefore configure Zilla to use TLS/SSL encrypted communication.

If the Kafka cluster is secured by a TLS server certificate that is provided by a public certificate authority, then configure Zilla add a TLS client binding as shown below with the trustcacerts option to set to true.

NOTE

The exit from kafka_client binding now changes to tls_client.

zilla.yaml

bindings:
  kafka_client:
    type: kafka
    kind: client
    exit: tls_client
  tls_client:
    type: tls
    kind: client
    options:
      trustcacerts: true
      sni:
        - BOOTSTRAP_SERVER_HOSTNAME
    exit: tcp_client
  tcp_client:
    type: tcp
    kind: client
    options:
      host: BOOTSTRAP_SERVER_HOSTNAME
      port: BOOTSTRAP_SERVER_PORT
    routes:
      - when:
          - cidr: 0.0.0.0/0

However, if the Kafka cluster is secured by a TLS server certificate that is signed by a private certificate authority then you need to add a vault config to provide access to certificates needed by the TLS client binding.

zilla.yaml

vaults:
  client_vault:
    type: filesystem
    options:
      trust:
        store: TRUSTORE_PATH
        type: STORE_TYPE
        password: TRUSTORE_PASSWORD
bindings:
  kafka_client:
    type: kafka
    kind: client
    exit: tls_client
  tls_client:
    type: tls
    kind: client
    vault: client_vault
    options:
      trust:
        - CA_CERT_ALIAS
      sni:
        - BOOTSTRAP_SERVER_HOSTNAME
    exit: tcp_client
  tcp_client:
    type: tcp
    kind: client
    options:
      host: BOOTSTRAP_SERVER_HOSTNAME
      port: BOOTSTRAP_SERVER_PORT
    routes:
      - when:
          - cidr: 0.0.0.0/0

Connect to Kafka over `TLS/SSL` using client certificates

Next, you will explore how to connect to Kafka cluster over TLS/SSL using client certificates.

The following items need to be prepared:

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

Kafka clients connecting to Kafka clusters that are configured for TLS mutual authentication require three files; a Client Key, a Client Certificate, and a CA Certificate.

You can use the scripts shown below to generate truststore.p12 and keystore.p12 files using the three files.

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

You also need to configure a vault with truststore and keystore, then reference the vault in the tls_client binding.

zilla.yaml

vaults:
  client_vault:
    type: filesystem
    options:
      trust:
        store: TRUSTORE_PATH
        type: STORE_TYPE
        password: TRUSTORE_PASSWORD
      keys:
        store: KEYSTORE_PATH
        type: STORE_TYPE
        password: KEYSTORE_PASSWORD
bindings:
  kafka_client:
    type: kafka
    kind: client
    exit: tls_client
  tls_client:
    type: tls
    kind: client
    vault: client_vault
    options:
      trust:
        - CA_CERT_ALIAS
      keys:
        - SIGNED_CLIENT_CERT_ALIAS
      sni:
        - BOOTSTRAP_SERVER_HOSTNAME
    exit: tcp_client
  tcp_client:
    type: tcp
    kind: client
    options:
      host: BOOTSTRAP_SERVER_HOSTNAME
      port: BOOTSTRAP_SERVER_PORT
    routes:
      - when:
          - cidr: 0.0.0.0/0

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.

Connect to Kafka over SASL

Apache Kafka brokers support client authentication using SASL. SASL authentication can be enabled concurrently with TLS/SSL encryption.

Apache Kafka supports the following SASL mechanisms are:

GSSAPI (Kerberos authentication)
OAUTHBEARER
SCRAM
PLAIN
Delegation Tokens
LDAP

NOTE

Zilla currently supports SASL PLAIN authentication to Kafka.

Please add your feedback to the SASL enhancement requestopen in new window.

Configure Zilla

zilla.yaml

bindings:
  kafka_client:
    type: kafka
    kind: client
    exit: tls_client
    options:
      sasl:
        mechanism: plain
        username: SASL_USERNAME
        password: SASL_PASSWORD
  tls_client:
    type: tls
    kind: client
    options:
      trustcacerts: true
      sni:
        - BOOTSTRAP_SERVER_HOSTNAME
    exit: tcp_client
  tcp_client:
    type: tcp
    kind: client
    options:
      host: BOOTSTRAP_SERVER_HOSTNAME
      port: BOOTSTRAP_SERVER_PORT
    routes:
      - when:
          - cidr: 0.0.0.0/0

To test the above config you can follow instructions in the README from the exampleopen in new window.