Configure Authentication and Encryption with Confluent Operator

This document describes how to configure authentication and network encryption with Confluent Operator. For security concepts in Confluent Platform, see Security.

The following are the authentication and encryption methods supported with Operator:

• Plaintext (no encryption) with SASL PLAIN authentication (default)
• TLS-encrypted network traffic with SASL PLAIN authentication
• TLS-encrypted traffic with no authentication
• TLS-encrypted traffic with mTLS authentication

Security in a Confluent Platform cluster is controlled by the security configured for the Apache Kafka® brokers. To configure Confluent Platform cluster security, configure security for the Kafka broker cluster, make sure it works, and then layer on additional security for the remaining Confluent Platform components. The following list provides the typical order for adding security to your cluster:

1. Configure Kafka broker security and validate accessibility.
2. Configure security for applicable Confluent Platform components and validate accessibility.
3. Configure security for external clients and validate accessibility.

At a high level, the following settings in the configuration file ($VALUES_FILE) control the encryption and authentication settings for Kafka.

kafka:
  tls:
    enabled:        # Specifies the encryption method
    authentication:
      type:         # Specifies the authentication method

Below is the summarized settings for the Kafka encryption and authentication supported with Operator.

• TLS encryption with no authentication

  kafka:
    tls:
      enabled: true
  

• TLS encryption and mTLS authentication

  kafka:
    tls:
      enabled: true
      authentication:
        type: tls
  

• TLS encryption with SASL PLAIN authentication

  kafka:
    tls:
      enabled: true
      authentication:
        type: plain
  

• No encryption with SASL PLAIN authentication

  kafka:
    tls:
      enabled: false
      authentication:
        type: plain
  

The examples in this guide use the following assumptions:

• $VALUES_FILE refers to the configuration file you set up in Create the global configuration file.

• To present simple and clear examples in the Operator documentation, all the configuration parameters are specified in the config file ($VALUES_FILE). However, in your production deployments, use the --set or --set-file option when applying sensitive data with Helm. For example:

  helm upgrade --install kafka \
   --set kafka.services.mds.ldap.authentication.simple.principal=”cn=mds,dc=test,dc=com” \
   --set kafka.services.mds.ldap.authentication.simple.credentials=”Developer!” \
   --set kafka.enabled=true
  

• operator is the namespace that Confluent Platform is deployed in.

• All commands are executed in the helm directory under the directory Confluent Operator was downloaded to.

Encryption

Operator supports the plaintext (no encryption) and TLS encryption methods for Confluent Platform with plaintext being the default.

Network encryption with TLS

Operator supports Transport Layer Security (TLS), an industry-standard encryption protocol, to protect network communications of Confluent Platform.

Certificates and keys

TLS relies on keys and certificates to establish trusted connections. This section describes how to manage keys and certificates in preparation to configure TLS encryption for Confluent Platform.

Generate self-signed certificates for testing

To validate your security configuration, follow the steps below to create a self-signed certificate for testing. You need to generate your own certificate for the production deployment.

1. Create a root key:

   openssl genrsa -out rootCA.key 2048
   

2. Create a root certificate:

   openssl req -x509  -new -nodes \
   -key rootCA.key \
   -days 3650 \
   -out rootCA.pem \
   -subj "/C=US/ST=CA/L=MVT/O=TestOrg/OU=Cloud/CN=TestCA"
   

3. Create a server private key:

   openssl genrsa -out server.key 2048
   

4. Generate a CSR for a server certificate:

   openssl req -new -key server.key \
    -out server.csr \
    -subj "/C=US/ST=CA/L=MVT/O=TestOrg/OU=Cloud/CN=*.operator.svc.cluster.local"
   

4. Sign the certificate:

   openssl x509 -req \
    -in server.csr \
    -extensions server_ext \
    -CA rootCA.pem \
    -CAkey rootCA.key \
    -CAcreateserial \
    -out server.crt \
    -days 365 \
    -extfile \
    <(echo "[server_ext]"; echo "extendedKeyUsage=serverAuth,clientAuth"; echo "subjectAltName=DNS:*.operator.svc.cluster.local")
   

The above steps create the following files that you map to the corresponding keys in the tls section of the config file ($VALUES_FILE) for cacerts, fullchain, and privkey:

• rootCA.pem contains cacerts.
• server.crt contains fullchain (the full chain).
• server.key contains privkey (the private key).

SAN attributes for certificates

When creating certificates for use by the Kafka brokers, configure the Subject Alternative Name (SAN) attribute. SAN allows you to specify multiple hostnames for a single certificate.

There are two ways to configure SAN attributes for accessing the Kafka clusters from outside of the Kubernetes.

• If you are permitted by your organization to use wildcard domains in your certificate SANs, use the following SAN attributes when generating certificates:

  • SAN attribute for the external bootstrap and broker addresses:

    *.<kafka-domain>
    

  • SAN attribute for the internal addresses:

    *.<component-name>.<namespace>.svc.cluster.local
    

    The <component-name> is the value set in name: under the component section in your config file ($VALUES_FILE).

• If wildcards are not permitted, you must provide multiple SAN attributes. Use the following SAN attributes, which are based on the Kafka broker prefix, the bootstrap prefix, and the number of brokers:

  • SAN attributes for the external bootstrap and broker addresses:

    <bootstrap-prefix>.<kafka-domain>
    
    <broker-prefix>0.<kafka-domain>
    <broker-prefix>1.<kafka-domain>
    ...
    <broker-prefix><N-1>.<kafka-domain>
    

    For example, if you have the following configuration:

    • Your Kafka domain is confluent-platform.example.com.
    • Your broker prefix is b (this is the default if you don’t explicitly set the broker prefix when configuring Kafka).
    • Your bootstrap prefix is kafka (this is the default).
    • You are deploying three Kafka brokers in the operator namespace.

    Use the following SANs when generating your external address certificates:

    b0.confluent-platform.example.com
    b1.confluent-platform.example.com
    b2.confluent-platform.example.com
    kafka.confluent-platform.example.com
    

  • SAN attributes for the internal Kafka bootstrap address and the specific internal addresses for each broker:

    <kafka-component-name>.<kafka-namespace>.svc.cluster.local
    
    <kafka-component-name>-0.<kafka-component-name>.<kafka-namespace>.svc.cluster.local
    <kafka-component-name>-1.<kafka-component-name>.<kafka-namespace>.svc.cluster.local
    ...
    <kafka-component-name>-<N-1>.<kafka-component-name>.<kafka-namespace>.svc.cluster.local
    

    The <kafka-component-name> is the value set in name: under the kafka component section in your config file ($VALUES_FILE).

    For example, if you have the following configuration:

    • Your Kafka component name is kafka (this is the default).
    • You are deploying three Kafka brokers in the operator namespace.

    Use the following SANs when generating your internal address certificates:

    kafka.operator.svc.cluster.local
    kafka-0.kafka.operator.svc.cluster.local
    kafka-1.kafka.operator.svc.cluster.local
    kafka-2.kafka.operator.svc.cluster.local
    

  • SAN attributes for the internal addresses of other components:

    <component-name>.<namespace>.svc.cluster.local
    

    The <component-name> is the value set in name: under the component section in your config file ($VALUES_FILE).

  Note that when you scale up your Kafka cluster, your certificate will need to have DNS SANs for the additional brokers in your cluster. If you want to avoid having to regenerate new certificates before adding new brokers, you could consider putting more DNS SANs in your certificate than your initial broker count. For instance, if you plan to start with 3 brokers but imagine you may need to scale up to 6 brokers, you could have DNS SANs for 6 (or more) brokers in your initial certificate so that when it comes time to scale up, you can do so without creating a new certificate.

Manage credentials outside of the configuration file

For increased security, you can keep credentials, such as private keys, outside of your config file ($VALUES_FILE). Furthermore, certificate data can be large and cumbersome, and if you have this data already in separate files, you may want to avoid copying and pasting that data into the $VALUES_FILE and dealing with YAML syntax.

You can pass the contents of these files when issuing Helm commands rather than putting them directly in the config file ($VALUES_FILE). For example:

helm upgrade --install kafka ./confluent-operator \
  --values $VALUES_FILE \
  --namespace operator \
  --set kafka.enabled=true \
  --set kafka.tls.enabled=true \
  --set kafka.metricReporter.tls.enabled=true \
  --set-file kafka.tls.cacerts=/tmp/ca-bundle.pem \
  --set-file kafka.tls.fullchain=/tmp/server-cert.pem \
  --set-file kafka.tls.privkey=/tmp/server-key.pem

Kafka configuration for TLS encryption

Enable and configure TLS encryption in the kafka section in your config file ($VALUES_FILE) as shown in the snippet below:

kafka:
  tls:
    enabled: true            ----- [1]
    interbrokerTLS: true     ----- [2]
    internalTLS: true        ----- [3]

    fullchain: |-            ----- [4]
      ---BEGIN CERTIFICATE---
      ... omitted
      ---END CERTIFICATE---
    privkey: |-              ----- [5]
      ---BEGIN RSA PRIVATE KEY---
      ... omitted
      ---END RSA PRIVATE KEY---

  configOverrides:
    server:
      - listener.name.internal.ssl.principal.mapping.rules=    --- [6]
      - listener.name.replication.ssl.principal.mapping.rules= --- [7]

The following should be set:

• [1] Set enabled: true to enable TLS encryption.

• [2] Set interbrokerTLS: true to enable TLS encryption for inter-broker communication and communication between Kafka and Replicator. [1] must be set to true for this setting to take effect.

  If [1] and [2] are set to true, the internal address must be included in the Kafka certificate.

  For interbrokerTLS: true, add the inter-broker listener principal mapping rules to the Kafka server configuration using configOverrides in [7].

• [3] Set internalTLS: true to enable TLS encryption for inter-component communication. [1] must be set to true for this setting to take effect.

  For internalTLS: true, add the internal listener principal mapping rules to the Kafka server configuration using configOverrides in [6].

• [4] Provide a full chain certificate. A fullchain consists of a root CA, any intermediate CAs, and finally the certificate for the broker, in that order.

  The external, internal, and inter-broker listeners use the same certificate.

  The certificate you provide must have DNS SANs for the external bootstrap and broker addresses, the internal Kafka bootstrap address, and the specific internal addresses for each broker. For information on configuring SANs in a certificate, see SAN attributes for certificates.

• [5] Provide the private key of the certificate. The privkey contains the private key associated with the broker certificate.

• [6] Add the following internal listener principal mapping rules when internalTLS: true.

  kafka:
    configOverrides:
      server:
        - "listener.name.internal.ssl.principal.mapping.rules=RULE:^CN=([a-zA-Z0-9.]*).*$/$1/L, DEFAULT"
  

• [7] Add the following internal listener principal mapping rules when interbrokerTLS: true.

  kafka:
    configOverrides:
      server:
        - "listener.name.replication.ssl.principal.mapping.rules=RULE:^CN=([a-zA-Z0-9.]*).*$/$1/L, DEFAULT"
  

Component configuration for TLS encryption

This section describes how to set up the rest of the Confluent Platform components so that they (a) successfully communicate with Kafka configured with TLS encryption, and (b) serve TLS-encrypted traffic themselves.

These are general guidelines and do not provide all security dependencies. Review the component values.yaml files in the <operator-home>/helm/confluent-operator/charts folder for additional information about component dependencies.

Configure the components as below in the configuration file ($VALUES_FILE):

<component>:
  tls:
    enabled: true                     ----- [1]
    internalTLS: true                 ----- [2]

      cacerts: |-                     ----- [3]
        ---BEGIN CERTIFICATE---
        ... omitted
        ---END CERTIFICATE-----
      fullchain: |-                   ----- [4]
        ---BEGIN CERTIFICATE---
        ... omitted
        ---END CERTIFICATE---
      privkey: |-                     ----- [5]
        -----BEGIN RSA PRIVATE KEY--
        ... omitted
        -----END RSA PRIVATE KEY----

• [1] External communication encryption mode. To serve TLS-encrypted traffic on its external listener, set enabled: true.

• [2] Internal communication encryption mode. To serve TLS-encrypted traffic on its internal listener, set internalTLS: true. [1] must be set to true for this setting to take effect.

• [3] One or more concatenated Certificate Authorities (CAs) for the component to trust the certificates presented by the Kafka brokers.

• [4] Provide the full certificate chain that the component will use to serve TLS-encrypted traffic. The fullchain consists of a root CA, any intermediate CAs, and finally the certificate for the broker, in that order.

  Some components such as Replicator, Connect, and Schema Registry can be configured with TLS for internal traffic. This means traffic between replicas, e.g. Replicator to Replicator in the same cluster, can now be encrypted with the same certificates as those used for their external listener.

• [5] Provide the private key associated with the broker certificate.

JMX and Jolokia configuration for TLS encryption

Confluent Operator supports TLS encryption for the JMX and Jolokia endpoints of every Confluent Platform component.

TLS is set up at port 7203 for JMX and at port 7777 for Jolokia.

To enable TLS encryption for JMX and Jolokia endpoints, set the following for each desired component in the configuration file ($VALUES_FILE):

<component>:
  tls:
    jmxTLS: true           ----- [1]
    fullchain:             ----- [2]
    privkey:               ----- [3]

• [1] Set jmxTLS: true to enable TLS encryption for JMX and Jolokia endpoints.
• [2] Provide the full TLS certificate chain.
• [3] Provide the private key for the certificate.

The TLS certificates used to secure the JMX and Jolokia endpoints are the same that will be used in general by the component. There is no separate fullchain and privkey setting just for the JMX and Jolokia endpoints.

Authentication

Operator supports the SASL PLAIN and mTLS authentication methods for Confluent Platform with SASL PLAIN being the default.

Authentication with SASL PLAIN

When PLAIN SASL authentication is configured, external clients and internal Confluent Platform components provide a username and password for both to authenticate with Kafka brokers.

Kafka configuration for SASL PLAIN authentication

SASL PLAIN is the default authentication method when you use Operator to manage Confluent Platform, and you do not need to explicitly enable SASL PLAIN. If you prefer to explicitly enable SASL PLAIN to clearly document the configuration, set it in the kafka section in the configuration file ($VALUES_FILE) as shown below:

kafka:
  tls:
    authentication:
      type: plain

Add global Confluent Platform user

Add the inter-broker user for Kafka. Other Confluent Platform components also use this user to authenticate to Kafka.

Specify the user name and password in the sasl section in your config file ($VALUES_FILE) as follows:

global:
  sasl:
    plain:
      username: <username>
      password: <password>

You can provide the above sensitive data using a Helm command line flag rather than directly in the config file ($VALUES_FILE). For example, to provide a password from the command line:

helm upgrade --install kafka ./confluent-operator \
  --values $VALUES_FILE \
  --namespace operator \
  --set kafka.enabled=true \
  --set global.sasl.plain.password=<my-password>

Add custom SASL users

To add the SASL users, add the users in the kafka section of the configuration file ($VALUES_FILE) as below:

kafka:
  sasl:
    plain:
      - <user1>=<password1>
      - <user2>=<password2>
      - <user3>=<password3>

This setting is dynamic and you can add users without restarting the running Kafka cluster.

Component configuration for SASL PLAIN authentication

To set up the rest of the Confluent Platform components to authenticate with Kafka using SASL PLAIN, set the Kafka authentication type to plain, type: plain, in the configuration file ($VALUES_FILE).

<component>:
  dependencies:
    kafka:
      tls:
        authentication:
          type: plain

Authentication with mTLS

Kafka configuration for mTLS authentication

Enable and configure mutual TLS (mTLS) authentication in the kafka section in your config file ($VALUES_FILE). To enable mTLS authentication, you must also enable TLS encryption. The following snippet enables mTLS authentication:

kafka:
  tls:
    enabled: true            ----- [1]
    authentication:
      type: tls              ----- [2]
    cacerts: |-              ----- [3]
      -----BEGIN CERTIFICATE-----
      ... omitted
      -----END CERTIFICATE-------
    fullchain: |-            ----- [4]
      -----BEGIN CERTIFICATE-----
      ... omitted
      -----END CERTIFICATE-------
    privkey: |-              ----- [5]
      -----BEGIN RSA PRIVATE KEY-
      ... omitted
      -----END RSA PRIVATE KEY---

• [1] Set enabled: true to enable TLS encryption.
• [2] Set type: tls to enable mTLS authentication.
• [3] Provide CA certs that consists of any CAs you want the Kafka brokers to use to authenticate certificates presented by clients.
• [4] Provide a full chain certificate that consists of a root CA, any intermediate CAs, and finally the certificate for the Kafka broker, in that order.
• [5] Provide the private key associated with the Kafka broker certificate.

Component configuration for mTLS authentication

To set up the rest of the Confluent Platform components to use mTLS to authenticate to Kafka, configure the components as below in the configuration file ($VALUES_FILE).

These are general guidelines and do not provide all security dependencies. Review the component values.yaml files in the <operator-home>/helm/confleunt-operator/charts folder for additional information about component dependencies.

<component>:
  dependencies:
    kafka:
      tls:
        enabled: true               ----- [1]
        authentication:
          type: tls                 ----- [2]
      bootstrapEndpoint:            ----- [3]
  tls:
    cacerts: |-                     ----- [4]
      -----BEGIN CERTIFICATE-------
      ... omitted
      -----END CERTIFICATE---------
    fullchain: |-                   ----- [5]
      -----BEGIN CERTIFICATE-------
      ... omitted
      -----END CERTIFICATE---------
    privkey: |-                     ----- [6]
      -----BEGIN RSA PRIVATE KEY---
      ... omitted
      -----END RSA PRIVATE KEY-----

• [1] External communication encryption mode. enabled: true is required for mTLS authentication.

• [2] Authentication methods. Set type: tls to use mTLS authentication.

• [3] Set the destination endpoint for the Kafka cluster as below.

  • For the component to communicate with Operator-deployed Kafka over Kafka’s internal listener:

    • If Kafka cluster is deployed to the same namespace as this component: <kafka-component-name>:9071
    • If Kafka cluster is deployed to a different namespace as this component: <kafka-component-name>.<kafka-namespace>.svc.cluster.local:9071

    The <kafka-component-name> is the value set in name under the kafka component section in your config file ($VALUES_FILE).

  • For the component to communicate with Operator-deployed Kafka over Kafka’s external listener:

    • Using load balancer: <bootstrap-prefix>.<domain>:9092

      These values are set in loadBalancer:bootstrapPrefix and loadBalancer:domain under the kafka section. If you have not set bootstrapPrefix, use the default value of kafka.

    • Using NodePort: <host>:<port-offset>

      These values are set in nodePort:host and nodePort:portOffset under the kafka section.

    • Using static host-based routing: <bootstrap-prefix>.<domain>:9092

      These values are set in staticForHostBasedRouting:bootstrapPrefix and staticForHostBasedRouting:domain under the kafka section. If you have not set bootstrapPrefix, use the default value of kafka.

    • Using static port-based routing: <host>:<port-offset>

      These values are set in staticForPortBasedRouting:host and staticForPortBasedRouting:portOffset under the kafka section.

  • For the component to communicate with a Kafka cluster that has not been deployed by this Operator, set this to that cluster’s bootstrap URL.

• [4] Provide CA certificate(s) for the component to trust the certificates presented by the Kafka brokers. It consists of any CAs you want the Kafka brokers to use to authenticate certificates presented by clients.

• [5] Provide the full certificate chain that the component will use to authenticate. The fullchain consists of a root CA, any intermediate CAs, and finally the certificate for the broker, in that order.

• [6] Provide the private key for the certificate in [5].

For example, if you configured the Kafka brokers with mTLS to encrypt internal and external communication, the configuration parameters in the Replicator security section would resemble the following:

replicator:
  name: replicator
  tls:
    cacerts: |-
    -----BEGIN CERTIFICATE-----
    ... omitted
    -----END CERTIFICATE-----
    fullchain: |-
    -----BEGIN CERTIFICATE-----
    ... omitted
    -----END CERTIFICATE-----
    privkey: |-
    -----BEGIN RSA PRIVATE KEY-----
    ... omitted
    -----END RSA PRIVATE KEY-----
  dependencies:
    kafka:
      tls:
        enabled: true
        internal: true
        authentication:
          type: "tls"
      bootstrapEndpoint: kafka.operator.svc.cluster.local:9092

JMX and Jolokoa configuration for mTLS authentication

Confluent Operator supports enabling mTLS authentication for the JMX and Jolokia endpoints of every Confluent Platform component.

Note: Currently, Operator does not support SASL PLAIN authentication for the JMX and Jolokia endpoints.

mTLS JMX is set up at port 7203 for JMX and at port 7777 for Jolokia.

To enable mTLS authentication for JMX and Jolokia, set the following for each desired component in the config file ($VALUES_FILE):

<component>:
  tls:
    jmxTLS: true           ----- [1]
    jmxAuthentication:
      type: tls            ----- [2]
    cacerts:               ----- [3]
    fullchain:             ----- [4]
    privkey:               ----- [5]

• [1] Set jmxTLS: true to enable TLS encryption for JMX and Jolokia endpoints.

• [2] Set type: tls to enable mTLS authentication for JMX and Jolokia endpoints.

• [3] Provide CA certificates to trust clients authenticating via mTLS.

• [4] Provide the full TLS certificate chain.

• [5] Provide the private key for the certificate.

  CA certificates, the full chain, and the private key values are used to secure both inter-component and external communication for the JMX and Jolokia endpoints.

Client configuration for encryption and authentication

Security configurations of clients depend on Kafka security settings.

Kafka security configuration information can be retrieved from the Kafka cluster using the following commands (using the example name kafka running on the namespace operator).

• For internal clients (running inside the Kubernetes cluster):

  kubectl get kafka kafka -ojsonpath='{.status.internalClient}' -n operator
  

• For external clients (running outside the Kubernetes cluster):

  kubectl get kafka kafka -ojsonpath='{.status.externalClient}' -n operator
  

To configure clients, refer to the following:

• If the Kafka cluster is using TLS encryption, configure the client as described in Encryption with SSL.
• If the Kafka cluster is using mTLS encryption and authentication, configure the client as described in Encryption and Authentication with SSL.
• If the Kafka cluster is using TLS encryption with SASL PLAIN authentication, configure the client as described in Encryption and Authentication with SASL.

Confluent Control Center encryption and authentication

Control Center supports the following encryption and authentication methods:

• Encryption: A REST endpoint over HTTPS on port 9021
• Authentication: Basic or LDAP

Based on the authentication method you select, configure the associated settings for the method in the config file ($VALUES_FILE).

controlcenter:
  auth:
    basic:
      enabled: false
      ##
      ## map with key as user and value as password and role
      property: {}
      # property:
      #  admin: Developer1,Administrators
      #  disallowed: no_access
    ldap:
      enabled: false
      nameOfGroupSearch: c3users
      property: {}