Kafka TLS-SSL Example Part 5: Configure the Scheduler

The final piece of the configuration is to set up the scheduler to use SSL when communicating with Kafka (and optionally with Vertica). When the scheduler runs a COPY command to get data from Kafka, it uses its own key and certificate to authenticate with Kafka. If you choose to have the scheduler use TLS/SSL to connect to Vertica, it can reuse the same keystore and truststore to make this connection.

Step 1: Create the Scheduler Truststore and Keystore

Because the scheduler is a separate component, it must have its own SSL key and certificate. The scheduler runs under Java, and uses the JDBC interface to connect to Vertica. Therefore, you must create a keystore and truststore for it to use when making an SSL-encrypted connection to Vertica.

This process is similar to creating the truststores and keystores in the previous parts of this example. The main change in these steps is using the keytool command's -dname option to set the Common Name (CN) for the key to a domain wildcard. Using this setting allows the key and certificate to match any host in the network. This ability is especially useful if you run multiple schedulers on different servers to provide redundancy. The schedulers can use the same key and certificate, no matter which server they are running on in your domain.

The steps to create the scheduler's truststore and keystore are:

  1. Create a truststore file for the scheduler. Add the CA that you used to sign the keystore of the Kafka cluster and Vertica cluster. If you are using more than one CA to sign all of the certificates, add all of the CAs that you used to sign the other certificates.

    $ keytool -keystore scheduler.truststore.jks -alias CARoot -import \ 
               -file root.crt
    Enter keystore password: some_password
    Re-enter new password: some_password
    Owner: EMAILADDRESS=myemail@mycompany.com, CN=*.mycompany.com, O=MyCompany, L=Cambridge, ST=MA, C=US
    Issuer: EMAILADDRESS=myemail@mycompany.com, CN=*.mycompany.com, O=MyCompany, L=Cambridge, ST=MA, C=US
    Serial number: c3f02e87707d01aa
    Valid from: Fri Mar 22 13:37:37 EDT 2019 until: Sun Apr 21 13:37:37 EDT 2019
    Certificate fingerprints:
             MD5:  73:B1:87:87:7B:FE:F1:6E:94:55:FD:AF:5D:D0:C3:0C
             SHA1: C0:69:1C:93:54:21:87:C7:03:93:FE:39:45:66:DE:22:18:7E:CD:94
             SHA256: 23:03:BB:B7:10:12:50:D9:C5:D0:B7:58:97:41:1E:0F:25:A0:DB:
    Signature algorithm name: SHA256withRSA
    Subject Public Key Algorithm: 2048-bit RSA key
    Version: 3
    #1: ObjectId: Criticality=false
    AuthorityKeyIdentifier [
    KeyIdentifier [
    0000: 50 69 11 64 45 E9 CC C5   09 EE 26 B5 3E 71 39 7C  Pi.dE.....&.>q9.
    0010: E5 3D 78 16                                        .=x.
    #2: ObjectId: Criticality=false
    #3: ObjectId: Criticality=false
    SubjectKeyIdentifier [
    KeyIdentifier [
    0000: 50 69 11 64 45 E9 CC C5   09 EE 26 B5 3E 71 39 7C  Pi.dE.....&.>q9.
    0010: E5 3D 78 16                                        .=x.
    Trust this certificate? [no]:  yes
    Certificate was added to keystore
  2. Initialize the keystore, passing it a wildcard host name as the Common Name. The alias parameter in this command is important, as you use it later to identify the key the scheduler must use when creating SSL conections:

    keytool -keystore scheduler.keystore.jks -alias vsched -validity 365 -genkey \
            -keyalg RSA  -dname CN=*.mycompany.com

    If you choose to use a file format other than the standard Java Keystore (JKS) format for your keystore or truststore files, you must use the correct file extension in the filename. For example, suppose you choose to use a keystore and truststore saved in PKCS#12 format. Then your keystore and trustore files must end with the .pfx or .p12 extension.
    If the scheduler does not recognize the file's extension (or there is no extension in the file name), it assumes that the file is in JKS format. If the file is not in JKS format, you will see an error message when starting the scheduler, similar to "Failed to create an SSLSocketFactory when setting up TLS: keystore not found."

  3. Export the scheduler's key so you can sign it with the root CA:

    keytool -keystore scheduler.keystore.jks -alias vsched -certreq \
            -file scheduler.unsigned.cert
  4. Sign the scheduler key with the root CA:

    openssl x509 -req -CA root.crt -CAkey root.key -in scheduler.unsigned.cert \
            -out scheduler.signed.cert -days 365 -CAcreateserial
  5. Re-import the scheduler key into the keystore:

    keytool -keystore scheduler.keystore.jks -alias localhost -import -file scheduler.signed.cert

Step 2: Set Environment Variable VKCONFIG_JVM_OPTS

You must pass several settings to the JDBC interface of the Java Virtual Machine (JVM) that runs the scheduler. These settings tell the JDBC driver where to find the keystore and truststore, as well as the key's password. The easiest way to pass in these settings is to set a Linux environment variable named VKCONFIG_JVM_OPTS. As it starts, the scheduler checks this environment variable and passes any properties defined in it to the JVM.

The properties that you need to set are:

  • javax.net.ssl.keystore: the absolute path to the keystore file to use.
  • javax.net.ssl.keyStorePassword: the password for the scheduler's key.
  • javax.net.ssl.trustStore: The absolute path to the truststore file.

The Linux command line to set the environment variable is:

export VKCONFIG_JVM_OPTS="$VKCONFIG_JVM_OPTS -Djavax.net.ssl.trustStore=/path/to/truststore \
                          -Djavax.net.ssl.keyStore=/path/to/keystore \

The previous command preserves any existing contents of the VKCONFIG_JVM_OPTS variable. If you find the variable has duplicate settings, remove the $VKCONFIG_JVM_OPTS from your statement so you override the existing values in the variable.

For example, suppose the scheduler's truststore and keystore are located in the directory /home/dbadmin/SSL. Then you could use the following command to set the VKCONFIG_JVM_OPTS variable:

                           -Djavax.net.ssl.trustStore=/home/dbadmin/SSL/scheduler.truststore.jks \
                           -Djavax.net.ssl.keyStore=/home/dbadmin/SSL/scheduler.keystore.jks \

The Java property names are case sensitive.

To ensure that this variable is always set, add the command to the ~/.bashrc or other startup file of the user account that runs the scheduler.

If you require TLS/SSL on the JDBC connection to Vertica, add TLSmode=require to the JDBC URL that the scheduler uses. The easiest way to add this is to use the scheduler's --jdbc-url option. Assuming that you use a configuration file for your scheduler, you can add this line to it:


For more information about using the JDBC with Vertica, see Programming JDBC Client Applications.

Step 3: Enable SSL in the Scheduler Configuration

The last step to configure the scheduler is to change its configuration to enable SSL. Every time you run vkconfig, you must pass it the following options:

Option Set to:
--enable-ssl true, to enable the scheduler to use SSL when connecting to Kafka.

Alias for the CA you used to sign your Kafka broker's keys. This must match the value you supplied to the -alias argument of the keytool command to import the CA into the truststore.

If you used more than one CA to sign keys, omit this option to import all of the CAs into the truststore.

--ssl-key-alias Alias assigned to the schedule key. This value must match the value you supplied to the -alias you supplied to the keytool command when creating the scheduler's keystore.
--ssl-key-password Password for the scheduler key.

See Common vkconfig Script Options for details of these options. For convenience and security, add these options to a configuration file that you pass to vkconfig. Otherwise, you run the risk of exposing the key password via the process list which can be viewed by other users on the same system. See Configuration File Format for more information on setting up a configuration file.

The following example shows the lines you can add to a scheduler configuration file to enable use of the keystore and truststore created earlier (plus the option to enable SSL for the connection to Vertica):


Step 4: Start the Scheduler

Once you have configured the scheduler to use SSL, start it and verify that it is load data. For example, to start the scheduler with a configuration file named weblog.conf, use the command:

$ vkconfig launch --conf weblog.conf &