Adding a Host to a Cluster

Steps to add hosts to a cluster.

Minimum Required Role: Full Administrator. This feature is not available when using Cloudera Manager to manage Data Hub clusters.

You can add one or more hosts to your cluster using the Add Hosts wizard, which installs the Oracle JDK, CDH, and Cloudera Manager Agent software. After the software is installed and the Cloudera Manager Agent is started, the Agent connects to the Cloudera Manager Server and you can use the Cloudera Manager Admin Console to manage and monitor CDH on the new host.

The Add Hosts wizard does not create roles on the new host; once you have successfully added the host(s) you can either add roles, one service at a time, or apply a host template, which can define role configurations for multiple roles.

Use one of the following methods to add a new host:

Using the Add Hosts Wizard to Add Hosts

You can use the Add Hosts wizard to install CDH, Impala, and the Cloudera Manager Agent on a host.

Disable TLS Encryption or Authentication

If you have enabled TLS encryption or authentication for the Cloudera Manager Agents, you must disable both of them before starting the Add Hosts wizard. Otherwise, skip to the next step.

If you perform this step, then skip step 2 (Alternate Method of Installing Cloudera Manager Agent without Disabling TLS). If you skip step 1 and perform step 2, then continue to step 3 (Using the Add Hosts Wizard to Add Hosts).
  1. From the Administration tab, select Settings.
  2. Select the Security category.
  3. Disable TLS by clearing the following options: Use TLS Encryption for Agents, and Use TLS Authentication of Agents to Server.
  4. Click Save Changes to save the settings.
  5. Log in to the Cloudera Manager Server host.
  6. Restart the Cloudera Manager Server.
    RHEL 7, SLES 12, Debian 8, Ubuntu 16.04 and higher
    sudo systemctl restart cloudera-scm-server
    RHEL 5 or 6, SLES 11, Debian 6 or 7, Ubuntu 12.04 or 14.04
    sudo service cloudera-scm-server restart

Alternate Method of Installing Cloudera Manager Agent without Disabling TLS

If you have TLS encryption or authentication enabled in your cluster, you must either disable TLS during the installation, or install the Cloudera Manager Agent manually using the following procedure:
  1. Copy the repository configuration file from an existing host in the cluster to the new host. For example:
    OS Command
    RHEL
    sudo scp mynode.example.com:/etc/yum.repos.d/cloudera-manager.repo /etc/yum.repos.d/cloudera-manager.repo
    SLES
    sudo scp mynode.example.com:/etc/zypp/zypper.conf/cloudera-cm.repo /etc/zypp/zypper.conf/cloudera-cm.repo
    Ubuntu or Debian
    sudo scp mynode.example.com:/etc/apt/sources.list.d/cloudera.list /etc/apt/sources.list.d/cloudera.list
  2. Remove cached package lists and other transient data by running the following command:
    OS Command
    RHEL
    sudo yum clean all
    SLES
    sudo zypper clean --all
    Ubuntu or Debian
    sudo apt-get clean
  3. Install the JDK package from the Cloudera Manager repository. Install the same version as is used on other cluster hosts. Only JDK 1.8 is supported:
    Table 1. Oracle JDK 1.8
    OS Command
    RHEL
    sudo yum install jdk1.8.0_144-cloudera
    SLES
    sudo zypper install jdk1.8.0_144-cloudera
    Ubuntu or Debian
    sudo apt-get install jdk1.8.0_144-cloudera
    Open JDK
    RHEL
    OpenJDK 8
    sudo yum install java-1.8.0-openjdk-devel
    OpenJDK 11
    su -c yum install java-11-openjdk-devel
    Ubuntu
    OpenJDK 8
    sudo apt-get install openjdk-8-jdk
    OpenJDK 11
    sudo apt-get install openjdk-11-jdk
    SLES
    OpenJDK 8
    sudo zypper install java-1_8_0-openjdk-devel
    OpenJDK 11
    sudo zypper install java-11-openjdk-devel
  4. Set up the TLS certificates using the same procedure that was used to set them up on other cluster hosts. See Configuring TLS Encryption for Cloudera Manager Using Auto-TLS. If you have set up a custom truststore, copy that file from an existing host to the same location on the new host.
  5. Install the Cloudera Manager Agent:
    OS Command
    RHEL
    sudo yum install cloudera-manager-agent
    SLES
    sudo zypper install cloudera-manager-agent
    Ubuntu or Debian
    sudo apt-get install cloudera-manager-agent
  6. Copy the Cloudera Manager Agent configuration file from an existing cluster host that is already configured for TLS to the same location on the new host. For example:
    sudo scp mynode.example.com:/etc/cloudera-scm-agent/config.ini /etc/cloudera-scm-agent/config.ini
  7. Create and secure the file containing the password used to protect the private key of the Agent:
    1. Use a text editor to create a file called agentkey.pw that contains the password. Save the file in the /etc/cloudera-scm-agent directory.
    2. Change ownership of the file to root:
      sudo chown root:root /etc/cloudera-scm-agent/agentkey.pw
    3. Change the permissions of the file:
      sudo chmod 440 /etc/cloudera-scm-agent/agentkey.pw
  8. Start the Agent on the new host:
    sudo service cloudera-scm-agent start
  9. Log in to Cloudera Manager and go to Hosts > All Hosts page and verify that the new host is recognized by Cloudera Manager.

Add Hosts to an Existing Cluster

  1. Click the Hosts tab.
  2. Click the Add Hosts button.
  3. Select Add hosts to cluster.
  4. If the cluster uses Kerberos authentication, ensure that the Kerberos packages are installed on the new hosts. If necessary, use the package commands provided on the Add Hosts screen to install these packages.
  5. Select the cluster where you want to add the host from the drop-down list.
  6. Click Continue.

    The Specify Hosts page displays. You can either add a new host to the cluster, or add an existing managed host to the cluster.

    Do one of the following:
    • Add a new host:
      1. On the Specify Hosts page, enter a host name or pattern (click "using patterns" for more information) to search for new hosts to add to the cluster.

        A list of matching hosts displays.

      2. Select the hosts that you want to add.
      3. Click Continue.
      4. Select the Repository Location where Cloudera Manager can find the software to install on the new hosts. Select Public Cloudera Repository or Custom Repository and enter the URL of a custom repository available on your local network.
      5. Click Continue.
      6. Follow the instructions in the wizard to install the Oracle JDK.
      7. Enter Login Credentials:
        1. Select root for the root account, or select Another user and enter the username for an account that has password-less sudo privileges.
        2. Select an authentication method:
          • If you choose password authentication, enter and confirm the password.
          • If you choose public-key authentication, provide a passphrase and path to the required key files.

          You can modify the default SSH port if necessary.

        3. Specify the maximum number of host installations to run at once. The default and recommended value is 10. You can adjust this based on your network capacity.
        4. Click Continue.

          The Install Agents page displays and Cloudera Manager installs the Agent software on the new hosts.

        5. When the agent installation finishes, click Continue.
    • Add an existing managed host:
      1. Click the Currently Managed Hosts tab.

        A list of hosts previously added to Cloudera Manager displays.

      2. Select the hosts that you want to add to the cluster.
      3. Click Continue.
  7. Cloudera Manager begins to install the CDH parcels.
  8. When the parcel installation finishes, click Continue.
  9. The Host Inspector runs and displays any problems with the hosts. Correct the problems before continuing.
  10. After correcting any problems, click Continue.
  11. To add role instances to the hosts now or select None to add them later.
  12. To add roles now:
    1. Select an existing host template, or create a new one.
    2. To create a new host template, click the Create... button. The Create New Host Template screen opens.. See Host Templates for details on how you select the role groups that define the roles that should run on a host. After you have created the template, it will appear in the list of host templates from which you can choose.
    3. Select the host template you want to use.
    4. By default Cloudera Manager will automatically start the roles specified in the host template on your newly added hosts. To prevent this, uncheck the option to start the newly-created roles.
  13. When the wizard is finished, you can verify the Agent is connecting properly with the Cloudera Manager Server by clicking the Hosts tab and checking the health status for the new host. If the Health Status is Good and the value for the Last Heartbeat is recent, then the Agent is connecting properly with the Cloudera Manager Server.

If you did not specify a host template during the Add Hosts wizard, then no roles will be present on your new hosts until you add them. You can do this by adding individual roles under the Instances tab for a specific service, or by using a host template. See Adding a Role Instance for information about adding roles for a specific service. See Host Templates to create a host template that specifies a set of roles (from different services) that should run on a host.

Add New Hosts To Cloudera Manager

This option allows you to add a host, but without adding them to a specific cluster. Later, you can use these hosts to create new clusters or expand existing clusters.

  1. Click the Hosts tab.
  2. Click the Add Hosts button.
  3. Select Add hosts to Cloudera Manager
  4. Specify the hosts to add:
    1. On the Specify Hosts page, enter a host name or pattern (click "using patterns" for more information) to search for new hosts to add to the cluster.

      A list of matching hosts displays.

    2. Select the hosts that you want to add.
    3. Click Continue.
    4. Select the Repository Location where Cloudera Manager can find the software to install on the new hosts. Select Public Cloudera Repository or Custom Repository and enter the URL of a custom repository available on your local network.
    5. Click Continue.
    6. Follow the instructions in the wizard to install the Oracle JDK.
    7. Enter Login Credentials:
      1. Select root for the root account, or select Another user and enter the username for an account that has password-less sudo privileges.
      2. Select an authentication method:
        • If you choose password authentication, enter and confirm the password.
        • If you choose public-key authentication, provide a passphrase and path to the required key files.

        You can modify the default SSH port if necessary.

      3. Specify the maximum number of host installations to run at once. The default and recommended value is 10. You can adjust this based on your network capacity.
      4. Click Continue.

        The Install Agents page displays and Cloudera Manager installs the Agent software on the new hosts.

      5. When the agent installation finishes, click Continue.
  5. If the cluster uses Kerberos authentication, ensure that the Kerberos packages are installed on the new hosts. If necessary, use the package commands provided on the Add Hosts screen to install these packages.
  6. Select the Repository Location where Cloudera Manager can find the software to install on the new hosts. Select Public Cloudera Repository or Custom Repository and enter the URL of a custom repository available on your local network.
  7. Follow the instructions in the wizard to install the Oracle JDK.
  8. Enter Login Credentials:
    1. Select root for the root account, or select Another user and enter the username for an account that has password-less sudo privileges.
    2. Select an authentication method:
      • If you choose password authentication, enter and confirm the password.
      • If you choose public-key authentication, provide a passphrase and path to the required key files.

      You can modify the default SSH port if necessary.

    3. Specify the maximum number of host installations to run at once. The default and recommended value is 10. You can adjust this based on your network capacity.
    4. Click Continue.

      The Install Agents page displays and Cloudera Manager installs the Agent software on the new hosts.

    5. When the agent installation finishes, click Continue.
  9. The Host Inspector runs and displays any problems with the hosts. Correct the problems before continuing.
  10. After correcting any problems, click Continue.

Enable TLS Encryption or Authentication

If you previously enabled TLS security on your cluster, you must re-enable the TLS options on the Administration page and also configure TLS on each new host after using the Add Hosts wizard. Otherwise, you can ignore this step. For instructions, see Configuring TLS Encryption for Cloudera Manager and CDH Using Auto-TLS.

Enable TLS/SSL for cluster Components

If you have previously enabled TLS/SSL on your cluster, and you plan to start these roles on this new host, make sure you install a new host certificate to be configured from the same path and naming convention as the rest of your hosts. Since the new host and the roles configured on it are inheriting their configuration from the previous host, ensure that the keystore or truststore passwords and locations are the same on the new host. For instructions on configuring TLS/SSL, see Configuring TLS Encryption for Cloudera Manager and CDH Using Auto-TLS.

Enable Kerberos

If you have previously enabled Kerberos on your cluster:
  1. Install the packages required to kinit on the new host (see the list in Enabling Kerberos Authentication for CDH ).
  2. If you have set up Cloudera Manager to manage krb5.conf, it will automatically deploy the file on the new host. Note that Cloudera Manager will deploy krb5.conf only if you use the Kerberos wizard. If you have used the API, you will need to manually perform the commands that the wizard calls.

    If Cloudera Manager does not manage krb5.conf, you must manually update the file at /etc/krb5.conf.

Adding a Host by Installing the Packages Using Your Own Method

If you used a different mechanism to install the JDK, Cloudera Runtime, and Cloudera Manager Agent packages, you can use that same mechanism to install the JDK, Cloudera Runtime, Cloudera Manager Agent packages and then start the Cloudera Manager Agent.

  1. Install the Oracle JDK, Cloudera Runtime, and Cloudera Manager Agent packages using your own method. For instructions on installing these packages, see Install Cloudera Manager Server.
  2. After installation is complete, start the Cloudera Manager Agent. For instructions, see Starting, Stopping, and Restarting Cloudera Manager Agents.
  3. After the Agent is started, you can verify the Agent is connecting properly with the Cloudera Manager Server by clicking the Hosts tab and checking the health status for the new host. If the Health Status is Good and the value for the Last Heartbeat is recent, then the Agent is connecting properly with the Cloudera Manager Server.
  4. If you have enabled TLS security on your cluster, you must enable and configure TLS on each new host. Otherwise, ignore this step.
    1. Enable and configure TLS on each new host by specifying 1 for the use_tls property in the /etc/cloudera-scm-agent/config.ini configuration file.
    2. Configure TLS security on the new hosts by following the instructions in Configuring TLS Encryption for Cloudera Manager and CDH Using Auto-TLS.
  5. If you have previously enabled TLS/SSL on your cluster, and you plan to start these roles on this new host, make sure you install a new host certificate to be configured from the same path and naming convention as the rest of your hosts. Since the new host and the roles configured on it are inheriting their configuration from the previous host, ensure that the keystore or truststore passwords and locations are the same on the new host. For instructions on configuring TLS/SSL, see Configuring TLS Encryption for Cloudera Manager and CDH Using Auto-TLS.

  6. If you have previously enabled Kerberos on your cluster:
    1. Install the packages required to kinit on the new host (see the list in Enabling Kerberos Authentication for CDH ).
    2. If you have set up Cloudera Manager to manage krb5.conf, it will automatically deploy the file on the new host. Note that Cloudera Manager will deploy krb5.conf only if you use the Kerberos wizard. If you have used the API, you will need to manually perform the commands that the wizard calls.

      If Cloudera Manager does not manage krb5.conf, you must manually update the file at /etc/krb5.conf.