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Prerequisite of Installing EloqKV

The eloqctl utility is installed and operated on a control node, it manages several EloqKV server nodes. We discuss how to establish trust between control node and the server nodes, and some system setting adjustments on the server nodes to make them run EloqKV better.

Establish Passwordless SSH and Sudo​

Before proceeding, please manually configure SSH mutual trust and passwordless sudo between the control node and the server nodes:

  1. Log in on control machine and each server machine as the root user. Create the eloq user account on each machine and set a login password:
useradd -m eloq && \
passwd eloq
  1. To configure passwordless sudo, run the following command and append the line eloq ALL=(ALL) NOPASSWD: ALL to the end of the file on each machine:
visudo
eloq ALL=(ALL) NOPASSWD: ALL
  1. Please ensure that both password authentication and public key authentication are enabled on each machine. Password authentication is necessary for the control machine to copy the public key to the authorized_keys file of the EloqKV nodes. Public key authentication, on the other hand, is used by the eloqctl tool to deploy EloqKV clusters. You can verify and configure these settings in the SSH configuration file as follows:
sudo vi /etc/ssh/sshd_config

Ensure the following line is set (uncomment if necessary):

PasswordAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile .ssh/authorized_keys

If you see the following line in /etc/ssh/sshd_config

Include /etc/ssh/sshd_config.d/*.conf

Make sure that all config files under /etc/ssh/sshd_config.d/ do not have the previous settings set.

grep -ri PasswordAuthentication /etc/ssh/sshd_config.d/
grep -ri PubkeyAuthentication /etc/ssh/sshd_config.d/
grep -ri AuthorizedKeysFile /etc/ssh/sshd_config.d/

Comment out these lines so that they won't override the settings in /etc/ssh/sshd_config.

Restart the SSH service to apply the changes:

sudo systemctl restart sshd
  1. Log in to the control machine as the eloq user, generate an SSH key, and configure SSH mutual trust between the control machine and itself. Note that password should be skipped when running ssk-keygen.
ssh-keygen -t rsa
cat .ssh/id_rsa.pub >> .ssh/authorized_keys

Please check permissions on .ssh directory.

chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

  1. Configure SSH mutual trust between the control machine and the server machines. Replace 10.0.0.1 with the IP address of your target machine, and enter the eloq user password for the target machine when prompted. Once the command is executed, SSH mutual trust will be established. Repeat this process for each EloqKV machine.
ssh-copy-id -i ~/.ssh/id_rsa.pub 10.0.0.1
  1. Log in to the control machine using the eloq user account, and then attempt to log in to the target machine's IP address using SSH. If you can log in without entering a password, SSH mutual trust has been successfully configured.
ssh 10.0.0.1
eloq@10.0.0.1:~$

System configuration for EloqKV Server Nodes​

Below are some necessary configurations to be made before installing EloqKV

  • Ensure your system is connected to the network and can update its package repositories using yum update or apt update.
  • Edit the system configuration file /etc/security/limits.conf or /etc/security/limits.d/20-nproc.conf using the following command 
    sudo vi /etc/security/limits.conf
    Add the following resource limit parameters at the end of the corresponding file 
    * soft nofile 524288
    * hard nofile 524288
    * hard core unlimited
    * soft core unlimited
  • Ensure DNS server is configured in /etc/resolv.conf.
  • Ensure hostname is configured. 
    sudo hostnamectl set-hostname my_hostname
    Edit /etc/hosts 
    my_ip my_hostname
  • Use the following command to edit the configuration file /etc/sysctl.conf 
    sudo vi /etc/sysctl.conf
    Add the following configuration parameters at the end of the corresponding file 
    kernel.core_pattern=/var/crash/core-%e-%s-%u-%g-%p-%t
  • Execute the following command to load the above parameter modification. 
    sudo sysctl -p
  • In order to display all limit resource information of the current system, modify the bash configuration file 
    sudo vi ~/.bashrc
    Add at the end of the corresponding file 
    ulimit -c unlimited
  • Add current user and group ownership to /var/crash folder 
    sudo chown -R $USER:$USER /var/crash