Ceph：Designing and Implementing Scalable Storage Systems

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How to do it...

As we did earlier, we will set up a Ceph client machine using Vagrant and VirtualBox. We will use the same Vagrantfile that we cloned in the last chapter i.e. Chapter 1, Ceph - Introduction and Beyond. Vagrant will then launch a CentOS 7.3 virtual machine that we will configure as a Ceph client:

From the directory where we cloned the Ceph-Designing-and-Implementing-Scalable-Storage-Systems GitHub repository, launch the client virtual machine using Vagrant:

         $ vagrant status client-node1
         $ vagrant up client-node1

      $ vagrant ssh client-node1
      $ sudo yum update -y

The username and password that Vagrant uses to configure virtual machines is vagrant, and Vagrant has sudo rights. The default password for the root user is vagrant.

Check OS and kernel release (this is optional):

        # cat /etc/centos-release
        # uname -r

Check for RBD support in the kernel:

        # sudo modprobe rbd

Allow ceph-node1 monitor machine to access client-node1 over SSH. To do this, copy root SSH keys from ceph-node1 to client-node1 Vagrant user. Execute the following commands from ceph-node1 machine until otherwise specified:

        ## Log in to the ceph-node1 machine
        $ vagrant ssh ceph-node1
        $ sudo su -
        # ssh-copy-id vagrant@client-node1

Provide a one-time Vagrant user password, that is, vagrant, for client-node1. Once the SSH keys are copied from ceph-node1 to client-node1, you should able to log in to client-node1 without a password.

Using Ansible, we will create the ceph-client role which will copy the Ceph configuration file and administration keyring to the client node. On our Ansible administration node, ceph-node1, add a new section [clients] to the /etc/ansible/hosts file:

Go to the /etc/ansible/group_vars directory on ceph-node1 and create a copy of clients.yml from the clients.yml.sample:

        # cp clients.yml.sample clients.yml

You can instruct the ceph-client to create pools and clients by updating the clients.yml file. By uncommenting the user_config and setting to true you have the ability to define customer pools and client names altogether with Cephx capabilities.

Run the Ansible playbook from ceph-node1:

        root@ceph-node1 ceph-ansible # ansible-playbook site.yml

On client-node1 check and validate that the keyring and ceph.conf file were populated into the /etc/ceph directory by Ansible:

On client-node1 you can validate that the Ceph client packages were installed by Ansible:

The client machine will require Ceph keys to access the Ceph cluster. Ceph creates a default user, client.admin, which has full access to the Ceph cluster and Ansible copies the client.admin key to client nodes. It's not recommended to share client.admin keys with client nodes. A better approach is to create a new Ceph user with separate keys and allow access to specific Ceph pools.
In our case, we will create a Ceph user, client.rbd, with access to the RBD pool. By default, Ceph Block Devices are created on the RBD pool:

Add the key to client-node1 machine for client.rbd user:

By this step, client-node1 should be ready to act as a Ceph client. Check the cluster status from the client-node1 machine by providing the username and secret key:


        # cat /etc/ceph/ceph.client.rbd.keyring >> /etc/ceph/keyring
        ### Since we are not using the default user client.admin we 
        need to supply username that will connect to the Ceph cluster
        # ceph -s --name client.rbd