Thursday, December 11, 2014

Setting up a minimal gluster server for libvirt testing

Recently I've been working on virt-install/virt-manager support for libvirt network storage pools like gluster and rbd/ceph. For testing I set up a single node minimal gluster server in an F21 VM. I mostly followed the gluster quickstart and hit only a few minor hiccups.

Steps for the gluster setup:
  • Cloned an existing F21 VM I had kicking around, using virt-manager's clone wizard. I called it f21-gluster.
  • In the VM, disable firewalld and set selinux to permissive. Not strictly required but I wanted to make this as simple as possible.
  • Setup the gluster server
    • yum install glusterfs-server
    • Edit /etc/glusterfs/glusterd.vol, add: option rpc-auth-allow-insecure on
    • systemctl start glusterd; systemctl enable glusterd
  • Create the volume:
    • mkdir -p /data/brick1/gv0
    • gluster volume create gv0 $VM_IPADDRESS:/data/brick1/gv0
    • gluster volume start gv0
    • gluster volume set gv0 allow-insecure on
  • From my host machine, I verified things were working: sudo mount -t glusterfs $VM_IPADDRESS:/gv0 /mnt
  • I added a couple example files to the directory: a stub qcow2 file, and a boot.iso.
  • Verified that qemu can access the ISO: qemu-system-x86_64 -cdrom gluster://$VM_IPADDRESS/gv0/boot.iso
  • Once I had a working setup, I used virt-manager to create a snapshot of the running VM config. So anytime I want to test gluster, I just start the VM snapshot and I know things are all nicely setup.
The bits about 'allow-insecure' is so that an unprivileged client can access the gluster share, see this bug for more info. The gluster docs also have a section about it but the steps don't appear to be complete.

The final bit is setting up a storage pool with libvirt. The XML I passed to virsh pool-define on my host looks like:

<pool type='gluster'>
  <name>f21-gluster</name>
  <source>
    <host name='$VM_IPADDRESS'/>
    <dir path='/'/>
    <name>gv0</name>
  </source>
</pool>

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