Devstack mounted via NFS

Devstack allows the developer to work with the master branches for upstream OpenStack development. But Devstack performs many operations (such as replacing pip) that might be viewed as corrupting a machine, and should not be done on your development workstation. I’m currently developing with Devstack on a Virtual Machine running on my system. Here is my setup:

Both my virtual machine and my Base OS are Fedora 20. To run a virtual machine, I use KVM and virt-manager. My VM is fairly beefy, with 2 GB of Ram allocated, and a 28 GB hard disk.

I keep my code in git repositories on my host laptop. To make the code available to the virtual machine, I export them via NFS, and mount them on the host VM in /opt/stack, owned by the ayoung user, which mirrors the setup on the base system.

Make sure NFS is running with:

sudo systemctl enable nfs-server.service 
sudo systemctl start  nfs-server.service

My /etc/exports:

/opt/stack/ *(rw,sync,no_root_squash,no_subtree_check)

And to enable changes in this file

sudo exportfs

Make sure firewalld has the port for nfs open, but only for the internal network. For me, this is interface

virbr0: flags=4163 UP,BROADCAST,RUNNING,MULTICAST  mtu 1500
        inet  netmask  broadcast

I used the firewall-config application to modify firewalld:

For both, make sure the Configuration select box is set on Permanent or you will be making this change each time you reboot.

First add the interface:


And enable NFS:


In the Virtual machine, I added a user (ayoung) with the same numeric userid and group id from my base laptop. To find these values:

$ getent passwd ayoung
ayoung:x:14370:14370:Adam Young:/home/ayoung:/bin/bash

I admit I created them when I installed the VM, which I did using the Anaconda installer and a DVD net-install image. However, the same thing can be done using user-add. I also added the user to the wheel group, which simplifies sudo.

On the remote machine, I created /opt/stack and let the ayoung user own them:

$ sudo mkdir /opt/stack ; sudo chown ayoung:ayoung /opt/stack

To mount the directory via nfs, I made an /etc/fstab entry: /opt/stack              nfs4  defaults 0 0 

And now I can mount the directory with:

$ sudo mount /opt/stack

I went through and updated the git repos in /opt/stack using a simple shell script.

 for DIR in `ls` ; do pushd $DIR ; git fetch ; git rebase origin/master ; popd ; done

The alternative is setting RECLONE=yes in /opt/stack/devstack/localrc.

When running devstack, I had to make sure that the directory /opt/stack/data was created on the host machine. Devstack attempted to create it, but got an error induced by nfs.

Why did I go this route? I need to work on code running in HTTPD, namely Horizon and Keystone. THat preclueded me from doing all of my work in a venv on my laptop. The NFS mount gives me a few things:

  • I keep my Git repo intact on my laptop. This includes the Private key to access Gerrit
  • I can edit using PyCharm on my Laptop.
  • I am sure that the code on my laptop and in my virtual machine is identical.

This last point is essential for remote debugging. I just go this to work for Keystone, and have submitted a patch that enables it for Keystone. I’ll be working up something comparable for Horizon here shortly.

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