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Use xhyve for development on OSX

Posted on | 711 words | ~4mins

If you are working on Mac and use Docker, you might noticed that Docker now runs natively on OSX using xhyve. The xhyve is a port of bhyve to OS X. It is built on top of Hypervisor.framework and available from OS X version 10.10.

If you are developing code that runs on Linux, your options on OSX are basically limited to Virtualbox, Parallels or VMWare. Not anymore! You can use xhyve to run your Linux VMs now and it is pretty easy.

First step is to get xhyve itself. It is available in brew:

$ brew install --HEAD xhyve

Next step is to install your Linux VM. I’m using Centos7 here:

$ mkdir -p vms/centos7 && cd vms/centos7

# Use your favorite centos7 mirror here.
$ wget http://ftp.fi.muni.cz/pub/linux/centos/7/isos/x86_64/CentOS-7-x86_64-Minimal-1511.iso
$ dd if=/dev/zero bs=2k count=1 of=/tmp/tmp.iso
$ dd if=CentOS-7-x86_64-Minimal-1511.iso bs=2k skip=1 >> /tmp/tmp.iso
$ hdiutil attach /tmp/tmp.iso

Now we need to copy the vmlinuz and initrd.gz:

$ cp /Volumes/CentOS\ 7\ x86_64/isolinux/{vmlinuz,initrd} .

Next we need to pre-allocate the file that will serve as hard drive for our VM. This command will create 8GB empty file:

$ dd if=/dev/zero of=hdd.img bs=1g count=8

Now it is time to start the installation. Run this script:

#!/bin/sh

KERNEL="./vmlinuz"
INITRD="./initrd.img"
CMDLINE="earlyprintk=serial console=ttyS0"

MEM="-m 1G"
SMP="-c 2"
NET="-s 2:0,virtio-net"
IMG_CD="-s 3,ahci-cd,${HOME}/vms/centos7/CentOS-7-x86_64-Minimal-1511.iso"
IMG_HDD="-s 4,virtio-blk,./hdd.img"
PCI_DEV="-s 0:0,hostbridge -s 31,lpc"
LPC_DEV="-l com1,stdio"
sudo xhyve $ACPI $MEM $SMP $PCI_DEV $LPC_DEV $NET $IMG_CD $IMG_HDD $UUID -f kexec,$KERNEL,$INITRD,"$CMDLINE"

After you run this, you will see the Linux kernel boot messages and then the Centos7 text mode installer will appear. You might set the root password, timezone and disk (use automatic partitioning). Also use the local media source for the installation. For networking choose the DHCP option. You should get an IP address similar to 192.168.64.XX.

Press b to begin the installation and wait until end. Do not exit the installation by pressing enter, but press the Ctrl+b 2 at the end. That will take you to the console. We have to copy the kernel and initrd once again, this time the files we just installed:

$ ifconfig # -> to see the IP address
$ cd /mnt/sysimage/boot/
$ ls # -> to see the file names
$ python -m SimpleHTTPServer

Now open a new tab in your terminal on the OSX machine and go to ~/vms/centos7 directory. Then run this commands using the IP address and file name we discovered above:

$ wget http://192.168.64.8:8000/vmlinuz-3.10.0-327.el7.x86_64
$ wget http://192.168.64.8:8000/initramfs-3.10.0-327.el7.x86_64.img

Now you can exit the installation (in some cases the installer will hang, in that case you can simply sudo pkill xhyve on the OSX to shut it down completely.

Now is time to create script that will run your VM:

#!/bin/sh

# Linux
KERNEL="./vmlinuz-3.10.0-327.el7.x86_64"
INITRD="./initramfs-3.10.0-327.el7.x86_64.img"
CMDLINE="earlyprintk=serial quiet console=ttyS0 acpi=off root=/dev/mapper/centos-root rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rw"

MEM="-m 4G"
SMP="-c 2"
NET="-s 2:0,virtio-net"
IMG_HDD="-s 4,virtio-blk,./hdd.img"
PCI_DEV="-s 0:0,hostbridge -s 31,lpc"
LPC_DEV="-l com1,stdio"
UUID="-U deadbeef-dead-dead-dead-deaddeafbeef"
sudo xhyve $ACPI $MEM $SMP $PCI_DEV $LPC_DEV $NET $IMG_CD $IMG_HDD $UUID \
  -f kexec,$KERNEL,$INITRD,"$CMDLINE"

It is important to set the root and rd.lvm.lv otherwise the Centos7 will fail to boot. Also the UUID field is important if you want to always get the same IP address for your VM. You can tweak the MEM and SMP to give the VM as much power as you need.

Now, when you run this script, you should see the login prompt and you can login as root (use the password you set during installation).

Done! You can now customize the VM and install whatever you want. You can also ssh into this VM from host using ssh [email protected].

The next step is to setup NFS sharing for your code folder on OSX host. Fire up a new terminal window and edit the /etc/exports file on OSX (you might want to create it). Write there something like:

/Users/mfojtik/go -mapall=mfojtik

AS you might guess, the first field is the folder you want to export via NFS and the second field is the user name on OSX.

Now restart the NFS server:

$ sudo nfsd enable # optional
$ sudo nfsd restart

Now, go back to your VM and add this into your /etc/fstab:

192.168.64.1:/Users/mfojtik/go /data nfs nolock,rw

You might want to create the “mfojtik” user in the VM with the same UID as you have on OSX (id command will tell you).