Computers for cross-platform development

[Lassi Kortela]

>> Get a single large machine and virtualize each one of the

> I double the sentiment for virtualization

Tripled :) Spending the same amount of money on a fast/spacious amd64 
system will probably give you more development speed and convenience and 
maybe even more stability than buying exotic hardware. (Unless you 
specifically love owning exotic hardware as a hobby in its own right.)

I run all of the following on VirtualBox on an Intel Mac:

* DragonFly
* FreeBSD
* OpenBSD
* NetBSD
* Solaris (OmniOS)
* Debian Linux
* Alpine Linux
* Haiku (BeOS clone)

Everything is very fast and convenient and surprisingly easy to set up 
nowadays. VirtualBox doesn't have as good a reputation as VMWare in the 
stability department but I've had very few crashes; it's perfectly 
usable for ordinary programming. It can use grow-on-demand virtual disks 
so if you make a 10 GiB disk it doesn't instantly use up 10 GiB of real 
space. Probably all virtualizers can do that nowadays.

For non-x86 platforms, QEmu on Linux may be your only reasonable option 
(I've successfully run Linux on VirtualBox and then QEmu inside the 
virtualized Linux box). QEmu is generally less stable than VirtualBox 
but the range of virtualized hardware is amazing. This would be the 
first approach I'd try to cover big-endian systems.

VirtualBox and QEmu can do TCP port forwarding, so you can make an 
extremely nice setup to ssh into your boxes by putting things like this 
in your ~/.ssh/config file:

     Host dragonfly
       HostName localhost
       Port 9001

     Host freebsd
       HostName localhost
       Port 9002

     Host alpine
       HostName localhost
       Port 9003

Then whenever you need to test things on a particular VM, just start it 
up, wait 30 seconds, and `ssh dragonfly` from your shell. All the usual 
things like scp/sftp, tmux and git pulls from the network run fine. 
Emacs will even let you remote-edit files inside VMs from your main 
editor session via ssh (Vim probably has something similar). ssh-copy-id 
your key into the VM for passwordless logins, install your favorite 
software and clone all your dotfiles, and you have an almost seamless 
cross-platforms development experience.

VirtualBox can also easily juggle like 5 different VMs at once if you 
have the RAM. Set up ssh port forwarding so each VM exposes a different 
port to your native OS, and you can have tmux and editor files open on 
all of them at once. Really great for cross-checking things quickly.

With not-all-that-much practice it's basically as easy as developing on 
a single platform. Except the portability concerns will make you write 
better software by avoiding over-complicated approaches and sticking to 
data structure / OS fundamentals ;) And it helps add inspiration and 
relieve some of the boredom of development when you visit different OSes 
regularly.

> As Justin mentioned, the frequency of the runs adjusts the value of VM vs physical.

With a reasonably beefy Intel machine (which will likely be more 
reliable and not more expensive than having separate computers), you can 
run a whole lot of things before a separate physical machine becomes 
easier/faster. Not sure is this applies to really CPU/RAM heavy 
workloads (if you can stomach closed-source software I'd evaluate VMWare 
for those).

> I don’t know if Travis CI supports every OS on your list, but it might and you could set up a testing framework with it.

When I started out I used to think that cross-platform CI is enough. But 
it turns out it's painfully slow to check your work using only a CI 
server since you have to push a new commit to try the simplest of 
things. I wish Travis provided an ordinary login shell running the same 
environment as their CI, would have already saved hours of my time. This 
is true in general, and doubly true for unfamiliar environments 
(different OSes than what you are used to). I gradually found out that 
instant ssh access from my main text editor and terminal is mandatory 
for programming sanity. The more slow/complex/annoying it is to access 
the boxes the less often you check stuff. I can't speak highly enough of 
the SSH-into-VirtualBox setup for getting real work done.

Nevertheless CI is great! Travis only has Linux/MacOS/Windows natively. 
Somebody managed to run FreeBSD in a Travis job by installing QEmu, 
downloading a BSD image, virtualizing BSD inside Travis's virtualized 
Linux and then making Travis ssh into the BSD to run the actual build 
script. Here are the gory details: 
<http://erouault.blogspot.com/2016/09/running-freebsd-in-travis-ci.html>. 
Genius or madness?

Cirrus CI apparently has native FreeBSD: 
<https://forums.freebsd.org/threads/cirrus-ci-free-freebsd-ci-testing-for-open-source-projects.68560/>.

SourceHut too but I can't find the details now: <https://meta.sr.ht/>.

Not sure if any CI services offer other BSDs but it seems to be a 
fast-moving field so there is hope.

Another possibility would be to rent some virtual servers running 
different operating systems as a group and pool money for the running 
bills. Vultr.com has a very good reputation and offers cheap servers 
with ready-made installations of many popular systems (including BSDs). 
They also have custom ISO image support.