Deploying Swift/Vapor Apps to Cloudhost

My Swift/Vapor deploying adventure with lots of words, because I stand in solidarity with the Recipe People. But no pictures, because I never think of that.

I thought it would be pretty straightforward. I’ve got Linux hosting at Cloudhost (not its real name) so I can just log in and install Swift and Vapor and build my app and run it, right?

Ha ha, good one.

But my hosting is modest - 1 GB of memory is plenty for my typical needs, which is usually limited to hosting an HTML site - Apache on Ubuntu 16.04.

So try and build a Vapor site? Nope, try and try and fail and fail - fatalError kind of stuff. Try adding -v to the build and re-run just that last command directly in Swift and all of a sudden I see the real problem: I’m running out of memory.

Well hell, of course I am!

So all I need to do is build my app off-site and copy the Run file, right? *Hey, don’t get ahead of me, this is my adventure.

Oh, I almost forgot this part. I’ve got a Linux system, and in fact I’ve already built my app there. Just copy the Run file, right? No, because this is Ubuntu 20.04 and so it depends on libraries and such that are four years newer than what’s running at Cloudhost.

But I’ve got this other PC and it’s got a bunch of memory. It might even ben running Linux already, who knows. Scrounge a keyboard and mouse and monitor. Plug it in. Beep beep beep. Won’t even POST.

No problem, pull the drive and drop it into yet another PC. Boot it up and wouldn’t you know, it’s actually running Ubuntu 16.04. In fact, there are ancient Swift directories from November 2016 when I thought I’d have time to play with the compiler. I didn’t. So get a network hooked up, get Swift installed, and…

$ swift -version

blah blah (I didn’t bother saving all the output)

Illegal Instruction

Oh yeah, if you are thinking about running Swift on Linux on an older PC, do this first:

$ cat /proc/cpuinfo | grep ssse3

because if it comes up blank, you’re going to have a bad time.

So no problem, that Ubuntu 20.04 PC is willing to sacrifice itself temporarily (and I know already it’s got ssse3) so unplug its drive and drop in the Ubuntu 16.04 drive.

Now here’s something I’m not 100% sure I needed to do, but I made sure that I installed Swift in the exact same place on both Ubuntu 16.04 systems - the one on my PC and the one at Cloudhost. In both cases, I have /opt/swift-5.4.1-RELEASE-ubuntu16.04. So if there are libraries that would cause a freakout because of different locations, that’s not going to happen.

And finally I see what I’ve been hoping for:

$ export PATH=/opt/swift-5.4.1-RELEASE-ubuntu16.04/usr/bin:"${PATH}"

$ swift -version

Swift version 5.4.1 (swift-5.4.1-RELEASE)

Target: x86_64-unknown-linux-gnu

So get Vapor installed, pull down my app, and (sudden thunder clap drum roll)

It works!!

*Oh wait… connect from the browser, no it doesn’t!! And this is something I didn’t realize about Vapor, you need to have the Resources/Views directory and all its .leaf (or .html) files. And, it turns out, your Public directory. No problem, so I did a clone of my whole app to get whatever files it needs. As they change, I can pull to refresh them. Then I re-copied the Run file, but this time dropped it in the same x86_64-linux-whatever location as where it came from. This way git doesn’t think I have any untracked files.

Now run it again, and it looks like it works, then hit it from the browser, and it actually does!!

So here are the takeaways:

• Here are the links for installing swift and vapor
• You'll have much better luck with your build system separate from your hosting
• `cat /proc/cpuinfo | grep ssse3` # to make sure your build system is up to running Swift
• Make sure you have enough memory on your build system (not sure how much that is tbh)
• Make sure your hosting and build systems have the same exact Ubuntu version (major.minor is probably enough, but…???)
• Install Swift to the same location on both build and hosting (not 100% sure you need to do this, but I think you do and it can’t hurt, right?)
• `git clone` your whole app, even though you don’t need the Sources, you do need Resources and Public folders
• scp .build/x86_64-linux-whatever/debug/Run from your build system to the same spot, so it’s ignored by git

I think that’s it. I hope this helps somebody!

Add Port to UFW

I'm running UFW (uncomplicated firewall) to restrict traffic into my Linux system.

And while being super restrictive is generally a good thing, there are times when you have to poke a new hole and connect from another system inside the house.

Usually it's a new app running on a new port and since I never remember the command to allow this, here it is:

$ sudo ufw allow from 192.168.1.0/24 to any port 3100

You're welcome, future self!

Mac + Virtualbox/Linux ALT=CMD

By default it seems that when you run Linux in Virtualbox on a Mac, ALT will be mapped to the OPTION key and SUPER will be mapped to CMD.

It's much more natural to swap these, i.e. to map ALT to CMD.

And here's how you do it:

Create ~/.Xmodmap containing...

clear mod1
clear mod4

keycode 133 = Alt_L NoSymbol Alt_L
keycode 64 = Super_L NoSymbol Super_L

add mod1 = Alt_L
add mod4 = Super_L

And then

$ xmodmap ~/.Xmodmap

Enjoy!

VNC black screen of sadness

Did you connect to your VNC server only to be greeted by a black screen of sadness? 

It happened to me not long ago and I don't know what made me try this, but here's what fixed it:

$ vncpasswd

As always, you're welcome.

I Repeat...

I'm always forgetting how to repeat a command. Here's how in tcsh:

$ repeat 9999 sh -c 'now=`date +%s` ; date > /tmp/tmp ; then=`date +%s` ; diff=`expr ${then} - ${now}` ; echo xxxxx ${diff} xxxxx ; if [ ${diff} -gt 0 ] ; then date ; fi ; sleep 15'

(The inner command is /bin/sh, of course)

Listening Ports

Here's a handy command to find out which ports are listening:

/usr/sbin/lsof -P | sed -e '/(LISTEN)/ ! d; s/.* TCP .*:\([0-9][0-9]*\) .*/\1/' | sort -n | uniq

And ymmv, but sudo is probably a good way to run that.

New cron job

Welcome to my crontab, new cron job!

18 * * * * ps -feww | grep -v grep | grep python | wc -l | sed -e '/^[0-4]$/ d; s/$/ pythons are running/g'

Why? If you've ever run into the problem where python cron jobs start piling up because of abrtd, and you've restarted abrtd, this will help you keep an eye on things. Every hour on the 18 (so as not to run into one of my running python scripts) I'm counting python processes and if there are more than four, I'll hear about it.

MySQL Reference

Doing some MySQL work over the past couple of days, I googled a couple topics I needed help with, and both times I ended up at the same place.

• Redhat Enterprise Linux (RHEL) Install and Configure MySQL Database Server
• How Do I Enable Remote Access To MySQL Database Server?

So thanks, nixCraft, for the assist!!

SCP and spaces

I was looking for help with linux SCP and spaces in file names. I found a somewhat helpful link here: http://www.thingy-ma-jig.co.uk/blog/14-05-2007/how-to-scp-a-path-with-spaces

Its advice didn't work for me out of the box, however.

What I ended up doing instead that did work was this:

scp -r 'myserver.com:"/path/with/a/Space\ In\ It' ./

Which is to say that I single-quoted the whole source argument and single-escaped each space.

I'm dealing with left-parentheses similarly:

scp -r 'myserver.com:"/path/with/a/Space\(s)\ In\ It' ./

Looks like there are other characters I need to escape, like single quotes, but I'm not going to worry about those right now. If you have any idea about escaping those in this context, please leave a comment.