Geolocation Fail

I was on Tor the other day, when I tried to access a Blogger blog. I got an infinite chain of redirections, because Google geolocates the IP and then issues a redirect to that country's blogger site.

For instance, with an IP geolocated to the Netherlands, *.blogspot.com and *.blogspot.de will redirect to *.blogspot.nl.  Tor Browser sees that as a new site and runs a new circuit with a different exit node, likely in a different country, causing another redirection.

Generally, the domain and exit node mapping remains fixed.  So, blogspot.com might redirect to blogspot.de, which would redirect to blogspot.nl, which might redirect to blogspot.com.  But the later accesses retain the original exit nodes, and all cause the redirections again.  Most sites work because they don't try to change domains per country.

A few attempts at "New Tor circuit for this site" finally broke the loops by changing the exit node for that single domain, but it's clear Google still puts too much faith in geolocation.

Any blogs that end up being accessed from EU exit nodes also get the cookie warning… generally in a language I can't read, because it's chosen by geolocation.  Even though my headers have "Accept-Language: en-US;q=0.5" and I'm visiting a page whose primary language is English. IK SNAP HET!

(Speaking of Tor, though. If you want to know whether a site uses CloudFlare, just load it in Tor Browser. You'll generally see a CloudFlare CAPTCHA on their sites. They're so aggressive about putting out high-difficulty puzzles, I generally don't bother to solve anymore.)

PGP

For the first time in over fifteen years of awareness about PGP, I met someone who actually wanted to use it.  I got to set trust on a key and see this awesome menu:

Please decide how far you trust this user to correctly verify other users' keys (by looking at passports, checking fingerprints from different sources, etc.)

1 = I don't know or won't say
2 = I do NOT trust
3 = I trust marginally
4 = I trust fully
5 = I trust ultimately

This reveals a lot about the assumptions of PGP and the problem it was trying to solve...

The menu clearly focuses on real-world identities, trying to get users to establish ‘trust’ that people correspond to the cyber-space identities. (Those digital identities are the keys: anyone with the key is indistinguishable from anyone else who has it.) Why else is the focus on “verifying” by looking at passports and fingerprints?

In short, PGP was the first Google+: built by nerds as an identity service for the masses… that failed to become mainstream.

Unikernels

I learned a new term recently: unikernel.  Wikipedia defines it as a “single address space machine image” or else uses the “library operating system” term, but the gist of it is:

Unikernel: A system where a single application runs in unprotected mode.

Instead of a “normal” operating system managing multiple processes, a unikernel has the OS services arranged as a library, and runs one process with that library in the kernel space of the host hardware.

This used to be fairly impractical, as you’d have to dedicate physical hardware to the unikernel, and it would still need drivers for that hardware. It was a lot of work and not very portable.  But with virtualization, a unikernel can build to the hypervisors’ interfaces, then run in any environment that supports the hypervisor.

Here’s the difference from other approaches once virtualization gets in the mix: a unikernel uses the hypervisor only to provide isolation and virtio devices, then runs one process with no further hardware protections inside the guest.  Networking, filesystems, and anything else normally provided by the OS through the syscall interface are, instead, built as function calls living in the same address space with the main application.

A container uses a host OS kernel in much the same way, to run each container as a host process.  While this requires a specific syscall interface, it also means the container environment can take advantage of the host OS’s drivers, filesystems, and networking.  The container and hypervisor are fully unaware of each other, which also enables them to run on a host OS that’s running on bare metal.

A traditional guest system, of course, runs a full OS inside the guest and ordinary processes inside the OS.  Like the unikernel, it boots anywhere with the requisite CPU/virtio support, regardless of underlying host OS, but like a container, it continues to provide OS services like networking, filesystems, and process management through the syscall interface.

(Plenty of other ink has been spilled about the security of all this, but the tl;dr is, hypervisors more-or-less secure multi-tenant hardware.  Running in the cloud means being virtualized, even with containers.)

Here’s a rough drawing of two virtual-machine architectures (KVM and Xen), and how they differ from containers and unikernels:

Obviously, unikernels are also a bigger change in application architecture from containers (a single package and its dependencies, minus a kernel) or a full OS, but they’re well-suited for single-language microservices.  Once a language has the “OS library” to provide networking and filesystems (if needed), any app written to that library can be compiled to a unikernel.

The unikernel, essentially, gives up composability in the pursuit of speed. Additional process can’t be added in, because the unikernel doesn’t support processes or process isolation without losing its essential difference from an ordinary OS or container.  (Threads are possible, but not processes.)

Perhaps, again, the difference is best described with a picture:

In the unikernel, what are ordinarily “operating system services” and shared library calls are compiled into a single address space as ordinary function calls.  Getting rid of the user/system split is of course their whole point, and shared libraries also disappear because, as one process, there is no “other” process to share with.  All the mechanics involved in doing so become unnecessary.

As noted above, hypervisors have made unikernels much more interesting and feasible lately.  There’s a full list at unikernel.org, particularly their projects page, but the two that look most interesting to me are:

• OS^v
• rumprun

I don’t know when—or even if—I’ll get around to doing anything with them, but those are likely to be the easiest-to-use unikernels, unless someone makes node.js into one.

API Gateway as an HTTP Service Proxy: Lessons Learned

At work, we’re finishing the implementation of our first API using the Amazon API Gateway for decoupling the API key management, logging, and throttling from the actual backend service. This also marks our first OAuth 2.0 Resource Server, and makes heavier use of Swagger 2.0 for the entire pipeline.  With all these “firsts,” I’d like to share a few notes on our setup.

Freezing Layers (static vs dynamic)

Let me warn you right up front: this is a philosophical and rambling post.  I'm trying to pull together a series of observations into a coherent structure and it's quite possible that I failed at that.  In addition, because of its lack of quality, “PHP” throughout refers to the 5.x and earlier lines.  Version 7.0 basically addresses the error complaint.  Now without further ado, here is your ancient, rambling post...

I've written some Perl code using FCGI managed by mod_fcgid, in which I constructed my own request loop and application pre-loader.  (And complained about the way mod_fcgid is set up, since it doesn't pre-fork fastcgi children—whenever concurrency is exceeded, starting from zero after a fresh startup, someone has to wait for the world to load just like the bad old CGI days.)

I've written plenty of PHP as well, where you get to generate a response in response to routing once the server environment gets around to delivering the request to you.  The only things that may persist from request to request are allocated on the C level, not by the PHP script directly: most famously, opcode caches and persistent database connections.

The Common Denominator

On my back-burner at work, following a company-wide deprecation of Perl, is porting our Perl-based API services to PHP.

This may be painful, because by the time I wrote the API code, I was fluently using Perl-isms in Perl code.  It’s possible this won’t be a straightforward port because most of that is missing in PHP.

In comparison, back when I first started working here, I ported a small sub-site from Perl to PHP.  It was written in a style where I mostly needed small, mechanical changes like taking out my.  The only “big” change was creating an equivalent for HTML::Template, but that was pretty small itself.

Maybe you can write Java in any language… but then it’s 10 times easier to port to another language.

Re: Pomodoro technique

I hear, once in a while, this “great life hack” called the Pomodoro Technique. The basic principle is, one works in small, focused bursts on a task.

There’s a major problem, though.  It doesn’t work for me.  It might take me the entire “focused burst” time to really get focused on the task at hand, and then, boom! A forced distraction takes me away, just as I get warmed up. Getting back into the next cycle then takes at least as long, or longer, and pretty soon there’s zero forward progress as my attention is sliced to ribbons by a timer.

(I observe the same problem with the average ‘typing break’ software that doesn’t bother monitoring actual typing.  I am too frequently just getting warmed up when a “scheduled break” arrives.)

tl;dr: the “pomodoro technique” is not a magic cure-all, and you don’t have to feel bad if it doesn’t work for you.  You can just stop using it.