Software Articles

Tiller, Ledger, and Sorbet

Tiller + Ledger

Thirteen years ago I started tracking my finances using a tool named Ledger. Up until 2018 I hand-entered every penny into my ledger files, which absolutely had value but eventually I decided that I wanted to automate things as much as I could.

I happened upon Tiller which scrapes bank accounts and puts the data into a Google spreadsheet. Importantly, Tiller adds a unique ID to every transaction it sees, which means if I want to automate something I don't have to try to implement deduplication.

Back in 2018 the script I used was rough, but I've polished it over the years and, just the other day, published the guts as LedgerTillerExport.

Using Let's Encrypt Without certbot

In my last post I talked about what a CDN is and why you might want one. To recap, my goal is automatic, magical DNS/SSL/caching management. Today we're going to talk about one aspect of this project: HTTPS and SSL.

SSL, or Secure Sockets Layer, is the mechanism web browsers use to secure and encrypt the connection between your computer and the server that is serving up the content you're looking for.

A few years ago browser vendors started getting very serious about wanting every website to be encrypted. At the time, SSL was expensive to implement because you needed to buy or pay to renew certificates at least once a year.

Almost simultaneously with this increased need for encryption, organizations including the Electronic Frontier Foundation and the Mozilla Foundation started a new certificate authority (organization that issues certificates) named Let's Encrypt. Let's Encrypt is different because it issues certificates for free with an API.

Most people use a tool named certbot that automates the process of acquiring certificates for a given website. However, certbot doesn't really work for my purposes. I want to centrally manage my certificates and copy them out to my CDN nodes on a regular basis, which means I need to use the DNS challenge type. certbot's support for the DNS challenge isn't really adequate for my needs.

What is a CDN and why do I need one?

In my earlier post I talked about how I'm building my own content delivery network (CDN) but I didn't really go into what a content delivery network even is or why someone would want such a thing. A little back story is probably in order.

My Own Private CDN

Hosting my own CDN has long been a completely irrational goal of mine. Wouldn't it be neat, I'd think, if I could tweak every knob instead of relying on CloudFront to do the right thing? Recently I read this article by Janos Pasztor about how he built a tiny CDN for his website. This just proves to me that at least it's not an uncommon irrational thought.

Yesterday I decided to actually start building something. Even if it doesn't make it into production, I'll at least have learned something.

Why your SaaS application should support SAML

Your SaaS application should support SAML (Security Assertion Markup Language) if you're at all interested in big fat contracts from large enterprise customers. And why is that?

One word: money. Large enterprise customers pay quite a lot of money for services that help them do their work with a minimum of fuss. They want to do as little management of your service as they can possibly get away with, preferrably zero. If you can't make that happen, but your competitor can, guess who's not getting that big fat contract.

Archiving Websites with Wget

Let's say you want to archive a website. Maybe they're closing down or changing focus, or maybe you just want to view it offline. You want to capture the whole site at a single point in time. How would you do that?

You could just use your browser to save the page, but you probably won't get the HTML or images. You could print the page to a PDF, but then it's in a weird format and might be stuck in the print stylesheet forever.

You could use a service like Pinboard but they only archive one page, whereas you want to capture the whole site.

So, what do you do?

Know How To Roll (Your SSL Certificates)

A few weeks ago Stripe's SSL certificate became invalid, along with several other major sites. Their certificate didn't expire, their certificate authority's root certificate did. This shouldn't happen, but as with most terrible things it crops up at rather inconvenient times.

There's not much you can do to protect yourself against a service provider's certificate expiring, but you can proactively protect yourself against your own certificate expiring. The biggest thing to do is have a schedule and a process.

Command Line Faxing

When I started Okapi LLC, my little consultancy and publishing house, I had to fax in some forms to the State of Michigan. The entire system for opening businesses in Michigan, in fact, is basically a fax driven API. Being a modern, hip millenial I don't subscribe to a land line phone, nor do I own a fax machine. How was I supposed to fax things?

Enter Phaxio. They have a whole bunch of fax machines (actually they're probably banks of modems) in a data center somewhere and they let you use them with a simple HTTP API. All you have to do is go sign up and make an initial deposit. They'll provide you with an API key and secret pair that you can then use to send faxes using curl.

Start a VirtualBox VM at Boot on Mac OS X

Sometimes you have a VirtualBox VM that's critical to your workflow. For example, the Mac mini in my basement hosts a VM that does things like host all of my private Git repos and provide a staging environment for all of my wacky ideas.

When I have to reboot that Mac mini for any reason, inevitably I find myself trying to push changes to some git repo and forgetting that I have to start up the VM again by hand. And then there's the yelling and the drinking and it's no good for anyone.

Self-hosted Git Server

I've had a GitHub account since 2008. June 16th, to be exact. For almost six years I've been hosting my code on someone else's servers. It was sure convenient, and free, and I don't regret it one bit, but the time has come to move that vital service in-house.

I've run my own private git server on the Mac mini in my living room since 2012. For the last few years, then, my GitHub account has become more of a public portfolio and mirror of a selection of my private repos. As of today, my GitHub account is deprecated. If you want to see what I'm working on now you can go to my Projects page. I'll be gradually moving old projects over to this page, and new projects will show up there first.

Using the Mailchimp API for Sales

One of the very first things I did when I started working on the idea that eventually became Mastering Modern Payments was set up a Mailchimp mailing list. People would land on the teaser page and add themselves to the list so that when the book came out they would get a little note. After the book launch (with 30% of that initial list eventually buying) I started putting actual purchasers on the list.

A Practical Exercise in Web Scraping

Yesterday a friend of mine linked me to a fictional web serial that he was reading and enjoying, but could be enjoying more if it was available as a Kindle book. The author, as of yet, hasn't made one available and has asked that fan-made versions not be linked publicly. That said, it's a very long story and would be much easier to read using a dedicated reading app, so I built my own Kindle version to enjoy. This post is the story of how I built it.

Simple Git-backed Microsites

A few days ago I built a new tool I'm calling Sites. It builds on top of git-backed wikis powered by GitHub's Gollum system and lets me build and deploy microsites in the amount of time it takes me to create a CNAME.

Something that I've wanted for a very long time is a way to stand up new websites with little more than a CNAME and a few clicks. I've gone through a few rounds of trying to make that happen but nothing ever stuck. Furthest progressed was a Rails app exclusively hosting Comfortable Mexican Sofa, a simple CMS engine. I never ended up putting any sites on it, though.

GitHub's Pages are of course one of the best answers, but I'm sticking to my self-hosting, built-at-home guns.

Simulating a Market in Ruby

Trading markets of all kinds are in the news pretty much continuously. The flavor of the week is of course the Bitcoin markets but equity and bond markets are always in the background. Just today there is an article on Hacker News about why you shouldn't invest in the stock market. I've participated in markets in one way or another for about a decade now but I haven't really understood how they work at a base level. Yesterday I built a tiny market simulator to fix that.

Little Data: How do we query personal data?

My wife and I recently moved from Portland, OR to Ann Arbor, MI. Among the cacophony of change that is involved with a move like that, we of course changed to the local utility company. Browsing around in their billing application one day I came across a page that showed a daily graph of our energy usage, supposedly valid through yesterday for both gas and electric. And it has a button that spits out a CSV file of the date, which means if I actually wanted to I could build my own tool to analyze our usage.

Post-mortem of a Dead-on-Arrival SaaS Product

A little over a year ago I announced the launch of my latest (at the time) product named Marginalia. The idea was to be a sort of online journal. A cheaper, more programmer friendly alternative to Evernote. It never took off, despite my best intentions, and so a few months ago I told the only active user that I was going to shut it down, and today I finally took that sad action. This post is a short history of the project and a few lessons learned.

DRY your Rails CRUD with Simple Form and Inherited Resources

When you're writing a Rails application you usually end up with a lot of CRUD-only controllers and views just for managing models as an admin. Your user-facing views and controllers should of course have a lot of thought and care put into their design, but for admin stuff you just want to put data in the database as simply as possible. Rails of course gives you scaffolds, but that's quite a bit of duplicated code. Instead, you could use the one-two-three combination of Simple Form, Inherited Resources, and Rails' built-in template inheritance to DRY up most of the scaffolding while still preserving your ability to customize where appropriate. This lets you build your admin interface without having to resort to something heavy like Rails Admin or ActiveAdmin while also not having to build from scratch every time.

Essential Tools for Starting a Rails App in 2013

Over the past few years I've written a number of Rails applications. It's become my default "scratch an itch" tool for when I need to build an app quickly to do a task. Even though Rails is mostly batteries-included, there are a few tools that make writing new applications so much easier. This is my list of tools that I use for pretty much every new Rails project.

Edit: The discussion on Hacker News has some great gems that you should consider using as well.

Making eBooks with Docverter

I've been writing my guide to integrating Stripe with Rails using markdown, as with most textual projects that I work on. Every chapter is a markdown-formatted file living in a git repo, sycned-on-save to my git server and S3 using SparkleShare. When I want to peek at the rendered version I use little previewer app running on a VM on my Mac mini that I talked about previously.

A good eBook needs a PDF version, of course. Awhile back I wrote an open-source service named Docverter that can render XHTML to PDF using a library named Flying Saucer, among other things. All you have to do is pipe in the HTML and other related files and you get back a rendered, self-contained PDF file. There are a few non-trivial aspects to this, of course, because HTML is not primarily intended for printable output. The W3C has worked up a whole CSS module for page-related styles but it's not the most readable document. There's a few simple-ish things that you can do to your document to make it look nice, though.

Page Viewer, a Simple Markdown Viewer

For various projects including Mastering Modern Payments I've found it really useful to be able to view the Markdown source rendered as HTML but I don't really care about editing it online. I put together a little gem named page_viewer which renders Markdown files like this:

Design for Failure: Processing Payments with a Background Worker

Processing payments correctly is hard. This is one of the biggest lessons I've learned while writing my various SaaS projects. Stripe does everything they can to make it easy, with quick start guides and great documentation. One thing they really don't cover in the docs is what to do if your connection with their API fails for some reason. Processing payments inside a web request is asking for trouble, and the solution is to run them using a background job.

Distributed Personal Wiki

For as long as I can remember I've been trying to find a good way to keep personal text notes. Recipes, notes, ideas, that kind of thing. Things that aren't really suited to blogging. Along the way I've used (and stuck with) PmWiki, DocuWiki, TiddlyWiki, and most recently I built my own sort-of-pseudo-wiki Marginalia.

Lately, though, it's been kind of a drag to use a web-based application just to write down some work notes. Having sort of an obsession with Markdown I decided to just start keeping notes in Markdown-formatted files in a directory. Of course, files that aren't backed up are likely to disappear at any moment, so I naturally stuck them in a git repository and pushed to my personal git server. But then, how do I deal with synching my work and home machines? I guess I'll manually merge changes...

Full Text Search with Whistlepig

Yesterday I suddenly developed the intense need to add search to this site. Among the problems with this is that the site is kind of a weird hybrid between static and dynamic, and it has no database backend. If posts were stored in Postgres this would be a trivial matter, but they're just markdown files on disk. After flailing around for awhile I came across a library named Whistlepig which purported to do in-memory full text indexing with a full query language.

November 5, 2013: I've removed search because nobody used it and this way the site can be 100% static.

Deploy 12-Factor Apps with Capistrano::Buildpack

Last month I wrote a short article describing a method of deploying a 12-factor application application to your own hardware or VPS, outside of Heroku. Today I'm happy to announce a gem named capistrano-buildpack which packages up and formalizes this deployment method.

Deploying a 12-Factor App with Capistrano

Deploying Heroku-style 12 factor applications outside of Heroku has been an issue for lots of people. I've written several different systems that scratch this particular itch, and in this post I'll be describing a version that deploys one particular app using a Heroku-style buildpack, Foreman, and launchd on Mac OS X via Capistrano.

Run Anything on Heroku with Custom Buildpacks

Heroku is a Platform as a Service running on top of Amazon Web Services where you can run web applications written using various frameworks and languages. One of the most distinguishing features of Heroku is the concept of Buildpacks, which are little bits of logic that let you influence Heroku as it builds your application. Buildpacks give you almost unlimited flexibility as to what you can do with Heroku's building blocks.

Hanging out in the #heroku irc channel, I sometimes see some confusion about what buildpacks are and how they work, and this article is my attempt to explain how they work and why they're cool.

Private Git Repositories with Gitolite and S3

Earlier this year I bought a new Mac mini for various reasons. One of the big ones was so I would have a place to stash private git repositories that I didn't want to host on 3rd party services like Github or Bitbucket. This post describes how I set up Gitolite and my own hook scripts, including how I mirror my git repos on S3 using JGit.

On-the-fly Markdown Conversion to PDF and Docx

Today I added PDF, Docx, and Markdown download links to the bottom of every post here on Bugsplat. Scroll down to the bottom to see them, the scroll back up here to read how it works.

Keeping a Programming Journal with Marginalia

In addition to writing on this blog, I've been keeping notes for various things on Marginalia, my web-based note taking and journaling app. In my previous post I talked about the why and how of Marginalia itself. In this post I'd like to talk more about what I actually use it for day to day, in particular to keep programming journals.

Update 2013-10-19: Marginalia is shut down and open source on GitHub

Task-oriented Dotfiles

Recently I sat down and reorganized my dotfiles around the tasks that I do day-to-day. For example, I have bits of configuration related to ledger and some other bits related to Ruby development. In my previous dotfile setup, this stuff was all mixed together in the same files. I had started to use site-specific profiles (i.e. home vs work), but that led to a lot of copied config splattered all over. I wanted my dotfiles more organized and modifiable than that.

Dokuen, a Personal App Platform

Dokuen (Japanese for "solo performance") is an amalgamation of open source components that I mashed together so I could run Heroku-style services on my shiny new Mac mini while retaining the paradigm of git push deployments and environment variables for configuration. Effectively, I wanted to be able to seamlessly deploy 12 factor applications in my local environment.

Update: I've rewritten Dokuen and released it as a gem. See this article for details.

Update 2: I've added linux support.

Another Tiny Webapp

Literally ten minutes after hitting the publish button on my last post I took a little tumble and broke a rather important bone in my back, and now I'm on medical leave from work for awhile.

That doesn't stop me from doing fun things, though, so this morning I cooked up a tiny webapp using [Sinatra][], [DataMapper][], and [Bootstrap][] that will help me keep track of when I take painkillers. It's called [Painkiller Jane][] after the comic book character.

Concurrency on Heroku Cedar

I started a small product a few weeks ago called FivePad, a simple easy way to organize your apartment search. It's basically the big apartment search spreadsheet that you and me and everyone we know has made at least three times, except FivePad is way smarter.

The initial versions of FivePad did everything in the web request cycle, including sending email and pulling down web pages. The other day I was about to add my third in-cycle process when I threw up my arms in disgust. The time had come to integrate resque, a great little redis based job queueing system. Except if I ran it the way Heroku makes things easy my costs would get a little bit out of control for a project that isn't making much money yet.

Perl with a Lisp

Browsing around on hacker news one day, I came across a link to a paper entitled "A micro-manual for Lisp - Not the whole truth" by John McCarthy, the self-styled discoverer of Lisp. One commentor stated that they have been using this paper for awhile as a code kata, implementing it several times, each in a different language, in order to better learn that language. The other day I was pretty bored and decided that maybe doing that too would be a good way to learn something and aleviate said boredom. My first implementation is in perl, mostly because I don't want to have to learn a new language and lisp at the same time. The basic start is after the jump.

Managing Your Processes with ProcLaunch.

Edit 2010-08-08: ProcLaunch now has a CPAN-compatible install process. See below for details.

I finally got the chance to work some more on proclaunch, my implementation of a user space process manager, like runit or mongrel or god. I wrote up a big overview of the currently available options [previously][12], but in summary: all of the existing options suck. They're either hard to setup, have memory leaks, have a weird configuration language, or are just plain strange. The only viable option was procer, and even that was just sort of a tech demo put together for the Mongrel2 manual.

That's why I started putting together proclaunch. I need some of the features of runit, namely automatic restart, with none of the wackyness, and I wanted it to be easy to automatically configure. I also wanted it to be standalone so I wouldn't have to install a pre-alpha version of Mongrel2 just to manage my own processes.

Daemons are Our Picky, Temperamental Friends

Modern web applications are complicated beasts. They've got database processes, web serving processes, and various tiers of actual application services. The first two generally take care of themselves. PostgreSQL, MySQL, Apache, Nginx, lighttpd, they all have well-understood ways of starting and keeping themselves up and running.

But what do you do if you have a bunch of processes that you need to keep running that aren't well understood? What if they're well-understood to crash once in a while and you don't want to have to babysit them? You need a user space process manager. Zed Shaw seems to have coined this term specifically for the Mongrel2 manual, and it describes pretty accurately what you'd want: some user-space program running above init that can launch your processes and start them again if they stop. Dropping privilages would be nice. Oh, and it'd be cool if it were sysadmin-friendly. Oh, and if it could automatically detect code changes and restart that'd be nifty too.

Data Mining "Lost" Tweets

Note: this article uses the Twitter V1 API which has been shut down. The concepts still apply but you'll need to map them to the new V2 API.

As some of you might know, Twitter provides a streaming API that pumps all of the tweets for a given search to you as they happen. There are other stream variants, including a sample feed (a small percentage of all tweets), "Gardenhose", which is a stastically sound sample, and "Firehose", which is every single tweet. All of them. Not actually all that useful, since you have to have some pretty beefy hardware and a really nice connection to keep up. The filtered stream is much more interesting if you have a target in mind. Since there was such a hubbub about "Lost" a few weeks ago I figured I would gather relevant tweets and see what there was to see. In this first part I'll cover capturing tweets and doing a little basic analysis, and in the second part I'll go over some deeper analysis, including some pretty graphs!

Iterating Elements in boost::tuple, template style

In my day job I use a mix of perl and C++, along with awk, sed, and various little languages. In our C++ we use a lot of boost, especially simple things like the date_time libraries and tuple. Tuple is a neat little thing, sort of like std::pair except it lets you have up to 10 elements of arbitrary type instead of just the two. One of the major things that it gives you is a correct operator<, which gives you the ability to use it as a key in std::map. Very handy. One tricky thing, though, is generically iterating over every element in the tuple. What then?

Everyone Needs Goals

Creating actionable information out of raw data is sometimes pretty simple, requiring only small changes. Of the few feature requests that I've received for Calorific, most (all) of them have been for goals. Always listen to the audience, that's my motto!

Building Battle Bots with Clojure

Once in a while at [Rentrak][] we have programming competitions, where anyone who wants to, including sysadmins and DBAs, can submit an entry for whatever the problem is. The previous contest involved writing a poker bot which had to play two-card hold'em, while others have involved problems similar in spirit to the Netflix Prize. This time we chose to build virtual robots that shoot each other with virtual cannons and go virtual boom! We'll be using [RealTimeBattle][], which is a piece of software designed specifically to facilitate contests of this sort. It's kind of like those other robot-battle systems, except instead of requiring you to write your robot in their own arbitrary, broken, horrible language, this lets you write your bot in any language that can talk on stdin and stdout.

Actionable Information

Let's pretend, just for a second, that you want to make some money on the stock market. Sounds easy, right? Buy low, sell high, yadda yadda blah blah blah. Except, how do you know when to buy and when to sell? Not so easy. Being a nerd, you want to teach your computer how to do this for you. But where to start? I discovered a few months ago that there are services out there that will sell you a data feed that literally blasts every single anonymous transaction that happens on any market in the US in real time. They'll also sell you access to a historical feed that provides the same tick-level information going back for several years.

Moose vs Mouse and OOP in Perl

After using Calorific for a month two things have become very clear. First, I need to eat less. Holy crap do I need to eat less. I went on to SparkPeople just to get an idea of what I should be eating, and it told me between 2300 and 2680 kcal. I haven't implemented averaging yet, but a little grep/awk magic tells me I'm averaging 2793 kcal per day. This is too much. So. One thing to work on.

Calorific, a Simple Calorie Tracker

I'm a nerd. I write software for a living. I spend a lot of my day either sitting in a chair in front of a computer, or laying on my couch using my laptop. I'm not what you'd call... athletic. I did start lifting weights about six months ago but that's really just led to gaining more weight, not losing it. A few years back I started counting calories and I lost some weight, and then stopped counting calories and gained it all back. Time to change that.