How to Run the Docker Registry 2.0

19 Apr 2015

The docker registry is a daemon/service that you can run privately to push and pull images locally. This is fantastic for sharing images within a team, caching images locally and hacking on docker without polluting the world. There’s been a python version of the docker registry for some time but recently there has been work to rewrite it in golang. I’ve been waiting for the golang port because go projects are usually very easy to install and provide binaries.

Running the docker registry 2.0 (hereafter called Distribution) isn’t intuitive. Typically on github you’ll do something like this:

git clone
cd bleh
# ./configure && make | go run bleh.go | bundle && rake | pip install -r requirements.txt | bower
# or something ...

That doesn’t work here. Distribution is expecting to be in a go workspace. That means that this doesn’t work:

cd ~/src/vendor
git clone
cd distribution
# oooh there's a Makefile!

cannot find package "" in any of:

Oh! It’s using godep. We’ll just grab the dependencies.

$ godep get
  can't load package: package ~/src/vendor/distribution: cannot find package "~/src/vendor/distribution"
  in any of:

Hmm. That doesn’t work either. Well I know we could probably go get the whole thing but that’s going to put binaries in a golang workspace path. I kind of just want binaries in the current working directory. I’m not really sure what the intent here is. Distribution comes with a Dockerfile so I’m assuming that this is the best option to getting it up and running on a server somewhere without having to set up a temporarity golang dev environment (language runtimes as program distribution anti-pattern).

More Than One Way To Do It

We can run docker build Dockerfile

$ git clone
$ cd distribution
$ docker build .

The problem with this approach is that it gives us an image that we have to further customize. The binary registry isn’t in the path and godeps is in a special work dir as specified by the Dockerfile.

$ ls /go/src/

So we could go down that road but you’ll have to commit the changes and tag it yourself.

We can go get it

If we do this:

$ go get

This will put a binary in our path somewhere but then we’ll have to put it on a server. This also requires us to cd into our gopath workspace and copy a binary. Alternatively we could clone Distribution into a tmp golang workspace but this is effectively the same thing just in a different location.

Originally this is how I tried but later realized it’s worse than below (thoughts anyone?).

We can pull the registry from docker hub

# create some directories - change to your tastes
$ mkdir /opt/docker_data/registry
$ cd /opt/docker_data
$ wget
$ mv config.yml registry.yml

$ docker run -d -p 5000:5000 -e STORAGE_PATH=/registry -v \
  /opt/docker_data:/data -v /opt/docker_data/registry:/registry \
  --restart=always --name docker_registry registry:2.0 /data/registry.yml

# set it to autostart, bob's your uncle
# see below for usage with boot2docker

This is pretty nice. We have to be careful to specify the registry:2.0 tag in order to get the golang version. Latest will grab the python version. You can see this if you run the image interactively (not sure the 2.0 can be run interactively because of ENTRYPOINT – but there’s your clue).

Boot2Docker and insecure-registry

Once you are running a private registry, it’s up to you to generate an SSL cert. If you are on mac, you don’t even have a docker daemon locally so this part is confusing. When you push to your registry, you’ll get a warning/error.

FATA[0000] Error response from daemon: v1 ping attempt failed with error: Get https://hostname:5000/v1/_ping: tls: oversized record received with length 20527. If this private registry supports only HTTP or HTTPS with an unknown CA certificate, please add `--insecure-registry hostname:5000` to the daemon's arguments. In the case of HTTPS, if you have access to the registry's CA certificate, no need for the flag; simply place the CA certificate at /etc/docker/certs.d/hostname:5000/ca.crt

This is like your browser warning message on a unknown self-signed cert. But how do we add an exception? The official boot2docker docs have an answer but I have an addition. Add the port number to the hostname. If your server is called bleep then add bleep:5000 to the boot2docker image file at /var/lib/boot2docker/profile

# on your mac
$ boot2docker ssh "echo $'EXTRA_ARGS=\"--insecure-registry bleep:5000\"' | sudo tee -a /var/lib/boot2docker/profile && sudo /etc/init.d/docker restart"

# now you can push
$ docker push bleep:5000/busybox
The push refers to a repository [bleep:5000/busybox] (len: 1)
8c2e06607696: Image already exists
6ce2e90b0bc7: Image successfully pushed
cf2616975b4a: Image successfully pushed
Digest: sha256:3cc6b183efb34ff773f81ce230362ef67288375fdeb9cc8d50c221820fbe5e3b

# testing
$ docker run -it --rm bleep:5000/busybox /bin/busybox env

# on the host
$ ls /opt/docker_data/registry/docker/registry/v2/repositories

Deleting Images

I couldn’t get this to work. I commented on an issue, someone had the same question as me.

$ curl -XGET http://private-host:5000/v2/busybox/manifests/latest
# GET included for effect only  :)

The API doc says that DELETE should work. So I just substitute http verbs above and get an unexpected error:

$ curl -XDELETE http://private-host:5000/v2/busybox/manifests/latest
{"errors":[{"code":"UNSUPPORTED","message":"The operation is unsupported."}]}

So I’m not sure what’s up there.


I ran into a weird issue while testing Distribution on ubuntu.

FATA[0000] Error response from daemon: Cannot start container
aa2a7765d5c67625fea17f1c5f0d8b90216418d44db95df5268822d8e3bcf21e: write /sys/fs/cgroup/cpu/docker/
aa2a7765d5c67625fea17f1c5f0d8b90216418d44db95df5268822d8e3bcf21e/cgroup.procs: no space left on device

My disk has plenty of space. docker info shows it using aufs which I believe doesn’t have the same disk space limits that devicemapper (like CentOS) has. By that, I mean the docker host + kernel combination. I’m actually not sure of where that interaction lies. I just know that docker info on different kernels show different output.

So how do I start over? I have my docker data in a docker directory. For this case, when all your data is safe and secure then you can just blow away everything and start over. For me, this was the fix. I had some package garbage ( and lxc-docker packages installed). So I apt-get remove --purge-d everything and installed docker 1.6 through apt-get. That fixed this croup problem and kept my containers/data in tact. I feel like this was an edge case.


The docker image is the best way to run the registry but it requires a tiny bit of setup beforehand. There’s also some things that aren’t covered here:

  • SSL cert
  • Logstash support is mentioned as an output format
  • Redis caching
  • Authentication / reverse proxy / webgate

Regardless, happy to see a golang version of the registry.

Nil, If and Collect in Ruby

18 Dec 2014

Ruby’s if statement returns the return value when matched. If it falls through, it returns nil. I sometimes forget this. It’s not a big deal until it bites you.

Here’s an overly simple example where this works very well.

numbers = [1,2,3,4,5].collect do |number|
  if number % 2 == 0
    "#{number}: even"
    "#{number}: odd"

# => ["1: odd", "2: even", "3: odd", "4: even", "5: odd"]

This is really handy because we don’t have to create like a temporary variable somewhere and use each. But this is also a really clean case because there’s only odd and even. In other words, our if statement never falls through to return nil. Nil is a pain in Ruby. Avdi’s book Confident Ruby is not just about nil but it talks about nil. Avdi’s screencasts about nil are a good place to learn more (and I often refer back to Avdi’s work).

Ok, back to our collect. When possible, I try to use collect to avoid mutation. Maybe it’s my concession to functional programming languages. Maybe it’s because state mutation in Ruby causes headaches. I think the most important reason for exploring this is so we know of one other way to skin a cat. So let’s look at a more real example.

users = [
  { name: "Jay", enabled: false },
  { name: "Joan", enabled: false },
  { name: "John", enabled: true }

# enable everyone!
users.each do |user|
  user[:enabled] = true if user[:enabled] == false

# users
# {:name=>"Jay", :enabled=>true}
# {:name=>"Joan", :enabled=>true}
# {:name=>"John", :enabled=>true}

Meh. Mutation. It’s good to know just one more way for us to do this. Return a new collection.

users = [
  { name: "Jay", enabled: false },
  { name: "Joan", enabled: false },
  { name: "John", enabled: true }

# enable everyone!
enabled = users.collect do |user|
  user.merge({enabled:true}) if user[:enabled] == false

# enabled
# {:name=>"Jay", :enabled=>true}
# {:name=>"Joan", :enabled=>true}

Whoops. Where did John go? Here’s that thing I was talking about. Our collect needs to handle the fallthrough from the if.

users = [
  { name: "Jay", enabled: false },
  { name: "Joan", enabled: false },
  { name: "John", enabled: true }

# enable everyone!
enabled = users.collect do |user|
  if user[:enabled] == false

# enabled
# {:name=>"Jay", :enabled=>true}
# {:name=>"Joan", :enabled=>true}
# {:name=>"John", :enabled=>true}#

# users
# {:name=>"Jay", :enabled=>false}
# {:name=>"Joan", :enabled=>false}
# {:name=>"John", :enabled=>true}#

Great! You can see we didn’t mutate state. Now the problem with doing this all the time in Ruby is tail call optimzation. If you go to the ends of the earth with this your stack will explode. But I still like this style when I can do it because I avoid changing state.

The end-game to this line of thinking is switching to or at least playing with a functional language like Clojure, Rust or Scala.

Mocking in Golang

28 Nov 2014

This was originally a stackoverflow but it got down voted and suggested it be a blog post. Ok! Here’s my toy program. I had it separated into package files but I figured that would be harder for you guys to run it yourself. Please bear with me while I step through this.

The first iteration:


package main

import "fmt"

type VisaGateway struct {
    Name string
    Url  string

func NewVisaGateway() *VisaGateway {
    return &VisaGateway{
        Name: "Visa",
        Url:  "",

func (v *VisaGateway) Charge() {
    fmt.Println("I am charging Visa -->")

type PaymentGateway interface {

func ChargeCustomer(g PaymentGateway) {

func main() {
    gateway := NewVisaGateway()

Running it.

$ go run charge.go
I am charging Visa -->

So we can test this with a mocking library (separate question) maybe but for now let’s just use this interface and make a test that passes in a fake gateway so our test suite doesn’t hit a real system.


package main

import (

type MockGateway struct {
    Name string
    Url  string

func (m *MockGateway) Charge() {
    fmt.Println("This is a fake gateway.  --> [no-op] <---")
    fmt.Println("Yay!  :) ")

func TestCharging(t *testing.T) {
    m := MockGateway{}


$ go test
This is a fake gateway.  --> [no-op] <---
Yay!  :)
ok 0.010s

What I’d probably want to do is use a library to help with the mocking setup. Previously I was trying to use a dependency injection style without interfaces and it didn’t work out.

Imagine that my Charge() method signature looks more like this (from

func ChargeCustomer(args ...interface{})
// code to init args and defaults -- see blog post linked above

This doesn’t work because type checking args breaks when you pass in a mock object with no interface. I’m not even sure if interfaces would fix this.

I was hoping to have a default value of the real type/struct and then in my test pass in a mock object. This is one nice side effect of default parameters and dependency injection. But that’s dynamic language style that I have to teach myself to let go of.

Ok. Let’s now using testify for mocking. Let’s add a return value so we can test something.



func (v *VisaGateway) Charge() bool {
    fmt.Println("I am charging Visa -->")
    return true

type PaymentGateway interface {
    Charge() bool

func ChargeCustomer(g PaymentGateway) bool {
    return g.Charge()

func main() {
    gateway := NewVisaGateway()


package main

import (

type MockGateway struct {

func (m *MockGateway) Charge() bool {
    args := m.Mock.Called()
    return args.Bool(0)

func TestCharging(t *testing.T) {
    m := MockGateway{}

    r := ChargeCustomer(m)

    assert := assert.New(t)
    assert.True(r, true)

The run result:

$ go test
ok 0.018s

In the mocking example we also added m.Mock.AssertExpectations there. That is additional test that captures and remembers the calls. If the wiring is wrong and the expected call is not called, the test will fail. For a while I was not testing this and I would have had a test coverage gap. Another mistake I made while figuring out the AssertExpectations test was not passing by reference. I continue to make this mistake because I’m pointer-nooby. For more information on this see my question on stackoverflow.

Ok, so that’s my first foray with mocking in Go. So here are some questions:

  • Do you use a mocking library?
  • Do you see how default arguments wouldn’t work to help with mocking? You can’t really DI. I’m ok with this. I just need to learn.
  • Do you like interfaces for (not only) testing reasons?
  • Do you like the interfaces version more than the mocking version?
  • It seems that mocking really needs an interface somewhere? Otherwise won’t you get a cannot use gateway (type *VisaGateway) as type PaymentGateway in argument to ChargeCustomer. I might have gotten this wrong from the testify docs. It wasn’t obvious until I wrote this question.

If you have anything to say or answers to this question tweet me at @squarism.

… and once again, rubber ducking on stackoverflow. Writing the question made me figure it out.

Follow Through and Fundamental Immovables

15 Nov 2014

You can imagine an end result without knowing about fundamental problems. If those fundamentals are core to your business or idea and they are immovable then you probably can’t pivot without fudging what pivot means.

Stay with me for a second and take this lead and gold atom.

alchemy atoms

Now if we could just remove three protons from the lead nucleus then three electrons would just float away it would turn to gold. How useful! How wonderful! Gold has many industrial applications. Lead is poisonous although it also has industrial applications. We could create a lead recycling center! My imagination is running wild with ideas even before we’ve gotten anywhere!

Hmm. So what if we had tiny tweezers? Oops, there’s our tweezers.

alchemy tweezers

Oops! Our tweezers are made of atoms too!

Our tiniest breakthrough, patent winning, best mankind could produce tweezers. Imagine you haven’t gone through any class / book / information that would give you a keyword like “Alchemy” or chunked knowledge like “Alchemy is bogus”. Wouldn’t it seem tempting to try these tweezers? To build these tweezers? When the tweezers don’t work, try pliers?

alchemy pliers

Pliers aren’t the problem. We have an fundamental immovable.

Here’s a wall. You can imagine walking up it can’t you? Well, how would that work exactly? Do you put your first foot on the wall and now you feel like you are doing splits? Or can you remove your foot as easily as a handshake? See, in physics there’s something called perpendicular force (relative to gravity). If I push a car, it’s easy. If I lift a car it’s hard. So are you stepping onto the wall? How hard is it to step up on a table? What transition is there? If you don’t strain like stepping up on a table, could you fall off the wall onto the floor? If you could, wouldn’t that create energy?

walking up a wall

We don’t know. Let’s find out together. This is why I like the TDD loop. Not just testing or test-first but actual TDD. I feel that it guides me. It allows for team discovery. How many more complicated problems like this are there? TDD is a like a science that mitigates human fallacies. More than TDD. Many things do. Science, Agile (whatever that meant before it died), feedback loops, Kanban. They are feedback systems that correct human bias.

It’s not about testing really, it’s about iterating and least-complexity. I really like this picture of shipping a minimum viable product.

agile car

I think this is also a function of diversity. If our team is made up of pliers, we’re in a tight spot. And I don’t even mean racial or gender diversity specifically. Think of this like a portfolio. Don’t put all your eggs in one basket but also make your eggs happen fast while not caring about eggs.

Where Do You Put Your Go Code?

14 Nov 2014

One of the most confusing parts of starting Go was learning the project layout or what Go calls the workspace. It’s changed a little bit in past releases (eschewing $GOROOT etc) but the confusion I think remains if you come from other languages and tools.

Internalize these things:

  1. Your code will go in a folder next to all the libraries you download.
  2. You probably cannot put your Go code next to your Java/Python/Ruby/Javascript/… unless you luck out on naming conventions that you’ve already started.
  3. If you are starting out and you don’t put stuff in ~/bin then just set $GOPATH to your home.
  4. If you don’t like that last rule, just create ~/gocode and set $GOPATH to that.
  5. You probably should not put your Go code in Dropbox.

You also do not need to create a account to put your projects in ~/gocode/src/{username}/hello_world. You can just go ahead and start your project. It’s just a namespace. If something else needs{username}/hello_world then it will import it. If it can find it in the GOPATH then it will work. That’s all this is.

When I started Go, I was worried that I was polluting system paths by starting projects in $GOPATH/src/{my_username}. You’re not. Don’t think about it.

I can’t put my crap code next to the likes of Docker!

It’s impostor syndrome. Just start your project. Just do it.

YAML and Maps in Go

13 Oct 2014

This wasn’t exactly clear. When using the (or packages, I was confused as to what to do with my data structure.

Let’s say we start off with this file.yml:

description: fruits are delicious
    - red
    - sweet
    - yellow
    - sour

Here’s a complete example to read this file in and you get a parsed data structure out of it:

package main

import (

type Config struct {
  Description string
  Fruits map[string][]string

func main() {
  filename, _ := filepath.Abs("./file.yml")

  yamlFile, err := ioutil.ReadFile(filename)

  var config Config

  err = yaml.Unmarshal(yamlFile, &config)

  fmt.Printf("Description: %#v\n", config.Description)
  fmt.Printf("Fruits: %#+v\n", config.Fruits)

func check(e error) {
  if e != nil {

What is Fruits map[string][]string in the Config type? It’s foo: ['a', 'b', 'c'].

This is roughly equivalent to what I would do in Ruby. Of course the Ruby code is much shorter because in Ruby, typically we abuse hashes. :) The surprise I had is this: when the YAML changes, we have to update our type Config. I’m ok with this. I was just surprised by a few things.

First, the keys are significant. If we change the YAML to be:

description: fruits are delicious
    - red
    - sweet
    - yellow
    - sour

It won’t work. But HOW it won’t work is confusing.

Description: "fruits are delicious"
Fruits: map[string][]string(nil)

You’ll get an empty map until you change your type to have Tambourines in it. You can’t just access .Tambourines either. The type/struct won’t have a method on it. So this is the trick and benefit the package gives you. You just model your YAML and it maps the keys for you. But you have to “know” what your YAML (dare I say schema?) is. So would you then validate that it loaded correctly by checking lengths etc?

Now what happens when you get it really wrong?

Continue Reading →

Ruby Slop Example

25 Sep 2014

One of my favorite features of slop is the automatic help generation. But it’s not intuitive. It doesn’t print out the help when the parsing fails. This isn’t very unix-y. So every time I want to use slop, I have to look up this snippet I saved for myself. So I’m posting it here. This is the only slop example you’ll ever need.

Unix style CLI program in Ruby

require 'slop'

opts = true, help: true) do
  banner 'Usage: slop_test.rb [options]'

  on 'resume=', 'Your resume file', required: true
  on :s, :skill=, 'Skill Name', as: Array, arguments: :optional
  on 'v', 'verbose', 'Enable verbose mode'  # same as adding required: false


  # validation passed
  puts "Here's the data"
  puts opts.to_hash
rescue Slop::Error => e
  puts e.message
  puts opts

Calling it like this will fail:

$ ruby ./slop_test.rb
Missing required option(s): resume
Usage: slop_test.rb [options]
        --resume       Your resume file
    -s, --skill        Skill Name
    -v, --verbose      Enable verbose mode
    -h, --help         Display this help message.

Great! Then using it correctly will do this:

$ ruby slop_test.rb --resume hechicero-del-relámpago.doc
Here's the data
{:resume=>"hechicero-del-relámpago.doc", :skill=>nil, :verbose=>nil, :help=>nil}

The resume flag is the only required one, so in this case that’s how it’s run correctly.

Update: I was very happy that @lee_jarvis (the slop author) accepted my pull request to put this example into the README.

Redis and 595 Timer States

24 Sep 2014

I wanted to learn about how a 595 timer chip works. I’m a code dude. So when I see this integrated chip and all its pins, it’s scary. I’m sure an EE major is giggling right now but that’s just Impostor Syndrome. For no reason beyond this, I wanted to visualize and grok a 595 timer’s state at any given point by having it’s pins mapped to Redis key/value pairs.

Here’s a quick video explanation of the project.

Continue Reading →

Positive Change

17 Aug 2014

I’ve been in Portland for a week. So far, it’s amazing. I really don’t want to blather on about how great it is because, to be honest, I’m afraid of boyish optimism. This town, like college, will probably give back whatever I put into it. So I’m pacing myself. I think it will be good though.

Our house is completely empty while we wait for our movers to arrive and that’s ok. I’ve been getting a lot done without all the distractions. One of my favorite pictures of Steve Jobs is where he is sitting in an almost empty room with nothing but books. I’m not trying to be Steve Jobs but I appreciate the minimalism because my house looks very similar to this picture right now.

Continue Reading →

Default DC Tech is Just Bad

06 Jun 2014

The opinions of this blog, but especially this post are mine and not my employers’.

I’m done with DC. I need to archive the reasons why for myself. I hope this serves as a free field trip to the DC area for anyone outside the beltway.


If you move to DC for the tech jobs, you are going to have to prune a lot of C-minus government work if you are good. All the while, you will be paying for local benefits you are not taking advantage of. This is the land of politics, military, intelligence, big government and lobbyists. I tried to influence from within but now it’s time for me to GTFO and move to Portland to try to find “actual reality” jobs.


I’ve Been Here Too Long

I’ve lived in the DC area for 30 years. I’ve been working for 14. You might as well say I’ve lived around DC my whole life. I went to School and College in Northern Virginia. Northern Virginia and Maryland are part of the DC metropolitan area or what we would call the “DC Metro”. This is a little bit confusing because if you say “The Metro” then you mean the subway. I’ve traveled around and lived other places but you could say I’ve been here for a long time. Recently, I’ve concluded that DC isn’t all bad but I’ve been here too long. Also I feel like a slow learner in that it has taken me so long to realize these things. I’m doing something about it and I’ll talk about that later.

I’ve done the DC government contracting circuit and I’ve concluded that I’ve seen enough. It doesn’t really matter what company you work for, it’s the same project with the same people and the same problems. However, a few years ago I found a small life raft. It’s a non-profit R&D shop and it’s the best big tech company I’ve found in DC. It’s not perfect but at the core of it is the non-profit bit. It’s not Beltway Bandit time.

Beltway bandit is a term for private companies located in or near Washington, D.C. whose major business is to provide consulting services to the US government.

Continue Reading →


19 May 2014

On a Ruby Rogues podcast about Passion, Avdi continued to enlighten and entertain me with his insights. I’ve really been enjoying his speaking style and voice lately through tapas and talks. If he reads this, I hope he understands I don’t disagree with what he is saying; I thought he would enjoy a related story.

Honestly, this topic is so massive I don’t think I can really offer too much more than the Rogues did on the podcast so I encourage you to listen to the episode yourself. It has almost nothing to do with programming or Ruby. I feel that philosophies and stories about passion are so close to the difficult and inevitable goal of “master yourself”, which is both complicated and personal, I can just barely approach the topic and then a rat’s nest of anecdotes and advice explodes all around us.

With that context laid out, here are a few stories.

Continue Reading →

DRY up Methods with Ruby Blocks

14 Sep 2013

Let’s do something terrible by hand. First, here’s our data. It comes from a database.

db_results = [
  { id: 1, login: 'mjay', roles: ['user'], projects: ['muffins'] },
  { id: 2, login: 'rroke', roles: ['admin', 'user'], projects: ['security'] },
  { id: 3, login: 'tpain', roles: ['user'], projects: ['muffins'] },
  { id: 4, login: 'ghaz', roles: ['admin', 'user'], projects: ['muffins', 'cakes'] },
  { id: 5, login: 'bbarker', roles: ['user'], projects: ['pies'] }

Now when working with these people, we probably could get away with doing something like this for a while:

# find all admins
admins = {|user| user[:roles].include? 'admin' }

Which is fine. Until you want to find out what people are on the Muffin Project:

# find all people working on the muffins project
people_on_muffins = {|user| user[:projects].include? 'muffins' }

But as you keep working, you might be getting a feeling of deja-vu. The two methods above are very similar. You might be inspired by other Ruby libraries which give you a tiny DSL or at least allow you to pass blocks into methods to be more expressive.

Continue Reading →

Problems with "The Cloud"

27 Aug 2013

I’ve been thinking about the problems with The Cloud outside it being a raging buzzword. It really comes down to Control and Connectivity. That’s the problem but allow me to elaborate.


Google Wave is a great example of control loss. If you really put a lot of energy, stock and trust into Google Wave as a content store for your team, brain or idea then you might feel deflated by its cancellation. Even as an idea and a disruptive alternative to E-mail or SMTP crappiness, it’s a shame it had to die. So what now? Wait for an open source version? Host your own?

The idea was to “put it in the cloud” and forget about it. But when the cloud changes outside your control, you have to be aware of it again. Now you really have to think about the cloud itself. It’s not such a vague black box which is what the cloud diagram really means.

Another example of control is YouTube. I use YouTube favorites as a persistent list. I see a cool video, I favorite it and I feel like I sort of own it, or at least it’s in a list that I can refer to later. But take a look at this:


What were those things? Who knows! Now, I have to think about “the cloud” again. These are temporary videos that someone else ultimately controls. I’m just adding references to a list. I don’t own the clips. They are transient. They are ephemeral. I’m out of control again. I don’t even know what media I’ve lost. Do I mitigate again? Do I suck down a list periodically and do a diff?


I recently got a Roku box for my TV. It’s a great box. During registration it does a bunch of sign up and account creation. But it doesn’t work without uPNP enabled on the router. This isn’t even a connectivity outage thing, it’s a connectivity assumption that I have a certain kind of firewall that can’t have holes punched in it … or that I’m not capable of punching the holes myself. I don’t even really know why Roku does this uPNP thing. All I know is, it wouldn’t even finish the setup until I made this change. Now here’s a device that doesn’t work without connectivity or a clear path to connectivity.

Think about how picky that is for a second. If it’s not picky then think about how many technical barriers there are to pure or uniform Internet. Everyone brings their own quilted environment and it’s a mess.

IPv6 Spike

28 Jul 2013

A spike is when you play around with something and then throw it away for the purposes of learning. So, let’s play around with IPv6. I had read a little bit about it but essentially my working experience with IPv6 was nothing except for disabling it. Let’s learn some stuff!

I’m going to skip over all the history of IPv6 and assume that you agree with me and think that this is important and relevant to the future of the Internet.


First, build 4 Ubuntu VMs. I’m using 13.04 but any current Linux distro should work, just the packages and paths will change. I found the best way is to build a simple VM and then clone it 3 more times (in Fusion this is copy/paste and resetting the MAC address). You’ll need four machines to simulate a local network. You won’t need any network hardware and VMware will be able to simulate everything we need. You can actually do this whole experiment on one real box (cool stuff)!

The goal of this spike is:

  • Build 4 VMs
  • Make a router, a web server, a dns server and a client
  • Hit a web page between two network boundaries over IPv6 only

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The Best Way to Read CSV in Ruby

16 Jun 2013

CSV is awful. CSV isn’t well formed. It isn’t hard to use because it’s bloated and slow. CSV is hard to use because it’s just a dumb data format. However, sometimes all you have is stupid data and who cares, let’s do this thing and blot out the memories.

I assume you know how to use the CSV module that’s built into Ruby. It’s pretty easy. You just read a file in and you get some 2D array back. It usually comes out pretty horrible with long methods and little room for nice abstractions.

So what if you want to polish it up a little bit? Maybe you aren’t just going to kludge this thing again and hate yourself later? What if you aren’t just going to load this into a database? What if you want to do some quick CSV analysis but at the same time make it come out sort of readable?

Let’s take a look at an abstraction layer and see how we could write a CSV loader for a guest list. We’re going to have a dinner party and evite gave us a crappy CSV dump of who’s responded so far. Well, it’s what we have. But how many people are coming and how many groups aren’t allergic to peanuts? We want to know how many peanut M&Ms to buy.

Here’s our data:

Name, Plus, RSVP'd, Peanut Allergies
Tom DeLuise, 1, No, Yes
Mel Brooks, 3, Yes, Yes
Lewis Black, 5, Yes, No
Jon Stewart, 3, Yes, Yes
Jim Gaffigan, 0, Yes, No

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Hi, I am
Chris Dillon