garthk

defmodule Smuggle do
  @moduledoc """
  Make it easier to smuggle data from one system to another.

  If your target is an `iex` prompt:

      Smuggle.dump(value)
      # copy
      # paste into other iex

garthk

defmodule PidSnitchFormatter do
  @moduledoc """
  Report test PIDs?

  ```bash
  mix test --formatter PidSnitchFormatter
  ```

  See `ExUnit.CLIFormatter` for protocol details.
  """

garthk

# docker build -t start_span .
# docker run --rm -ti start_span

FROM elixir:1.10.3-alpine
RUN cd /usr/local/src && mix new start_span
WORKDIR /usr/local/src/start_span
COPY mix.exs README.md ./
COPY start_span.ex lib/
RUN mix local.hex --force && mix local.rebar --force && mix deps.get
CMD ["mix", "dialyzer"]

garthk

defmodule TelemetryTracingExperimentTest do
  use ExUnit.Case, async: true

  @doc """
  Dump a variable to standard output, ANSI formatted, and pretty.
  """
  def dump(v) do
    opts = IEx.Config.inspect_opts()

    [:reset, "\n", get_in(opts, [:syntax_colors, :reset]) || :reset, inspect(v, opts), :reset]

garthk

defmodule AutoRecords do

  defmacro __using__(_opts) do
    quote do
      require OpenTelemetry.Records.Auto
      import OpenTelemetry.Records.Auto, only: [auto_record: 2]
    end
  end

  defmacro auto_record(name, from_lib) do

garthk

FROM amazonlinux:2
COPY scalyr.key /etc/pki/rpm-gpg/RPM-GPG-KEY-scalyr-1
COPY scalyr.repo /etc/yum.repos.d/
RUN yum install -y jq systemd-python python2-pip scalyr-agent-2
RUN pip2 install docker-py
CMD ["python2", "-c", "import docker; docker.APIClient"]

garthk

#! /usr/bin/env elixir

defmodule FindEmoji do
  def find_emoji_in_git_log do
    :ok =
      stream_executable("git", ["log"])
      |> Stream.filter(&contains_emoji?/1)
      |> Stream.each(&IO.puts/1)
      |> Stream.run()
  end

garthk

Collisions in Key-Sortable Unique Identifiers (KSUIDs)

Expanding on my thread, it’s been nagging me that the random tail on small key sortable unique IDs (KSUID) might not provide as much protection vs collision as I’d trusted. Segment were able to throw bits at the problem, but I needed to pack my identifiers in smaller spaces.

After sparing 32 bits for the timestamp I might have room for only 32, 40, or 96 random bits. There’s that cryptographers’ rule of thumb about collision needing half the bit count… but how likely is it we’ll get at least one collision?

My math being a bit rusty, I decided to brute force it (birthday.exs). I didn't like my results.exs:

• 39% failure for 2¹⁶ random choices from 2³² possible keys (3443 rounds)
• 45% failure for 2²⁰ random choices from 2⁴⁰ possible keys (163 rounds)

garthk

  @doc "Convert a string or atom to a pascal case string"
  @spec pascal_case(String.t() | atom()) :: String.t()
  def pascal_case(name)
  def pascal_case(name) when is_atom(name), do: name |> Atom.to_string() |> pascal_case()

  def pascal_case(name) when is_binary(name) do
    ~r{(\W|_)+}
    |> Regex.split(name)
    |> Enum.map(&capitalise/1)
    |> Enum.to_list()

garthk

FROM elixir:1.9.4-alpine
ADD . /root
WORKDIR /root
RUN mix do local.hex --force, deps.get
ENTRYPOINT []
CMD ["mix", "credo", "--strict", "credo732.ex"]