Hits Elixir

Elixir implementation of: https://github.com/dwyl/hits

Why?

Because Elixir == ❤️!! see: github.com/dwyl/learn-elixir#why

What?

A basic "web counter", see: https://github.com/dwyl/hits#what

Assumptions / Prerequisites

• Elixir installed: https://github.com/dwyl/learn-elixir#how
• Basic knowledge/understanding of Elixir syntax: https://elixir-lang.org/crash-course.html

How?

To run the app on your localhost follow these 3 easy steps:

1. Clone/Download the Code

git clone https://github.com/dwyl/hits-elixir.git && cd hits-elixir

2. Install the Dependencies

Install dependencies and create necessary directories (to store the data):

mix deps.get && mkdir -p logs/agents

3. Run the App

mix run --no-halt

That's it!

Visit: http://localhost:8080/ (in your web browser)

Or visit any endpoint that includes .svg in the url, e.g: http://localhost:8080/yourname/project.svg

Refresh the page a few times and watch the count go up!

note: I've increased the "zoom" in chrome to 500% for effect.

Now, take your time to peruse the code in /test and /lib, and ask any questions by opening GitHub Issues: https://github.com/dwyl/hits-elixir/issues

Run the Tests

You

mix test

If you want to run the tests with coverage, copy-paste the following command into your terminal:

mix cover

If you want to view the coverage in a web browser:

mix cover && open cover/excoveralls.html

Research & Background Reading

We found the following links/articles/posts useful when learning how to build this mini-project:

Plug (the Elixir HTTP Library)

• Plug Docs: https://hexdocs.pm/plug/readme.html (the official Plug docs)
• Plug Conn (connection struct specific) Docs: https://hexdocs.pm/plug/Plug.Conn.html (the are feature-complete but no practical/usage examples!)
• Understanding Plug (Phoenix Blog): https://hexdocs.pm/phoenix/plug.html
• Elixir School Plug: https://elixirschool.com/en/lessons/specifics/plug/
• Getting started with Plug in Elixir: https://www.brianstorti.com/getting-started-with-plug-elixir (has a good/simple example of "Plug.Builder")
• Elixir Plug unveiled: https://medium.com/@kansi/elixir-plug-unveiled-bf354e364641
• Building a web framework from scratch in Elixir: https://codewords.recurse.com/issues/five/building-a-web-framework-from-scratch-in-elixir
• Testing Plugs: https://robots.thoughtbot.com/testing-elixir-plugs

SHA Cryptographic Hash Functions in Elixir/Erlang

• Cryptographic hash functions in Elixir by @djm: https://www.djm.org.uk/posts/cryptographic-hash-functions-elixir-generating-hex-digests-md5-sha1-sha2/

Mix Tasks

• How to create your own Mix Tasks: https://joeyates.info/2015/07/25/create-a-mix-task-for-an-elixir-project/

Compact sub-string syntax

iex> "1test2" == "test"
false
iex> "1test2" =~ "test"
true

• https://elixir-recipes.github.io/strings/checking-if-strings-contain-substring

Generate Random Strings in Elixir

:rand.uniform(n)

• https://stackoverflow.com/questions/38778054/how-to-generate-a-random-number-in-elixir

Unix Timestamp in Elixir

iex> DateTime.utc_now |> DateTime.to_unix
1486035766

iex> System.system_time(:second)
1486035766

iex> System.system_time(:millisecond)
1504975995312

• https://michal.muskala.eu/2017/02/02/unix-timestamps-in-elixir-1-4.html