Proof of concept to explore NGINX round robin redirect + logging

README.md

gist-nginx-round-robin

We want to get an easier to use system than bit.ly which doesn't support updating URL redirects. Our current idea is to use NGINX with its basic logging.

However, we also want to see if round robin redirects work (a la A/B testing) as we are using it for donations.

Here's our setup:

# Clone our repository
git clone https://gist.github.com/a26174b833b66d2ad05688dceee755c8.git gist-nginx-round-robin
cd gist-nginx-round-robin

# Launch a container via Docker with a bash shell
# DEV: We could replace this with Vagrant but this is lighter
./run.sh

# In this Docker container, run our bootstrap script
/docker/bootstrap.sh

# Request from our server
curl --include http://localhost:80/
# ...
# Location: http://paypal.me/twolfson
# or
# Location: http://flattr.com/twolfson

# View NGINX logs
cat /var/log/nginx/round-robin.access.log
# 127.0.0.1 - - [19/May/2016:09:31:03 +0000] "GET / HTTP/1.1" 301 193 "-" "curl/7.35.0" "-" "paypal"
# 127.0.0.1 - - [19/May/2016:09:31:04 +0000] "GET / HTTP/1.1" 301 193 "-" "curl/7.35.0" "-" "flattr"
# 127.0.0.1 - - [19/May/2016:09:31:04 +0000] "GET / HTTP/1.1" 301 193 "-" "curl/7.35.0" "-" "flattr"
# 127.0.0.1 - - [19/May/2016:09:31:05 +0000] "GET / HTTP/1.1" 301 193 "-" "curl/7.35.0" "-" "paypal"

To tear down the Docker container, stop and remove it via:

./rm.sh

bootstrap.sh

#!/usr/bin/env bash
# Exit on first error
set -e

# If apt hasn't been updated, then update it
if ! test -f ~/.apt-get-updated; then
  apt-get update
  touch ~/.apt-get-updated
fi

# Install development dependencies
if ! which curl &> /dev/null; then
  apt-get install -y curl wget man nano
fi

# If NGINX isn't installed, then install NGINX
if ! test -x /etc/init.d/nginx; then
  apt-get install -y nginx
  rm /etc/nginx/sites-enabled/default
  /etc/init.d/nginx reload
fi

# If our NGINX file contents are out of sync, then align them and reload NGINX
src_file="/docker/round-robin.conf"
target_file="/etc/nginx/conf.d/round-robin.conf"
if ! test -f target_file || test "$(cat "$src_file")" != "$(cat "$target_file")"; then
  cp "$src_file" "$target_file"
  /etc/init.d/nginx reload
fi

rm.sh

#!/usr/bin/env bash
# Exit on first error
set -e

# If a docker instance exists, then stop and remove it
container_name="gist-nginx-round-robin"
if docker ps --all | grep "$container_name" &> /dev/null; then
  docker stop "$container_name" &> /dev/null
  docker rm "$container_name" &> /dev/null
fi

round-robin.conf

# Determine client bucket for redirects
# http://nginx.org/en/docs/http/ngx_http_split_clients_module.html
# DEV: This is included in core
#   d942041b2016770e41da69689389bfe117ed4fa8
# DEV: Use date as a random variable
#   https://www.viget.com/articles/split-test-traffic-distribution-with-nginx
split_clients "${remote_addr}${http_user_agent}${date_gmt}" $variant {
  50% flattr;
  # TODO: Add dollar amount variance (e.g. `paypal-1`)
  50% paypal;
}

server {
  # Listen on port 80
  listen 80;
  server_name localhost 127.0.0.1;

  # TODO: Require repo query parameter?

  # Declare domains based on keys
  # DEV: We use `set + if` over `map` as this can handle query parameters (e.g. `$arg_repo`)
  if ($variant = paypal) {
    set $redirect_url https://www.paypal.me/twolfson/5;
  }
  if ($variant = flattr) {
    # TODO: Ditch flattr, it's really annoying
    set $redirect_url https://flattr.com/thing/2553273/twolfsonsexy-bash-prompt-on-GitHub;
  }

  # Log our variant
  log_format variant '$remote_addr - $remote_user [$time_local] "$request" '
                  '$status $body_bytes_sent "$http_referer" '
                  '"$http_user_agent" "$http_x_forwarded_for" "$variant" "$arg_repo"';
  access_log /var/log/nginx/round-robin.access.log variant;
  error_log /var/log/nginx/round-robin.error.log;

  # Redirect to our domain
  location / {
    return 302 $redirect_url;
  }
}

run.sh

#!/usr/bin/env bash
# Exit on first error
set -e

# If a docker instance already exists, then verify it's running and connect to it
container_name="gist-nginx-round-robin"
if docker ps --all | grep "$container_name" &> /dev/null; then
  docker start "$container_name" &> /dev/null
  docker exec --interactive --tty "$container_name" /bin/bash
# Otherwise, start it up
else
  docker run --name "$container_name" --interactive --tty --volume "$PWD:/docker" ubuntu:14.04 /bin/bash
fi