Simon Eskildsen sirupsen

## ping_less.rb
# frozen_string_literal: true

# By default, ActiveRecord will issue a PING command to the database to check
# if it is active at various points. This overhead is unnecessary; we instead
# attempt to issue queries without checking the connection, then if the query
# returns an error and the connection was closed, try to reconnect.
# This also allows for reconnection during a single UoW, improving resiliency
# under transient connection failure (e.g. ProxySQL restarts).
#
# To avoid amplifying load when a database is intermittently down, the attempt

## book.rb
class Book < Airrecord::Table
  class Endorser < Airrecord::Table
    self.base_key = ""
    self.table_name = "Endorser"
  end

  self.base_key = ""
  self.table_name = "Books"

  has_many :endorsements, class: 'Book::Endorser', column: 'Endorsements'

## setup.sh
WORKDIR="/home/vagrant/src"

clone_repo() {
  local name=$1; shift
  local repo=$1; shift

  if [[ ! -d "$WORKDIR/$name" ]]; then

## gist:f3111d7f12f9d736d68a
def load_customer
  if customer_id = session[:customer_id]
    @customer = Customer.find_by_id(session[:customer_id])
  end
  # in reality e.g. a redis exception thrown from the driver
  # could be raised from circuit breaker or semian as well (see later)
rescue Sessions::DataStoreUnavailable
  flash[:notice] = 'Customer sign in is currently unavailable'
  @customer = nil
end

## gist:44f6c7293f25cf69382d
def test_storefront_resilient_to_sessions_down
  Toxiproxy[:sessions_data_store].down do
    get '/'
    assert_equal 'Customer sign in is currently unavailable', flash[:notice]
    assert_response :success
  end
end

## gist:3b3762c74355f42ac7bc
def load_customer
  if customer_id = session[:customer_id]
    @customer = Customer.find_by_id(customer_id)
  end
end

## gist:96326faaf94fc3051d0b
def test_section_a_resilient_to_data_store_b_being_down
  Toxiproxy[:data_store_b].down do
    get '/section_a'
    assert_response :success
  end
end

## resiliency.sh
#!/bin/bash

if [[ -z $1 ]]; then
  echo -e "\x1b[31mMust supply src + dest port"
  exit 1
fi

echo -e "\x1b[32mForwarded port $2 --> $1\x1b[33m"
sudo iptables -t nat -I OUTPUT -p tcp -o lo --dport $2 -j REDIRECT --to-ports $1

## gist:7ebd15c7e2e7469ce0e1
#!/bin/bash

TOTAL=$(sudo btrfs filesystem show /dev/mapper/lvroot-u | grep -oP '(?<=size )\d+\.\d+')
USED=$(sudo btrfs filesystem show /dev/mapper/lvroot-u | grep -oP '(?<=used )\d+\.\d+' | head -n1)
ALLOCATED=$(sudo btrfs filesystem show /dev/mapper/lvroot-u | grep -oP '(?<=used )\d+\.\d+' | tail -n1)
FREE=$(echo "$TOTAL - $USED" | bc)

echo -e -n "system.btrfs.total:$TOTAL|g" > /dev/udp/127.0.0.1/8125
echo -e -n "system.btrfs.used:$USED|g" > /dev/udp/127.0.0.1/8125
echo -e -n "system.btrfs.allocated:$USED|g" > /dev/udp/127.0.0.1/8125

## gist:d2a3fd24ef6a605fc782
$ sudo apt-get install maven
The following extra packages will be installed:
  ant ant-optional aspectj bsh fop java-wrappers junit junit4 libaether-java libaopalliance-java libapache-pom-java libasm3-java
  libaspectj-java libasync-http-client-java libatinject-jsr330-api-java libavalon-framework-java libbatik-java libbsf-java libbsh-java
  libcdi-api-java libcglib-java libclassworlds-java libcommons-beanutils-java libcommons-cli-java libcommons-codec-java
  libcommons-collections3-java libcommons-configuration-java libcommons-digester-java libcommons-httpclient-java libcommons-io-java
  libcommons-jexl2-java libcommons-jxpath-java libcommons-lang-java libcommons-logging-java libcommons-net2-java libcommons-parent-java
  libcommons-vfs-java libdom4j-java libdoxia-java libeasymock-java libfop-java libganymed-ssh2-java libgeronimo-interceptor-3.0-spec-java
  libgeronimo-jpa-2.0-spec-java libgeronimo-osgi-support-java libguava-java libguice-java libhamcrest-java libhttpclient-java
  libhttpcore-java libitext1-ja