Arjeno

# This makes sure Chrome is always up to date in your test suite
# On average this adds about 10 seconds to your build suite
# Be sure to use Ubuntu 14.04 (Trusty) in the CircleCI's OS setting (Settings > Build Environment)
dependencies:
  pre:
    - curl -L -o google-chrome.deb https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
    - sudo dpkg -i google-chrome.deb
    - sudo sed -i 's|HERE/chrome\"|HERE/chrome\" --disable-setuid-sandbox|g' /opt/google/chrome/google-chrome
    - rm google-chrome.deb

tamoyal

# Be sure to save your config files. Optional but I do:
sudo cp /etc/postgresql/9.3/main/postgresql.conf ~
sudo cp /etc/postgresql/9.3/main/pg_hba.conf ~

# Package repo (for apt-get)
wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ precise-pgdg main" >> /etc/apt/sources.list.d/postgresql.list'

# Also probably optional but I like to update sources and upgrade
sudo apt-get update

dideler

TL;DR

Create a backup:

pg_dumpall > mybackup.sql

Perform the upgrade:

sudo pg_dropcluster 9.4 main --stop

dhh

# autoload concerns
module YourApp
  class Application < Rails::Application
    config.autoload_paths += %W(
      #{config.root}/app/controllers/concerns
      #{config.root}/app/models/concerns
    )
  end
end