entrypoint

#! /bin/bash

# The Docker App Container's development entrypoint.
# This is a script used by the project's Docker development environment to
# setup the app containers and databases upon runnning.
set -e

: ${APP_PATH:="/usr/src/app"}
: ${APP_TEMP_PATH:="$APP_PATH/tmp"}
: ${APP_SETUP_LOCK:="$APP_TEMP_PATH/setup.lock"}
: ${APP_SETUP_WAIT:="5"}

# 1: Define the functions lock and unlock our app containers setup processes:
function lock_setup { mkdir -p $APP_TEMP_PATH && touch $APP_SETUP_LOCK; }
function unlock_setup { rm -rf $APP_SETUP_LOCK; }
function wait_setup { echo "Waiting for app setup to finish..."; sleep $APP_SETUP_WAIT; }

# 2: 'Unlock' the setup process if the script exits prematurely:
trap unlock_setup HUP INT QUIT KILL TERM EXIT

# 7: Specify a default command, in case it wasn't issued:
if [ -z "$1" ]; then set -- rails server -p 3000 -b 0.0.0.0 "$@"; fi

if [[ "$1" = "rails" || "$1" = "sidekiq" || "$1" = "guard" ]]
then
  # 3: Wait until the setup 'lock' file no longer exists:
  while [ -f $APP_SETUP_LOCK ]; do wait_setup; done

  # 4: 'Lock' the setup process, to prevent a race condition when the project's
  # app containers will try to install gems and setup the database concurrently:
  lock_setup

  # 5: Check if the database exists, or setup the database if it doesn't, as it is
  # the case when the project runs for the first time.
  #
  # We'll use a custom script `checkdb` (inside our app's `bin` folder), instead
  # of running `rails db:version` to avoid loading the entire rails app for this
  # simple check:
  bundle exec checkdb || setup

  # 6: 'Unlock' the setup process:
  unlock_setup

  # 8: If the command to execute is 'rails server', then force it to write the
  # pid file into a non-shared container directory. Suddenly killing and removing
  # app containers without this would leave a pidfile in the project's tmp dir,
  # preventing the app container from starting up on further attempts:
  if [[ "$2" = "s" || "$2" = "server" ]]; then rm -rf /usr/src/app/tmp/pids/server.pid; fi
fi

# 9: Execute the given or default command:
exec "$@"