PostgreSQL setup script for nix-shell

setup-db.sh

trap_stack_name() {
  local sig=''${1//[^a-zA-Z0-9]/_}
  echo "__trap_stack_$sig"
}

extract_trap() {
  echo ''${@:3:$(($#-3))}
}

get_trap() {
  eval echo $(extract_trap `trap -p $1`)
}

trap_push() {
  local new_trap=$1
  shift
  local sigs=$*
  for sig in $sigs; do
    local stack_name=`trap_stack_name "$sig"`
    local old_trap=$(get_trap $sig)
    eval "''${stack_name}"'[''${#'"''${stack_name}"'[@]}]=$old_trap'
    trap "''${new_trap}" "$sig"
  done
}

trap_prepend() {
  local new_trap=$1
  shift
  local sigs=$*
  for sig in $sigs; do
    if [[ -z $(get_trap $sig) ]]; then
      trap_push "$new_trap" "$sig"
    else
      trap_push "$new_trap ; $(get_trap $sig)" "$sig"
    fi
  done
}

function initPG() {
  ${nixpkgs.lib.optionalString nixpkgs.stdenv.isDarwin "export TMPDIR=/tmp"}
  ${nixpkgs.lib.optionalString (!nixpkgs.stdenv.isDarwin) "export LANG=C.UTF-8"}
  ${nixpkgs.lib.optionalString (!nixpkgs.stdenv.isDarwin) "export LC_ALL=C.UTF-8"}
  ${nixpkgs.lib.optionalString (!nixpkgs.stdenv.isDarwin) "export LC_CTYPE=C.UTF-8"}
  export TZ='UTC'
  export PGHOST=$(mktemp -d)
  export PGDATA=$(pwd)/.postgres
  export PGSOCK=$PGHOST/.s.PGSQL.$PGPORT
  # We set these environment variables so postgresql-typed knows how
  # to connect to the database at compile-time to make sure all SQL
  # queries are well typed and well formed
  export TPG_SOCK=$PGSOCK
  export TPG_DB=$PGDATABASE
  export TPG_USER=$PGUSER
  #
  ${pg}/bin/initdb -E UTF8 $PGDATA
  # avoid conflicts on travis and elsewhere
  echo "port = $PGPORT" >> $PGDATA/postgresql.conf
  ${pg}/bin/postgres -D $PGDATA -k $PGHOST  &
  echo -n "Waiting for database to start up..."
  while [[ ! -e $PGSOCK ]]; do sleep 0.1; done
  ${pg}/bin/createuser -h $PGHOST -U $(id -u --name) -s $PGUSER
  ${pg}/bin/createdb -h $PGHOST -O $PGUSER $PGDATABASE

  echo "Created database PGDATABASE=$PGDATABASE at PGHOST=$PGHOST."
  echo "Call killPG to stop and delete it. Call initPG to re-create it"
}
function killPG() {
  echo "Killing postgres database at $PGHOST"
  pg_ctl stop || true
  echo "Waiting for postgres database to die ..."
  while [[ -e $PGSOCK ]]; do sleep 0.1; done
  echo "Postgres is dead, deleting its data dir"
  rm -rf $PGHOST
}
function reinitPG {
  killPG && initPG
}
# export the functions so they're available in the development nix-shell
# so the database can be re-created easly
export -f initPG
export -f killPG
export -f reinitPG

trap_prepend "killPG" EXIT