Expects to be run from a `bin/` subdirectory within the main project directory

development-services.sh

#!/bin/bash
set -euo pipefail

help_text="
Usage: bin/development-services [-h|--help] [-n|--no-attach]

Executes the commands listed in the 'Procfile.development' file, each in its
own pane of a new tmux session, and then attaches to that session.

If an appropriate tmux session already exists then we attach to it without
starting anything.

    --no-attach: Don't attach to the session, just ensure it is started and
                 then wait for it to terminate
"

show_help=false
no_attach=false
unknown_arg=''

while [[ $# -gt 0 ]]; do
  case "$1" in
      -h|--help)
        show_help=true;;
      -n|--no-attach)
        no_attach=true;;
      *)
        unknown_arg="$unknown_arg $1";;
  esac
  shift
done

if $show_help; then
  echo "$help_text"
  exit 0
fi
if [[ -n "$unknown_arg" ]]; then
  echo "UNRECOGNISED ARGUMENT:$unknown_arg"
  echo "$help_text"
  exit 1
fi

# Change in the project root directory
unset CDPATH
cd "$( dirname "${BASH_SOURCE[0]}" )/.."

process_file="$PWD/Procfile.development"

# Default project data directory if not already set
: ${PROJECT_DATA_DIR:="$PWD/data"}
export PROJECT_DATA_DIR

socket_path="$PROJECT_DATA_DIR/tmux.socket"

# Check tmux is installed
if ! which tmux >/dev/null; then
  echo "You must install tmux to use this script"
  echo "Note: you can always run the commands listed in the '$process_file' file manually."
  exit 1
fi

# tmux wrapper function which uses the correct socket file
_tmux() {
  tmux -2 -S "$socket_path" "$@"
}

process_list="$(sed --regexp-extended --quiet 's/^([A-Za-z0-9_]+):\s*(.+)$/\1:\2/p' "$process_file")"

if ! _tmux has-session 2>/dev/null; then

  echo "Starting new tmux session on $socket_path"

  mkdir -p "$(dirname "$socket_path")"
  _tmux new-session -d
  # Show pane titles in their borders
  _tmux set pane-border-status
  # Enable mouse mode so clicking in a pane will select it
  _tmux set mouse on

  IFS=$'\n'
  first=true
  for process_definition in $process_list; do
    # Extract substring up to first colon
    process_name="${process_definition%%:*}"
    # Extract substring after first colon
    process_command="${process_definition#*:}"
    if $first; then
      first=false
    else
      # Split pane, giving 95% of remaining space to new pane so we have plenty
      # of space to keep opening more panes (panes will be resized evenly at
      # the end of the loop)
      _tmux split-window -p 95
    fi
    echo "Starting service '$process_name': $process_command"
    # Sets the current pane title to the process name using the required escape
    # sequence. We use a tiny delay to avoid writing characters before the
    # shell is ready (everything will still work if this happens, we may just
    # get some extraneous characters appearing in the pane which looks a bit
    # untidy). We use a leading space to avoid polluting bash history.
    sleep 0.01
    _tmux send-keys " printf '\\033]2;%s\\033\\\\' '$process_name'; clear" enter
    sleep 0.01
    # Run the process command
    _tmux send-keys "$process_command" enter
  done
  # Resize all panes to be equal height
  _tmux select-layout even-vertical

else

  echo "Found existing tmux session on $socket_path"

fi

if ! $no_attach; then
  echo "Attaching to session"
  exec tmux -2 -S "$socket_path" attach-session
else
  echo "Waiting for session to close"
  while _tmux has-session 2>/dev/null; do
    sleep 1
  done
  echo 'Session closed'
fi