Add shoreman.sh and a Procfile for easily running a local setup

Procfile

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+server: RUST_LOG=debug ./target/debug/synchronik-server -c examples/server.yml
+agent: RUST_LOG=debug ./target/debug/synchronik-agent

scripts/shoreman.sh

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+#!/usr/bin/env bash
+# [shoreman](https://github.com/chrismytton/shoreman) is an
+# implementation of the **Procfile** format. Inspired by the original
+# [foreman](http://ddollar.github.com/foreman/) tool for ruby.
+
+# Make sure that any errors cause the script to exit immediately.
+set -eo pipefail
+[[ "$TRACE" ]] && set -x
+
+# ## Usage
+
+# Usage message that is displayed when `--help` is given as an argument.
+usage() {
+  echo "Usage: shoreman [procfile|Procfile] [envfile|.env]"
+  echo "Run Procfiles using shell."
+  echo
+  echo "The shoreman script reads commands from [procfile] and starts up the"
+  echo "processes that it describes."
+}
+
+# ## Logging
+
+# For logging we want to prefix each entry with the current time, as well
+# as the process name. This takes two arguments, the name of the process
+# with its index, and then reads data from stdin, formats it, and sends it
+# to stdout.
+log() {
+  local index="$2"
+  local format="%s %s\t| %s"
+
+  # We add colors when output is a terminal. `SHOREMAN_COLORS` can override it.
+  if [ -t 1 -o "$SHOREMAN_COLORS" == "always" ] \
+     && [ "$SHOREMAN_COLORS" != "never" ]; then
+    # Bash colors start from 31 up to 37. We calculate what color the process
+    # gets based on its index.
+    local color="$((31 + (index % 7)))"
+    format="\033[0;${color}m%s %s\t|\033[0m %s"
+  fi
+
+  while IFS= read -r data
+  do
+    printf "$format\n" "$(date +"%H:%M:%S")" "$1" "$data"
+  done
+}
+
+# ## Running commands
+
+# When a process is started, we want to keep track of its pid so we can
+# `kill` it when the parent process receives a signal, and so we can `wait`
+# for it to finish before exiting the parent process.
+store_pid() {
+  pids="$pids $1"
+}
+
+# This starts a command asynchronously and stores its pid in a list for use
+# later on in the script.
+start_command() {
+  bash -c "$1" 2>&1 | log "$2" "$3" &
+  pid="$(jobs -p %%)"
+  store_pid "$pid"
+}
+
+# ## Reading the .env file
+
+# The .env file needs to be a list of assignments like in a shell script.
+# Shell-style comments are permitted.
+load_env_file() {
+  local env_file=${1:-'.env'}
+
+  # Set a default port before loading the .env file
+  export PORT=${PORT:-5000}
+
+  if [[ -f "$env_file" ]]; then
+    export $(grep "^[^#]*=.*" "$env_file" | xargs)
+  fi
+}
+
+# ## Reading the Procfile
+
+# The Procfile needs to be parsed to extract the process names and commands.
+# The file is given on stdin, see the `<` at the end of this while loop.
+run_procfile() {
+  local procfile=${1:-'Procfile'}
+  # We give each process an index to track its color. We start with 1,
+  # because it corresponds to green which is easier on the eye than red (0).
+  local index=1
+  while read line || [[ -n "$line" ]]; do
+    if [[ -z "$line" ]] || [[ "$line" == \#* ]]; then continue; fi
+    local name="${line%%:*}"
+    local command="${line#*:[[:space:]]}"
+    start_command "$command" "${name}" "$index"
+    echo "'${command}' started with pid $pid" | log "${name}" "$index"
+    index=$((index + 1))
+  done < "$procfile"
+}
+
+# ## Cleanup
+
+# When a `SIGINT`, `SIGTERM` or `EXIT` is received, this action is run, killing the
+# child processes. The sleep stops STDOUT from pouring over the prompt, it
+# should probably go at some point.
+onexit() {
+  echo "SIGINT received"
+  echo "sending SIGTERM to all processes"
+  kill $pids
+  sleep 1
+}
+
+main() {
+  local procfile="$1"
+  local env_file="$2"
+
+  # If the `--help` option is given, show the usage message and exit.
+  expr -- "$*" : ".*--help" >/dev/null && {
+    usage
+    exit 0
+  }
+
+  load_env_file "$env_file"
+  run_procfile "$procfile"
+
+  trap onexit INT TERM
+
+  exitcode=0
+  for pid in $pids; do
+      # Wait for the children to finish executing before exiting.
+      # If said children exitcode is not successful, collect it.
+      wait "${pid}" || exitcode=$?
+  done
+  exit $exitcode
+}
+
+main "$@"