Automatic code reloading in Go

I wrote a short Bash script to automatically reload Go programs.

The script acts as a light wrapper around go run, stopping and restarting it whenever a .go file in your current directory or $GOPATH/src folder is saved. I've been using it mainly when developing web applications, in the same way that I use Shotgun or Guard when working with Ruby.

You can grab this from the GitHub repository.

File: go-reload

#!/bin/bash
function monitor() {
  if [ "$2" = "true" ];  then
    # Watch all files in the specified directory
    # Call the restart function when they are saved
    inotifywait -q -m -r -e close_write -e moved_to $1 |
    while read line; do
      restart
    done
  else
    # Watch all *.go files in the specified directory
    # Call the restart function when they are saved
    inotifywait -q -m -r -e close_write -e moved_to --exclude '[^g][^o]$' $1 |
    while read line; do
      restart
    done
  fi
}

# Terminate and rerun the main Go program
function restart {
  if [ "$(pidof $PROCESS_NAME)" ]; then
    killall -q -w -9 $PROCESS_NAME
  fi
  echo ">> Reloading..."
  eval "go run $ARGS &"
}

# Make sure all background processes get terminated
function close {
  killall -q -w -9 inotifywait
  exit 0
}

trap close INT
echo "== Go-reload"

WATCH_ALL=false
while getopts ":a" opt; do
  case $opt in
    a)
      WATCH_ALL=true
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      exit 0
      ;;
  esac
done

shift "$((OPTIND - 1))"

FILE_NAME=$(basename $1)
PROCESS_NAME=${FILE_NAME%%.*}

ARGS=$@

# Start the main Go program
echo ">> Watching directories, CTRL+C to stop"
eval "go run $ARGS &"

# Monitor all /src directories on the GOPATH
OIFS="$IFS"
IFS=':'
for path in $GOPATH
do
  monitor $path/src $WATCH_ALL &
done
IFS="$OIFS"

# If the current working directory isn't on the GOPATH, monitor it too
if [[ $PWD != "$GOPATH/"* ]]
then
  monitor $PWD $WATCH_ALL
fi

wait

Usage

The only dependency for this script is inotify-tools, which is used to monitor the filesystem for changes.

$ sudo apt-get install inotify-tools

Once you've downloaded (or copy-pasted) the script, you'll need to make it executable and move it to /usr/local/bin or another directory on your system path:

$ wget https://raw.github.com/alexedwards/go-reload/master/go-reload
$ chmod +x go-reload
$ sudo mv go-reload /usr/local/bin/

You should then be able to use the go-reload command in place of go run:

$ go-reload main.go
== Go-reload
>> Watching directories, CTRL+C to stop

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