leaf

General purpose reloader for all projects.

Command leaf watches for changes in the working directory and runs the specified set of commands whenever a file updates. A set of filters can be applied to the watch and directories can be excluded.

Contents

1. Installation
   1. Using go get
   2. Manual
2. Usage
   1. Command line help
   2. Configuration file
3. Custom reloader

Installation

Using go get

The following command will download and build Leaf in your $GOPATH/bin.

❯ go get -u github.com/vrongmeal/leaf/cmd/leaf

Manual

1. Clone the repository and cd into it.
2. Run make build to build the leaf as build/leaf.
3. Move the binary somewhere in your $PATH.

Usage

❯ leaf -x 'make build' -x 'make run'

The above command runs make build and make run commands (in order).

Command line help

The CLI can be used as described by the help message:

❯ leaf help

Command leaf watches for changes in the working directory and
runs the specified set of commands whenever a file updates.
A set of filters can be applied to the watch and directories
can be excluded.

Usage:
  leaf [flags]
  leaf [command]

Available Commands:
  help        Help about any command
  version     prints leaf version

Flags:
  -c, --config string     config path for the configuration file (default "<CWD>/.leaf.yml")
      --debug             run in development (debug) environment
  -d, --delay duration    delay after which commands are run on file change (default 500ms)
  -e, --exclude strings   paths to exclude from watching (default [.git/,node_modules/,vendor/,venv/])
  -x, --exec strings      exec commands on file change
  -z, --exit-on-err       exit chain of commands on error
  -f, --filters strings   filters to apply to watch
  -h, --help              help for leaf
  -o, --once              run once and exit (no reload)
  -r, --root string       root directory to watch (default "<CWD>")

Use "leaf [command] --help" for more information about a command.

Configuration file

In order to configure using a configuration file, create a YAML or TOML or even a JSON file with the following structure and pass it using the -c or --config flag. By default a file named .leaf.yml in your working directory is taken if no configuration file is found.

# Leaf configuration file.

# Root directory to watch.
# Defaults to current working directory.
root: .

# Exclude directories while watching.
# If certain directories are not excluded, it might reach a
# limitation where watcher doesn't start.
exclude:
  - DEFAULTS # This includes the default ignored directories
  - build/
  - scripts/

# Filters to apply on the watch.
# Filters starting with '+' are includent and then with '-'
# are excluded. This is not like exclude, these are still
# being watched yet can be excluded from the execution.
# These can include any regex supported by filepath.Match
# method or even a directory.
filters:
  - '+ go.mod'
  - '+ go.sum'
  - '+ *.go'
  - '+ cmd/'

# Commands to be executed. These are run in the provided order.
exec:
  - make format
  - make build

# Stop the command chain when an error occurs
exit_on_err: true

# Delay after which commands are executed.
delay: 1s

The above config file is suitable to use with the current project itself. It can also be translated into a command as such:

❯ leaf -z -x 'make format' -x 'make build' -d '1s' \
  -e 'DEFAULTS' -e 'build' -e 'scripts' \
  -f '+ go.*' -f '+ *.go' -f '+ cmd/'

Custom reloader

The package github.com/vrongmeal/leaf comes with utilities that can aid in creating a reloader with a simple go program.

Let's look at an example where the watcher watches the src/ directory for changes and for any changes builds the project.

package main

import (
	"fmt"
	"log"
	"os"
	"path/filepath"

	"github.com/vrongmeal/leaf"
)

func main() {
	// Use a context that cancels when program is interrupted.
	ctx := leaf.NewCmdContext(func(os.Signal) {
		log.Println("Shutting down.")
	})

	cwd, err := os.Getwd()
	if err != nil {
		log.Fatalln(err)
	}

	// Root is <cwd>/src
	root := filepath.Join(cwd, "src")

	// Exclude "src/index.html" from results.
	filters := []leaf.Filter{
		{Include: false, Pattern: "src/index.html"},
	}

	filterCollection := leaf.NewFilterCollection(
		filters,
		// Matches directory or filepath.Match expressions
		leaf.StandardFilterMatcher,
		// Definitely excludes and shows only includes (if any)
		leaf.StandardFilterHandler)

	watcher, err := leaf.NewWatcher(
		root,
		// Standard paths to exclude, like vendor, .git,
		// node_modules, venv etc.
		leaf.DefaultExcludePaths,
		filterCollection)
	if err != nil {
		log.Fatalln(err)
	}

	cmd, err := leaf.NewCommand("npm run build")
	if err != nil {
		log.Fatalln(err)
	}

	log.Printf("Watching: %s\n", root)

	for change := range watcher.Watch(ctx) {
		if change.Err != nil {
			log.Printf("ERROR: %v", change.Err)
			continue
		}
		// If no error run the command
		fmt.Printf("Running: %s\n", cmd.String())
		cmd.Execute(ctx)
	}
}

Made with khoon, paseena and love :-) by

Vaibhav (vrongmeal)