grunt-dockertimes

Persist file timestamps for Docker image builds.

This plugin will store the mtime timestamps and SHA1 hashes of your project files into a cache file called .dockertimes.json. When the plugin is executed again later, it will scan the cache file and restore the original mtime timestamps of any files whose contents still match the original SHA1 hash.

The purpose of this operation is to ensure that Docker does not generate a new image layer when you ADD unmodified files in your Dockerfile. Docker considers both the file contents and the mtime timestamps when determining which files have changed.

You should place the dockertimes operation at the end of your Grunt build task, to ensure that all files are processed:

grunt.initConfig({
  ...
  dockertimes: {
    files: 'dist/**'
  }
});
grunt.registerTask('build', ['build_into_dist...', '...', 'dockertimes']);

Getting Started

This plugin requires Grunt ~0.4.5

If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:

npm install grunt-dockertimes --save-dev

Once the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:

grunt.loadNpmTasks('grunt-dockertimes');

The "dockertimes" task

Overview

In your project's Gruntfile, add a section named dockertimes to the data object passed into grunt.initConfig().

grunt.initConfig({
  dockertimes: {
    // Default target
    files: ['dist/**']
    your_target: {
      // Target-specific file lists and/or options go here.
      cwd: 'build',
      cache: 'build/.dockertimes.json'
      files: ['another_dir/**']
    },
  },
});

Options

cwd

Type: String Default value: '.'

The files paths will be expanded relative to this directory. Note however that the cache file will not be relative to this directory.

cache

Type: String Default value: '.dockertimes.json'

The timestamp and SHA1 hash cache is stored in the specified file.

Usage Examples

Default Options

In this example, the dist directory is processed with default options.

grunt.initConfig({
  dockertimes: {
    files: 'dist/**'
  }
});

grunt.registerTask('build', ['all_build_operations...', '...', 'dockertimes']);

Custom Options

In this example, the dist directory is processed, relative to build, which is used as the current directory. The cache file is stored in the build directory.

grunt.initConfig({
  dockertimes: {
    cwd: 'build',
    cache: 'build/.dockertimes.json',
    files: 'dist/**'
  },
});

grunt.registerTask('build', ['all_build_operations...', '...', 'dockertimes']);

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.

Release History

• 0.1.0 Initial version.