metalsmith

Metalsmith

An extremely simple, pluggable static site generator.

In Metalsmith, all of the logic is handled by plugins. You simply chain them together. Here's what the simplest blog looks like...

Metalsmith(__dirname)
  .use(markdown())
  .use(layouts('handlebars'))
  .build(function (err) {
    if (err) throw err
    console.log('Build finished!')
  })

...but what if you want to get fancier by hiding your unfinished drafts and using custom permalinks? Just add plugins...

Metalsmith(__dirname)
  .use(drafts())
  .use(markdown())
  .use(permalinks('posts/:title'))
  .use(layouts('handlebars'))
  .build(function (err) {
    if (err) throw err
    console.log('Build finished!')
  })

...it's as easy as that!

Special thanks to Ian Storm Taylor, Andrew Meyer, Dominic Barnes, Andrew Goodricke, Kevin Van Lierde and others for their contributions!

Installation

NPM:

npm install metalsmith

Yarn:

yarn add metalsmith

Plugins

Check out the website for a list of plugins.

How does it work?

Metalsmith works in three simple steps:

1. Read all the files in a source directory.
2. Invoke a series of plugins that manipulate the files.
3. Write the results to a destination directory!

Each plugin is invoked with the contents of the source directory, and each file can contain YAML front-matter that will be attached as metadata, so a simple file like...

---
title: A Catchy Title
date: 2021-12-01
---

An informative article.

...would be parsed into...

{
  'path/to/my-file.md': {
    title: 'A Catchy Title',
    date: <Date >,
    contents: <Buffer 7a 66 7a 67...>
  }
}

...which any of the plugins can then manipulate however they want. And writing the plugins is incredibly simple, just take a look at the example drafts plugin.

Of course they can get a lot more complicated too. That's what makes Metalsmith powerful; the plugins can do anything you want!

The secret...

We keep referring to Metalsmith as a "static site generator", but it's a lot more than that. Since everything is a plugin, the core library is actually just an abstraction for manipulating a directory of files.

Which means you could just as easily use it to make...

• A simple project scaffolder.
• A simple build tool for Sass files.
• A simple static site generator.
• A Jekyll-like static site generator.
• A Wintersmith-like static site generator.

Resources

• Gitter community chat
• Getting to Know Metalsmith - a great series about how to use Metalsmith for your static site.
• Building a Blog With Metalsmith - a blog post about how to create a basic blog with Metalsmith. Check out the related video of the talk too!
• Awesome Metalsmith - great collection of resources, examples, and tutorials

CLI

In addition to a simple Javascript API, the Metalsmith CLI can read configuration from a metalsmith.json file, so that you can build static-site generators similar to Jekyll or Wintersmith easily. The example blog above would be configured like this:

{
  "source": "src",
  "destination": "build",
  "plugins": [
    { "@metalsmith/drafts": true },
    { "@metalsmith/markdown": true },
    { "@metalsmith/permalinks": "posts/:title" },
    { "@metalsmith/layouts": {} }
  ]
}

You can specify your plugins as either an object or array. Using an array would allow you to specify use of the same plugin multiple times. The above example is then defined as so:

{
  "source": "src",
  "destination": "build",
  "plugins": [
    { "@metalsmith/drafts": true },
    { "@metalsmith/markdown": true },
    { "@metalsmith/permalinks": "posts/:title" },
    { "metalsmith-layouts": true }
  ]
}

And then just install metalsmith and the plugins and run the metalsmith CLI...

metalsmith

# Metalsmith · reading configuration from: /path/to/metalsmith.json
# Metalsmith · successfully built to: /path/to/build

Options recognised by metalsmith.json are source, destination, concurrency, metadata, clean and frontmatter - See "API" section below for usage.

Checkout the static site, Jekyll or Wintersmith examples to see the CLI in action.

If you want to use a custom plugin, but feel like it's too domain-specific to be published to the world, you can include plugins as local npm modules: (simply use a relative path from your root directory)

{
  "plugins": [{ "./lib/metalsmith/plugin.js": true }]
}

API

Checkout the project scaffolder or build tool examples to see a real example of the Javascript API in use.

new Metalsmith(dir)

Create a new Metalsmith instance for a working dir.

#use(plugin)

Add the given plugin function to the middleware stack. Metalsmith uses ware to support middleware, so plugins should follow the same pattern of taking arguments of (files, metalsmith, callback), modifying the files or metalsmith.metadata() argument by reference, and then calling callback to trigger the next step.

#build(fn)

Build with the given settings and a callback having signature fn(err, files).

#source(path)

Set the relative path to the source directory, or get the full one if no path is provided. The source directory defaults to ./src.

#destination(path)

Set the relative path to the destination directory, or get the full one if no path is provided. The destination directory defaults to ./build.

#concurrency(max)

Set the maximum number of files to open at once when reading or writing. Defaults to Infinity. To avoid having too many files open at once (EMFILE errors), set the concurrency to something lower than ulimit -n.

#clean(boolean)

Set whether to remove the destination directory before writing to it, or get the current setting. Defaults to true.

#frontmatter(boolean)

Set whether to parse YAML frontmatter. Defaults to true.

#ignore(path)

Ignore files/paths from being loaded into Metalsmith.

path can be a string, a function, or an array of strings and/or functions. Strings use the glob syntax from minimatch to match files and directories to ignore. Functions are called with the full path to the file as their first argument, and the stat object returned by Node's fs.stat function as their second argument, and must return either true to ignore the file, or false to keep it.

#metadata(json)

Get the global metadata. This is useful for plugins that want to set global-level metadata that can be applied to all files.

#path(paths...)

Resolve any amount of paths... relative to the working directory. This is useful for plugins who want to read extra assets from another directory, for example ./layouts.

#run(files, fn)

Run all of the middleware functions on a dictionary of files and callback with fn(err, files), where files is the altered dictionary.

#process(fn)

Process the files like build without writing any files. Callback signature fn(err, files).

Metadata API

Add metadata to your files to access these build features. By default, Metalsmith uses a few different metadata fields:

• contents - The body content of the file, not including any YAML frontmatter.
• mode - The numeric version of the file's mode.

You can add your own metadata in two ways:

• Using YAML frontmatter at the top of any file.
• Enabling a plugin that adds metadata programmatically.

mode

Set the mode of the file. For example, a cleanup.sh file with the contents

---
mode: 0764
---

#!/bin/sh

rm -rf .

would be built with mode -rwxrw-r--, i.e. user-executable.

Troubleshooting

Node Version Requirements

Metalsmith 3.0.0 will support NodeJS versions 12 and higher. Metalsmith 2.4.0 supports NodeJS versions 8 and higher. Metalsmith 2.3.0 and below support NodeJS versions all the way back to 0.12.

License

Changelog

[2.4.1] - 2022-01-31

Fixed

Bugfix: include index.js in package.json files