Adding Netlify CMS to Metalsmith

Update on Jul 26, 2023: Netlify CMS is now called Decap CMS. The CMS changed ownership and is again under active development. This means that what I am discussing here may be outdated.

Let's be frank, the editing experience with any Static Site Generator (SSG) could be better for anybody who is not a developer. As developer-friendly as SSGs are, most "normal" people dislike editing Markdown content. Many editors are used to a Wordpress-like editing experience, and that's what they expect. This post will look at how to add the Netlify CMS to a Metalsmith website so users can enjoy non-code editing.

Netlify CMS in their own words

Static + content management = ♥

Get the speed, security, and scalability of a static site, while still providing a convenient editing interface for content.

An integrated part of your Git workflow

Content is stored in your Git repository alongside your code for easier versioning, multi-channel publishing, and the option to handle content updates directly in Git.

An extensible CMS built on React

Netlify CMS is built as a single-page React app. Create custom-styled previews, UI widgets, and editor plugins or add backends to support different Git platform APIs.

Adding Netlify CMS to your Metalsmith site

There is a good, official tutorial on their website, so I'll limit this post to some observations and comments that I find noteworthy based on implementing this CMS on a Metalsmith Netlify Starter website. The GitHub repository for this site can be found here.

Adding local editing

According to their website, local editing is in beta. I have been using it on the Metasmith Netlify Starter website with no issues.

1 Configure the Netlify CMS proxy server port number

Create a .env file in the metalsmith root folder and define the PORT you'd like the proxy server to use. The dev server runs on http://localhost:3000.


2 Add the local_backend object in config.yml

  name: git-gateway

  # when using a custom proxy server port
  url: http://localhost:3002/api/v1

3 Add this script to the package.json file

"edit": "cross-env NODE_ENV=development NODE_PATH=./node_modules npx netlify-cms-proxy-server & npm run watch & npm run serve"

Run npm run edit will start the local site. Navigate to http://localhost:3000/admin/ and click the login button... et voilà... the Netlify CMS.

Styling the preview pane

For the CMS to use our CSS, we'll need to register the style sheet first in the admin/index.html file.

  <script src="^2.0.0/dist/netlify-cms.js"></script>

Creating Custom Previews

By default, the CMS shows all frontmatter fields and the page's content body in the preview pane. For the preview to display the page as in production, we must duplicate the whole page structure in React components. This process is explained here.

As we can see in the tutorial, building the React component is done without the benefit of JSX. I am used to JSX, but the browser doesn't understand it. Instead, to make this work with JSX, we'd have to install Babel and convert JSX to Javascript. I'd love to use JSX, but I want to avoid adding a compile step to my front-end code.

Fortunately, there is a solution, htm, with a jsx-like syntax in plain javascript. HTM looks the same as JSX, except it uses template literals. It will parse the template literals and convert them to javascript that the browser can digest.

With htm, a preview page template may look like this:

// use htm so we don't have to build templates with h()
import htm from "";
const html = htm.bind(h);

// Preview component for a Page
const Page = createClass({
  render() {
    const entry = this.props.entry;

    return html`
        <h1>${entry.getIn(["data", "title"], null)}</h1>

export default Page;

Have a look at the CMS setup for the starter to get a better idea of what this may look like.


Unfortunately, Netlify CMS does not support image sub-folders. All site images will be stored in one folder. Of course, WordPress users have been doing this forever, so a whole cottage industry of file manager plugins has emerged, but I digress...

Yes, we'll have all images in a single directory; this will work for small sites. For larger sites, I'd recommend using a digital asset management tool like Cloudinary has a free tier that will work for most small sites.

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