Introduction

This tutorial will show you how to create a simple theme in Hugo. I assume that you are familiar with HTML, the bash command line, and that you are comfortable using Markdown to format content. I’ll explain how Hugo uses templates and how you can organize your templates to create a theme. I won’t cover using CSS to style your theme.

We’ll start with creating a new site with a very basic template. Then we’ll add in a few pages and posts. With small variations on that, you will be able to create many different types of web sites.

In this tutorial, commands that you enter will start with the “$” prompt. The output will follow. Lines that start with “#” are comments that I’ve added to explain a point. When I show updates to a file, the “:wq” on the last line means to save the file.

Here’s an example:

## this is a comment
$ echo this is a command
this is a command

## edit the file
$ vi foo.md
+++
date = "2014-09-28"
title = "creating a new theme"
+++

bah and humbug
:wq

## show it
$ cat foo.md
+++
date = "2014-09-28"
title = "creating a new theme"
+++

bah and humbug
$

Some Definitions

There are a few concepts that you need to understand before creating a theme.

Skins

Skins are the files responsible for the look and feel of your site. It’s the CSS that controls colors and fonts, it’s the Javascript that determines actions and reactions. It’s also the rules that Hugo uses to transform your content into the HTML that the site will serve to visitors.

You have two ways to create a skin. The simplest way is to create it in the layouts/ directory. If you do, then you don’t have to worry about configuring Hugo to recognize it. The first place that Hugo will look for rules and files is in the layouts/ directory so it will always find the skin.

Your second choice is to create it in a sub-directory of the themes/ directory. If you do, then you must always tell Hugo where to search for the skin. It’s extra work, though, so why bother with it?

The difference between creating a skin in layouts/ and creating it in themes/ is very subtle. A skin in layouts/ can’t be customized without updating the templates and static files that it is built from. A skin created in themes/, on the other hand, can be and that makes it easier for other people to use it.

The rest of this tutorial will call a skin created in the themes/ directory a theme.

Note that you can use this tutorial to create a skin in the layouts/ directory if you wish to. The main difference will be that you won’t need to update the site’s configuration file to use a theme.

The Home Page

The home page, or landing page, is the first page that many visitors to a site see. It is the index.html file in the root directory of the web site. Since Hugo writes files to the public/ directory, our home page is public/index.html.

Site Configuration File

When Hugo runs, it looks for a configuration file that contains settings that override default values for the entire site. The file can use TOML, YAML, or JSON. I prefer to use TOML for my configuration files. If you prefer to use JSON or YAML, you’ll need to translate my examples. You’ll also need to change the name of the file since Hugo uses the extension to determine how to process it.

Hugo translates Markdown files into HTML. By default, Hugo expects to find Markdown files in your content/ directory and template files in your themes/ directory. It will create HTML files in your public/ directory. You can change this by specifying alternate locations in the configuration file.

Content

Content is stored in text files that contain two sections. The first section is the “front matter,” which is the meta-information on the content. The second section contains Markdown that will be converted to HTML.

Front Matter

The front matter is information about the content. Like the configuration file, it can be written in TOML, YAML, or JSON. Unlike the configuration file, Hugo doesn’t use the file’s extension to know the format. It looks for markers to signal the type. TOML is surrounded by “+++”, YAML by “---”, and JSON is enclosed in curly braces. I prefer to use TOML, so you’ll need to translate my examples if you prefer YAML or JSON.

The information in the front matter is passed into the template before the content is rendered into HTML.

Markdown

Content is written in Markdown which makes it easier to create the content. Hugo runs the content through a Markdown engine to create the HTML which will be written to the output file.

Template Files

Hugo uses template files to render content into HTML. Template files are a bridge between the content and presentation. Rules in the template define what content is published, where it’s published to, and how it will rendered to the HTML file. The template guides the presentation by specifying the style to use.

There are three types of templates: single, list, and partial. Each type takes a bit of content as input and transforms it based on the commands in the template.

Hugo uses its knowledge of the content to find the template file used to render the content. If it can’t find a template that is an exact match for the content, it will shift up a level and search from there. It will continue to do so until it finds a matching template or runs out of templates to try. If it can’t find a template, it will use the default template for the site.

Please note that you can use the front matter to influence Hugo’s choice of templates.

Single Template

A single template is used to render a single piece of content. For example, an article or post would be a single piece of content and use a single template.

List Template

A list template renders a group of related content. That could be a summary of recent postings or all articles in a category. List templates can contain multiple groups.

The homepage template is a special type of list template. Hugo assumes that the home page of your site will act as the portal for the rest of the content in the site.

Partial Template

A partial template is a template that can be included in other templates. Partial templates must be called using the “partial” template command. They are very handy for rolling up common behavior. For example, your site may have a banner that all pages use. Instead of copying the text of the banner into every single and list template, you could create a partial with the banner in it. That way if you decide to change the banner, you only have to change the partial template.

Create a New Site

Let’s use Hugo to create a new web site. I’m a Mac user, so I’ll create mine in my home directory, in the Sites folder. If you’re using Linux, you might have to create the folder first.

The “new site” command will create a skeleton of a site. It will give you the basic directory structure and a useable configuration file.

$ hugo new site ~/Sites/zafta
$ cd ~/Sites/zafta
$ ls -l
total 8
drwxr-xr-x  7 quoha  staff  238 Sep 29 16:49 .
drwxr-xr-x  3 quoha  staff  102 Sep 29 16:49 ..
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 archetypes
-rw-r--r--  1 quoha  staff   82 Sep 29 16:49 config.toml
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 content
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 layouts
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 static
$

Take a look in the content/ directory to confirm that it is empty.

The other directories (archetypes/, layouts/, and static/) are used when customizing a theme. That’s a topic for a different tutorial, so please ignore them for now.

Generate the HTML For the New Site

Running the hugo command with no options will read all the available content and generate the HTML files. It will also copy all static files (that’s everything that’s not content). Since we have an empty site, it won’t do much, but it will do it very quickly.

$ hugo --verbose
INFO: 2014/09/29 Using config file: config.toml
INFO: 2014/09/29 syncing from /Users/quoha/Sites/zafta/static/ to /Users/quoha/Sites/zafta/public/
WARN: 2014/09/29 Unable to locate layout: [index.html _default/list.html _default/single.html]
WARN: 2014/09/29 Unable to locate layout: [404.html]
0 draft content
0 future content
0 pages created
0 tags created
0 categories created
in 2 ms
$

The “--verbose” flag gives extra information that will be helpful when we build the template. Every line of the output that starts with “INFO:” or “WARN:” is present because we used that flag. The lines that start with “WARN:” are warning messages. We’ll go over them later.

We can verify that the command worked by looking at the directory again.

$ ls -l
total 8
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 archetypes
-rw-r--r--  1 quoha  staff   82 Sep 29 16:49 config.toml
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 content
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 layouts
drwxr-xr-x  4 quoha  staff  136 Sep 29 17:02 public
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 static
$

See that new public/ directory? Hugo placed all generated content there. When you’re ready to publish your web site, that’s the place to start. For now, though, let’s just confirm that we have what we’d expect from a site with no content.

$ ls -l public
total 16
-rw-r--r--  1 quoha  staff  416 Sep 29 17:02 index.xml
-rw-r--r--  1 quoha  staff  262 Sep 29 17:02 sitemap.xml
$

Hugo created two XML files, which is standard, but there are no HTML files.

Test the New Site

Verify that you can run the built-in web server. It will dramatically shorten your development cycle if you do. Start it by running the “server” command. If it is successful, you will see output similar to the following:

$ hugo server --verbose
INFO: 2014/09/29 Using config file: /Users/quoha/Sites/zafta/config.toml
INFO: 2014/09/29 syncing from /Users/quoha/Sites/zafta/static/ to /Users/quoha/Sites/zafta/public/
WARN: 2014/09/29 Unable to locate layout: [index.html _default/list.html _default/single.html]
WARN: 2014/09/29 Unable to locate layout: [404.html]
0 draft content
0 future content
0 pages created
0 tags created
0 categories created
in 2 ms
Serving pages from /Users/quoha/Sites/zafta/public
Web Server is available at http://localhost:1313
Press Ctrl+C to stop

Connect to the listed URL (it’s on the line that starts with “Web Server”). If everything is working correctly, you should get a page that shows the following:

index.xml
sitemap.xml

That’s a listing of your public/ directory. Hugo didn’t create a home page because our site has no content. When there’s no index.html file in a directory, the server lists the files in the directory, which is what you should see in your browser.

Let’s go back and look at those warnings again.

WARN: 2014/09/29 Unable to locate layout: [index.html _default/list.html _default/single.html]
WARN: 2014/09/29 Unable to locate layout: [404.html]

That second warning is easier to explain. We haven’t created a template to be used to generate “page not found errors.” The 404 message is a topic for a separate tutorial.

Now for the first warning. It is for the home page. You can tell because the first layout that it looked for was “index.html.” That’s only used by the home page.

I like that the verbose flag causes Hugo to list the files that it’s searching for. For the home page, they are index.html, _default/list.html, and _default/single.html. There are some rules that we’ll cover later that explain the names and paths. For now, just remember that Hugo couldn’t find a template for the home page and it told you so.

At this point, you’ve got a working installation and site that we can build upon. All that’s left is to add some content and a theme to display it.

Create a New Theme

Hugo doesn’t ship with a default theme. There are a few available (I counted a dozen when I first installed Hugo) and Hugo comes with a command to create new themes.

We’re going to create a new theme called “zafta.” Since the goal of this tutorial is to show you how to fill out the files to pull in your content, the theme will not contain any CSS. In other words, ugly but functional.

All themes have opinions on content and layout. For example, Zafta uses “post” over “blog”. Strong opinions make for simpler templates but differing opinions make it tougher to use themes. When you build a theme, consider using the terms that other themes do.

Create a Skeleton

Use the hugo “new” command to create the skeleton of a theme. This creates the directory structure and places empty files for you to fill out.

$ hugo new theme zafta

$ ls -l
total 8
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 archetypes
-rw-r--r--  1 quoha  staff   82 Sep 29 16:49 config.toml
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 content
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 layouts
drwxr-xr-x  4 quoha  staff  136 Sep 29 17:02 public
drwxr-xr-x  2 quoha  staff   68 Sep 29 16:49 static
drwxr-xr-x  3 quoha  staff  102 Sep 29 17:31 themes

$ find themes -type f | xargs ls -l
-rw-r--r--  1 quoha  staff  1081 Sep 29 17:31 themes/zafta/LICENSE.md
-rw-r--r--  1 quoha  staff     0 Sep 29 17:31 themes/zafta/archetypes/default.md
-rw-r--r--  1 quoha  staff     0 Sep 29 17:31 themes/zafta/layouts/_default/list.html
-rw-r--r--  1 quoha  staff     0 Sep 29 17:31 themes/zafta/layouts/_default/single.html
-rw-r--r--  1 quoha  staff     0 Sep 29 17:31 themes/zafta/layouts/index.html
-rw-r--r--  1 quoha  staff     0 Sep 29 17:31 themes/zafta/layouts/partials/footer.html
-rw-r--r--  1 quoha  staff     0 Sep 29 17:31 themes/zafta/layouts/partials/header.html
-rw-r--r--  1 quoha  staff    93 Sep 29 17:31 themes/zafta/theme.toml
$

The skeleton includes templates (the files ending in .html), license file, a description of your theme (the theme.toml file), and an empty archetype.

Please take a minute to fill out the theme.toml and LICENSE.md files. They’re optional, but if you’re going to be distributing your theme, it tells the world who to praise (or blame). It’s also nice to declare the license so that people will know how they can use the theme.

$ vi themes/zafta/theme.toml
author = "michael d henderson"
description = "a minimal working template"
license = "MIT"
name = "zafta"
source_repo = ""
tags = ["tags", "categories"]
:wq

## also edit themes/zafta/LICENSE.md and change
## the bit that says "YOUR_NAME_HERE"

Note that the the skeleton’s template files are empty. Don’t worry, we’ll be changing that shortly.

$ find themes/zafta -name '*.html' | xargs ls -l
-rw-r--r--  1 quoha  staff  0 Sep 29 17:31 themes/zafta/layouts/_default/list.html
-rw-r--r--  1 quoha  staff  0 Sep 29 17:31 themes/zafta/layouts/_default/single.html
-rw-r--r--  1 quoha  staff  0 Sep 29 17:31 themes/zafta/layouts/index.html
-rw-r--r--  1 quoha  staff  0 Sep 29 17:31 themes/zafta/layouts/partials/footer.html
-rw-r--r--  1 quoha  staff  0 Sep 29 17:31 themes/zafta/layouts/partials/header.html
$