Pre-compress your Pelican site using gzip, zopfli, and brotli!

Are you using Pelican, the static site generator? If so, great! Are you pre-compressing your static files to have the fastest site possible? If not, install pelican_precompress today! It's the plugin that makes your visitors happy and saves you money!

There are three steps required to start using static compression:

1. Install the plugin and any supporting Python packages you want.
2. Configure Pelican to use the pelican_precompress plugin.
3. Configure your web server to use static, pre-compressed files.

At minimum, you'll need to install the pelican_precompress plugin. It will automatically generate gzip files because gzip is built into the Python standard library.

However, if you want highly-optimized gzip files you'll need the zopfli module. And if you want to have the very best compression currently available, you'll need to install the brotli module (which will require extra work in step 3).

$ pip install pelican_precompress
$ pip install zopfli  # This produces smaller gzip'd files. Use it!
$ pip install brotli  # This requires extra work in step 3.

Further reading: zopfli, brotli

If you're using Pelican 4.5 or higher then you might not need to configure anything. pelican_precompress supports Pelican's namespace plugin architecture and will be automatically detected and loaded when Pelican runs.

However, if you're maintaining a list of plugins for Pelican to use (even in Pelican 4.5) then you'll need to add it to the list of active plugins.

Feel free to copy and paste the code below into your Pelican configuration file. Just uncomment and edit the configuration lines to your liking...or leave them alone because the defaults are awesome!

# Pelican 4.5 introduced automatic plugin discovery and loading.
# You only need to add pelican_precompress to your PLUGINS list
# if your configuration file already has a PLUGINS list!
#
# PLUGINS = ['pelican.plugins.precompress']

# These options can be customized as desired.
#
# PRECOMPRESS_GZIP = True or False
# PRECOMPRESS_ZOPFLI = True or False
# PRECOMPRESS_BROTLI = True or False
# PRECOMPRESS_OVERWRITE = False
# PRECOMPRESS_MIN_SIZE = 20
# PRECOMPRESS_TEXT_EXTENSIONS = {
#     '.atom',
#     '.css',
#     '.html',
#     '.but-the-default-extensions-are-pretty-comprehensive',
# }

Further reading: Pelican plugins

nginx supports gzip compression right out of the box. To enable it, add something like this to your nginx configuration file:

http {
    gzip_static on;
    gzip_vary on;
}

At the time of writing, nginx doesn't natively support brotli compression. To get it, you'll need to compile the static brotli module as an nginx dynamic module, or recompile nginx from scratch. When it's done you'll add something like this to your nginx configuration file:

load_module /usr/lib/nginx/modules/ngx_http_brotli_static_module.so;

http {
    brotli_static on;
}

Further reading: gzip_static, gzip_vary, nginx brotli module

There are a small number of configuration options available. You set them in your Pelican configuration file.

• PRECOMPRESS_GZIP (bool, default is True)

  This is always True unless you set this to False. For example, you might turn this off during development.

• PRECOMPRESS_ZOPFLI (bool, default is True if zopfli is installed)

  If the zopfli module is installed this will default to True. You might set this to False during development. Note that if you try to enable zopfli compression but the module isn't installed then nothing will happen.

• PRECOMPRESS_BROTLI (bool, default is True if brotli is installed)

  If the brotli module is installed this will default to True. You might set this to False during development. Like PRECOMPRESS_ZOPFLI, if you set this to True when the brotli module isn't installed then nothing will happen.

• PRECOMPRESS_OVERWRITE (bool, default is False)

  When pelican_precompress encounters an existing compressed file it will refuse to overwrite it. If you want the plugin to overwrite files you can set this to True.

• PRECOMPRESS_TEXT_EXTENSIONS (Set[str])

  This setting controls which file extensions will be pre-compressed.

  If you modify this setting in the Pelican configuration file it will completely replace the default extensions!

• PRECOMPRESS_MIN_SIZE (int, default is 20)

  Small files tend to result in a larger file size when compressed, and any improvement is likely to be marginal. The default setting is chosen to avoid speculatively compressing files that are likely to result in a larger file size after compression.

  To try compressing every file regardless of size, set this to 0.

If you'd like to develop and/or test the code yourself, clone the git repository and run these commands to set up a Python virtual environment, install dependencies, and run the test suite:

python -m venv .venv

# Activate the virtual environment (Linux)
source .venv/bin/activate

# Activate the virtual environment (Windows)
& .venv/Scripts/Activate.ps1

python -m pip install poetry pre-commit tox
pre-commit install
poetry install

# Run the test suite
tox

The test suite uses tox to setup multiple environments with varying dependencies using multiple Python interpreters; pytest allows the test suite to have parametrized tests; pyfakefs creates a fake filesystem that the tests safely create and erase files in; and coverage keeps track of which lines of code have been run.

pelican_precompress has 100% test coverage, but there may still be bugs. Please report any issues that you encounter.

Further reading: poetry, tox, venv, pytest, pyfakefs, coverage