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A Static File Server with options.

Project description

A Static File Server with options.


  • A dedicated static file server.

  • Emulates common behaviors of various popular servers (index files, extensionless files, index directories, etc.) See options for specifics.

  • Serves custom error pages.

  • Does not require the server root to be the current working directory.

  • build coverage status version format pyversions license


To install Rheostatic run the following command:

pip install rheostatic


Rheostatic is a pure Python library with no external dependencies. It should run without issue on CPython versions 3.6, 3.7, 3.8, and 3.9 as well as PyPy3.

Use as a Command Line Tool

From the root directory of your site, run the command rheostatic:

$ cd /var/www
$ rheostatic
Starting server at http://localhost:8000/...
Serving files from /var/www
Press ctrl+c to stop.

Alternatively, pass the root directory to the rheostatic command:

$ rheostatic path/to/root
Starting server at http://localhost:8000/...
Serving files from /absolute/path/to/root
Press ctrl+c to stop.

For detailed usage instructions and options, run rheostatic --help.

If the rheostatic command cannot be found, try running python -m rheostatic instead.

Use as a Python Library

For basic usage, import the rheostatic.serve function, which accepts any and all options as keywords:

from rheostatic import serve

serve(address=('', 80), root='/some/path', default_type='text/plain')

Note that address expects a tuple of the host and port. The host must be a string and the port an integer. All other keywords correspond to the available options.

Under the hood, the serve function creates an instance of the class rheostatic.base.Rheostatic and passes it to a simple wsgi server as a wsgi application. For lower level usage, an instance of the class may be created and passed to any wsgi server. When initializing the class, you may pass in any options as keywords:

from rheostatic.base import Rheostatic

app = Rheostatic(root='/some/path', index_file='README.html')

Rheostatic accepts keywords which correspond to any of the available options. All options are also stored as attributes on the class instance:

print app.root

Preparing your Files

Before running the server, you need some files to serve. All files must be in the root directory and its sub-directories. In fact, an error will occur if a file is requested outside of the root directory. The root directory can exist anywhere on your filesystem as long as Rheostatic has permission to read the files.

Ensure that all files are saved using the same encoding and that that encoding is being used by Rheostatic. See encoding for details.

A file’s ContentType is determined by its file extension. For best results, use common file extensions for your files. A list of known file extensions and the ContentType used for each can be found in rheostatic/

If you would like a file to be served when the client requests a directory (for example /, or /path/to/some/dir/), then that directory needs to contain an index file. Be sure to use the file name for the index file set by the index_file option. The default for most servers (including Rheostatic) is index.html.

If a directory does not contain an index file, then Rheostatic will return a directory listing of all the files in that directory (excluding files with names that start with a dot).

For custom error pages, include files in the “root” directory named <code>.html where <code> is the HTTP error code which the error page corresponds to. For example, a file named 404.html would be returned for 404 (Not Found) errors. Supported error codes include 404 (Not Found), and 405 (Method Not Allowed). If a custom error page is not found, then Rheostatic serves a simple plain-text error page.


Rheostatic currently supports the following options:


The local file system directory which the server should use as its “root” directory. Usually represented by / in the URL (for example When root is set to a relative path, the local filesystem path is resolved as an absolute path relative to the current working directory. Absolute paths are used as-is.


The name of the file returned when a directory is requested (a URL ending with a /). A file by that name must be present in the requested directory. Defaults to index.html.

For example, a request to / would return the file at /index.html without redirecting the client.


The ContentType returned for a file when the type is unknown. Defaults to application/octet-stream.


The encoding used to read and serve the files. Be sure all your files are saved using the same encoding. Defaults to utf-8.


An HTML template used to display a directory listing when no index file is available for the requested directory. Defaults to the string defined at utils.directory_template.


The extension to use for extensionless URLs. The requested URL must not end in an extension or a slash (/). This feature is disabled by default. To enable the feature, set the option to a string which contains both a dot and the desired extension. For example, with the option set to .html, a request to /foo would return the file /foo.html without redirecting the client.

Infrequently Asked Questions

Why Does this Exist?

The existing solutions have different goals and do not offer the specific set of features that I needed. While some libraries could be subclassed to alter the behavior, attempts to provide patches upstream always result in rejection as the libraries generally where intended to serve static support files (images, CSS files, JavaScript, etc), specifically to support dynamic content (cgi, wsgi, Django, etc.). However, I needed to serve a static site; specifically static HTML files along with their supporting media files (generated from a static site generator). I can’t trust that the existing solutions will continue to work, as their goals do not align with my needs.

On the other hand, other simple servers often don’t offer enough features to emulate a real server. Thus, Rheostatic was created to offer the flexibility and features to meet all of the needs of static site generators.

Why is it called “Rheostatic”?

I wanted something that accurately conveyed the purpose and function of the library/tool. Note that the similar word, “rheostat” comes from the Greek “rheos” (stream) and is defined as “[a]n electrical instrument used to control a current by varying the resistance.” Rheostatic doesn’t control current, but it does control a stream of static files served to a client, which can be varied by adjusting the settings. I also liked the name and it doesn’t appear to have been used by anyone else.

Could you add my pet feature?

Maybe. If the feature does not add support for dynamic content and it can be easily replicated by popular web servers, I may consider it. Naturally, if you do the work it’s more likely to get added, than if you wait for me to work on something I don’t care about and/or need.


Rheostatic is licensed under the MIT License as defined in LICENSE.

Change Log

Version 0.0.2 (2020-10-27)

  • Added support for text/cache-manifest content type.

  • Dropped support for Python versions less that 3.6.

Version 0.0.1 (2016-11-03)

The initial release.

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